LIFE IN THE LOWER SUSQUEHANNA RIVER WATERSHED
A Natural History of Conewago Falls—The Waters of Three Mile Island
To take advantage of this unusually mild late-winter day, observers arrived by the thousands to have a look at an even greater number of migratory birds gathered at the Pennsylvania Game Commission’s Middle Creek Wildlife Management Area. Here are some highlights…
As week-old snow and ice slowly disappears from the Lower Susquehanna River Watershed landscape, we ventured out to see what might be lurking in the dense clouds of fog that for more than two days now have accompanied a mid-winter warm spell.
If scenes of a January thaw begin to awaken your hopes and aspirations for all things spring, then you’ll appreciate this pair of closing photographs…
Colder temperatures and gusty northwest winds are prompting our largest migratory raptors to continue their southward movements. Here are some of the birds seen earlier today riding updrafts of air currents along one of the Lower Susquehanna River Watershed’s numerous ridges.
As winter begins clawing at the door, now is great time to visit a hawk watch near you to see these late-season specialties. Remember to dress in layers and to click the “Hawkwatcher’s Helper: Identifying Bald Eagles and other Diurnal Raptors” tab at the top of this page. Hawkwatcher’s Helper is your guide to regional hawk watching locations and raptor identification. Be sure to check it out. And remember, it’s cold on top of those ridges, so don’t forget your hat, your gloves, and your chap stick!
With nearly all of the Neotropical migrants including Broad-winged Hawks gone for the year, observers and counters at eastern hawk watches are busy tallying numbers of the more hardy species of diurnal raptors and other birds. The majority of species now coming through will spend the winter months in temperate and sub-tropical areas of the southern United States and Mexico.
Here is a quick look at the raptors seen this week at two regional counting stations: Kiptopeke Hawk Watch near Cape Charles, Virginia, and Second Mountain Hawk Watch at Fort Indiantown Gap, Pennsylvania.
During coming days, fewer and fewer of these birds will be counted at our local hawk watches. Soon, the larger raptors—Red-tailed Hawks, Red-shouldered Hawks, and Golden Eagles—will be thrilling observers. Cooler weather will bring several flights of these spectacular species. Why not plan a visit to a lookout near you? Click on the “Hawkwatcher’s Helper: Identifying Bald Eagles and other Diurnal Raptors” tab at the top of this page for site information and a photo guide to identification. See you at the hawk watch!
Looks like I’m gonna be in the doghouse again—this time by way of the hen house. But why should I care? Here we go.
A few weeks ago, back when eggs were still selling for less than five dollars a dozen, the Pennsylvania Department of Agriculture renewed calls for owners and caretakers of outdoor flocks of domestic poultry (backyard chickens) to keep their birds indoors to protect them from the spread of bird flu—specifically “Highly Pathogenic Avian Influenza” (H.P.A.I.). At least one story edited and broadcast by a Susquehanna valley news outlet gave the impression that “vultures and hawks” are responsible for the spread of avian flu in chickens. To see if recent history supports such a deduction, let’s have a look at the U.S.D.A.’s Animal and Plant Health Inspection Service’s 2022-2023 list of the detection of Highly Pathogenic Avian Influenza in birds affected in counties of the Lower Susquehanna River Watershed in Pennsylvania.
This listing includes date of detection, county of collection, type/species of bird, and number of birds affected. WOAH (World Organization for Animal Health) birds include backyard poultry, game birds raised for eventual release, domestic pet species, etc.
12/30/2022 Adams Black Vulture
12/15/2022 Lancaster Canada Goose
12/15/2022 Lebanon Black Vulture
12/15/2022 Adams Black Vulture (3)
11/8/2022 Cumberland Black Vulture (4)
11/4/2022 Dauphin WOAH Non-Poultry (130)
10/19/2022 Dauphin Captive Wild Rhea (4)
10/17/2022 Adams Commercial Turkey (15,100)
10/11/2022 Adams WOAH Poultry (2,800)
9/30/2022 Lancaster Mallard
9/30/2022 Lancaster Mallard
9/29/2022 Lancaster WOAH Non-Poultry (180)
9/29/2022 York Commercial Turkey (25,900)
8/24/2022 Dauphin Captive Wild Crane
7/15/2022 Lancaster Great Horned Owl
7/15/2022 York Bald Eagle
7/15/2022 Dauphin Bald Eagle
6/16/2022 Dauphin Black Vulture
6/16/2022 Dauphin Black Vulture (4)
5/31/2022 Lancaster Black Vulture (2)
5/31/2022 Lancaster Black Vulture
5/10/2022-Lncstr-Commercial Egg Layer (72,300)
4/29/2022-Lncstr-Commercial Duck (19,300)
4/27/2022-Lncstr-Commercial Broiler (18,100)
4/26/2022-Lncstr-Commercial Egg Layer (307,400)
4/22/2022-Lncstr-Commercial Broiler (50,300)
4/20/2022-Lncstr-Commercial Egg Layer (1,127,700)
4/20/2022-Lncstr-Commercial Egg Layer (879,400)
4/15/2022-Lncstr-Commercial Egg Layer (1,380,500)
In the Lower Susquehanna River Watershed, it’s pretty obvious that the outbreak of avian flu got its foothold inside some of the area’s big commercial poultry houses. Common sense tells us that hawks, vultures, and other birds didn’t migrate north into the Lower Susquehanna River Watershed carrying bird flu, then kick in the doors of the enclosed hen houses to infect the flocks of chickens therein. Anyone paying attention during these past three years knows that isolation and quarantine are practices more easily proposed than sustained. Human footprints are all over the introduction of this infection into these enormous flocks. Simply put, men don’t wipe their feet when no one is watching! The outbreak of bird flu in these large operations was brought under control quickly, but not until teams of state and federal experts arrived to assure proper sanitary and isolation practices were being implemented and used religiously to prevent contaminated equipment, clothing, vehicles, feed deliveries, and feet from transporting virus to unaffected facilities. Large poultry houses aren’t ideal enclosures with absolute capabilities for excluding or containing viruses and other pathogens. Exhaust systems often blow feathers and waste particulates into the air surrounding these sites and present the opportunity for flu to be transported by wind or service vehicles and other conveyances that pass through contaminated ground then move on to other sites—both commercial and non-commercial. Waste material and birds (both dead and alive) removed from commercial poultry buildings can spread contamination during transport and after deposition. The sheer volume of the potentially infected organic material involved in these large poultry operations makes absolute containment of an outbreak nearly impossible.
Looking at the timeline created by the list of U.S.D.A. detections, the opportunity for bird flu to leave the commercial poultry loop probably happened when wild birds gained access to stored or disposed waste and dead animals from an infected commercial poultry operation. For decades now, many poultry operations have dumped dead birds outside their buildings where they are consumed by carrion-eating mammals, crows, vultures, Bald Eagles, and Red-tailed Hawks. For these species, discarded livestock is one of the few remaining food sources in portions of the Lower Susquehanna River Watershed where high-intensity farming has eliminated other forms of sustenance. They will travel many miles and gather in unnatural concentrations to feast on these handouts—creating ideal circumstances for the spread of disease.
The sequence of events indicated by the U.S.D.A. list would lead us to infer that vultures and Bald Eagles were quick to find and consume dead birds infected with H5N1—either wild species such as waterfowl or more likely domestic poultry from commercial operations or from infectious backyard flocks that went undetected. As the report shows, Black Vultures in particular seem to be susceptible to morbidity. Their frequent occurrence as victims highlights the need to dispose of potentially infectious poultry carcasses properly—allowing no access for hungry wildlife including scavengers.
The positive test on a Great Horned Owl is an interesting case. While the owl may have consumed an infected wild bird such as a crow, there is the possibility that it consumed or contacted a mammalian scavenger that was carrying the virus. Aside from rodents and other small mammals, Great Horned Owls also prey upon Striped Skunks with some regularity. Most of the dead poultry from flu-infected commercial flocks was buried onsite in rows of above-ground mounds. Skunks sniff the ground for subterranean fare, digging up invertebrates and other food. Buried chickens at a flu disposal site would constitute a feast for these opportunistic foragers. A skunk would have no trouble at all finding at least a few edible scraps at such a site. Then a Great Horned Owl could easily seize and feed upon such a flu virus-contaminated skunk.
Before we proceed, the reader must understand the seldom-stated and never advertised mission of the Pennsylvania Department of Agriculture—to protect the state’s agriculture industry. That’s it; that’s the bottom line. Regulation and enforcement of matters under the purview of the agency have their roots in this goal. While they may also protect the public health, animal health, and other niceties, the underlying purpose of their existence in its current manifestation is to protect the agriculture industry(s) as a whole.
This is not a trait unique to the Pennsylvania Department of Agriculture. It is at the core of many other federal and state agencies as well. Following the publication of Upton Sinclair’s The Jungle in 1906, a novel decrying “wage slavery” in the meat packing industry, the federal government took action, not for the purpose of improving the working conditions for labor, but to address the unsanitary food-handling practices described in the book by creating an inspection program to restore consumer confidence in the commercially-processed meat supply so that the industry would not crumble.
Locally, few things make the dairy industry and the Pennsylvania Department of Agriculture more nervous than small producers selling “raw milk”. In the days before pasteurization and refrigeration, people were frequently sickened and some even died from drinking bacteria-contaminated “raw milk”. In Pennsylvania, the production and sale of dairy products including “raw milk” is closely regulated and requires a permit. Retention of a permit requires submitting to inspections and passing periodic herd and product testing. Despite the dangers, many consumers continue to buy “raw milk” from farms without permits. These sales are like a ticking time bomb. The bad publicity from an outbreak of food-borne illness traced back to a dairy product—even if it originated in an “outlaw” operation—could decimate sales throughout the industry. Because just one sloppy farm selling “raw milk” could instantly erode consumer confidence and cause an industry-wide collapse of the market resulting in a loss of millions of dollars in sales, it is a deeply concerning issue.
Enter the backyard chicken—a two-fold source of anxiety for the poultry industry and its regulators. Like unregulated meat and dairy products, eggs and meat from backyard poultry flocks are often marketed without being monitored for the pathogens responsible for the transmission of food-borne illness. From the viewpoint of the poultry industry, this situation poses a human health risk that in the event of an outbreak, could erode consumer confidence, not only in homegrown organic and free-range products, but in the commercial line of products as well. Consumers can be very reactive upon hearing news of an outbreak, recalling few details other than “the fowl is foul”— then refraining from buying poultry products. The second and currently most concerning source of trepidation among members of the poultry industry though is the threat of avian flu and other diseases being harbored in and transmitted via flocks of backyard birds.
The Green Revolution, the post-World War II initiative that integrated technology into agriculture to increase yields and assure an adequate food supply for the growing global population, brought changes to the way farmers raised poultry for market. Small-scale poultry husbandry slowly disappeared from many farms. Instead, commercial operations concentrated birds into progressively-larger indoor flocks to provide economy of scale. Over time, genetics and nutrition science have provided the American consumer with a line of readily available high-quality poultry products at an inexpensive price. Within these large-scale operations, poultry health is closely monitored. Though these enclosures may house hundreds of thousands of birds, the strategy during an outbreak of communicable disease is to contain an outbreak to the flock therein, writing it off so to speak to prevent the pathogens from finding their way into the remainder of the population in a geographic area, thus saving the industry at the expense of the contents of a single operation. Adherence to effective biosecurity practices can contain outbreaks in this way.
The renewed popularity of backyard poultry is a reversal of the decades-long trend towards reliance on ever-larger indoor operations for the production of birds and eggs. But backyard flocks may make less-than-ideal neighbors for commercial operations, particularly when birds are left to roam outdoors. Visitors to properties with roaming chickens, ducks, geese, and turkeys may pick up contamination on their shoes, clothing, tires, and equipment, then transmit the pathogenic material to flocks at other sites they visit without ever knowing it. Even the letter carrier can carry virus from a mud puddle on an infected farm to a grazing area on a previously unaffected one. Unlike commercial operations, hobby farms frequently buy, sell, and trade livestock and eggs without regard to disease transmission. The rate of infection in these operations is always something of a mystery. No state or county permits are required for keeping small numbers of poultry and outbreaks like avian flu are seldom reported by caretakers of flocks of home-raised birds, though their occurrence among them may be widespread. The potential for pathogens like avian flu virus circulating long-term among flocks of backyard poultry in close proximity to commercial houses is a real threat to the industry.
There are a variety of motivations for tending backyard poultry. While for some it is merely a form of pet keeping, others are more serious about the practice—raising and breeding exotic varieties for show and trade. Increasingly, backyard flocks are being established by people seeking to provide their own source of eggs or meat. For those with larger home operations, supplemental income is derived from selling their surplus poultry products. Many of these backyard enthusiasts are part of a movement founded on the belief that, in comparison to commercially reared birds, their poultry is raised under healthier and more humane conditions by roaming outdoors. Organic operators believe their eggs and meat are safer for consumption—produced without the use of chemicals. For the movement’s most dedicated “true believers”, the big poultry industry is the antagonist and homegrown fowl is the only hope. It’s similar to the perspective members of the “raw milk” movement have toward pasteurized milk. True believers are often willing to risk their health and well-being for the sake of the cause, so questioning the validity of their movement can render a skeptic persona non grata.
For the consumer, the question arises, “Are eggs and poultry from the small-scale operations better?”
While many health-conscious animal-friendly consumers would agree to support the small producer from the local farm ahead of big business, the reality of supplying food for the masses requires the economy of scale. The billions of people in the world can’t be fed using small-scale and/or organic growing methods. The Green Revolution has provided record-high yields by incorporating herbicides, insecticides, plastic, and genetic modification into agriculture. To protect livestock and improve productivity, enormous indoor operations are increasingly common. Current economics tell the story—organic production can’t keep up with demand, that’s why the prices for items labelled organic are so much higher.
To the consumer, buying poultry raised outdoors is an appealing option. Compared to livestock crowded into buildings, they feel good about choosing products from small operations where birds roam free and happy in the sunshine.
But is the quality really better? Some research indicates not. Salmonella outbreaks have been traced back to poultry meat sourced from small unregulated operations. Studies have found dioxins in eggs produced by hens left to forage outdoors. The common practice of burning trash can generate a quantity of ash sufficient to contaminate soils with dioxins, chemical compounds which persist in the environment and in the fatty tissue of animals for years. The presence of elevated levels of dioxins in eggs from outdoor grazing operations may pose a potential consumer confidence liability for the entire egg industry.
Birds raised or kept in an outdoor zoo or backyard poultry setting can be susceptible to viruses and other pathogens when wild birds including vultures and hawks become attracted to the captives’ food and water when it is placed in an accessible location. In addition, hunting and scavenging birds are opportunistic— attracted to potential food animals when they perceive vulnerability. Selective breeding under domestication has rendered food poultry fat, dumb, and too genetically impaired for survival in the wild. These weaknesses instantly arouse the curiosity of raptors and other predators whose function in the food web is to maintain a healthy population of animals at lower tiers of the food chain by selectively consuming the sickly and weak. In settings such as those created by high-intensity agriculture and urbanization, wild birds may find the potential food sources offered by outdoor zoos and backyard poultry irresistible. As a result they may perch, loaf, and linger around these locations—potentially exposing the captive birds to their droppings and transmission of bird flu and other diseases.
While outdoor poultry operations usually raise far fewer birds than their commercial counterparts, their animals are still kept in densities high enough to promote the rapid spread of microbiological diseases. Clusters of outdoor flocks can become a reservoir of pathogens with the capability of repeatedly circulating disease into populations of wild birds and even into commercial poultry operations—threatening the industry and food supply for millions of people. For this reason, state and federal agencies are encouraging operators to keep backyard poultry indoors—segregated from natural and anthropogenic disease vectors and conveyances that might otherwise visit and interact with the flock.
The hobby farmer, the homesteader, the pet keeper, and the consumer seldom realize what the modern farmer is coming to know—domestic livestock must be segregated from the sources of contamination and disease that occur outdoors. Adherence to this simple concept helps assure improved health for the animals and a safer food supply for consumers. In the future, outdoor production of domestic animals, particularly those used as a food supply, is likely to be classified as an outdated and antiquated form of animal husbandry.
If there are three things the world learned from the SARS CoV-2 (Covid-19) epidemic, it’s that 1) eating or handling bush meat can bring unwanted surprises, 2) dense populations of very mobile humans are ideal mediums for uncontrolled transmission of disease, and 3) quarantine is easier said than done.
If you think viruses are bad, you don’t even want to know about prions. Prions are a prime example of why now is a good time to begin housing domestic animals, including pets, indoors to segregate them from wildlife. And prions are a good example of why we really ought to think twice about relying on wild animals as a source of food. Prions may make us completely rethink the way we interact with animals of any kind—but we had better do our thinking fast because prions turn the brains of their victims into Swiss cheese.
Diseases caused by prions are rapidly progressing neurodegenerative disorders for which there is no cure. Prions are an abnormal isoform of a cellular glycoprotein. They are currently rare, but prions, because they are not living entities, possess the ability to begin accumulating in the environment. They not only remain in detritus left behind by the decaying carcasses of afflicted animals, but can also be shed in manure—entering soils and becoming more and more prevalent over time. Some are speculating that they could wind up being man’s downfall.
The Centers for Disease Control lists these human afflictions caused by prions…
The Centers for Disease Control lists these prion-caused ailments of other animals…
SOURCES
Schoeters, Greet, and Ron Hoogenboom. 2006. Contamination of Free-range Chicken Eggs with Dioxins and Dioxin-like Polychlorinated Biphenyls. Molecular Nutrition and Food Research. (10):908-14.
Szczepan, Mikolajczyk, Marek Pajurek, Malgorzata Warenik-Bany, and Sebastian Maszewski. 2021. Environmental Contamination of Free-range Hen with Dioxin. Journal of Veterinary Research. 65(2):225-229.
U.S.D.A. Animal and Plant Inspection Service. 2022 Confirmations of Highly Pathogenic Avian Influenza. aphis.usda.gov/aphis/ourfocus/animalhealth/animal-disease-information/avian/avian-influenza/hpai-2022/2022-hpai-commercial-backyard-flocks as accessed January 14, 2023.
U.S.D.A. Animal and Plant Inspection Service. 2022 Confirmations of Highly Pathogenic Avian Influenza. aphis.usda.gov/aphis/ourfocus/animalhealth/animal-disease-information/avian/avian-influenza/hpai-2022/2022-hpai-wild-birds as accessed January 14, 2023.
With colder temperatures arriving on gusty northwest winds, the next couple of days will be ideal for seeing migrating birds of prey along the ridges of the Lower Susquehanna River Watershed. It’s still peak time for movements of four of our largest species: Red-shouldered Hawk, Red-tailed Hawk, Bald Eagle, and Golden Eagle—so let’s grab our binoculars and have a look!
Be certain to click the “Hawkwatcher’s Helper” tab at the top of this page to select a lookout for observing and enjoying the passage of these spectacular late-season raptors. To improve your chances of seeing a Golden Eagle, visit a counting station in the Ridge and Valley Province, but do bundle up—it’s cold on those mountaintops.
Why would otherwise sensible people perch themselves atop a rocky outcrop on a Pennsylvania mountaintop for ten hours on a windy bone-numbing bitter cold and sometimes snowy November day? To watch migrating raptors of course.
November is the time when big hawks and eagles migrate through and into the lower Susquehanna valley. And big birds rely on big wind to create updrafts and an easy ride along the region’s many ridges. The most observable flights often accompany the arrival of cold air surging across the Appalachian Mountains from the northwest. These conditions can propel season-high numbers of several of the largest species of raptors past hawk-counting sites.
Earlier this week, two windy days followed the passage of a cold front to usher-in spectacular hawk and eagle flights at the the Waggoner’s Gap Hawk Watch station on Blue Mountain north of Carlisle, Pennsylvania. Steady 30 M.P.H. winds from the northwest on Monday, November 2, gusted to 50 M.P.H. at times. Early that morning, two Rough-legged Hawks, rarities at eastern hawk watches, were seen. They and two American Goshawks (Accipiter atricapillus) provided a preview of the memorable sightings to come. Two dozen Golden Eagles migrated past the lookout that day. Then on November 3, thirty Golden Eagles were tallied, despite west winds at speeds not exceeding half those of the day before.
Here are some of the late-season raptors seen by hardy observers at Waggoner’s Gap on Monday and Tuesday, November 2 & 3.
While visiting a hawk watch, one will certainly have the opportunity to see other birds too.
As a finale of sorts, near the close of the day on November 3, two Golden Eagles sailed past the north side of the Waggoner’s Gap lookout, one possessing what appeared to be a tracking transmitter on its back. An effort was commenced by the official count staff to report the sighting to the entity monitoring the bird—to track down the tracker, so to speak.
To see the count reports from Waggoner’s Gap and other hawk watches throughout North America, be certain to visit hawkcount.org
Nothing beats spending a day at a hawk watch lookout—except of course spending a day at a hawk watch lookout when the birds are parading through nonstop for hours on end.
Check out Waggoner’s Gap, a hawk count site located on the border of Cumberland and Perry Counties atop Blue Mountain just north of Carlisle, Pennsylvania. It is by far the Lower Susquehanna River Watershed’s best location for observing large numbers of migrating raptors during the October and November flights.
Waggoner’s Gap is a hardy birder’s paradise. During the latter portion of the season, excellent flights often occur on days that follow the passage of a cold front and have strong northwest winds. But be prepared, it can be brutal on those rocks during a gusty late-October or early-November day after the leaves fall—so dress appropriately.
To see the daily totals for the raptor count at Waggoner’s Gap Hawk Watch and other hawk watches in North America, and to learn more about each site, be sure to visit hawkcount.org
Early October is prime time for hawk watching, particularly if you want to have the chance to see the maximum variety of migratory species. In coming days, a few Broad-winged Hawks and Ospreys will still be trickling through while numbers of Sharp-shinned Hawks, Cooper’s Hawks, Northern Harriers, and falcons swell to reach their seasonal peak. Numbers of migrating Red-tailed and Red-shouldered Hawks are increasing during this time and late-season specialties including Golden Eagles can certainly make a surprise early visit.
If you enjoy the outdoors and live in the southernmost portion of the lower Susquehanna valley, Rocky Ridge County Park in the Hellam Hills just northwest of York, Pennsylvania, is a must see. The park consists of oak forest and is owned and managed by the York County Parks Department. It features an official hawk watch site staffed by volunteers and park naturalists. Have a look.
If you’re a nature photographer, you might be interested to know that there are still hundreds of active butterflies in Rocky Ridge’s utility right-of-way. Here are a few.
To see the daily totals for the raptor count at Rocky Ridge Hawk Watch and other hawk watches in North America, and to learn more about each site, be certain to visit hawkcount.org
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 (Cygnus columbianus), 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.
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.
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.
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).
SOURCES
Klots, Elsie B. 1966. The New Field Book of Freshwater Life. G. P. Putnam’s Sons. New York, NY.