Shad Run at Conowingo Dam

As the Flowering Dogwoods remind us, it’s time for adult sea-run shad and other fishes to ascend the Susquehanna to spawn.  So yep, we’re off to Fisherman’s Park on the river’s west shoreline below Conowingo Dam in Harford County, Maryland, to check it out.

Anglers at Conowingo Dam
Anglers were in the water and seeing action as we arrived below Conowingo Dam’s powerhouse at Fisherman’s Park.  The east lift, which was constructed during the 1990s to raise American Shad and other migratory fish over the dam during their spring spawning runs, sits idle at the impoundment end of the wing wall in the distance.
The entrance to the idle east fish lift at Conowingo Dam.
The entrance to the idle east fish lift at Conowingo Dam.
Northern Snakehead
Within minutes, we watched one of the culprits responsible for the lift’s shutdown being reeled in.  The invasive population of introduced Northern Snakeheads continues to thrive in the waters of the Susquehanna and its tributaries below the dam.  To prevent it from expanding its range to upriver sections of the watershed, all American Shad are being manually separated from among the snakeheads and other fish species deposited into sorting tanks using the west lift near the powerhouse.
Shad Transport Truck
One of several specialized transport vehicles returns from a “shad run” to the waters of the Susquehanna above York Haven Dam at Conewago Falls after delivering and releasing American Shad sorted from among the fish collected at Conowingo’s west lift earlier in the day.
American Shad began their run up the Susquehanna as water temperatures reached 60 degrees Fahrenheit…just about the time the Flowering Dogwoods started to bloom within the river’s riparian woodlands.  Later this month, spawning activity peaks when the water warms to about 65 degrees.  Earlier in the season, when the water reached about 55 degrees, another anadromous species, the Hickory Shad (seen here), began their spring spawning run from sea to freshwater rivers and streams.
While American Shad are seldom caught on hook and line, Hickory Shad are a popular catch-and-release target.  Though they will energetically strike baits like the small shad dart seen here, Hickory Shad are very cautious while ascending the river; they very rarely enter the fish lifts to join the dozens of other species that readily accept their use.  With water temperatures now in the sixties, an angler is seen here bringing in what may be among the last of this season’s Hickory Shad.  Their spawning run is presently drawing to a close for the year.
Gizzard Shad
The most commonly caught herring at Fisherman’s Park is the Gizzard Shad.  This plankton feeder seldom takes bait; it is instead foul-hooked.  Though not a sea-run species, Gizzard Shad by the tens of thousands leave open waters to seek shallower flowing riffles and pools to spawn.
Gizzard Shad
Unlike the other herring occurring in the Susquehanna, the Gizzard Shad has a blunt, snub-nosed appearance to the snout. The mouth is small and often unnoticeable.
Gizzard Shad
The Gizzard Shad is the only species of Susquehanna herring that can legally be harvested.  All others are sea-run migrants in varying degrees of population peril and must be returned to the water without delay.
Gizzard Shad
Note the elongated last ray on the dorsal fin of this foul-hooked Gizzard Shad.  It’s a not-often-visible but nevertheless tell-tale field mark.
Double-crested Cormorant
Humans aren’t the only creatures attracted by the fish migration on the lower Susquehanna.  This is just one of hundreds of Double-crested Cormorants we watched during our visit.
Cormorant along the base of Conowingo Dam
Hungry cormorants gather along the base of the dam where ascending fish congregate and become further disoriented by water turbulence.
Double-crested Cormorants
Fishing efforts here can bring great success to these accomplished piscivores.
Double-crested Cormorant with Gizzard Shad
Latching onto an oversize Gizzard Shad can make you very popular with your peers.
Double-crested Cormorant with Gizzard Shad
So popular that you may never have the opportunity to eat your lunch.
Double-crested Cormorant with Gizzard Shad
Take it from this old bird: you’ve gotta swallow ’em fast, head first, tail and all.
Bald Eagle with Gizzard Shad
A Bald Eagle hauls off a Gizzard Shad.
Osprey with Gizzard Shad
An Osprey saw this Gizzard Shad swimming close enough to the water’s surface to dive in and snag it with its talons.
Bald Eagle with Gizzard Shad
And yet another successful Bald Eagle calls out to its mate as it approaches its nest and hungry young.
Striped Bass
An angler releases a small Striped Bass caught on a shad dart while fishing for Hickory Shad.  To reduce pressure on their populations during the spring spawning run, the “Striper” harvest is presently closed.  The fishing season resumes later this month in some areas, in June within others.  On the Susquehanna Flats and other Chesapeake Bay waters, Striped Bass are also known as “Rockfish”.
Angler in Action
This angler is reeling in a big one.
Channel Catfish
A nice Channel Catfish weighed in at about six pounds and was released.
White Perch
This angler brought in yet another interesting catch.
White Perch
The White Perch (Morone americana) is a bay species that ascends the Chesapeake’s tributaries to spawn during the spring.  On the lower Susquehanna, numbers of this relative of the Striped Bass are falling, very possibly due to depredation by invasive snakeheads, Blue Catfish, and Flathead Catfish.
Double-crested Cormorant with Blue Catfish
A Double-crested Cormorant does its duty and snatches up an invasive Blue Catfish.   Very large Blue Catfish exceeding 24 inches in length are becoming increasingly plentiful on the upper Chesapeake and its tributaries resulting in a significant negative impact on the aquatic ecosystems there.  Like the Northern Snakehead and Flathead Catfish, these invasive species are very palatable and anglers are encouraged to catch and keep as many as they like.
Maryland DNR sign at Fisherman’s Park.
Angler with Northern Snakehead
What can we do about the plague of Northern Snakeheads (Channa argus) in the Susquehanna?  Well, let’s start by answering a question with a question…Why deplete ocean stocks when you can follow this angler’s example and harvest excellent fillets while helping to control an invasive species at the same time?  And no, you don’t have to call them “Chesapeake Channa” if you don’t want to.  Though you will make us laugh if you start calling them “Susquehanna Channa” or  just “Susquechanna” from time to time.

Eagles at Conowingo Dam

Few places in North America offer an observer the opportunity to stand in one spot and, with a single 180° sweep of a pair of binoculars, count 165 Bald Eagles.  Sounds impossible, but we experienced just that earlier today along the Susquehanna River below Conowingo Dam at Fisherman’s Park off U.S. Route 1 west of Rising Sun, Maryland.  More than 200 eagles are there right now, so you really ought to think about visiting to see it for yourself.  If you can’t make the trip, or if you need a little more convincing, we’ve put together a big collection of photographs for you to enjoy.  Have a look…

Eagle Watchers at Fisherman's Park, Conowingo Dam
In late November and December, hundreds of eagle watchers and photographers travel to Fisherman’s Park along the west shore of the Susquehanna River below Conowingo Dam/U.S. Route 1 to witness the largest annual gathering of our national symbol on the east coast.
Fisherman's Park at Conowingo Dam
The park provides facilities for viewing right on the waterfront and is maintained by the operator of the hydroelectric dam, Constellation Energy.
Bald Eagles along the East Shore of the Susquehanna below Conowingo Dam
From the riverside viewing area, we counted 165 Bald Eagles on the rocks along the east shore of the river and on the electric transmission line trestles.  That count didn’t include scores of additional birds obstructed from our view along the near shore downstream and along the east shore behind the mid-river island below the dam.
Bald Eagles
A closeup of some of the 165 Bald Eagles we counted.  Many of these birds, particularly the adults, are eagles that nest to our north and are here for a short winter stay.  Local breeding pairs, including several with nests along the river below the dam, are already courting, copulating, and defending territories; the latter no easy task for the Conowingo birds facing all these visitors.
Bald Eagles
The concentrations of Bald Eagles at Conowingo Dam sometimes provide an excellent opportunity to study the plumage of birds from the various age classes.  Today’s assemblage put on a clinic.
Hatch-year Bald Eagle
A nice, neat hatch-year/juvenile Bald Eagle in its first full set of feathers shows no molt.
Hatch-year Bald Eagle
This bird was an unusual find, a hatch-year/juvenile Bald Eagle with early signs of molt. There’s even a new secondary feather visible in the gap on the left wing.
Second-year Bald Eagle
The wings of a second-year/basic I immature Bald Eagle have a ragged appearance created by the long juvenile secondary feathers that have yet to be dropped.
Second-year Bald Eagle
Another second-year/basic I immature Bald Eagle showing some longer juvenile secondaries on each wing.
Third-year Bald Eagle
A third-year/basic II immature Bald Eagle showing a neater, cleaner trailing edge of the wings with no more long juvenile flight feathers.  The wide dark stripe through the face gives the bird an osprey-like appearance.  The bill color is usually more noticeably yellow than a second-year bird, but both can have extensive white in the belly feathers and elsewhere on the underside and shoulders.
Third-year Bald Eagles
Third-year/basic II immature Bald Eagles exhibiting aggressive behavior.
Fourth-year Bald Eagle
A fourth-year/basic III immature Bald Eagle with a black-bordered tail, yellow bill, and a thin dark line through the eye.  Birds this age are mostly dark below, but often retain some white feathers which present a spotted appearance.
Gulls at the Conowingo Dam Turbine House
The water passing through the dam not only attracts eagles, but other birds as well.  Many, including these gulls, are looking for fish stunned or disoriented by their trip through the turbines, gates, or spillways.
Ring-billed Gull
More than one hundred Ring-billed Gulls are currently being seen at Conowingo Dam.
American Herring Gull
We saw a few American Herring Gulls as well.
Juvenile American Herring Gull
A juvenile American Herring Gull.
Black Vultures
Probably a hundred Black Vultures or more were in the vicinity.
Black Vulture
A Black Vulture by the park’s riverside lookout.
Peregrine Falcon
We heard this Peregrine Falcon as it tangled with several eagles behind us before it quickly darted away across the top of the powerhouse and dam.
Double-crested Cormorant
Double-crested Cormorants were diving persistently in search of unwary prey.
Double-crested Cormorant eating Gizzard Shad.
A composite image of a Double-crested Cormorant gulping down a Gizzard Shad.
Eagle Photographers at Conowingo Dam
But these vigilant eagle watchers and photographers don’t come to Conowingo Dam and Fisherman’s Park to see Bald Eagles of various age classes flying around.  Nor do they come to see the other amazing birds attracted to the waters passing through the dam.
Bald Eagles Mix It Up
And they don’t even come to see some pretty good aerial fights among the numerous eagles congregated in the river gorge.
Immature Bald Eagle Fishing
They come specifically to see and photograph Bald Eagles swooping in to grab a fish.  That’s their objective and they’re serious about it!
Fourth-year Bald Eagle with Gizzard Shad
A probable fourth-year/basic III immature Bald Eagle with a Gizzard Shad.
Immature Bald Eagle Fishing
An immature Bald Eagle swoops in to grab a fish.
Immature Bald Eagle Fishing
An immature Bald Eagle stretches its wings forward with a deep stroke to lift a fish from the Susquehanna.
Bald Eagle with Gizzard Shad
A Bald Eagle, possibly a fifth-year/basic IV bird, carrying away a freshly caught Gizzard Shad.
Adult Bald Eagle Fishing
An adult Bald Eagle comes in for the grab.
Bald Eagle with Gizzard Shad
An adult Bald Eagle comes away with a Gizzard Shad.
Bald Eagle with Gizzard Shad
Now the hard part, finding a place to eat its catch in peace.

If you go to Fisherman’s Park, time your visit for when the light is at its best—late morning through early afternoon.  Don’t forget, it’s very cold down along the river, so dress appropriately.  And finally, visit on a weekday if you can.  The parking area can fill to capacity during the weekend and you may be turned away.

Don’t wait.  The eagles visiting the Susquehanna at Conowingo Dam could get pushed further south by rough winter weather.  Then again, adult pairs may take advantage of milder conditions to begin returning north early to nest.

Eagle Time on the Ridges and River

As we enter November, migratory raptor flights through the Lower Susquehanna River Watershed transition to the bigger birds.  Whether you’re on the river, on a mountain, or just outside your humble abode, persistent alertness to soaring avians can yield rewarding views of a number of late-season specialties.

Red-tailed Hawk
Red-tailed Hawks dominate the southbound raptor flights in November.
Juvenile Red-tailed Hawk
Juvenile (hatch-year) Red-tailed Hawks are generally less wary and more inquisitive than the more experienced adult birds.  Their curiosity frequently gets them into trouble, particularly when they try to hunt small rodents in traffic along busy roadways.
Adult Red-shouldered Hawk
Far fewer in number are migratory Red-shouldered Hawks.  In our region, these denizens of bottomland forests more commonly migrate along the southern edge of the Piedmont and through the upper Atlantic Coastal Plain.
A hatch-year (juvenile) Red-shouldered Hawk
A southbound hatch-year (juvenile) Red-shouldered Hawk.
Peregrine Falcon
Mixed-race Peregrine Falcons, the descendants of birds reintroduced into the Mid-Atlantic States during the late twentieth century, often roam our region during the late-fall and winter months before settling into their nesting territories with the approach of spring.  We spotted this one along a local ridge, but you may be more likely to see them in the city or near a bridge or dam on the river.
Peregrine Falcon
As this adult peregrine passed the lookout, we noted its full crop.  A sign it just completed a successful hunt.

A visit to a ridgetop on a breezy day—particularly after passage of a cold front—may give you the chance to see numerous eagles as well.

A second-year (Basic I) Bald Eagle rolls over while pursuing an adult Bald Eagle.
A second-year (Basic I) Bald Eagle barrel rolls while pursuing an adult Bald Eagle.

This afternoon, we got lucky and were treated to a bit of an aging clinic presented by the Bald Eagles we observed and photographed.  Careful determination of the age classes of raptors counted by hawkwatchers can provide an early warning of problems in the ecosystems that support populations of these top-of-the-food-chain predators.  For example: during the 1950s and early 1960s, a progressively lower percentage of juvenile and other non-adult age classes among the Bald Eagles being observed forewarned of the dangers of dichlorodiphenyltrichloroethane (DDT) pesticide in the environment.  The principle effect of accumulations of the DDT toxins in eagles, Ospreys, Peregrine Falcons, and other predatory birds that consumed waterfowl and/or fish was to thin their eggs shells.  The result was widespread brood failure and a near total loss of new generations of offspring.  Eventually, nearly all Bald Eagles being seen in areas impacted by DDT were progressively older adults, most of which failed as nesting pairs.  As the adult birds began dying off, the Bald Eagle population dwindled to numbers that raised fears of the species’ extinction.  Implementation of the DDT cancellation order and the Clean Water Act in 1972, and the Endangered Species Act in 1973, helped save the Bald Eagle.  But our regional “Eastern Peregrine Falcon”, a bird with a shorter life span than the Bald Eagle, was unable to endure the years of DDT use, dioxin pollution, and illegal hunting and egg collecting.  Its population is gone.

Hatch-year Bald Eagle
A hatch-year (juvenile) Bald Eagle is typically dark headed and in a fresh set of juvenile flight feathers that exhibit no signs of molt.  If the reproduction season and the months that followed were favorable for this year’s brood of new eagles, there should be nearly as many hatch-year birds as there are adults in an overall population.
Second-year Bald Eagle
By November, second-year (Basic I) Bald Eagles are replacing many of their flight feathers and often show ragged trailing edges in the wings due to the retention of some of the well-worn and notably longer juvenile feathers.  Varying amounts of white mottling are visible on the breast, belly, and underwing coverts.  Due to mortality, there are usually fewer second-year Bald Eagles than there are hatch-year or adult birds.
Second-year (Basic I) Bald Eagle.
Another example of a second-year (Basic I) Bald Eagle.
Third-year Bald Eagle
Third-year (Basic II) Bald Eagles show more yellow in the bill and an “osprey face”, a white head with a wide dark line through the eye.  Most of the juvenile flight feathers have been replaced, so the wing edges appear more uniform.  Like the second-year eagles, there is a varying amount of white in the breast, belly, and underwing coverts.  In an overall population of eagles, birds in this age class are usually less common than those that are younger or those that are adults.
Bald Eagle Age Classes: First Three Years
Composite image of Bald Eagles in typical November plumage during their first three years.  To see more images like this, be certain to click the “Hawkwatcher’s Helper: Identifying Bald Eagles and other Diurnal Raptors” tab at the top of this page.
Fourth-year Bald Eagle
A fourth year (Basic III) Bald Eagle will often be seen with a black-bordered tail and a thin dark line through the eye.  In some birds, traces of these traits can linger into the fifth year and beyond.  These plumage types are usually the least frequently observed among an overall population of Bald Eagles.  (Note:  In these older birds, there develops significant variation in the timing of feather molt.  In rare cases, fourth-year Bald Eagles may show minimal dark color in the tail or eye line and may appear to be in near definitive adult plumage.)
A possible fifth-year (Basic IV) Bald Eagle.
A possible fifth-year (Basic IV) Bald Eagle.
Adult Bald Eagles in definitive plumage. 
Adult Bald Eagles in definitive plumage.  Birds in this plumage class are often the most frequently observed because the group includes all eagles five or six years of age and older.

While the Bald Eagles are still stealing the show, cold and gusty weather should bring an increasing number of Golden Eagles our way during the remainder of the month.  Some are already trickling through…

A "before-third-year" Golden Eagle.
This “before-third-year” Golden Eagle shows no visible signs of molt in its juvenile (hatch-year) plumage, but a look at the upperwing coverts is needed to properly age the bird.  To learn more about the molt sequence in Golden Eagles, be sure to click the “Golden Eagle Aging Chart” tab at the top of this page.
A "before-third-year" Golden Eagle passing the lookout along with a second-year Bald Eagle.
A “before-third-year” Golden Eagle (top) passing the lookout along with a second-year Bald Eagle (bottom).
"Before-third-year" Golden Eagle.
Another “before-third-year” Golden Eagle.  More are on the way!

Later this month, Bald Eagle numbers on the lower Susquehanna below Conowingo Dam (U.S. 1) near Rising Sun, Maryland, will begin to grow.  Fisherman’s Park, located along the west shoreline below the dam, is an excellent place to observe and photograph scores of these regal birds.  And few places provide a better opportunity to learn to differentiate Bald Eagle age classes.  If you’re really lucky, a Golden Eagle or two may drop in as well.  So plan to make the trip.  The best time to visit is on a weekday.  The parking lot can become overcrowded on weekends and will be closed under such circumstances.  It’s best to avoid the long Thanksgiving weekend as well.

Migrating Adult Bald Eagles
Remember to always look up.

Chesapeake Bay Maritime Accidents and Their Impact on Susquehanna Wildlife

Tuesday’s collision of the container ship Dali into Baltimore’s Francis Scott Key Bridge and the nearly immediate collapse of the span into the chilly waters below reminds us just how unforgiving and deadly maritime accidents can be.  Upon termination of rescue and recovery operations, salvage and cleanup will be prioritized as the next steps in the long-term process of reopening the navigable waters to ship traffic and construction of a new bridge.  Part of the effort will include monitoring for leaks of fuels and other hazardous materials from the ship, its damaged cargo containers, and vehicles and equipment that were on the bridge when it failed.

Damage to the hull of the Dali and to the cargo containers on her deck could lead to leaks of hazardous liquids or other materials into Chesapeake Bay.  (United States Army Corps of Engineers Baltimore image)

On the waters and shores of today’s Chesapeake, numerous county, state, and federal agencies, including the United States Coast Guard, monitor and inspect looking for conditions and situations that could lead to point-source or accidental discharges of petroleum products and other hazardous materials into the bay.  Many are trained, equipped, and organized for emergency response to contain and mitigate spills upon detection.  But this was not always the case.

Through much of the twentieth century, maritime spills of oil and other chemicals magnified the effects of routine discharges of hazardous materials and sanitary sewer effluent into the Chesapeake and its tributaries.  The cumulative effect of these pollutants progressively impaired fisheries and bay ecosystems leading to noticeable declines in numbers of many aquatic species.  Rather frequently, spills or discharges resulted in conspicuous fish and/or bird kills.

One of the worst spills occurred near the mouth of the Potomac River on February 2, 1976, when a barge carrying 250,000 gallons of number 6 oil sank in a storm and lost its cargo into the bay.  During a month-long cleanup, the United States Coast Guard recovered approximately 167,000 gallons of the spilled oil, the remainder dispersed into the environment.  A survey counted 8,469 “sea ducks” killed.  Of the total number, the great majority were Horned Grebes (4,347 or 51.3%) and Long-tailed Ducks (2,959 or 34.9%).  Other species included Surf Scoter (Melanitta perspicillata) (405 or 4.8%), Common Loon (195 or 2.3%), Bufflehead (166 or 2.0%), Ruddy Duck (107 or 1.3%), Common Goldeneye (78 or 0.9%), Tundra Swan (46 or 0.5%), Greater Scaup (19 or 0.2%), American Black Duck (12 or 0.2%), Common Merganser (11 or 0.1%), Canvasback (10 or 0.1%), Double-crested Cormorant (10 or 0.1%), Canada Goose (8 or 0.1%), White-winged Scoter (Melanitta deglandi) (7 or 0.1%), Redhead (5 or 0.1%), gull species (10 or 0.1%), miscellaneous ducks and herons (13 or 0.2%) and unidentified (61 or 0.7%).  During the spring migration, a majority of these birds would have made their way north and passed through the lower Susquehanna valley.  The accident certainly impacted the occurrence of the listed species during that spring in 1976, and possibly for a number of years after.

Horned Grebe during migration on the Susquehanna near Haldeman Riffles.
Of the 8,469 birds killed by the February 2, 1976, oil spill on the Chesapeake, 51.3% (4,347) were Horned Grebes.  Many of them would have migrated north through the Lower Susquehanna River Watershed during the coming spring.

The Federal Water Pollution Control Act Amendments of 1972, commonly known as the Clean Water Act, put teeth into the original FWCPCA of 1948 and began reversing the accumulation of pollutants in the bay and other bodies of water around the nation.  Additional amendments in 1977 and 1987 have strengthened protections and changed the culture of “dump-and-run” disposal and “dilution-is-the-solution” treatment of hazardous wastes.  During the late nineteen-seventies and early nineteen-eighties, emergency response teams and agencies began organizing to control and mitigate spill events.  The result has been a greater awareness and competency for handling accidental discharges of fuels and other chemicals into Chesapeake Bay and other waterways.  These improvements can help minimize the environmental impact of the Dali’s collision with the Francis Scott Key Bridge in Baltimore.

Hickory Shad
Oil spills and other pollution in the Chesapeake can impact populations of migratory fish including the anadromous Hickory Shad which are presently transiting the bay on their way to the waters of the Susquehanna below Conowingo Dam.

SOURCES

Roland, John V., Moore, Glenn E., and Bellanca, Michael A.  1977.  “The Chesapeake Bay Oil Spill—February 2, 1976: A Case History”.  International Oil Spill Conference Proceedings (1977).  1977 (1): 523-527.

Photo of the Day

Bald Eagle
The last of the year’s migrating Bald Eagles are streaming down the ridges of the mid-Atlantic region and many of them will be stopping for at least a part of the winter season along the lower Susquehanna River.  If you want to see them, now is the best time.  Taking a walk along a riverside recreation trail is a relaxing way to spend some time checking them out.  To see the greatest concentrations of these majestic birds, plan a visit to one of the lower river’s hydroelectric dams.  Conowingo Dam, located where U.S. Route 1 crosses the river at Rising Sun, Maryland, is currently hosting dozens of visiting eagles.  If you’ve never been there, we can assure you that it’s certainly worth the trip.

A Limpkin’s Journey to Pennsylvania: A Waffle House Serving Escargot at Every Exit

Mid-summer can be a less than exciting time for those who like to observe wild birds.  The songs of spring gradually grow silent as young birds leave the nest and preoccupy their parents with the chore of gathering enough food to satisfy their ballooning appetites.  To avoid predators, roving families of many species remain hidden and as inconspicuous as possible while the young birds learn how to find food and handle the dangers of the world.

But all is not lost.  There are two opportunities for seeing unique birds during the hot and humid days of July.

First, many shorebirds such as sandpipers, plovers, dowitchers, and godwits begin moving south from breeding grounds in Canada.  That’s right, fall migration starts during the first days of summer, right where spring migration left off.  The earliest arrivals are primarily birds that for one reason on another (age, weather, food availability) did not nest this year.  These individuals will be followed by birds that completed their breeding cycles early or experienced nest failures.  Finally, adults and juveniles from successful nests are on their way to the wintering grounds, extending the movement into the months we more traditionally start to associate with fall migration—late August into October.

For those of you who find identifying shorebirds more of a labor than a pleasure, I get it.  For you, July can bring a special treat—post-breeding wanderers.  Post-breeding wanderers are birds we find roaming in directions other than south during the summer months, after the nesting cycle is complete.  This behavior is known as “post-breeding dispersal”.  Even though we often have no way of telling for sure that a wandering bird did indeed begin its roving journey after either being a parent or a fledgling during the preceding nesting season, the term post-breeding wanderer still applies.  It’s a title based more on a bird sighting and it’s time and place than upon the life cycle of the bird(s) being observed.  Post-breeding wanderers are often southern species that show up hundreds of miles outside there usual range, sometimes traveling in groups and lingering in an adopted area until the cooler weather of fall finally prompts them to go back home.  Many are birds associated with aquatic habitats such as shores, marshes, and rivers, so water levels and their impact on the birds’ food supplies within their home range may be the motivation for some of these movements.  What makes post-breeding wanderers a favorite among many birders is their pop.  They are often some of our largest, most colorful, or most sought-after species.  Birds such as herons, egrets, ibises, spoonbills, stilts, avocets, terns, and raptors are showy and attract a crowd.

While it’s often impossible to predict exactly which species, if any, will disperse from their typical breeding range in a significant way during a given year, some seem to roam with regularity.  Perhaps the most consistent and certainly the earliest post-breeding wanderer to visit our region is the “Florida Bald Eagle”.  Bald Eagles nest in “The Sunshine State” beginning in the fall, so by early spring, many of their young are on their own.   By mid-spring, many of these eagles begin cruising north, some passing into the lower Susquehanna valley and beyond.  Gatherings of dozens of adult Bald Eagles at Conowingo Dam during April and May, while our local adults are nesting and after the wintering birds have gone north, probably include numerous post-breeding wanderers from Florida and other Gulf Coast States.

So this week, what exactly was it that prompted hundreds of birders to travel to Middle Creek Wildlife Management Area from all over the Mid-Atlantic States and from as far away as Colorado?

Birders observing something special at Middle Creek Wildlife Management Area on July 10, 2023.

Was it the majestic Great Blue Herons and playful Killdeer?

Great Blue Heron
Great Blue Heron and a Killdeer.

Was it the colorful Green Herons?

Green Heron
Green Heron

Was it the Great Egrets snapping small fish from the shallows?

Great Egret
Great Egret

Was it the small flocks of shorebirds like these Least Sandpipers beginning to trickle south from Canada?

Least Sandpipers
Least Sandpipers

All very nice, but not the inspiration for traveling hundreds or even thousands of miles to see a bird.

It was the appearance of this very rare post-breeding wanderer…

Limpkin at Middle Creek Wildlife Management Area
A Limpkin at Middle Creek Wildlife Management Area in Lancaster County.  The Limpkin (Aramus guarauna) is the only surviving member of the family Aramidae.

…Pennsylvania’s first record of a Limpkin, a tropical wading bird native to Florida, the Caribbean Islands, and South America.  Many observers visiting Middle Creek Wildlife Management Area had never seen one before, so if they happen to be a “lister”, a birder who keeps a tally of the wild bird species they’ve seen, this Limpkin was a “lifer”.

The Limpkin is an inhabitant of vegetated marshlands where it feeds almost exclusively upon large snails of the family Ampullariidae, including the Florida Applesnail (Pomacea paludosa), the largest native freshwater snail in the United States.

Native and Non-native Range of Florida Applesnail
In the United States, the native range of the Limpkin lies within the native range of the Florida Applesnail, shown here in gold.  Introduced populations of the snail are shown in brown.  (United States Geological Survey Nonindigenous Aquatic Species image)
A spectacular nineteenth-century rendition of the Florida Applesnail, including an egg mass, illustrated by Helen E. Lawson in Samuel S. Haldeman’s “Monograph of the Freshwater Univalve Mollusca of the United States”.

Observations of the Limpkin lingering at Middle Creek Wildlife Management Area have revealed a pair of interesting facts.  First, in the absence of Florida Applesnails, this particular Limpkin has found a substitute food source, the non-native Chinese Mystery Snail (Cipangopaludina chinensis).  And second, Chinese Mystery Snails have recently become established in the lakes, pools, and ponds at the refuge, very likely arriving as stowaways on Spatterdock (Nuphar advena) and/or American Lotus (Nelumbo lutea), native transplants brought in during recent years to improve wetland habitat and process the abundance of nutrients (including waterfowl waste) in the water.

A Chinese Mystery Snail.
The Chinese Mystery Snail is the largest freshwater snail in the Lower Susquehanna River Watershed.  (Vintage 35 mm image)
By hitching a ride on aquatic transplants like this Spatterdock, non-native freshwater snails are easily vectored into new areas outside their previous range.
Spatterdock, a native species also known as Yellow Pond Lily or Cow Lily.
Spatterdock, a native species also known as Yellow Pond Lily or Cow Lily, flowering in August.
American Lotus in flower at Middle Creek Wildlife Management Area.
Blooming American Lotus transplants in a pool at Middle Creek Wildlife Management Area during August.
The Limpkin at Middle Creek W.M.A. capturing a Chinese Mystery Snail.
The Limpkin at Middle Creek W.M.A. capturing a Chinese Mystery Snail.
The Limpkin at Middle Creek carrying a Chinese Mystery Snail.
The Limpkin at Middle Creek carrying a Chinese Mystery Snail.
Limpkin holding Chinese Mystery Snail
The Limpkin is seen here maneuvering the the snail in its bill, a set of mandibles specially adapted for extracting the bodies of large freshwater snails from their shells.
Limpkin Grasping Chinese Mystery Snail
The tweezers-like tip of the bill is used to grasp the shell by the rim of the opening or by the “trapdoor” (operculum) that protects the snail inside.
Chinese Mystery Snail
A posed Chinese Mystery Snail showing its “trapdoor”, the operculum protecting the soft body tissue when the animal withdraws inside.  The tips of the Limpkin’s bill close tightly like the end of a tweezers to grasp the operculum and remove it and the snail’s body from the shell.  (Vintage 35 mm image)
Limpkin Removing Chinese Mystery Snail from Shell
The tweezers-tipped bill, which is curved slightly to the right in some Limpkins, is slid into the shell to grasp the snails body and remove it for consumption.  The entire extraction process takes 10 to 30 seconds.

The Middle Creek Limpkin’s affinity for Chinese Mystery Snails may help explain how it was able to find its way to Pennsylvania in apparent good health.  Look again at the map showing the range of the Limpkin’s primary native food source, the Florida Applesnail.  Note that there are established populations (shown in brown) where these snails were introduced along the northern coast of Georgia and southern coast of South Carolina…

Native and Non-native Range of Florida Applesnail
Native (gold) and non-native (brown) ranges of the Florida Applesnail.  (United States Geological Survey Nonindigenous Aquatic Species image)

…now look at the latest U.S.G.S. Nonindigenous Aquatic Species map showing the ranges (in brown) of established populations of non-native Chinese Mystery Snails…

Range (in brown) of established populations of non-native Chinese Mystery Snails.  (United States Geological Survey Nonindigenous Aquatic Species image)

…and now imagine that you’re a happy-go-lucky Limpkin working your way up the Atlantic Coastal Plain toward Pennsylvania and taking advantage of the abundance of food and sunshine that summer brings to the northern latitudes.  It’s a new frontier.  Introduced populations of Chinese Mystery Snails are like having a Waffle House serving escargot at every exit along the way!

Be sure to click the “Freshwater Snails” tab at the top of this page to learn more about the Chinese Mystery Snail and its arrival in the Lower Susquehanna River Watershed.  Once there, you’ll find some additional commentary about the Limpkin and the likelihood of Everglade Snail Kites taking advantage of the presence of Chinese Mystery Snails to wander north.  Be certain to check it out.

Everglade Snail Kite
The endangered Everglade Snail Kite (Rostrhamus sociabilis plumbeus), a Florida Applesnail specialist, has survived in part due to its ability to adapt to eating the non-native Pomacea maculata applesnails which have become widespread in Florida following releases from aquaria.  The adaptation?…a larger body and bill for eating larger snails.  (National Park Service image)

Photo of the Day

A juvenile Ring-billed Gull with a freshly caught Gizzard Shad is pursued by a hungry adult Great Black-backed Gull on the Susquehanna at Conowingo Dam.
A juvenile Ring-billed Gull with a freshly caught Gizzard Shad is pursued by a hungry adult Great Black-backed Gull on the Susquehanna at Conowingo Dam.

Hey, Let’s Go to Conowingo: It’s Bald Eagle Time

Why are there dozens of people with enormous lenses on complicated cameras atop sturdy tripods gathered at Fisherman’s Park below the Conowingo Dam on the lower Susquehanna River in Maryland?  It’s Bald Eagle time, that’s why.  Here are some photos from the scene, taken just two days ago.

Dozens of observers and photographers line up along the Harford County shoreline of the Susquehanna downstream of the powerhouse at the Conowingo Hydroelectric Station, the majority awaiting the opportunity to catch a shot of a Bald Eagle grabbing a fish from the river just in front of them.  Visitors travel to Conowingo from all over the continental United States to see and photograph eagles in concentrations that are often rivaled only in less accessible areas of Alaska and Canada.
Bald Eagles migrate to the lower Susquehanna near Conowingo and the upper Chesapeake Bay to spend the early winter in congregations that can, in good years, number in the hundreds of birds. There are presently at least 60 to 80 Bald Eagles present, and numbers are increasing.
If you visit, you’ll have a chance to see Bald Eagles in the various stages of plumage transition experienced during the six years needed to acquire the familiar all-white head and tail of adulthood.  This particular immature eagle is in its third year.  Birds at this age are sometimes known as “Osprey face” Bald Eagles due to the dark stripe through the eye.  Be certain to click the “Hawkwatchers Helper: Identifying Bald Eagles and other Diurnal Raptors” tab at the top of this page to see a photographic guide to aging the eagles and other birds of prey you observe.
An adult Bald Eagle snags a fish from the Susquehanna in front of photographers and gets the cameras clicking and other eagles in the area cackling and chattering.
The majority of the Bald Eagles at Conowingo are there for the early winter only; they’ll disperse to their nesting grounds later in the season.  An exception is this mated pair that is already at their nest site adjacent to the Fisherman’s Park car lot.  They can often be seen perched in the treetops directly above visitor’s vehicles.

To reach Exelon Energy’s Conowingo Fisherman’s Park from Rising Sun, Maryland, follow U.S. Route 1 south across the Conowingo Dam, then turn left onto Shuresville Road, then make a sharp left onto Shureslanding Road.  Drive down the hill to the parking area along the river.  The park’s address is 2569 Shureslanding Road, Darlington, Maryland.

Do make an excursion to the lower Susquehanna at Conowingo soon.  To avoid crowds and parking congestion, plan to visit on a weekday.  You’ll want warm clothing, binoculars, and a camera too.

The Fisherman’s Park Bald Eagles copulating.  If you don’t know what that is, ask your mother…no, wait, on second thought, look it up on the internet.

Conowingo Dam: Cormorants, Eagles, Snakeheads and a Run of Hickory Shad

Meet the Double-crested Cormorant,  a strangely handsome bird with a special talent for catching fish.  You see, cormorants are superb swimmers when under water—using their webbed feet to propel and maneuver themselves with exceptional speed in pursuit of prey.

Like many species of birds that dive for their food, Double-crested Cormorants run across the surface of the water to gain speed for a takeoff.  Smaller wings may make it more difficult to get airborne, but when folded, they provide improved streamlining for submerged swimming.

Double-crested Cormorants, hundreds of them, are presently gathered along with several other species of piscivorous (fish-eating) birds on the lower Susquehanna River below Conowingo Dam near Rising Sun, Maryland.  Fish are coming up the river and these birds are taking advantage of their concentrations on the downstream side of the impoundment to provide food to fuel their migration or, in some cases, to feed their young.

Double-crested Cormorants, mostly adult birds migrating toward breeding grounds to the north, are gathered on the rocks on the east side of the river channel below Conowingo Dam.  A Great Blue Heron from a nearby rookery can be seen at the center of the image.
Bald Eagles normally gather in large numbers at Conowingo Dam in the late fall and early winter.  Presently there are more than 50 there, and the majority of them are breeding age adults.  Presumably they are still on their way north to nest.  Meanwhile, local pairs are already feeding young, so it seems these transient birds are running a bit late.  Many of them can be seen on the rocks along the east side of the river channel,…
…on the powerline trestles on the island below the dam…
…in the trees along the east shore,…
…and in the trees surrounding Fisherman’s Park on the west shore.

In addition to the birds, the movements of fish attract larger fish, and even larger fishermen.

Anglers gather to fish the placid waters below the dam’s hydroelectric powerhouse .  Only a few of the generating turbines are operating, so the flow through the dam is minimal.
Some water is being released along the west shoreline to attract migratory river herring to the west fish lift for sorting and retention as breeding stock for a propagation program.  The east lift, the passage that hoists American Shad (Alosa sapidissima) to a trough that allows them to swim over the top of the dam to waters upriver, will begin operating as soon as these larger migratory fish begin arriving.

The excitement starts when the sirens start to wail and the red lights begin flashing.  Yes friends, it’s showtime.

Red lights and sirens are a warning that additional flow is about to be released from the dam.  Boaters should anticipate rough water and persons in and along the river need to seek higher ground immediately.
Gates are opened at mid-river to release a surge of water through the dam.
The wake from the release quickly reaches the shoreline, raising the water level in moments.
Experienced anglers know that the flow through the dam gets fish moving and can improve the catch significantly, especially in spring when many species are ascending the river.

Within minutes of the renewed flow, birds are catching fish.

A Double-crested Cormorant with a young Channel Catfish (Ictalurus punctatus).
A Double-crested Cormorant fleeing others trying to steal its Channel Catfish.
Another Double-crested Cormorant eating a Channel Catfish.  Did you realize that Channel Catfish were an introduced species in the Susquehanna River system?
An Osprey with a stick, it’s too busy building a nest right now to fish.
Great Blue Herons swallow their prey at the spot of capture, then fly back to the nest to regurgitate a sort of “minced congealed fish product” to their young.

Then the anglers along the wave-washed shoreline began catching fish too.

This young man led off a flurry of catches that would last for the remainder of the afternoon.
Though Gizzard Shad are filter feeders that don’t readily take baits and lures, they are regularly foul-hooked and reeled in from the large schools that ascend the river in spring.
Gizzard Shad are very abundant in the lower Susquehanna, providing year-round forage for many species of predatory animals including Bald Eagles.
A Double-crested Cormorant swallowing a Gizzard Shad.
This angler soon helped another fisherman by landing his large catch, a Northern Snakehead (Channa argus).
The teeth of a Northern Snakehead are razor sharp.  It is an aggressive non-native invasive species currently overtaking much of the Lower Susquehanna River Watershed.  Anglers are encouraged to fish for them, catch them, keep them, and kill them at the site of capture.  Never transport a live Northern Snakehead  anywhere at any time.  It is illegal in both Maryland and Pennsylvania to possess a live snakehead. 
Northern Snakehead advisory sign posted at Exelon Energy’s Conowingo Fishermen’s Park.
A stringer of Northern Snakeheads.  This species was imported from Asia as a food fish, so it has excellent culinary possibilities.  It’s better suited for a broiler or frying pan than a river or stream.
Another stringer of Northern Snakeheads.  It’s pretty safe to say that they have quickly become one of the most abundant predatory fish in the river.  Their impact on native species won’t be good, so catch and eat as many as you can.  Remember, snakeheads swim better in butter and garlic than in waters with native fish.
This foul-hooked Shorthead Redhorse (Moxostoma macrolepidotum), a native species of sucker, was promptly released.
Striped Bass are anadromous fish that leave the sea in spring to spawn in fresh water.  They ascend the Susquehanna in small numbers, relying upon the operation of the fish passages at the Conowingo, Holtwood, Safe Harbor, and York Haven Dams to continue their journey upstream.  During spring spawning, Striped Bass in the Susquehanna River and on the Susquehanna Flats portion of the upper Chesapeake Bay are not in season and may not be targeted, even for catch-and-release.  This accidental catch was immediately turned loose.
After removal from the hook, this hefty Smallmouth Bass was returned to the river.  Many anglers are surprised to learn that Smallmouth Bass are not native to the Susquehanna basin.
This angler’s creel contains a Northern Snakehead (left) and a Walleye (right).  Did you know that the Walleye (Sander vitreus) is an introduced species in the Susquehanna watershed?
By late afternoon, anglers using shad darts began hooking into migrating Hickory Shad (Alosa mediocris), a catch-and-release species in Maryland.
Hickory Shad are recognized by their lengthy lower jaw.  They are anadromous herring that leave the sea to spawn in freshwater streams.  Hickory Shad ascend the Susquehanna as far as Conowingo Dam each year, but shy away from the fish lifts.  Downriver from the dam, they do ascend Deer Creek along the river’s west shore and Octoraro Creek on the east side.  In Pennsylvania, the Hickory Shad is an endangered species.
A Hickory Shad angled on a dual shad dart rig.  During the spring spawning run, they feed mostly on small fish, and are the most likely of the Susquehanna’s herring to take the hook.
Simultaneous hook-ups became common after fours hours worth of release water from the dam worked its way toward the mouth of the river and got the schools moving.  Water temperatures in the mid-to-upper-fifties trigger the ascent of Hickory Shad.  On the Susquehanna, those temperatures were slow to materialize in the spring of 2021, so the Hickory Shad migration is a bit late.
Catch-and-release fishing for Hickory Shad appears to be in full swing not only at the dam, but along the downstream shoreline to at least the mouth of Deer Creek at Susquehanna State Park too.
Many Hickory Shad could be seen feeding on some of the millions of caddisflies (Trichoptera) swarming on the river.  These insects, along with earlier hatches of Winter Stoneflies (Taeniopterygidae), not only provide forage for many species of fish, but  are a vital source of natural food for birds that migrate up the river in March and April each year.  Swallows, Ring-billed Gulls, and Bonaparte’s Gulls are particularly fond of snatching them from the surface of the water.
A Winter Stonefly (Taeniopterygidae) from an early-season hatch on the Susquehanna River at the Veteran’s Memorial Bridge at Columbia/Wrightsville, Pennsylvania.  (March 3, 2021)
Just below Conowingo Dam, a lone fly fisherman was doing a good job mimicking the late-April caddisfly hatch, successfully reeling in numerous surface-feeding Hickory Shad.
You may have noticed the extraordinary number of introduced fish species listed in this account of a visit to Conowingo Dam.  Sorry to say that there are two more: the Flathead Catfish (Pylodictis olivaris) and the Blue Catfish (Ictalurus furcatus).  Like the Northern Snakehead, each has become a plentiful invasive species during recent years.  Unlike the Northern Snakehead, these catfish are “native transplants”, species introduced from populations in the Mississippi River and Gulf Slope drainages of the United States.  So if you visit the area, consider getting a fishing license and catching a few.  Like the snakeheads, they too are quite palatable.

The arrival of migrating Hickory Shad heralds the start of a movement that will soon include White Perch, anadromous American Shad, and dozens of other fish species that swim upstream during the springtime.  Do visit Fisherman’s Park at Conowingo Dam to see this spectacle before it’s gone.  The fish and birds have no time to waste, they’ll soon be moving on.

To reach Exelon’s Conowingo Fisherman’s Park from Rising Sun, Maryland, follow U.S. Route 1 south across the Conowingo Dam, then turn left onto Shuresville Road, then make a sharp left onto Shureslanding Road.  Drive down the hill to the parking area along the river.  The park’s address is 2569 Shureslanding Road, Darlington, Maryland.

A water release schedule for the Conowingo Dam can be obtained by calling Exelon Energy’s Conowingo Generation Hotline at 888-457-4076.  The recording is updated daily at 5 P.M. to provide information for the following day.

And remember, the park can get crowded during the weekends, so consider a weekday visit.

Bald Eagles Arriving at Conowingo Dam

You need to see this to believe it—dozens, sometimes hundreds, of Bald Eagles doing their thing and you can stand or sit in just one place to take it all in.

Conowingo Dam on the Susquehanna River near Darlington, Maryland, attracts piscivores galore.  Young Gizzard Shad (Dorosoma cepedianum) and other small fishes are temporarily stunned as they pass through the turbines and gated discharges at the hydroelectric facility’s power house.  Waiting for them in the rapids below are predatory fishes including Striped Bass (Morone saxatilis), White Perch (Morone americana), several species of catfishes, and more.  From above, fish-eating birds are on the alert for a disoriented turbine-traveler they can easily seize for a quick meal.

U.S. Route 1 crosses the Susquehanna River atop the Conowingo Dam.  Conowingo Fisherman’s Park, the observation site for the dam’s Bald Eagles and other birds, is located downstream of the turbine building along the river’s west (south) shore.  As the name implies, the park is a superb location for angling.
Heed this warning.  Close your windows and sunroof or the vultures will subject your vehicle’s contents to a thorough search for food.  Then they’ll deposit a little consolation prize on your paint.
Scavenging Black Vultures congregate by the hundreds at Conowingo Dam to clean up the scraps left behind by people and predators.  They’ll greet you right in the parking lot.
Photographers line up downstream of the turbine building for an opportunity to get the perfect shot of a Bald Eagle.
The operator of the Conowingo Hydroelectric Generating Station, Exelon Energy, provides clean comfortable facilities for fishing, sightseeing, and wildlife observation.
There’s almost always a Peregrine Falcon zooming around the dam to keep the pigeons on their toes.
Double-crested Cormorants on the boulders that line the channel below the dam.  Hundreds are there right now.
Double-crested Cormorants dive for fish near the power house discharge, which, while just one small generator is operating, seems nearly placid.  The feeding frenzy really gets going when Conowingo begins generating with multiple large turbines and these gently flowing waters become torrential rapids filled with disoriented fishes.
Ring-billed Gulls seek to snag a small fish from the water’s surface.
After successfully nabbing shad or perch, these Double-crested Cormorants need to swallow their catch fast or risk losing it.  Stealing food is a common means of survival for the gulls, eagles, and other birds found here.
Where do migrating eagles go?  There are, right now, at least 50 Bald Eagles at Conowingo Dam, with more arriving daily.  Numbers are likely to peak during the coming weeks.
Eagles can be seen perched in the woods along both river shorelines, even in the trees adjacent to the Conowingo Fisherman’s Park car lot.  Others take stand-by positions on the boulders below the dam.
To remind visiting eagles that they are merely guests at Conowingo, a resident Bald Eagle maintains a presence at its nest on the wooded slope above Fisherman’s Park.  Along the lower Susquehanna, female Bald Eagles lay eggs and begin incubation in January.
When an eagle decides to venture out and attempt a dive at a fish, that’s when the photographers rush to their cameras for a chance at a perfect shot.
The extraordinary concentrations of Bald Eagles at Conowingo make it an excellent place to study the plumage differences between birds of various ages.
Here’s a first-year Bald Eagle, also known as a hatch-year or juvenile bird.
A second-year or Basic I immature Bald Eagle.  Note the long juvenile secondaries giving the wings a ragged-looking trailing edge.
A third-year or Basic II immature Bald Eagle.
A second-year/Basic I immature Bald Eagle (top) and a third-year/Basic II immature Bald Eagle (bottom).
A second-year/Basic I immature Bald Eagle (bottom) and a third-year/Basic II immature Bald Eagle (top).  Note the white feathers on the backs of eagles in these age classes.
A third-year/Basic II immature Bald Eagle perched in a tree alongside the parking area.  Note the Osprey-like head plumage.
A sixth-year or older adult Bald Eagle in definitive plumage (left) and a fourth-year or Basic III immature Bald Eagle (right).
If you want to see the Bald Eagles at Conowingo Dam, don’t wait.  While many birds are usually present throughout the winter, the large concentrations may start dispersing as early as December when eagles begin wandering in search of other food sources, particularly if the river freezes.
A pair of Bald Eagles is already working on a nest atop this powerline trestle downstream of Conowingo Dam.  By late December, most adult eagles will depart Conowingo to begin spending their days establishing and defending breeding territories elsewhere.  Any non-adult eagles still loitering around the dam will certainly begin receiving encouragement from the local nesting pair(s) to move along as well.

To reach Exelon’s Conowingo Fisherman’s Park from Rising Sun, Maryland, follow U.S. Route 1 south across the Conowingo Dam, then turn left onto Shuresville Road, then make a sharp left onto Shureslanding Road.  Drive down the hill to the parking area along the river.  The park’s address is 2569 Shureslanding Road, Darlington, Maryland.

As Bald Eagle numbers continue to increase, expect the parking lot to become full during weekends and over the Thanksgiving holiday.  To avoid the crowds, plan to visit during a weekday.

You can get the generating schedule for the Conowingo Dam by calling the Conowingo Generation Hotline at 888-457-4076.  The recording is updated daily at 5 P.M. to provide information for the following day.

Shocking Fish Photos!

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.

Electrofishing on the Conewago Creek in Lebanon County, PA
Matt Kofroth, Watershed Specialist with the Lancaster County Conservation District, operates the electrofishing wand in Conewago Creek while his team members prepare to net and collect momentarily-stunned fish.  Three other electrofishing units operated by staff from the Susquehanna River Basin Commission and aided by teams of netters were in action at other sample locations along the Conewago on this day.
Fishes of the Lower Susquehanna River Watershed: Common Carp
Really big fish, such as this Common Carp (Cyprinus carpio), were identified, counted, and immediately returned to the water downstream of the advancing electrofishing team. 
Fishes of the Lower Susquehanna River Watershed: Swallowtail Shiner, Fallfish, Red-breast Sunfish, and suckers.
Other fish, such as the Swallowtail Shiner, Redbreast Sunfish (Lepomis auritus), Fallfish, and suckers seen here,  were placed in a sorting tank.
Fishes of the Lower Susquehanna River Watershed: Fallfish
Fallfish (Semotilus corporalis) are very active and require plenty of dissolved oxygen in the water to survive.  Fallfish, Rainbow Trout (Oncorhynchus mykiss), and Smallmouth Bass (Micropterus dolomieu) were quickly identified and removed from the sorting tank for release back into the stream.  Other larger, but less active fish, including suckers, quickly followed.
Fishes of the Lower Susquehanna River Watershed: Fathead Minnow
Small fish like minnows were removed from the sorting tank for a closer look in a hand-held viewing tank.  This Fathead Minnow (Pimephales promelas) was identified, added to the tally sheet, and released back into the Conewago.  The Fathead Minnow is not native to the Susquehanna drainage.  It is the minnow most frequently sold as bait by vendors.
Fishes of the Lower Susquehanna River Watershed: a breeding male Bluntnose Minnow
A breeding condition male Bluntnose Minnow (Pimephales notatus).
Fishes of the Lower Susquehanna River Watershed: Cutlips Minnow
The Cutlips Minnow (Exoglossum maxillingua) is a resident of clear rocky streams.  Of the more than 30 species collected during the day, two native species which are classified as intolerant of persisting stream impairment were found: Cutlips Minnow and Swallowtail Shiner.
Fishes of the Lower Susquehanna River Watershed: Central Stoneroller
The Central Stoneroller (Campostoma anomalum) is a benthic feeder in creeks over gravel and sand.
Fishes of the Lower Susquehanna River Watershed: Eastern Blacknose Dace
The Eastern Blacknose Dace (Rhinichthys atratulus) is found in clear water over pebble and stone substrate.
Fishes of the Lower Susquehanna River Watershed: Longnose Dace
The Longnose Dace (Rhinichthys cataractae) is another species of pebbly rocky streams.
Fishes of the Lower Susquehanna River Watershed: juvenile Golden Shiner
A juvenile Golden Shiner (Notemigonus crysoleucas).  Adults lack the side stripe and grow to the size of a sunfish.
Fishes of the Lower Susquehanna River Watershed: Swallowtail Shiner
A Swallowtail Shiner (Notropis procne) and a very young White Sucker (Catostomus commersonii) in the upper left of the tank.
Fishes of the Lower Susquehanna River Watershed: Spotfin Shiner
A probable Spotfin Shiner (Cyprinella spiloptera).
Fishes of the Lower Susquehanna River Watershed: Spotfin Shiner
A breeding male Cyprinella shiner, probably a Spotfin Shiner.  Show-off!
Fishes of the Lower Susquehanna River Watershed: Margined Madtom
The Margined Madtom (Noturus insignis) is a small native catfish of pebbly streams.
Fishes of the Lower Susquehanna River Watershed: Banded Killifish
The Banded Killifish (Fundulus diaphanus) is adept at feeding upon insects, including mosquitos.
Fishes of the Lower Susquehanna River Watershed: a juvenile Rock Bass
A young Rock Bass (Ambloplites rupestris).  This species was introduced to the Susquehanna and its tributaries.
Fishes of the Lower Susquehanna River Watershed: Greenside Darter
The Greenside Darter (Etheostoma blennioides) is not native to the Susquehanna basin.  The species colonized the Conewago Creek (east) from introduced local populations within the last five years.
Fishes of the Lower Susquehanna River Watershed: Tessellated Darter
The Tessellated Darter (Etheostoma olmstedi) is a native inhabitant of the Susquehanna and its tributaries.
Fishes of the Lower Susquehanna River Watershed: American Eel
The stars of the day were the American Eels (Anguilla rostrata).
Fishes of the Lower Susquehanna River Watershed: American Eel
After collection, each eel was measured and weighed using a scale and dry bucket.  This specimen checked in at 20 inches and one pound before being released.
Fishes of the Lower Susquehanna River Watershed: American Eel
Prior to the construction of large dams, American Eels were plentiful in the Susquehanna and its tributaries, including the Conewago.  They’ve since been rarities for more than half a century.  Now they’re getting a lift.
Eastern Elliptio
American Eels serve as an intermediate host for the microscopic parasitic glochidia (larvae) of the Eastern Elliptio (Elliptio complanata), a declining native freshwater mussel of the Lower Susquehanna River Watershed.  While feeding on their host (usually in its gills), the glochidia cause little injury and soon drop off to continue growth, often having assured distribution of their species by accepting the free ride.  Freshwater mussels are filter feeders and improve water quality.  They grow slowly and can live for decades.
Fishes of the Lower Susquehanna River Watershed: American Eel
American Eels are a catadromous species, starting life as tiny glass eels in the saltwater of the Atlantic Ocean, then migrating to tidal brackish marshes and streams (males) or freshwater streams (females) to mature.  This 20-incher probably attempted to ascend the Susquehanna as an elver in 2016 or 2017.  After hitching a ride with some friendly folks, she bypassed the three largest dams on the lower Susquehanna (Conowingo, Holtwood, and Safe Harbor) and arrived in the Conewago where she may remain and grow for ten years or more.  To spawn, a perilous and terminally fatal journey to the Sargasso Sea awaits her.  (You may better know the area of the Sargasso Sea as The Bermuda Triangle…a perilous place to travel indeed!)

SOURCES

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.