A Visit to a Beaver Pond

To pass the afternoon, we sat quietly along the edge of a pond created recently by North American Beavers (Castor canadensis).  They first constructed their dam on this small stream about five years ago.  Since then, a flourishing wetland has become established.  Have a look.

A Beaver Pond
Vegetation surrounding the inundated floodplain helps sequester nutrients and sediments to purify the water while also providing excellent wildlife habitat.
A beaver lodge.
The beaver lodge was built among shrubs growing in shallow water in the middle of the pond.
Woolgrass in a beaver pond.
Woolgrass (Scirpus cyperinus) is a bulrush that thrives as an emergent and as a terrestrial plant in moist soils bordering the pond.
A male Common Whitetail dragonfly keeping watch over his territory.
A male Common Whitetail dragonfly keeping watch over his territory.
A Twelve-spotted Skimmer perched on Soft Rush.
A Twelve-spotted Skimmer perched on Soft Rush.
A Blue Dasher dragonfly seizing a Fall Field Cricket (Gryllus pennsylvanicus).
A Blue Dasher dragonfly seizing a Fall Field Cricket (Gryllus pennsylvanicus).
A Spicebush Swallowtail visiting Cardinal Flower.
A Spicebush Swallowtail visiting a Cardinal Flower.
Green Heron
A Green Heron looking for small fish, crayfish, frogs, and tadpoles.
A Green Heron stalks potential prey.
The Green Heron stalking potential prey.
A Wood Duck feeding on Lesser Duckweed.
A Wood Duck feeding on the tiny floating plant known as Lesser Duckweed (Lemna minor).
A Least Sandpiper feeding along the muddy edge of a beaver pond.
A Least Sandpiper poking at small invertebrates along the muddy edge of the beaver pond.
Solitary Sandpiper
A Solitary Sandpiper.
A Solitary Sandpiper testing the waters for proper feeding depth.
A Solitary Sandpiper testing the waters for proper feeding depth.
Pectoral Sandpiper
A Pectoral Sandpiper searches for its next morsel of sustenance.
A Sora rail in a beaver pond.
The Sora (Porzana carolina) is a seldom seen rail of marshlands including those created by North American Beavers.  Common Cattails, sedges, and rushes provide these chicken-shaped wetland birds with nesting and loafing cover.

Isn’t that amazing?  North American Beavers build and maintain what human engineers struggle to master—dams and ponds that reduce pollution, allow fish passage, and support self-sustaining ecosystems.  Want to clean up the streams and floodplains of your local watershed?  Let the beavers do the job!

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.
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.

Maximum Variety

You’ll want to go for a walk this week.  It’s prime time to see birds in all their spring splendor.  Colorful Neotropical migrants are moving through in waves to supplement the numerous temperate species that arrived earlier this spring to begin their nesting cycle.  Here’s a sample of what you might find this week along a rail-trail, park path, or quiet country road near you—even on a rainy or breezy day.

The Black-throated Blue Warbler is one of more than two dozen species of warblers passing through the Lower Susquehanna River Watershed right now.  Look for it in the middle and bottom branches of deciduous forest growth.
The Veery and other woodland thrushes sing a melodious song.  Veerys remain through the summer to nest in damp mature deciduous forests.
The American Redstart, this one a first-spring male, is another of the variety of warblers arriving now.  Redstarts nest in deciduous forests with a dense understory.
Adaptable inquisitive Gray Catbirds are here to nest in any shrubby habitat, whether in a forest or a suburban garden.
Blue-gray Gnatcatchers (Polioptilia caerulea) arrive in April, so they’ve been here for a while.  They spend most of their time foraging in the treetops.  The gnatcatcher’s wheezy call alerts the observer to their presence.
Look way up there, it’s a pair of Blue-gray Gnatcatchers building a nest.
The Eastern Phoebe, a species of flycatcher, often arrives as early as mid-March.  This particular bird and its mate are already nesting beneath a stone bridge that passes over a woodland stream.
Orchard Orioles (Icturus spurius) are Neotropical migrants that nest locally in habitats with scattered large trees, especially in meadows and abandoned orchards.
In the lower Susquehanna region, the Baltimore Oriole is a more widespread breeding species than the Orchard Oriole.  In addition to the sites preferred  by the latter, it will nest in groves of mature trees on farms and estates, in parks, and in forest margins where the canopy is broken.
The Warbling Vireo (Vireo  gilvus) nests in big trees along streams, often sharing habitat with our two species of orioles.
Eastern Towhees arrive in numbers during April.  They nest in thickets and hedgerows, where a few stragglers can sometimes be found throughout the winter.
The Yellow-breasted Chat (Icteria virens) is a migrant from the tropics that sometimes nests locally in thorny thickets.  Its song consists of a mixed variety of loud phrases, reminding the listener of mimics like catbirds, thrashers, and mockingbirds.
Thickets with fragrant blooms of honeysuckle and olive attract migrating Ruby-throated Hummingbirds.  Look for them taking a break on a dead branch where they can have a look around and hold on tight during gusts of wind.
The Eastern Kingbird, a Neotropical flycatcher, may be found near fields and meadows with an abundance of insects.  In recent years, high-intensity farming practices have reduced the occurrence of kingbirds as a nesting species in the lower Susquehanna valley.  The loss of pasture acreage appears to have been particularly detrimental.
Savannah Sparrows (Passerculus sandwichensis) can be found in grassy fields throughout the year.  Large parcels that go uncut through at least early July offer them the opportunity to nest.
Male Bobolinks have been here for just more than a week.  Look for them in alfalfa fields and meadows.  Like Savannah Sparrows, Bobolinks nest on the ground and will lose their eggs and/or young if fields are mowed during the breeding cycle.
Cattail marshes are currently home to nesting Swamp Sparrows.  Wetlands offer an opportunity to see a variety of unique species in coming weeks.
Shorebirds like this Solitary Sandpiper will be transiting the lower Susquehanna basin through the end of May.  They stop to rest in wetlands, flooded fields, and on mudflats and alluvial islets in the region’s larger streams.  Many of these shorebirds nest in far northern Canada.  So remember, they need to rest and recharge for the long trip ahead, so try not to disturb them.

The Layover

After nearly a full week of record-breaking cold, including two nights with a widespread freeze, warm weather has returned.  Today, for the first time this year, the temperature was above eighty degrees Fahrenheit throughout the lower Susquehanna region.  Not only can the growing season now resume, but the northward movement of Neotropical birds can again take flight—much to our delight.

A rainy day on Friday, May 8, preceded the arrival of a cold arctic air mass in the eastern United States.  It initiated a sustained layover for many migrating birds.

Bobolinks (Dolichonyx oryzivorus) in flocks of as many as fifty birds gathered in weedy meadows and alfalfa fields for the week.
A Bobolink sheltering in a field of Sweet Vernal Grass (Anthoxanthum odoratum) during the rain on Friday, May 8th.
Two of seven Solitary Sandpipers (Tringa solitaria) in a wet field on Friday, May 8.  Not-so-solitary after all.
Grounded by inclement weather, Rose-breasted Grosbeaks (Pheucticus ludovicianus) made visits to suburban bird feeders in the lower Susquehanna valley.  (Charles A. Fox image)

Freeze warnings were issued for five of the next six mornings.  The nocturnal flights of migrating birds, most of them consisting of Neotropical species by now, appeared to be impacted.  Even on clear moonlit nights, these birds wisely remained grounded.  Unlike the more hardy species that moved north during the preceding weeks, Neotropical birds rely heavily on insects as a food source.  For them, burning excessive energy by flying through cold air into areas that may be void of food upon arrival could be a death sentence.  So they wait.

A freeze warning was issued for Saturday morning, May 9, in the counties colored dark blue on the map.  (NOAA/National Weather Service image)
This radar image from 3:28 A.M. Saturday morning, May 9, indicates a minor movement of birds in the Great Plains, but there are no notable returns shown around weather radar sites in the freeze area, including the lower Susquehanna valley.  (NOAA/National Weather Service image)
To avoid the cold wind on Saturday, May 9, this Veery was staying low to the ground within a thicket of shrubs in the forest.
This Black-throated Blue Warbler avoided the treetops and spent time in the woodland understory.  He sang not a note.  With birds conserving energy for the cold night(s) ahead, it was uncharacteristically quiet for the second Saturday in May.
A secretive Northern Waterthrush (Parkesia noveboracensis) remained in a wetland thicket.
A Scarlet Tanager (Piranga olivacea) tucks his bill beneath a wing and fluffs-up to fight off the cold during a brief May 9th snow flurry.
In open country, gusty winds kept Eastern Kingbirds, a species of flycatcher, near the ground in search of the insects they need to sustain them.
Horned Larks are one of the few birds that attempt to scratch out an existence in cultivated fields.  The application of herbicides and the use of systemic insecticides (including neonicotinoids) eliminates nearly all weed seeds and insects in land subjected to high-intensity farming.  For most birds, including Neotropical migrants, cropland in the lower Susquehanna valley has become a dead zone.  Birds and other animals might visit, but they really don’t “live” there anymore.
Unable to find flying insects over upland fields during the cold snap, swallows concentrated over bodies of water to feed.  Some Tree Swallows may have abandoned their nests to survive this week’s cold.  Fragmentation of habitats in the lower Susquehanna valley reduces the abundance and diversity of natural food sources for wildlife.  For birds like swallows, events like late-season freezes, heat waves, or droughts can easily disrupt their limited food supply and cause brood failure.
For this Barn Swallow, attempting to hunt insects above the warm pavement of a roadway had fatal consequences.
Another freeze warning was issued for Sunday morning, May 10, in the counties colored dark blue on this map.  (NOAA/National Weather Service image)
This radar image from 4:58 A.M. Sunday morning, May 10, again indicates the absence of a flight of migrating birds in the area subjected to freezing temperatures.  Unlike migrants earlier in the season, the Neotropical species that move north during the May exodus appear unwilling to resume their trek during freezing weather.  (NOAA/National Weather Service image)
On Sunday evening, May 10, a liftoff of nocturnal migrants is indicated around radar sites along the Atlantic Coastal Plain and, to a lesser degree, in central Pennsylvania.  The approaching rain and yet another cold front quickly grounded this flight.
After a one day respite, yet another freeze warning was issued for Tuesday morning, May 12.  (NOAA/National Weather Service image)
And again, no flight in the freeze area.  (NOAA/National Weather Service image)
The freeze warning for Wednesday morning, May 13.  (NOAA/National Weather Service image)
And the nocturnal flight: heavy in the Mississippi valley and minimal in the freeze area.  (NOAA/National Weather Service image)
The freeze on Thursday morning, May 14.  (NOAA/National Weather Service image)
At 3:08 A.M. on May 14th, a flight is indicated streaming north through central Texas and dispersing into the eastern half of the United States, but not progressing into New England.  (NOAA/National Weather Service image)
The flight at eight minutes after midnight this morning.  Note the stormy cold front diving southeast across the upper Mississippi valley.  As is often the case, the concentration of migrating birds is densest in the warm air ahead of the front.  (NOAA/National Weather Service image)

Today throughout the lower Susquehanna region, bird songs again fill the air and it seems to be mid-May as we remember it.  The flights have resumed.

Indigo Bunting numbers are increasing as breeding populations arrive and migrants continue through.  Look for them in thickets along utility and railroad right-of-ways.
Common Yellowthroats and other colorful warblers are among the May migrants currently resuming their northward flights.
The echoes of the songs of tropical birds are beginning to fill the forests of the lower Susquehanna watershed.  The flute-like harmonies of the Wood Thrush are among the most impressive.
Ovenbirds are ground-nesting warblers with a surprisingly explosive song for their size.  Many arrived within the last two days to stake out a territory for breeding.  Listen for “teacher-teacher-teacher” emanating from a woodland near you.