There are two Conewago Creek systems in the Lower Susquehanna River Watershed. One drains the Gettysburg Basin west of the river, mostly in Adams and York Counties, then flows into the Susquehanna at the base of Conewago Falls. The other drains the Gettysburg Basin east of the river, flowing through Triassic redbeds of the Gettysburg Formation and York Haven Diabase before entering Conewago Falls near the south tip of Three Mile Island. Both Conewago Creeks flow through suburbia, farm, and forest. Both have their capacity to support aquatic life impaired and diminished by nutrient and sediment pollution.
This week, some of the many partners engaged in a long-term collaboration to restore the east shore’s Conewago Creek met to have a look at one of the prime indicators of overall stream habitat health—the fishes. Kristen Kyler of the Lower Susquehanna Initiative organized the effort. Portable backpack-mounted electrofishing units and nets were used by crews to capture, identify, and count the native and non-native fishes at sampling locations which have remained constant since prior to the numerous stream improvement projects which began more than ten years ago. Some of the present-day sample sites were first used following Hurricane Agnes in 1972 by Stambaugh and Denoncourt and pre-date any implementation of sediment and nutrient mitigation practices like cover crops, no-till farming, field terracing, stormwater control, nutrient management, wetland restoration, streambank fencing, renewed forested stream buffers, or modernized wastewater treatment plants. By comparing more recent surveys with this baseline data, it may be possible to discern trends in fish populations resulting not only from conservation practices, but from many other variables which may impact the Conewago Creek Warmwater Stream ecosystem in Dauphin, Lancaster, and Lebanon Counties.
So here they are. Enjoy these shocking fish photos.
Normandeau Associates, Inc. and Gomez and Sullivan. 2018. Muddy Run Pumped Storage Project Conowingo Eel Collection Facility FERC Project 2355. Prepared for Exelon.
Stambaugh, Jr., John W., and Robert P. Denoncourt. 1974. A Preliminary Report on the Conewago Creek Faunal Survey, Lancaster County, Pennsylvania. Proceedings of the Pennsylvania Academy of Sciences. 48: 55-60.
One can get a stiff neck looking up at the flurry of bird activity in the treetops at this time of year. Many of the Neotropical migrants favor rich forests as daytime resting sites after flying through the night. For others, these forests are a destination where they will nest and raise their young.
For the birds that arrive earlier in spring than the Neotropical migrants, the breeding season is well underway. The wet weather may be impacting the success of the early nests.
So long for now, if you’ll excuse me please, I have a sore neck to tend to.
In the event you found yourself missing the spectacle of the migration of Neotropical birds through the northeastern United States earlier this month, there is good news. Apparently the cool and wet weather has prolonged the spring flights which by now are normally slowing to a trickle. Take a look at this composite radar loop and see the masses of birds rising skyward as nightfall progresses from east to west during the past couple of hours.
Any of the birds presently moving through Texas could travel for another week or more to reach the Susquehanna region—so there’s still time to see the show. Let’s grab a camera or some binoculars and go have a look. It’s not too late.
The warm weather late last week and the several inches of rain that followed have left the farm fields of the lower Susquehanna valley a soggy muddy mess…waterlogged. Runoff has made its way down the tributaries to raise the waters of the river and fill up its banks.
Migrating gulls find it difficult to locate food when the Susquehanna becomes a silty turbid torrent. It’s not at all unusual to find hundreds of them enjoying a feast of earthworms in the agricultural uplands when conditions such as these exist. As you may have guessed, the birds alluded to are the familiar Ring-billed Gulls, the same species seen mooching french fries and other snacks in fast-food restaurant parking lots. They are by far the most common inland gull in eastern North America.
Ring-billed Gulls are notorious for loafing and feeding in flocks which seldom include other species of gulls. They are frequently the smallest gull found in their inland habitats, so it is understandable that they may avoid the company of the larger and often more aggressive species.
However, today I was reminded that one must be ever vigilant and check for other species among those flocks presumed to consist solely of Ring-billed Gulls, particularly during times when the river is so inhospitable to passing migrants.
It seems as though the birds have grown impatient for typical spring weather to arrive. The increase in hours of daylight has signaled them that breeding time is here. No further delays can be entertained. They’ve got a schedule to keep.
Thursday, March 29: Winds began blowing from the southwest, breaking a cold spell which had persisted since last week’s snowfall. Birds were on the move ahead of an approaching rainy cold front.
Friday, March 30: Temperatures reached 60 degrees at last. Birds were again moving north through the day, despite rain showers and a change in wind direction—from the northwest and cooler following the passage of the front in the late morning.
Saturday, March 31: It was cooler, but birds were still on the wing headed north.
Sunday, April 1: The morning was pleasant, but conditions became cooler and breezy in the afternoon. Migratory and resident birds began feeding ahead of another storm.
Monday, April 2: Snow fell again, overnight and through the morning—a couple of inches. Most of the snow had melted away by late afternoon.
“Fear is the darkroom where negatives are developed.”
I celebrate alone, entering my fortieth year of fame. Everyone knows me; they’ve all heard my name. The world won’t recognize Berwick, Salem, Peach Bottom, or the place near Springfield (not the one with the donut-eating man who drools when he sleeps on the job, the real one in Montgomery County, Pennsylvania). Oyster Creek, Beaver Valley, Hope Creek, and dozens of others won’t ring a bell, but they’ll recall me with emotion or story, and often with myth as well—I’m a Nuclear Star.
I’m the ultimate thriller, generating anxiety from day one. My worldwide debut was the stuff of legend; you saw me on the news. You remember all the dramatic tension, don’t you? Like all celebrities, I blew off a little steam, had a little gas, and then everyone waited, trying to figure out what was going to happen next. But I kept things under wraps, shrouded in a fog of mystery, not a sole eyewitness to the events in my inner sanctum. Confusion reigned. There was a sense of great danger and imminent catastrophe. There prevailed a sweaty uncertainty over the threat of disaster and invisible death.
Would I melt down?
Would I blow my top?
Those iconic and sinister towers, what kind of horrid poisons pour from them to burn the sky and land?
The world needed to know. People demanded information.
Well, I know your trust in me was eroded and you felt deceived by my agents. You saw it, how they withered in the spotlight of fame while trying to protect themselves and the new Nuclear Star. The uncertainty they caused motivated many of my neighbors to leave. Many more were pushed beyond rational skepticism about me to an enduring cynicism which persists to this day. Fortunately, a genuine, competent, straight-talking communicator arrived to allay everyone’s fears with frank and understandable explanations of the situation. Then, a visit by the President of the United States assuaged the trepidations of a frightened public and provided reassurance to those who left that it was safe to return.
I want everyone to know that I had plans for a long quiet career. Then, three months into it, a handler pressed my buttons the wrong way and I’ve been in the limelight ever since. I did melt down a bit, but thanks to a timely intervention, I didn’t drop through the floor. For the same reason, I didn’t go through the roof either. You need to know that I’m no bomb. I was built to last for the long haul, and I won’t go to pieces. Remember, I’m a Nuclear Star. Oh, and those really are just big fluffy white steam clouds coming out of those towers, nothing more. It’s true.
I’m really not so scary. There’s no scheming evil little man hiding in my shadow planning the demise of the planet. Only the flies sit around rubbing their tiny hands together as they contemplate their next move, and I’ll remind you that not even one of them was hurt here.
I’m a Nuclear Star; my legacy is secured. Come look at me and feel the awe. After all these years, I continue to make nervous those who see me in person. You’ll still see the crowds and cameras outside my gates from time to time, demanding to know what kind of devious scheme is being hatched inside. I remain a central figure, but typecast as the villain. Without fail, I’m presumed to be the deleterious factor when man or nature ails. It’s not the coal-choker down the river, or the dam wall next door. It’s not the smoldering trash cookers north and south, or the sludge on the fields. It’s not the junk mixed into the food, or the spraying willy-nilly. Nor is it the filth in the water, the lazy life, or the smog in the city. It’s not the cigarette in your mouth, the synthetics in your house, the hours in your car. It’s Three Mile Island. That’s what did it. I’m a Nuclear Star.
Oh, and by the way, the plant in Montgomery County is called Limerick, in case you were wondering.
Snow accumulations from yesterday’s storm amounted to approximately 12 inches in the vicinity of Conewago Falls, some areas of the lower Susquehanna valley receiving more.
American Robins were in the process of moving north through the region in abundance just prior to the arrival of our latest “nor’easter”. When the storm struck in the early morning hours yesterday, their flights were grounded. After sunrise this morning, hungry robins quickly seized the opportunity to feed using the only open ground available—the edges of cleared roadways, particularly where they pass through woodlots and agricultural lands. Other migrants use the same strategy, picking and probing the wet soils alongside quickly thawing pavement to search for morsels of sustenance.
You remember the signs of an early spring, don’t you? It was a mild, almost balmy, February. The earliest of the spring migrants such as robins and blackbirds were moving north through the Lower Susquehanna River Watershed. The snow had melted and ice on the river had passed. Everyone was outdoors once again. At last, winter was over and only the warmer months lie ahead…beginning with March.
Ah yes, March, the cold windy month of March. We remember February fondly, but this March has startled us out of our vernal daydreams to wrestle with the reality of the season. And if you’re anywhere near the Mid-Atlantic states on this first full day of spring, you know that a long winter’s nap and visions of sugar peas would be time better spent than a stroll outdoors. Presently it’s dusk, and the snow from the 4th “Nor’easter” in a month is a foot deep and still falling.
In honor of “The Spring That Was”, here then is a sampling of some of the migratory waterfowl that have found their way to the Lower Susquehanna River Watershed during March. Some are probably lingering and feeding for a while. All will move along to their breeding grounds within a couple of weeks, regardless of the weather.
Many are wont to say that they have no capacity for scientific pursuits, and having no capacity, they consequently have no love for them. I do not believe, that as a general thing, a love for science is necessarily innate in any man. It is the subject of cultivation and is therefore acquired. There are doubtless many, whose love for these and kindred pursuits is hereditary, through the mental biases and preoccupations of their progenitors, but in the masses of mankind it is quite otherwise. In this consists its redeeming qualities, for I do not think the truly scientific mind can either be an idle, a disorderly, or a very wicked one. There may be scientific men, who, forgetful of its teachings, are imperious and ambitious–who may have foregone their fealty to their country and their God, but as a general thing they are humble, social and law-abiding. If, therefore, there is a human being who desires to break off from old and evil associations, and form new and more virtuous ones, I would advise him to turn his attention to some scientific specialty, for the cultivation of a new affection, if there are no other and higher influences more accessible. In this pursuit he will, in time, be enabled to supplant the old and heartfelt affection. The occupation of his mind in the pursuit of scientific lore will wean him from vicious, trivial, and unmanly pursuits, and point out to him a way that is pleasant and instructive to walk in, which will ultimately lead to moral and intellectual usefulness. I wish I was accessible to them, and possessed the ability to impress this truth with sufficient emphasis upon the minds of the rising generation. This fact, that in all moral reformations, a love for the opposite of any besetting evil must be cultivated, before that evil can be surely eradicated, has been too much overlooked and too little valued in moral ethics. But true progress in this direction implies that, under all circumstances, men should “act in freedom according to reason.”
-Simon S. Rathvon
In the cellar of the North Museum on the campus of Franklin and Marshall College in Lancaster, Pennsylvania, is an assemblage of natural history specimens of great antiquity. The core of the collection has its origins in the endeavors of a group of mid-to-late nineteenth-century naturalists whose diligence provided a most thorough study of the plants and animals found within what was at the time America’s most productive farming county.
The members of the Linnaean Society of Lancaster City and County shared a passion for collecting, identifying, classifying, and documenting the flora and fauna of the region. Some members were formally educated and earned a living in the field of science, but the majority were in the process of self-education and balanced their natural history occupation with an unrelated means to provide financially for their families. The latter benefited greatly from their associations with the former, gaining expertise and knowledge while participating in the functions of the group.
On February 24, 1866, Simon S. Rathvon, the society’s Treasurer, read an essay in commemoration of the group’s fourth anniversary. Rathvon earned a living as a tailor, first in Marietta, a thriving river town at the time, then in Lancaster City. In 1840, Rathvon was elected into the Marietta Natural History Lyceum where, as a collections curator, he became associated with principals Judge John J. Libhart, an amateur ornithologist, and Samuel S. Haldeman, a geologist and soon to be widely-known malacologist. Haldeman, in 1842, upon noticing the new member’s interest in beetles and other insects, provided books, guidance, and inspiration, thus intensifying Rathvon’s study of entomology. Rathvon’s steadfast dedication eventually led to his numerous achievements in the field which included the publication of over 30 papers, many on the topic of agricultural entomology. Rathvon’s scientific understanding of insect identification and taxonomy was a foundation for his practical entomology, which moved beyond mere insect collection to focus upon the study of the life histories of insects, particularly the good and bad things they do. He then applied that knowledge to help growers solve pest problems, often stressing the value of beneficial species for maintaining a balance in nature. From 1869 through 1884, Rathvon edited and published Lancaster Farmer, a monthly (quarterly from 1874) agricultural journal in which he educated patrons with his articles on “economic entomology”. Rathvon continued earning a living in the tailor business, seemingly frustrated that his financially prudent advice on insect control in Lancaster Farmer failed to entice more would-be readers to part with the one dollar annual subscription fee. For many years, Rathvon crafted articles for local newspapers and wrote reports for the United States Department of Agriculture. In recognition of his achievements, Simon Rathvon received an honorary Ph.D. from Franklin and Marshall College in 1878.
In Rathvon’s anniversary essay, he details the origins of the Linnaean Society as a natural science committee within the “Lancaster Historical, Mechanical, and Horticultural Society” founded in 1853. The members of the committee, not finding sufficient support within the parent organization for their desired mission, “the cultivation and investigation of the natural history of Lancaster County…”, sought to form an independent natural history society. In February of 1862, the “Linnaean Society of Lancaster City and County” was founded to fulfill these ambitions.
Above all else, the written works by the members of the Linnaean Society and their predecessors have provided us with detailed accounts of the plants and animals found in Lancaster County, and in the lower Susquehanna River valley, using scientific binomial nomenclature, a genus and species name, as opposed to the variable folk and common names which, when used exclusively, often confuse or mislead readers. Consider the number of common names a species could have if just one was assigned by each of the languages of the world. Binomial nomenclature assigns one designation, a genus name and species name, in Latin, to each life-form (such as Homo sapiens for Humans), and it is adopted universally.
Rathvon would say of the naming of the Linnaean Society:
“…the name which the Society has adopted is in honorable commemoration of LINNAEUS, the great Swedish naturalist—one who may be justly regarded as a father in Natural Science. To him belongs the honor of having first promulgated the “binomial system of nomenclature,” a system that has done more to simplify the study of natural science than any light that has been brought to the subject by any man in any age.”
Carl Linnaeus lived from 1707 to 1778, and published his first edition of Systema Naturae in 1735.
The names of a number of the members and corresponding members on the Linnaean Society of Lancaster City and County’s rolls remain familiar. John P. McCaskey (educator) served as Corresponding Secretary. Doctor Abram P. Garber was a prominent Lancaster botanist and society member. Professor Samuel S. Haldeman (naturalist, geologist, and philologist), Professor J. L. LeConte (entomologist), Judge John J. Libhart, Professor Asa Gray (botanist), and the foremost legal egalitarian in the United States House of Representatives, the Honorable Thaddeus Stevens, were listed among the roster of corresponding members.
By the end of its fourth year, Rathvon enumerated the specimens in the collections of the society to exceed 32,000. These included all the species of mosses and plants known in the county, 200 bird specimens, an enormous insect collection with nearly 12,000 Coleoptera (Beetles), and more than 1,400 mollusk shells. The work of the society had already provided a thorough baseline of the flora and fauna of the lower Susquehanna River valley and Lancaster County.
Rathvon would continue as Treasurer and primary curator through the group’s first twenty-five years, their most active. By 1887, their library contained over 1,000 volumes, they possessed over 40,000 specimens, and more than 600 scientific papers had been read at their meetings.
Many of the society’s specimens were moved to the custody of Franklin and Marshall College following the group’s dissolution. In 1953, the collection found a home on the F&M campus at the newly constructed North Museum, named for benefactor Hugh M. North, where many of the specimens, particularly the birds, are on prominent display.
Among the mounted specimens in the North Museum collection is a Heath Hen, once a numerous coastal plain bird which was also of limited abundance in the Piedmont Province areas of southeast Pennsylvania prior to its rapid decline during the first half of the nineteenth century. In southern Lancaster County, the burned grasslands of the serpentine barrens in Fulton Township may have provided suitable Heath Hen habitat prior to the bird’s demise. Curiously, Judge John J. Libhart did not note the Heath Hen in his enumeration of the birds of Lancaster County in either 1844 or 1869, indicating it was seriously imperiled or may have already been extirpated.
The Heath Hen was extirpated from its entire Atlantic Coastal Plain mainland range by the mid-1860s. The last remaining population was restricted to Martha’s Vineyard where, for the first time, a conservation effort was initiated to try to save a species. After some promising rebounds, the Heath Hen’s recovery failed for a variety of reasons including: the population’s isolation on an island, severe winter storms, feral cat predation, and a flawed understanding of methods for conducting mosaic burns to maintain the bird’s scrub habitat and prevent large catastrophic fires. A large fire in 1906 reduced the island population to just 80 birds, then there was a strong rebound to an estimated 2,000 birds (800 counted) by April, 1916. One month later, a fire burned twenty percent of Martha’s Vineyard, striking while females were on the nest, and leaving mostly males as survivors. A downward spiral in numbers followed for another decade. Finally, from 1929 until his death in 1932, “Booming Ben”, the last Heath Hen, searched the island every spring for a mate that wasn’t there.
Based on life history and the morphology of specimens, the Heath Hen has long been considered to be a subspecies of the Greater Prairie Chicken (Tympanuchus cupido pinnatus), a bird of the tallgrass prairies. However, for more than a decade now, modern DNA analysis has kept taxonomists busy reclassifying and reworking the “tree of life”. For certain species, genetic discoveries often disqualify the long-trusted practice of determining a binomial name based on the visual appearance of specimens. Molecular study is making Linnaean classification more scientific, and is gradually untangling a web of names that man has been weaving for 200 years, often with scant evidence, in an effort to better understand the world around him. In the case of the Heath Hen, DNA research has thus far failed to conclusively determine its relationship to other species of prairie chickens. The lack of a sufficient pool of genetic material, particularly from mainland Heath Hens, reduces the ability of researchers to draw conclusions on this group of birds. There remains the possibility that the Heath Hen was genetically distinct from the Greater Prairie Chickens of the mid-western United States. This would be bad news for organizations studying the possibility of introducing the latter into the former’s historic range as a restoration program.
The last Carolina Parakeet (the only parrot species native to the eastern United States) died in captivity in the Cincinnati Zoo on February 21, 1918, one hundred years ago this past week. It was a species inhabiting primarily the lowland forests of the southeastern United States
In Lancaster County, Judge John J. Libhart wrote of the species in 1869, “…Carolina Parrot, Accidental; a flock seen near Manheim by Mr. G. W. Hensel.” Libhart did not mention the species in his earlier ornithological writings (1844). Therefore, the Hensel sighting probably occurred sometime between 1844 and 1869. The fate of a specimen reported to have been collected in the town of Willow Street sometime during the nineteenth century is unknown, the written details lack the date of its origin and other particulars that may clarify the authenticity of the sighting.
McKinley (1979) researched numerous historical sight records of Carolina Parakeets, but found no specimen from Lancaster County, or from Pennsylvania, New Jersey, Delaware, the District of Columbia, or Maryland to substantiate any of the reports in the Mid-Atlantic states. In the days prior to high-speed photography, verification and documentation of the presence of an animal species relied on what seems today to be a brutal and excessive method of nature study, killing. Lacking a specimen, the historical status of Carolina Parakeets in Pennsylvania, an area often considered to be within the bird’s former range, may be considered by many authorities to be hypothetical.
The Passenger Pigeon, too, has been extinct for more than a century. In Lancaster County, Judge John J. Libhart listed the Passenger Pigeon by the common name “Wild Pigeon” and wrote of the species in 1869, “Migratory; spring and autumn; feeds on grain, oak and beach, mostly on berries; stragglers sometimes remain and breed in the county.” There are numerous accounts of their precipitous decline both locally and throughout their former range, each illustrating the tragic loss of another portion of the North American natural legacy.
Martha, the last surviving Passenger Pigeon, died on September 1, 1914, in the Cincinnati Zoo. Ironically, the last Carolina Parakeet would die in the same enclosure just three-and-one-half years later. In the wild, the final three records of Passenger Pigeons were all of birds that were shot for taxidermy mounts in 1900, 1901, and 1902—an embarrassing human legacy.
By the early twentieth century, concerned citizens were beginning to realize the danger posed to many species of flora and fauna by man’s activities. In the eastern United States, the vast forests had been logged, the wetlands drained, and the streams and rivers dammed. Nearly all of the landscape had been altered in some way. Animals were harvested with little concern for the sustenance of their populations. Nearly unnoticed, the seemingly endless abundance and diversity of wildlife found in the early days of European colonization had dwindled critically.
The movement to conserve and protect threatened species from relentless persecution owes its start to the Linnaean taxonomists, the specimen collectors who gave uniformly recognizable names to nearly all of North America’s plants and animals. Significant too were John James Audubon and many others who used specimens as models to create accurate artwork which allowed scientists and citizens alike to learn to identify and name the living things they were seeing and, as time went by, not seeing.
Binomial nomenclature enabled the new conservationists to communicate accurately, reducing misunderstandings resulting from the use of many different names for one species or a shared name for multiple species. Discussions on the status of Columba migratorius (the binomial name for Passenger Pigeon in the nineteenth century) could occur without using the confusing local names for the Passenger Pigeon such as Wood Pigeon or, here in Pennsylvania, Wild Pigeon, a term which could describe any number of free-ranging pigeon or dove species. A binomial name, genus and species, makes the identity of a particular plant or animal, for lack of a more fitting term, specific.
Appreciation for the work completed by taxonomists who killed thousands of animals so each could be classified and assigned a name particular to its lineage is what finally motivated some to seek a cessation of the unchecked catastrophic killing of living things. It’s the paradox of late nineteenth-century conservation. The combined realization that a species is unique among other life-forms and that continuing to kill it for specimens, “style”, “sport”, or just an adrenaline thrill could eliminate it forever became an intolerable revelation. The blood would be on the hands of an audacious mankind, and it was unthinkable. Something had to be done. Unfortunately for the Passenger Pigeon, the Carolina Parakeet, and the Heath Hen, help came too late.
Greenburg, Joel. 2014. A Feathered River Across the Sky: The Passenger Pigeon’s Flight to Extinction. Bloomsbury Publishing. New York.
Libhart, John J. 1844. “Birds of Lancaster County”. I. Daniel Rupp’s History of Lancaster County. Gilbert Hills. Lancaster, PA.
Libhart, John J. 1869. “Ornithology”. J. I. Mombert’s An Authentic History of Lancaster County. J. E. Barr and Company. Lancaster, PA.
McKinley, Daniel. 1979. “History of the Carolina Parakeet in Pennsylvania, New Jersey, Delaware, Maryland, and the District of Columbia”. Maryland Birdlife. 35(1):1-10.
Palkovacs, Eric P.; Oppenheimer, Adam J.; Gladyshev, Eugene; Toepfer, John E.; Amato, George; Chase, Thomas; Caccone, Adalgesia. 2004. “Genetic Evaluation of a Proposed Introduction: The Case of the Greater Prairie Chicken and the Extinct Heath Hen”. Molecular Ecology. 13(7):1759-1769.
Rathvon, S. S. 1866. An Essay on the Origin of the Linnaean Society of Lancaster City and County, Its Objects and Progress. Pearsol and Geist. Lancaster, Pennsylvania.
Wheeler, Alfred G., Jr. and Miller, Gary L. 2006. “Simon Snyder Rathvon: Popularizer of Agricultural Entomology in Mid-19th Century America”. American Entomologist. 52(1):36-47.
Winpenny, Thomas R. 1990. “The Triumphs and Anguish of a Self-Made Man: 19th Century Naturalist S. S. Rathvon”. Pennsylvania History. 57(2):136-149.
At the moment there is a heavy snow falling, not an unusual occurrence for mid-February, nevertheless, it is a change in weather. Forty-eight hours ago we were in the midst of a steady rain and temperatures were in the sixties. The snow and ice had melted away and a touch of spring was in the air.
Anyone casually looking about while outdoors during these last several days may have noticed that birds are indeed beginning to migrate north in the lower Susquehanna valley. Killdeer, American Robins, Eastern Bluebirds, Red-winged Blackbirds, and Common Grackles are easily seen or heard in most of the area now.
Just hours ago, between nine o’clock this morning and one o’clock this afternoon, there was a spectacular flight of birds following the river north, their spring migration well underway. In the blue skies above Conewago Falls, a steady parade of Ring-billed Gulls was utilizing thermals and riding a tailwind from the south-southeast to cruise high overhead on a course toward their breeding range.
The swirling hoards of Ring-billed Gulls attracted other migrants to take advantage of the thermals and glide paths on the breeze. Right among them were 44 Herring Gulls, 3 Great Black-backed Gulls, 12 Tundra Swans (Cygnuscolumbianus), 10 Canada Geese, 3 Northern Pintails (Anas acuta), 6 Common Mergansers, 3 Red-tailed Hawks, a Red-shouldered Hawk, 6 Bald Eagles (non-adults), 8 Black Vultures, and 5 Turkey Vultures.
In the afternoon, the clouds closed in quickly, the flight ended, and by dusk more than an inch of snow was on the ground. Looks like spring to me.
Two days ago, widespread rain fell intermittently through the day and steadily into the night in the Susquehanna drainage basin. The temperature was sixty degrees, climbing out of a three-week-long spell of sub-freezing cold in a dramatic way. Above the ice-covered river, a very localized fog swirled in the southerly breezes.
By yesterday, the rain had ended as light snow and a stiff wind from the northwest brought sub-freezing air back to the region. Though less than an inch of rain fell during this event, much of it drained to waterways from frozen or saturated ground. Streams throughout the watershed are being pushed clear of ice as minor flooding lifts and breaks the solid sheets into floating chunks.
Today, as their high flows recede, the smaller creeks and runs are beginning to freeze once again. On larger streams, ice is still exiting with the cresting flows and entering the rising river.
The events of today provide a superb snapshot of how Conewago Falls, particularly the Diabase Pothole Rocks, became such a unique place, thousands of years in the making. Ice and flood events of varying intensity, duration, and composition have sculpted these geomorphologic features and contributed to the creation of the specialized plant and animal communities we find there. Their periodic occurrence is essential to maintaining the uncommon habitats in which these communities thrive.
Is this the same Conewago Falls I visited a week ago? Could it really be? Where are all the gulls, the herons, the tiny critters swimming in the potholes, and the leaping fish? Except for a Bald Eagle on a nearby perch, the falls seems inanimate.
Yes, a week of deep freeze has stifled the Susquehanna and much of Conewago Falls. A hike up into the area where the falls churns with great turbulence provided a view of some open water. And a flow of open water is found downstream of the York Haven Dam powerhouse discharge. All else is icing over and freezing solid. The flow of the river pinned beneath is already beginning to heave the flat sheets into piles of jagged ice which accumulate behind obstacles and shallows.
A steady stream of birds was on the move this morning over Conewago Falls. There were hundreds of Ring-billed Gulls, scores of Herring Gulls, and a few Great Black-backed Gulls to dominate the flight. Then too there were thirteen Mallards, Turkey Vultures and a Black Vulture, twenty or more American Robins, a half a dozen Bald Eagles (juvenile and immature birds), a couple of Red-winged Blackbirds, and, perhaps most unusual of all, a flock of a dozen Scoters (Melanitta species), a waterfowl typical of the Mid-Atlantic surf in winter. All of these birds were diligently following the river, and into a headwind no less.
“Hold on just a minute there, buster,” you may say, “I’ve looked at the migration count by dutifully clicking on the logo above and there is nothing but zeroes on the count sheet for today. The season totals have not changed since the previous count day!”
Ah-ha, my dedicated friend, correct you are. It seems that today’s bird flight was solely in one direction. And that direction was upriver, moving north into a north breeze, on a heading which conflicts with all logic for creatures that should still be headed south for winter. As a result, none of the birds observed today were counted on the “Autumn Migration Count”.
You might say, “Don’t you know that Winter Solstice was three days ago, so autumn and autumn migration is over.”
Okay, point well taken. I should therefore clarify that what we title as “Autumn Migration Count” is more accurately a census of birds, insects, and other creatures transiting from northerly latitudes to more favorable latitudes to the south for winter. This transit can begin as early as late June and extend into the first weeks of winter. While most of this movement is motivated by the reduced hours of daylight during the period, late season migrants are often responding to ice, bad weather, or lack of food to prompt a journey further south. Migration south in late December and January occurs even while the amount of daylight is increasing slightly in the days following the Winter Solstice.
So what of the birds seen flying north today? There was some snow cover that has melted away, and the ice that formed on the river a week ago is gone due to the milder than normal temperatures this week.
One may ask, “Were the birds seen today migrating north?”
Let’s look at the species seen moving upriver today a try to determine their motivation.
First, and perhaps most straight-forward, is the huge flight of gulls. Wintering gulls on the Susquehanna River near Conewago Falls tend to spend their nights in flocks on the water or on treeless islands and rocky outcrops in the river. Many hundreds, sometimes thousands, find such favorable sites along the fifteen mile stretch of river from Conewago Falls downstream to Lake Clarke and the Conejohela Flats at Washington Boro. Each morning most of these gulls venture out to suburbia, farmland, landfill, hydroelectric dams, and other sections of river in search of food. Gulls are very able fliers and easily cover dozens of miles outbound and inbound each day in search of food. Many of the gulls seen this morning were probably on their way to the Harrisburg metropolitan area to eat trash. Barring any extraordinary buildups of ice on this section of river, one would expect these gulls to remain and make these daily excursions to food sources through early spring.
Second, throughout the season Bald Eagles have been tallied on the migration count with caution. Flight altitude, behavior, plumage, and the reaction of the “local” eagles to these transients was carefully considered before counting an eagle as a migrant. They roam a lot, particularly when young, and range widely to feed. The movement of eagles up the river today was probably food related. A gathering of adult, juvenile, and immature Bald Eagles could be seen more than a half mile upstream from the migration count lookout. Those moving up the river seemed to assemble with the “locals” there throughout the morning. White-tailed Deities occasionally drown, particularly when there is thin or unstable ice on the river (as there was last week) and they attempt to tread upon it. Then, their bodies are often stranded among rocks, in trees, or on the crown of the dam. After such a mishap, their carcasses become meals for carrion-eaters in the falls. Such an unfortunate deity, or another source of food, may have been attracting the eagles in numbers today.
Next, Black and Turkey Vultures often roam widely in search of food. The small numbers seen headed up-river today would tend to mean very little when trying to determine if there is a trend or population shift. Again, food may have been luring them upriver from nearby roosts.
And finally, the scoters, Mallards, American Robins, and Red-winged Blackbirds may have been wandering as well. Toward mid-day, the wind speed picked up and the direction changed to the east. This raises the possibility that these and others of the birds seen today may sense a change in weather, and may seek to take flight from the inclement conditions. Prompted by the ocean breeze and in an attempt to avoid a storm, was there some movement away from the Atlantic Coastal Plain to the upper Piedmont today? Many species may make these types of reactive movements. Is it possible that some birds flee or avoid ever-changing storm tracks and alter there wintering locations based on jet streams, water currents, and other climatic conditions? Probably. These are interesting dynamics and something worthy of study outside the simpler methods of a migration count.
…And if it snows that stretch down south won’t ever stand the strain… –Jimmy Webb
The lower Susquehanna valley’s first snowfall of the season arrived yesterday. By this morning it measured just an inch in depth at Conewago Falls, more to the south and east, less to the west and north. By mid-morning a cold fresh to moderate breeze from the northwest was blowing through the falls and stirring up ripples on the river.
Gulls sailed high overhead on the wind, taking a speedy ride downriver toward Chesapeake Bay, the Atlantic coast, and countless fast-food restaurant parking lots where surviving winter weather is more of a sure thing. Nearly a thousand Ring-billed Gulls soared past the migration count lookout today. Thirteen Herring Gulls and four Great Black-backed Gulls were among them.
Other migrants today included a Mallard, twenty-nine American Black Ducks, two Bald Eagles, eleven Black Vultures, fifteen Turkey Vultures, five American Goldfinches, and fifteen Red-winged Blackbirds. The wintery weather seems to be prompting these late-season travelers to be on their way.
You know, today was like many other days at the falls. As I arrive, I have the habit of checking all the power line towers on both river shorelines to see what may be there awaiting discovery. More often than not, something interesting is perched on one or more of the structures…
Yes friends, while the birds migrated through high above, down below a coordinated effort was underway to replace some of the electric transmission cable that stretches across the Susquehanna River at Conewago Falls. As you’ll see, this project requires precise planning, preparation, and skill. And it was fascinating to watch!
A very light fog lifted quickly at sunrise. Afterward, there was a minor movement of migrants: forty-nine Ring-billed Gulls, a few Herring Gulls, a Red-shouldered Hawk following the river to the southeast, and small flocks totaling nine Cedar Waxwings and twenty-eight Red-winged Blackbirds.
In the Riparian Woodland, small mixed flocks of winter resident and year-round resident birds were actively feeding. They must build and maintain a layer of body fat to survive blustery cold nights and the possible lack of access to food during snowstorms. There’s no time to waste; nasty weather could bring fatal hardship to these birds soon.
It was a crisp clear morning with birdless blue skies. The migration has mostly drawn to a close; very little was seen despite a suitable northwest breeze to support a flight. There were no robins and no blackbirds. Not even a starling was seen today. The only highlights were a Bufflehead (Bucephala albeola) and a couple of Swamp Sparrows.
And now ladies and gentlemen, boys and girls, it’s time for a Thanksgiving Day culinary reminder from the local Conewago Falls Turkey…
Temperatures plummeted to well below freezing during the past two nights, but there was little sign of it in Conewago Falls this morning. The fast current in the rapids and swirling waters in flooded Pothole Rocks did not freeze. Ice coated the standing water in potholes only in those rocks lacking a favorable orientation to the sun for collecting solar heat during the day to conduct into the water during the cold nights.
On the shoreline, the cold snap has left its mark. Ice covers the still waters of the wetlands. Frost on exposed vegetation lasted until nearly noontime in shady areas. Insect activity is now grounded and out of sight. The leaves of the trees tumble and fall to cover the evidence of a lively summer.
The nocturnal bird flight is narrowing down to just a few species. White-throated Sparrows, a Swamp Sparrow (Melospiza georgiana), and Song Sparrows are still on the move. Though their numbers are not included in the migration count, hundreds of the latter are along the shoreline and in edge habitat around the falls right now. Song Sparrows are present year-round, migrate at night, and are not seen far from cover in daylight, so migratory movements are difficult to detect. It is certain that many, if not all of the Song Sparrows here today have migrated and arrived here recently. The breeding population from spring and summer has probably moved further south. And many of the birds here now may remain for the winter. Defining the moment of this dynamic, yet discrete, population change and logging it in a count would certainly require different methods.
Diurnal migration was foiled today by winds from southerly directions and moderating temperatures. The only highlight was an American Robin flight that extended into the morning for a couple of hours after daybreak and totaled over 800 birds. This flight was peppered with an occasional flock of blackbirds. Then too, there were the villains.
They’re dastardly, devious, selfish, opportunistic, and abundant. Today, they were the most numerous diurnal migrant. Their numbers made this one of the biggest migration days of the season, but they are not recorded on the count sheet. It’s no landmark day. They excite no one. For the most part, they are not recognized as migrants because of their nearly complete occupation of North America south of the taiga. If people build on it or alter it, these birds will be there. They’re everywhere people are. If the rotten attributes of man were wrapped up into one bird, an “anthropoavian”, this would be it.
Meet the European Starling (Sturnus vulgaris). Introduced into North America in 1890, the species has spread across the entire continent. It nests in cavities in buildings and in trees. Starlings are aggressive, particularly when nesting, and have had detrimental impacts on the populations of native cavity nesting birds, particularly Red-headed Woodpeckers, Purple Martins (Progne subis), and Eastern Bluebirds. They commonly terrorize these and other native species to evict them from their nest sites. European Starlings are one of the earlier of the scores of introduced plants and animals we have come to call invasive species.
Today, thousands of European Starlings were on the move, working their way down the river shoreline and raiding berries from the vines and trees of the Riparian Woodlands. My estimate is between three and five thousand migrated through during the morning. But don’t worry, thousands more will be around for the winter.
The NOAA National Weather Service radar images from last evening provided an indication that there may be a good fallout of birds at daybreak in the lower Susquehanna valley. The moon was bright, nearly full, and there was a gentle breeze from the north to move the nocturnal migrants along. The conditions were ideal.
The Riparian Woodlands at Conewago Falls were alive with migrants this morning. American Robins and White-throated Sparrows were joined by new arrivals for the season: Brown Creeper (Certhia americana), Ruby-crowned Kinglets (Regulus calendula), Golden-crowned Kinglets (Regulus satrapa), Dark-eyed Junco (Junco hyemalis), and Yellow-rumped Warbler (Setophaga coronata). These are the perching birds one would expect to have comprised the overnight flight. While the individuals that will remain may not yet be among them, these are the species we will see wintering in the Mid-Atlantic states. No trip to the tropics for these hardy passerines.
It was a placid morning on Conewago Falls with blue skies dotted every now and then by a small flock of migrating robins or blackbirds. The jumbled notes of a singing Winter Wren (Troglodytes hiemalis) in the Riparian Woodland softly mixed with the sounds of water spilling over the dam. The season’s first Wood Ducks (Aix sponsa), Blue-winged Teal (Spatula discors), Herring Gull (Larus argentatus), Horned Larks (Eremophila alpestris), and White-throated Sparrows (Zonotrichia albicollis) were seen.
There was a small ruckus when one of the adult Bald Eagles from a local pair spotted an Osprey passing through carrying a fish. This eagle’s effort to steal the Osprey’s catch was soon interrupted when an adult eagle from a second pair that has been lingering in the area joined the pursuit. Two eagles are certainly better than one when it’s time to hustle a skinny little Osprey, don’t you think?
But you see, this just won’t do. It’s a breach of eagle etiquette, don’t you know? Soon both pairs of adult eagles were engaged in a noisy dogfight. It was fussing and cackling and the four eagles going in every direction overhead. Things calmed down after about five minutes, then a staring match commenced on the crest of the dam with the two pairs of eagles, the “home team” and the “visiting team”, perched about 100 feet from each other. Soon the pair which seems to be visiting gave up and moved out of the falls for the remainder of the day. The Osprey, in the meantime, was able to slip away.
In recent weeks, the “home team” pair of Bald Eagles, seen regularly defending territory at Conewago Falls, has been hanging sticks and branched tree limbs on the cross members of the power line tower where they often perch. They seem only to collect and display these would-be nest materials when the “visiting team” pair is perched in the nearby tower just several hundred yards away…an attempt to intimidate by homesteading. It appears that with winter and breeding time approaching, territorial behavior is on the increase.
In the afternoon, a fresh breeze from the south sent ripples across the waters among the Pothole Rocks. The updraft on the south face of the diabase ridge on the east shore was like a highway for some migrating hawks, falcons, and vultures. Black Vultures (Coragyps atratus) and Turkey Vultures streamed off to the south headlong into the wind after leaving the ridge and crossing the river. A male and female Northern Harrier (Circus hudsonius), ten Red-tailed Hawks, two Red-shouldered Hawks (Buteo lineatus), six Sharp-shinned Hawks, and two Merlins crossed the river and continued along the diabase ridge on the west shore, accessing a strong updraft along its slope to propel their journey further to the southwest. Four high-flying Bald Eagles migrated through, each following the east river shore downstream and making little use of the ridge except to gain a little altitude while passing by.
Late in the afternoon, the local Bald Eagles were again airborne and cackling up a storm. This time they intercepted an eagle coming down the ridge toward the river and immediately forced the bird to climb if it intended to pass. It turned out to be the best sighting of the day, and these “home team” eagles found it first. It was a Golden Eagle (Aquila chrysaetos) in crisp juvenile plumage. On its first southward voyage, it seemed to linger after climbing high enough for the Bald Eagles to loose concern, then finally selected the ridge route and crossed the river to head off to the southwest.
The humid rainy remains of Hurricane Nate have long since passed by Pennsylvania, yet mild wet weather lingers to confuse one’s sense of the seasons. This gloomy misty day was less than spectacular for watching migrating birds and insects, but some did pass by. Many resident animals of the falls are availing themselves of the opportunity to continue active behavior before the cold winds of autumn and winter force a change of lifestyle.
Warm drizzle at daybreak prompted several Northern Spring Peepers (Pseudacris crucifer crucifer) to begin calling from the wetlands in the Riparian Woodlands of Conewago Falls. An enormous chorus of these calls normally begins with the first warm rains of early spring to usher in this tiny frog’s mating season. Today, it was just a few “peeps” among anxious friends.
Any additional river flow that resulted from the rains of the previous week is scarcely noticeable among the Pothole Rocks. The water level remains low, the water column is fairly clear, and the water temperatures are in the 60s Fahrenheit.
It’s no real surprise then to see aquatic turtles climbing onto the boulders in the falls to enjoy a little warmth, if not from the sun, then from the stored heat in the rocks. As usual, they’re quick to slide into the depths soon after sensing someone approaching or moving nearby. Seldom found anywhere but on the river, these skilled divers are Common Map Turtles (Graptemys geographica), also known as Northern Map Turtles. Their paddle-like feet are well adapted to swimming in strong current. They are benthic feeders, feasting upon a wide variety of invertebrates found among the stone and substrate of the river bottom.
Adult Common Map Turtles hibernate communally on the river bottom in a location protected from ice scour and turbulent flow, often using boulders, logs, or other structures as shelter from strong current. The oxygenation of waters tumbling through Conewago Falls may be critical to the survival of the turtles overwintering downstream. Dissolved oxygen in the water is absorbed by the nearly inactive turtles as they remain submerged at their hideout through the winter. Though Common Map Turtles, particularly males, may occasionally move about in their hibernation location, they are not seen coming to the surface to breathe.
The Common Map Turtles in the Susquehanna River basin are a population disconnected from that found in the main range of the species in the Great Lakes and upper Mississippi basin. Another isolated population exists in the Delaware River.
Committee on the Status of Endangered Wildlife in Canada. 2002. Status Report of the Northern Map Turtle. Canadian Wildlife Service. Ottawa, Ontario.
A moderate breeze from the south placed a headwind into the face of migrants trying to wing their way to winter quarters. The urge to reach their destination overwhelmed any inclination a bird or insect may have had to stay put and try again another day.
Blue Jays were joined by increasing numbers of American Robins crossing the river in small groups to continue their migratory voyages. Killdeer (Charadrius vociferous) and a handful of sandpipers headed down the river route. Other migrants today included a Cooper’s Hawk (Accipiter cooperii), Eastern Bluebirds (Sialia sialis), and a few Common Mergansers (Mergus merganser), House Finches (Haemorhous mexicanus), and Common Grackles (Quiscalus quiscula).
The afternoon belonged to the insects. The warm wind blew scores of Monarchs toward the north as they persistently flapped on a southwest heading. Many may have actually lost ground today. Painted Lady (Vanessa cardui) and Cloudless Sulphur butterflies were observed battling their way south as well. All three of the common migrating dragonflies were seen: Common Green Darner (Anax junius), Wandering Glider (Pantala flavescens), and Black Saddlebags (Tramea lacerata).
The warm weather and summer breeze are expected to continue as the rain and wind from Hurricane Nate, today striking coastal Alabama and Mississippi, progresses toward the Susquehanna River watershed during the coming forty-eight hours.
A fresh breeze from the north brought cooler air and a reminder that summer is gone and autumn has arrived.
Fast-moving dark clouds provided a perfect backdrop for viewing passing diurnal migrants. Bald Eagles utilized the tail wind to cruise down the Susquehanna toward Chesapeake Bay and points further south. A migrating Merlin began a chase from which a Northern Flicker narrowly escaped by finding shelter among Pothole Rocks and a few small trees. The season’s first American Black Duck (Anas rubripes), Common Loon (Gavia immer), Yellow-bellied Sapsucker (Sphyrapicus varia), and American Pipits (Anthus rubescens) moved through.
Blue Jays continued their hesitant crossings of the river at Conewago Falls. The majority completed the journey by forming groups of a dozen or more birds and following the lead of a lone American Robin, a Northern Flicker, or, odd as it appeared, a small warbler.
By far the most numerous migrants today were swallows. Thousands of Northern Rough-winged Swallows and hundreds of Tree Swallows were on the wing in search of what was suddenly a sparse flying insect supply. To get out of the brisk wind, some of the more resourceful birds landed on the warm rocks. To satisfy their appetite, many were able to pick crawling arthropods from the surface of the boulders. They swallow them whole.
The Neotropical birds that raised their young in Canada and in the northern United States have now logged many miles on their journey to warmer climates for the coming winter. As their density decreases among the masses of migrating birds, a shift to species with a tolerance for the cooler winter weather of the temperate regions will be evident.
Though it is unusually warm for this late in September, the movement of diurnal migrants continues. This morning at Conewago Falls, five Broad-winged Hawks (Buteo platypterus) lifted from the forested hills to the east, then crossed the river to continue a excursion to the southwest which will eventually lead them and thousands of others that passed through Pennsylvania this week to wintering habitat in South America. Broad-winged Hawks often gather in large migrating groups which swarm in the rising air of thermal updrafts, then, after gaining substantial altitude, glide away to continue their trip. These ever-growing assemblages from all over eastern North America funnel into coastal Texas where they make a turn to south around the Gulf of Mexico, then continue on toward the tropics. In the coming weeks, a migration count at Corpus Christi in Texas could tally 100,000 or more Broad-winged Hawks in a single day as a large portion of the continental population passes by. You can track their movement and that of other diurnal raptors as recorded at sites located all over North America by visiting hawkcount.org on the internet. Check it out. You’ll be glad you did.
Nearly all of the other migrants seen today have a much shorter flight ahead of them. Red-bellied Woodpeckers (Melanerpes carolinus), Red-headed Woodpeckers (Melanerpes erythrocephalus), and Northern Flickers (Colaptes auratus) were on the move. Migrating American Robins (Turdus migratorius) crossed the river early in the day, possibly leftovers from an overnight flight of this primarily nocturnal migrant. The season’s first Great Black-backed Gulls (Larus marinus) arrived. American Goldfinches are easily detected by their calls as they pass overhead. Look carefully at the goldfinches visiting your feeder, the birds of summer are probably gone and are being replaced by migrants currently passing through.
By far, the most conspicuous migrant today was the Blue Jay. Hundreds were seen as they filtered out of the hardwood forests of the diabase ridge to cautiously cross the river and continue to the southwest. Groups of five to fifty birds would noisily congregate in trees along the river’s edge, then begin flying across the falls. Many wary jays abandoned their small crossing parties and turned back. Soon, they would try the trip again in a larger flock.
A look at this morning’s count reveals few Neotropical migrants. With the exception of the Broad-winged Hawks and warblers, the migratory species seen today will winter in a sub-tropical temperate climate, primarily in the southern United States, but often as far north as the lower Susquehanna River valley. The individual birds observed today will mostly continue to a winter home a bit further south. Those that will winter in the area of Conewago Falls will arrive in October and later.
The long-distance migrating insect so beloved among butterfly enthusiasts shows signs of improving numbers. Today, more than two dozen Monarchs were seen crossing the falls and slowly flapping and gliding their way to Mexico.
They get a touch of it here, and a sparkle or two there. Maybe, for a couple of hours each day, the glorious life-giving glow of the sun finds an opening in the canopy to warm and nourish their leaves, then the rays of light creep away across the forest floor, and it’s shade for the remainder of the day.
The flowering plants which thrive in the understory of the Riparian Woodlands often escape much notice. They gather only a fraction of the daylight collected by species growing in full exposure to the sun. Yet, by season’s end, many produce showy flowers or nourishing fruits of great import to wildlife. While light may be sparingly rationed through the leaves of the tall trees overhead, moisture is nearly always assured in the damp soils of the riverside forest. For these plants, growth is slow, but continuous. And now, it’s show time.
So let’s take a late-summer stroll through the Riparian Woodlands of Conewago Falls, minus the face full of cobwebs, and have a look at some of the strikingly beautiful plants found living in the shadows.
Long, David; Ballentine, Noel H.; and Marks, James G., Jr. 1997. Treatment of Poison Ivy/Oak Allergic Contact Dermatitis With an Extract of Jewelweed. American Journal of Contact Dermatitis. 8(3): pp. 150-153.
Newcomb, Lawrence. 1977. Newcomb’s Wildflower Guide. Little, Brown and Company. Boston, Massachusetts.
A few nocturnal migrants flew through the moonlit night to arrive at Conewago Falls for a sunrise showing this morning. A dozen warblers were in the treetops and a Wood Thrush (Hylocichla mustelina) chattered away in the understory of the Riparian Woodlands. Three species of shorebirds were in the falls and on the Pothole Rocks: Least Sandpiper (Calidris minutilla), Lesser Yellowlegs (Tringa flavipes), and Greater Yellowlegs (Tringa melanoleuca).
The diurnal migration was highlighted by a Merlin (Falco columbarius), an Osprey, and a Bald Eagle, each flying down the river. Most of the other birds in the falls seemed content to linger and feed. There’s no need to hurry folks, only trouble lurks down there in paradise at the moment.
A couple of inches of rain this week caused a small increase in the flow of the river, just a burp, nothing major. This higher water coincided with some breezy days that kicked up some chop on the open waters of the Susquehanna upstream of Conewago Falls. Apparently it was just enough turbulence to uproot some aquatic plants and send them floating into the falls.
Piled against and upon the upstream side of many of the Pothole Rocks were thousands of two to three feet-long flat ribbon-like opaque green leaves of Tapegrass, also called Wild Celery, but better known as American Eelgrass (Vallisneria americana). Some leaves were still attached to a short set of clustered roots. It appears that most of the plants broke free from creeping rootstock along the edge of one of this species’ spreading masses which happened to thrive during the second half of the summer. You’ll recall that persistent high water through much of the growing season kept aquatic plants beneath a blanket of muddy current. The American Eelgrass colonies from which these specimens originated must have grown vigorously during the favorable conditions in the month of August. A few plants bore the long thread-like pistillate flower stems with a fruit cluster still intact. During the recent few weeks, there have been mats of American Eelgrass visible, the tops of their leaves floating on the shallow river surface, near the east and west shorelines of the Susquehanna where it begins its pass through the Gettysburg Basin near the Pennsylvania Turnpike bridge at Highspire. This location is a probable source of the plants found in the falls today.
The cool breeze from the north was a perfect fit for today’s migration count. Nocturnal migrants settling down for the day in the Riparian Woodlands at sunrise included more than a dozen warblers and some Gray Catbirds (Dumetella carolinensis). Diurnal migration was underway shortly thereafter.
Four Bald Eagles were counted as migrants this morning. Based on plumage, two were first-year eagles (Juvenile) seen up high and flying the river downstream, one was a second-year bird (Basic I) with a jagged-looking wing molt, and a third was probably a fourth year (Basic III) eagle looking much like an adult with the exception of a black terminal band on the tail. These birds were the only ones which could safely be differentiated from the seven or more Bald Eagles of varying ages found within the past few weeks to be lingering at Conewago Falls. There were as many as a dozen eagles which appeared to be moving through the falls area that may have been migrating, but the four counted were the only ones readily separable from the locals.
Red-tailed Hawks (Buteo jamaicensis) were observed riding the wind to journey not on a course following the river, but flying across it and riding the updraft on the York Haven Diabase ridge from northeast to southwest.
Bank Swallows (Riparia riparia) seem to have moved on. None were discovered among the swarms of other species today.
Ruby-throated Hummingbirds, Caspian Terns, Cedar Waxwings (Bombycilla cedrorum), and Chimney Swifts (Chaetura pelagica) were migrating today, as were Monarch butterflies.
Not migrating, but always fun to have around, all four wise guys were here today. I’m referring to the four members of the Corvid family regularly found in the Mid-Atlantic states: Blue Jay (Cyanocitta cristata), American Crow (Corvus brachyrhynchos), Fish Crow (Corvus ossifragus), and Common Raven (Corvus corax).
Klots, Elsie B. 1966. The New Field Book of Freshwater Life. G. P. Putnam’s Sons. New York, NY.
We all know that birds (and many other animals) migrate. It’s a survival phenomenon which, above all, allows them to utilize their mobility to translocate to a climate which provides an advantage for obtaining food, enduring seasonal weather, and raising offspring.
In the northern hemisphere, most migratory birds fly north in the spring to latitudes with progressively greater hours of daylight to breed, nest, and provide for their young. In the southern hemisphere there are similar movements, these to the south during their spring (our autumn). The goal is the same, procreation, though the landmass offering sustenance for species other than seabirds is limited “down under”. Interestingly, there are some seabirds that breed in the southern hemisphere during our winter and spend our summer (their winter) feeding on the abundant food sources of the northern oceans.
Each autumn, migratory breeding birds leave their nesting grounds as the hours of sunlight slowly recede with each passing day. They fly to lower latitudes where the nights aren’t so long and the climate is less brutal. There, they pass their winter season.
Food supply, weather, the start/finish of the nesting cycle, and other factors motivate some birds to begin their spring and autumn journeys. But overall, the hours of daylight and the angle of the sun prompt most species to get going.
But what happens after birds begin their trips to favorable habitats? Do they follow true north and south routes? Do they fly continuously, day and night? Do they ease their way from point to point, stopping to feed along the way? Do they all migrate in flocks? Well, the tactics of migration differ widely from bird species to species, from population to population, and sometimes from individual to individual. The variables encountered when examining the dynamics of bird migration are seemingly endless, but fascinatingly so. Bird migration is well-studied, but most of its intricacies and details remain a mystery.
Consider for a moment that just 10,000 years ago, an Ice Age was coming to an end, with the southernmost edge of the most recent glaciers already withdrawn into present-day Canada from points as near as the upper Susquehanna River watershed. Back then, the birds migrating to the lower portion of the drainage basin each spring probably weren’t forest-dwelling tropical warblers, orioles, and other songbirds. The migratory birds that nested in the lower Susquehanna River valley tens of millennia ago were probably those species found nesting today in taiga and tundra much closer to the Arctic Circle. And the ancestors of most of the tropical migrants that nest here now surely spent their entire lives much closer to the Equator, finding no advantage by journeying to the frigid Susquehanna valley to nest. It’s safe to say that since those times, and probably prior to them, migration patterns have been in a state of flux.
During the intervening years since the great ice sheets, birds have been able to adapt to the shifts in their environment on a gradual basis, often using their unmatched mobility to exploit new opportunities. Migration patterns change slowly, but continuously, resulting in differences that can be substantial over time. If the natural transformations of habitat and climate have kept bird migration evolving, then man’s impact on the planet shows great potential to expedite future changes, for better or worse.
Now, let’s look at two different bird migration strategies, that of day-fliers or diurnal migrants, and that of night-fliers, the nocturnal migrants.
Diurnal migrants are the most familiar to people who notice birds on the move. The majority of these species have one thing in common, some form of defense to lessen the threat of becoming the victim of a predator while flying in daylight. Of course the vultures, hawks, and eagles fly during the day. Swallows and swifts employ speed and agility on the wing to avoid becoming prey, as do hummingbirds. Finches have an undulating flight, never flying on a horizontal plane, which makes their capture more difficult. Other songbirds seen migrating by day, Red-winged Blackbirds for example, congregate into flocks soon after breeding season to avoid being alone. Defense flocks change shape constantly as birds position themselves toward the center and away from the vulnerable fringes of the swarm. The larger the flock, the safer the individual. For a lone bird, large size can be a form of protection against all but the biggest of predators. Among the more unusual defenses is that of birds like Indigo Buntings and other tropical migrants that fly across the Gulf of Mexico each autumn (often completing a portion of the flight during the day), risking exhaustion at sea to avoid the daylight hazards, including numerous predators, found in the coastal and arid lands of south Texas. Above all, diurnal migrants capture our attention and provide a spectacle which fascinates us. Perhaps diurnal migrants attract our favor because we can just stand or sit somewhere and watch them go by. We can see, identify, and even count them. It’s fantastic.
What about a bird like the Canada Goose (Branta canadensis)? It is often seen migrating in flocks during the day (the truly migratory ones flying much higher than the local year-round resident “transplants”), but then, during the big peak movements of spring and fall, they can be heard overhead all through the night. Perhaps the Canada Goose and related waterfowl bridge the gap between day and night, introducing us to the secretive starlight and moonshine commuters, the nocturnal migrants.
The skies are sometimes filled with thousands of them, mostly small perching birds and waders. These strangers in the night fly inconspicuously in small groups or individually, and most can be detected when passing above us only when heard making short calls to remain in contact with their travel partners. They need not worry about predators, but instead must have a method of finding their way. Many, like the Indigo Bunting, can navigate by the stars, a capability which certainly required many generations to refine. The nocturnal migrants begin moving just after darkness falls and ascend without delay to establish a safe flight path void of obstacles (though lights and tall structures can create a deadly counter to this tactic). Often, the only clue we have that a big overnight flight has occurred is the sudden appearance of new bird species or individuals, on occasion in great numbers, in a place where we observe regularly. Just days ago, the arrival of various warbler species at Conewago Falls indicated that there was at least a small to moderate movement of these birds during previous nights.
In recent years, the availability of National Weather Service radar has brought the capability to observe nocturnal migrants into easy reach. Through the night, you can log on to your local National Oceanic and Atmospheric Administration’s National Weather Service radar page (State College for the Conewago Falls area) and watch on the map as the masses of migrating bird pass through the sweep of the radar beam. As they lift off just after nightfall, rising birds will create an echo as they enter the sweeping beam close to the radar site. Then, due to the incline of the transmitted signal and the curvature of the earth, migrants will be displayed as an expanding donut-like ring around the radar’s map location as returns from climbing birds are received from progressively higher altitudes at increasing distances from the center of the site’s coverage area. On a night with a local or regional flight, several radar locations may show signs of birds in the air. On nights with a widespread flight, an exodus of sorts, the entire eastern half of the United States may display birds around the sites. You’ll find the terrain in the east allows it to be well-covered while radars in the west are less effective due to the large mountains. At daybreak, the donut-shaped displays around each radar site location on the map contract as birds descend out of the transmitted beam and are no longer detected.
Weather systems sometimes seem to motivate some flights and stifle others. The first example seen below is a northbound spring exodus, the majority of which is probably migrants from the tropics, the Neotropical migrants, including our two dozen species of warblers. A cold front passing into the northeastern United States appears to have stifled any flight behind it, while favorable winds from the southwest are motivating a heavy concentration ahead of the front.
The second and third examples seen below are an autumn nocturnal migration movement, probably composed of many of the same tropics-bound species which were on the way north in the previous example. Note that during autumn, the cold front seems to motivate the flight following its passage. Ahead of the front, there is a reduced and, in places, undetectable volume of birds. The two images below are separated by about 42 hours.
You can easily learn much more about birds (and insects and bats) on radar, including both diurnal and nocturnal migrants, by visiting the Clemson University Radar Ornithology Laboratory (CUROL) website. There you’ll find information on using the various mode settings on NEXRAD (Next-Generation Radar) to differentiate between birds, other flying animals, and inanimate airborne or grounded objects. It’s superbly done and you’ll be glad you gave it a try.
Clemson University Radar Ornithology Laboratory (CUROL) website: http://virtual.clemson.edu/groups/birdrad/ as accessed September 6, 2017.
A Baltimore Oriole (Icterus galbula) glowed in the first sunlight of the day as it began illuminating the treetops. I’m not certain of the cause, but I often have the urge to dig into a bowl of orange sherbet after seeing one these magnificent blackbirds. That’s right, in the Americas, orioles and blackbirds are members of the same family, Icteridae. Look at blackbirds more carefully, you might see the resemblance.
Sunshine at dawn and migrating warblers were again active in the foliage. Eight species were identified today. Off to the tropics they go. To the land of palm and citrus, yes citrus…limes, lemons, grapefruits, and oranges.
The Ruby-throated Hummingbirds (Archilochus colubris) are on the way toward the gulf states, then on to Central and South America. Five dashed by the rocky lookout in the falls this morning. Remember, keep your feeders clean, wash and rinse all the parts, and refill them with a fresh batch of “nectar”, four or five parts water to one part sugar. Repeating this process daily during hot weather should keep contamination from overtaking your feeder. It’s not a bad idea to rotate two feeders. Have one cleaned, rinsed, and air drying while the second is filled and in use at your feeding station, then just swap them around. Your equipment will be just as clean as it is at the sanitary dairy…you know, where they make sherbet.
The first of the season Caspian Terns (Hydroprogne caspia), giant freshwater versions of the terns you see at the seashore, passed through the falls late this morning. Their bills are blood-red, not orange like the more familiar terns on the coast. They’re stunning.
Ring-billed Gulls (Larus delawarensis) have been at the falls for several weeks. Total numbers and the composition of the age groups in the flock change over the days, so birds appear to be trickling through and are then replaced by others coming south. The big push of southbound migrants for this and many other species that winter locally in the Mid-Atlantic region and in the southern United States is still more than a month away. There are still plenty more birds to come after the hours of daylight are reduced and the temperatures take a dip.
Some migrating butterflies were counted today. Cloudless Sulphurs, more of a vagrant than a migrant, and, of course, Monarchs. I’ll bet you know the Monarch, it’s black and orange. How can you miss them, colored orange.
That’s it, that’s all for now, I bid you adieu…I’m going to have a dip of orange sherbet, or two.
Rain from the remnants of Hurricane/Tropical Storm Harvey ended just after daybreak this morning. Locally, the precipitation was mostly absorbed into the soil. There was little runoff and no flooding. The river level at Conewago Falls is presently as low as it has been all summer. Among the pools and rapids of the Pothole Rocks, numbers of migrating birds are building.
Mist and a low cloud ceiling created poor visibility while trying to see early morning birds, but they’re here. The warblers are moving south and a small wave of them was filtering through the foliage on the edge of the Riparian Woodlands. One must bend backwards to have a look, and most could not be identified due to the poor lighting in the crowns of the trees where they were zipping about. Five species of warblers and two species of vireos were discerned.
There are increasing concentrations of swallows feeding on insects over the falls. Hundreds were here today, mostly Tree Swallows (Tachycineta bicolor). Bank Swallows (Stelgidopteryx riparia) numbered in the hundreds, far below the thousands, often 10,000, which staged here for migration and peaked during the first week of September annually during the 1980s and 1990s. Their numbers have been falling steadily. Loss of nesting locations in embankments near water may be impacting the entire population. A reduction in the abundance of late-summer flying insects here on the lower Susquehanna River may be cause for them to abandon this area as a migration staging point.
Clear weather in the coming nights and days may get the migrants up and flying in large numbers. For those species headed to the tropics for winter, the time to get moving has arrived.
When we look at birds, we are fascinated by the unique structure and appearance of their feathers. They set birds apart from all other life forms on the planet. Feathers enable most birds to achieve a feat long envied by humans…flight. Birds on the wing awaken a curiosity in man. They are generally the largest animals one will see in the air. People want to know the name of a bird they see flying by, and want to know more about it. The method and style of bird flight can aid an observer who attempts to determine which of the world’s 10,000 bird species he or she is studying. Body shape and bird sounds often tell us a lot about the birds we encounter. But most often, we rely on the unique colors, patterns, and shapes of the feathers, the plumage, to identify the bird we are seeing.
To birds, feathers are survival. They are lightweight and strong to support the mechanics of flight. Feathers are superb insulators against the elements, and provide additional buoyancy for birds spending time on the water. For most birds, feathers provide a coloration and a texture similar to their surroundings, enabling them to hide from predators or to stalk prey. In the case of some species, extravagant showy plumage is acquired, at least during the breeding season, and often only by males, as a way to attract a mate, intimidate rivals, defend a territory, or lure an intruder away from a nest site. Because they become worn and damaged, all feathers are periodically molted and replaced by fresh plumage.
The feathers worn by a young bird leaving the nest are called the juvenile plumage. Typically, this is followed by a molt into a basic (non-breeding) plumage. The oft times extravagant breeding feathers are the result of a molt into an alternate (breeding) plumage.
While making field observations, the species, subspecies, gender, age, and other vital statistics of a bird can often by discerned easily by noting the plumage. In the case of some other birds, diligence, experience, research, and an exceptionally good look and/or a photograph may be required to interpret these particulars. In still other instances, a trained expert with a specimen in the hand is the only method of learning the bird’s identity and background.
The age at which birds acquire adult breeding and non-breeding plumages varies by species. Many juvenile birds resemble adults in basic (non-breeding) plumage as soon as they leave the nest. For these birds, there is little difference between their juvenile plumage and the appearance of the feathers which follow the molt into their first basic (non-breeding) plumage. Bird species which sexually mature within their first year may acquire their first basic (non-breeding) plumage before arrival of their first winter, followed by an alternate (breeding) plumage by their first spring. This is particularly true for smaller short-lived birds. Other species, normally larger long-lived ones, may experience a sequence of molts through multiple basic (non-breeding) plumages over a period of years prior to resembling an adult. Some of these species, such as eagles, retain their juvenile plumage for as long as a year before extensive molting into a first basic (non-breeding) plumage begins. Still others, including many gulls, attain a first-winter (formative) plumage prior to molting into their first basic (non-breeding) set of feathers. Sexual maturity and initiation of an annual molt to alternate (breeding) plumage, if there is one, may take as long as three to five years for these bigger birds.
For nearly all species of birds, the molts which produce basic (non-breeding) plumage occur on at least an annual basis and include a total replacement of feathers. This process renews worn and missing plumes including the flight feathers of the wings and tail. Any molt to alternate (breeding) plumage often excludes the replacement of the feathers of the wings and tail. There are many exceptions to these generalities.
The Juvenile and non-breeding (basic) plumages of late-summer may seem drab and confusing, but learning them is a worthwhile endeavor. Consider that most of the birds coming south during the migration will be adorned in this fashion. The birds of North America are in their greatest numerical mass of the year right now, and nearly all are females, juveniles, other non-adults, or molting males. There are few males in breeding plumage among the autumn waves of migrants. In the coming months, there will be an abundance of opportunities to enjoy these marvels on wings, so getting to know the birds in non-breeding feathers is time well spent. Make haste and get ready. For our feathered friends, it’s autumn and they’re on their way south.
Dunne, Pete. 2006. Pete Dunne’s Essential Field Guide Companion. Houghton Mifflin Company. New York.
Hayman, Peter; John Marchant, and Tony Prater. 1986. Shorebirds, An Identification Guide to the Waders of the World. Houghton Mifflin Company. New York.
Kauman, Kenn. 1996. Lives of North American Birds. Houghton Mifflin Company. New York.
McCullough, Mark A. 1989. Molting Sequence and Aging Of Bald Eagles. The Wilson Bulletin. 101:1-10.
Let’s imagine that you spend your summer as a singer and you have to strut your stuff in a blue suit all day long just so the other guys know that you’re not going to tolerate any nonsense with either of your two gals. And…you’re responsible for feeding the adolescent kids while each of the girls begins a second family. Wouldn’t you be ready for a break by late August?
The boys must think so. They’re quiet now. This week was the end. They’ve done their duty. They protected their homes and got the youngsters out on their own. It’s time to eat, get out of the dress blues, and prepare to take a flight to warmer climates, maybe even the tropics…for a holiday of sorts.
The male Indigo Bunting (Passerina cyanea) has a busy schedule. Before arriving at Conewago Falls in early May, he has molted from the plainest of plain brown plumage and donned an iridescent set of feathers that glow a brilliant blue and purple in sunlight. He chooses a territory with plenty of shrubby and weedy growth along the edge of a woodland, and begins to sing and defend his parcel, often from a dead tree or other perch.
At Conewago Falls, the Indigo Bunting is a common breeding bird, finding the mosaic of electric transmission wire right-of-ways, railroads, and the Riverine Grasslands to be absolutely perfect habitat. The female, inconspicuous in her uniformly brown plumage, builds the nest, incubates the 3 to 4 eggs (11 to 14 days), and feeds the young in the nest (9 to 12 days). Being quite the showboats, some males will have more than one mate nesting in their territory. In addition to defending the nest(s), the male Indigo Bunting will sometimes feed the fledged young so that the female(s) can begin incubating a second brood. The summertime diet is mostly invertebrates, but seeds are also consumed.
By late August, the young of the year are mostly on their own. The male’s territorial urges, including the nearly non-stop singing, come to an end. Soon, his blue feathers are beginning to drop and a molt is underway into a brown plumage resembling that of the females and juveniles.
Indigo Buntings evacuate their breeding range in eastern North America to winter mostly south of the United States. These nocturnal travelers have been the subject of migration behavior studies. They are among a number of small bird species known to cross the Gulf of Mexico on their way south. Also, Indigo Buntings can navigate by the stars.
On the wintering grounds, Indigo Buntings are flocking birds. At this time of year, they consume more seeds as a component of their diet and are known to visit bird feeders.
By April, the blue suit is back, and the males and females are on the way north. Hope to see you then pal.
Dunne, Pete. 2006. Pete Dunne’s Essential Field Guide Companion. Houghton Mifflin Company. New York.
Kaufman, Kenn. 1996. Lives of North American Birds. Houghton Mifflin Company. New York.
Was there a better place to have a look at the dark side of the moon easing across the summer sun than from the Pothole Rocks at Conewago Falls? O.K., alright, so there must have been a venue or two with bigger crowds, grand emotions, prepared foods, and near darkness, but the pseudolunar landscape of the falls seemed like an ideal observation point for the great North American solar eclipse of 2017.
Being the only person on the entire falls had its advantages, not the least of which was the luxury of pointing the camera directly at the sun and clicking off a few shots without getting funny looks and scolding comments. Priceless solitude.
If you think it looks like the above photograph was taken in a house of mirrors, then you’re pretty sharp. You’ve got it figured out. After getting a bad case of welder’s burns on the first day of a job at a metal fabricating shop during my teen years, I learned the value of a four dollar piece of glass.
For those of you who prefer not to look at the sun, even with protection (I heard those S.P.F. 30 sunblock eye drops were a fraud…I hope you didn’t buy any.), here is the indirect viewing method as it happened today.
If you were to our south in the path of totality for this eclipse, you probably noted reactions by flora and fauna. Here, there was really not much to report. The leaves of Partridge Pea didn’t fold for the night, birds didn’t fly away to roost, and the chorus of evening and nighttime singing insects didn’t get cranked up. The only sensation was the reduced brightness of the sun, as if a really dark cloud was filtering the light without changing its color or eliminating shadows. And that was the great solar eclipse of 2017.
It’s tough being good-looking and liked by so many. You’ve got to watch out, because popularity makes you a target. Others get jealous and begin a crusade to have you neutralized and removed from the spotlight. They’ll start digging to find your little weaknesses and flaws, then they’ll exploit them to destroy your reputation. Next thing you know, people look at you as some kind of hideous scoundrel.
Today, bright afternoon sunshine and a profusion of blooming wildflowers coaxed butterflies into action. It was one of those days when you don’t know where to look first.
Purple Loosestrife (Lythrum salicaria) has a bad reputation. Not native to the Americas, this prolific seed producer began spreading aggressively into many wetlands following its introduction. It crowds out native plant species and can have a detrimental impact on other aquatic life. Stands of loosestrife in slow-moving waters can alter flows, trap sediment, and adversely modify the morphology of waterways. Expensive removal and biological control are often needed to protect critical habitat.
The dastardly Purple Loosestrife may have only two positive attributes. First, it’s a beautiful plant. And second, it’s popular; butterflies and other pollinators find it to be irresistible and go wild over the nectar.
Don’t you just adore the wonderful butterflies. Everybody does. Just don’t tell anyone that they’re pollinating those dirty filthy no-good Purple Loosestrife plants.
Brock, Jim P., and Kenn Kaufman. 2003. Butterflies of North America. Houghton Mifflin Company. New York.
Newcomb, Lawrence. 1977. Newcomb’s Wildflower Guide. Little, Brown and Company. Boston, Massachusetts.