Lakes – LIFE IN THE LOWER SUSQUEHANNA RIVER WATERSHED

May 13, 2024May 14, 2024

See Food and an Oriole Doubleheader

The rain and clouds have at last departed. With blue skies and sunshine to remind us just how wonderful a spring afternoon can be, we took a stroll at Memorial Lake State Park in Lebanon County, Pennsylvania, to look for some migratory birds.

Though running just a few days later than usual, Indigo Buntings have arrived to begin nesting.

This Common Loon dropped by Memorial Lake during a storm several days ago and decided to stay awhile. It’s a species that winters in oceanic waters along the Atlantic seaboard and nests on glacial lakes to our north.

Shoreline Vegetation at Memorial Lake — **Clear Water-** Memorial Lake is one of the few man-made lakes in the Lower Susquehanna River Watershed to be appropriately vegetated with an abundance of submerged, floating, and emergent plants. As a result, the water from Indiantown Run that passes through the impoundment is minimally impacted by nutrient loads and the algal blooms they can cause. Buffers of woody and herbaceous growth along the lake’s shorelines provide additional nutrient sequestering and help prevent soil erosion and siltation.

The breeding season has begun for Neotropical migrants including this Baltimore Oriole, which we found defending a nesting territory in a stand of Black Walnut trees.

Along the edge of the lake, this Orchard Oriole and its mate were in yet another stand of tall walnut trees.

Early in the season and early in the day, we started seeing Common Nighthawks flying above wooded areas north of the lake at 4 o’clock this afternoon. After all the raw and inclement weather they’ve experienced in recent days, the warm afternoon was probably their first opportunity to feed on flying insects in quite a while.

What? You thought we were gonna drop in on Maryland’s largest city for a couple of ball games and some oysters, clams, and crab cakes—not likely.

January 10, 2024January 18, 2024

Piscivorous Waterfowl Visiting Lakes and Ponds

Heavy rains and snow melt have turned the main stem of the Susquehanna and its larger tributaries into a muddy torrent. For fish-eating (piscivorous) ducks, the poor visibility in fast-flowing turbid waters forces them to seek better places to dive for food. With man-made lakes and ponds throughout most of the region still ice-free, waterfowl are taking to these sources of open water until the rivers and streams recede and clear.

Common Mergansers — The Common Merganser is a species of diving duck with a primary winter range that, along the Atlantic Coast, reaches its southern extreme in the lower Susquehanna and Potomac watersheds. Recently, many have left the main stem of the muddy rivers to congregate on waters with better visibility at some of the area’s larger man-made lakes.

Common Mergansers Feeding — Common Mergansers dive to locate and capture prey, primarily small fish. During this century, their numbers have declined along the southern edge of their winter range, possibly due to birds remaining to the north on open water, particularly on the Great Lakes. In the lower Susquehanna valley, some of these cavity-nesting ducks can now be found year-round in areas where heavy timber again provides breeding sites in riparian forests. After nesting, females lead their young to wander widely along our many miles of larger rivers and streams to feed.

Several Common Mergansers Intimidating a Male with a Freshly Caught Fish — The behavior of these mergansers demonstrates the stiff competition for food that can result when predators are forced away from ideal habitat and become compressed into less favorable space. On the river, piscivores can feed on the widespread abundance of small fish including different species of minnows, shiners, darters, and more. In man-made lakes stocked for recreational anglers with sunfish, bass, and other predators (many of them non-native), small forage species are usually nonexistent. As a result, fish-eating birds can catch larger fish, but are successful far less often. Seen here are several mergansers resorting to intimidation in an effort to steal a young bass away from the male bird that just surfaced with it. While being charged by the aggressors, he must quickly swallow his oversize catch or risk losing it.

With a hard freeze on the way, the fight for life will get even more desperate in the coming weeks. Lakes will ice over and the struggle for food will intensify. Fortunately for mergansers and other piscivorous waterfowl, high water on the Susquehanna is expected to recede and clarify, allowing them to return to their traditional environs. Those with the most suitable skills and adaptations to survive until spring will have a chance to breed and pass their vigor on to a new generation of these amazing birds.

August 28, 2023September 7, 2023

Shorebirds on the Mud in York County, Pennsylvania

At Lake Redman just to the south of York, Pennsylvania, a draw down to provide drinking water to the city while maintenance is being performed on the dam at neighboring Lake Williams, York’s primary water source, has fortuitously coincided with autumn shorebird migration. Here’s a sample of the numerous sandpipers and plovers seen today on the mudflats that have been exposed at the southeast end of the lake…

Least Sandpiper at Lake Redman, York County, Pennsylvania. — One of a hundred or more Least Sandpipers seen on mudflats at Lake Redman today.

A Semipalmated Plover and a Least Sandpiper at Lake Redman, York County, Pennsylvania. — A Semipalmated Plover and a Least Sandpiper

Pectoral Sandpipers at Lake Redman, York County, Pennsylvania. — Pectoral Sandpipers.

A Pectoral Sandpiper and Least Sandpipers at Lake Redman, York County, Pennsylvania. — A Pectoral Sandpiper and two Least Sandpipers.

A Semipalmated Sandpiper at Lake Redman, York County, Pennsylvania. — A Semipalmated Sandpiper.

A Stilt Sandpiper at Lake Redman, York County, Pennsylvania. — A Stilt Sandpiper feeding.

Stilt Sandpiper consuming an edible at Lake Redman, York County, Pennsylvania. — Stilt Sandpiper consuming an edible.

Stilt Sandpiper at rest at Lake Redman, York County, Pennsylvania. — Stilt Sandpiper at rest.

A Solitary Sandpiper at Lake Redman, York County, Pennsylvania. — A Solitary Sandpiper

A Lesser Yellowlegs at Lake Redman, York County, Pennsylvania. — A Lesser Yellowlegs.

A Greater Yellowlegs at Lake Redman, York County, Pennsylvania. — A Greater Yellowlegs.

Osprey at Lake Redman, York County, Pennsylvania. — Stirring up the shorebird crowd every now and then were several Ospreys, but all would soon be back to the business of feeding in the mud.

An Osprey hovers above shallow water near the mudflats as it searches for fish.

Not photographed but present at Lake Redman were at least two additional species of shorebirds, Killdeer and Spotted Sandpiper—bringing the day’s tally to ten. Not bad for an inland location! It’s clearly evident that these waders overfly the lower Susquehanna valley in great numbers during migration and are in urgent need of undisturbed habitat for making stopovers to feed and rest so that they might improve their chances of surviving the long journey ahead of them. Mud is indeed a much needed refuge.

August 25, 2022August 26, 2022

Photo of the Day

Freshwater Bryozoan Colony (Pectinatella magnifica) and an Eastern Amberwing — Those who happen to come upon it might think this football-sized gelatinous blob is a sure sign of pollution. A freshwater bryozoan (Pectinatella magnifica) colony is composed of a single microscopic founder and its many clones. Despite its bizarre appearance, the “moss animal” is an indicator of good water quality. Pectinatella magnifica is found in clear lentic (still) waters of streams, lakes, and ponds where each individual in the colony feeds by extending a disk of sticky tentacles, called a lophophore, from within its protective sheath to capture single-celled algae (e.g., diatoms) and other plankton. From now through autumn, these bryozoans are reproducing by means of cell-filled statoblasts, durable little seedlike pods which can survive the harsh conditions of both winter and drought and sometimes be transported by animals, wind, or water currents to new areas. Spring weather and/or rehydration of a dried-up lentic pool stimulates a statoblast to open, the cells contained therein then develop into a zooid that attempts to start a new colony by cloning itself.