Thoughts of October in the Lower Susquehanna River Watershed bring to mind scenes of brilliant fall foliage adorning wooded hillsides and stream courses, frosty mornings bringing an end to the growing season, and geese and other birds flying south for the winter.
The autumn migration of birds spans a period equaling nearly half the calendar year. Shorebirds and Neotropical perching birds begin moving through as early as late July, just as daylight hours begin decreasing during the weeks following their peak at summer solstice in late June. During the darkest days of the year, those surrounding winter solstice in late December, the last of the southbound migrants, including some hawks, eagles, waterfowl, and gulls, may still be on the move.
The Rough-legged Hawk (Buteo lagopus), a rodent-eating raptor of tundra, grassland, and marsh, is rare as a migrant and winter resident in the lower Susquehanna valley. It may arrive as late as January, if at all.
During October, there is a distinct change in the list of species an observer might find migrating through the lower Susquehanna valley. Reduced hours of daylight and plunges in temperatures—particularly frost and freeze events—impact the food sources available to birds. It is during October that we say goodbye to the Neotropical migrants and hello to those more hardy species that spend their winters in temperate climates like ours.
During several of the first days of October, two hundred Chimney Swifts remained in this roost until temperatures warmed from the low forties at daybreak to the upper fifties at mid-morning; then, at last, the flock ventured out in search of flying insects. When a population of birds loses its food supply or is unable to access it, that population must relocate or perish. Like other insectivorous birds, these swifts must move to warmer climes to be assured a sustained supply of the flying bugs they need to survive. Due to their specialized food source, they can be considered “specialist” feeders in comparison to species with more varied diets, the “generalists”. After returning to this chimney every evening for nearly two months, the swifts departed this roost on October 5 and did not return.
A Northern Parula lingers as an October migrant along the Susquehanna. This and other specialist feeders that survive almost entirely on insects found in the forest canopy are largely south of the Susquehanna watershed by the second week of October.
The Blackpoll Warbler is among the last of the insectivorous Neotropical warblers to pass through the riparian forests of the lower Susquehanna valley each fall. Through at least mid-October, it is regularly seen searching for crawling insects and larvae among the foliage and bark of Northern Hackberry (Celtis occidentalis) trees near Conewago Falls. Most other warblers, particularly those that feed largely upon flying insects, are, by then, already gone.
The Blue-headed Vireo, another insectivore, is the last of the vireo species to pass through the valley. They linger only as long as there are leaves on the trees in which they feed.
Brown Creepers begin arriving in early October. They are specialist feeders, well-adapted to finding insect larvae and other invertebrates among the ridges and peeling bark of trees like this hackberry, even through the winter months.
Ruby-crowned Kinglets can be abundant migrants in October. They will often behave like cute little flycatchers, but quickly transition to picking insects and other invertebrates from foliage and bark as the weather turns frosty. Some may spend the winter here, particularly in the vicinity of stands of pines, which provide cover and some thermal protection during storms and bitter cold.
Beginning in early October, Golden-crowned Kinglets can be seen searching the forest wood for tiny invertebrates. They are the most commonly encountered kinglet in winter.
The Yellow-bellied Sapsucker, a woodpecker, is an October migrant that specializes in attracting small insects to tiny seeps of sap it creates by punching horizontal rows of shallow holes through the tree bark. Some remain for winter.
The Yellow-rumped Warbler arrives in force during October. It is the most likely of the warblers to be found here in winter. Yellow-rumped Warblers are generalists, feeding upon insects during the warmer months, but able to survive on berries and other foods in late fall and winter. Wild foods like these Poison Ivy berries are crucial for the survival of this and many other generalists.
American Robins are most familiar as hunters of earthworms on the suburban lawn, but they are generalist feeders that rely upon fruits like these Eastern Red Cedar (Juniperus virginiana) berries during their southbound migration in late October and early November each year. Robins remain for the winter in areas of the lower Susquehanna valley with ample berries for food and groves of mature pines for roosting.
Like other brown woodland thrushes, the Hermit Thrush (Catharus guttatus) is commonly seen scratching through organic matter on the moist forest floor in search of invertebrates. Unlike the other species, it is a cold-hardy generalist feeder, often seen eating berries during the southbound October migration. Small numbers of Hermit Thrushes spend the winter in the lower Susquehanna valley, particularly in habitats with a mix of wild foods.
Due to their feeding behavior, Cedar Waxwings can easily be mistaken for flycatchers during the nesting season, but by October they’ve transitioned to voracious consumers of small wild fruits. During the remainder of the year, flocks of waxwings wander widely in search of foods like this Fox Grape (Vitis labrusca). An abundance of cedar, holly, Poison Ivy, hackberry, bittersweet , hawthorn, wild grape, and other berries is essential to their survival during the colder months.
Red-breasted Nuthatches have moved south in large numbers during the fall of 2020. They were particularly common in the lower Susquehanna region during mid-October. Red-breasted Nuthatches can feed on invertebrates during warm weather, but get forced south from Canada in droves when the cone crops on coniferous trees fail to provide an adequate supply of seeds for the colder fall and winter seasons. In the absence of wild foods, these generalists will visit feeding stations stocked with suet and other provisions.
Purple Finches (Haemorhous purpureus) were unusually common as October migrants in 2020. They are often considered seed eaters during cold weather, but will readily consume small fruits like these berries on an invasive Mile-a-minute Weed (Persicaria perfoliata) vine. Purple Finches are quite fond of sunflower seeds at feeding stations, but often shy away if aggressive House Sparrows or House Finches are present.
The need for food and cover is critical for the survival of wildlife during the colder months. If you are a property steward, think about providing places for wildlife in the landscape. Mow less. Plant trees, particularly evergreens. Thickets are good—plant or protect fruit-bearing vines and shrubs, and allow herbaceous native plants to flower and produce seed. And if you’re putting out provisions for songbirds, keep the feeders clean. Remember, even small yards and gardens can provide a life-saving oasis for migrating and wintering birds. With a larger parcel of land, you can do even more.
GOT BERRIES? Common Winterbery (Ilex verticillata) is a native deciduous holly that looks its best in the winter, especially with snow on the ground. It’s slow-growing, and never needs pruning. Birds including bluebirds love the berries and you can plant it in wet ground, even along a stream, in a stormwater basin, or in a rain garden where your downspouts discharge. Because it’s a holly, you’ll need to plant a male and a female to get the berries. Full sun produces the best crop. Fall is a great time to plant, and many garden centers that sell holiday greenery still have winterberry shrubs for sale in November and December. Put a clump of these beauties in your landscape. Gorgeous!
For those of you who dare to shed that filthy contaminated rag you’ve been told to breathe through so that you might instead get out and enjoy some clean air in a cherished place of solitude, here’s what’s around—go have a look.
Northern Flickers have arrived. Look for them anywhere there are mature trees. Despite the fact that flickers are woodpeckers, they often feed on the ground. You’ll notice the white rump and yellow wing linings when they fly away.
The tiny Chipping Sparrow frequently nests in small trees in suburban gardens. Lay off the lawn treatments to assure their success.
Field Sparrows (Spizella fusilla) are a breeding species in abandoned fields where successional growth is underway.
White-throated Sparrows spend the winter in the lower Susquehanna valley. Their numbers are increasing now as waves of migrants pass through on their way north.
Northbound flocks of Rusty Blackbirds (Euphagus carolinus) are currently found feeding in forest swamps along the Susquehanna. Their noisy calls sound like a chorus of squeaking hinges.
Migratory Red-shouldered Hawks are also making feeding stops at area wetlands.
The Palm Warbler (Setophaga palmarum) is easily identified by its tail pumping behavior. Look for it in shrubs along the river shoreline or near lakes and streams. Palm Warblers are among the earliest of the warblers to move through in the spring.
The springtime show on the water continues…
Common Loons will continue migrating through the area during the upcoming month.
Buffleheads are still transiting the watershed.
Horned Grebes are occurring on the river and on local lakes.
Seeing these one-year-old male Hooded Mergansers, the bachelors, wandering around without any adult males or females is a good sign. The adults should have moved on to the breeding grounds and local pairs should be well into a nesting cycle by now. Hatching could occur any day.
Like Hooded Mergansers, Wood Ducks are cavity nesters, but their egg laying, incubation, and hatching often occurs a month or more later than that of the hoodies. Judging by the attentiveness of the drake, this pair of woodies is probably in the egg-laying stage of its breeding cycle right now.
Redheads (Aythya americana) are stopping for a rest on their way north.
In spring, Double-crested Cormorants proceed up the river in goose-like flocks with adult birds like these leading the way.
Hey, what are those showy flowers?
That’s Lesser Celandine (Ficaria verna). It’s often called Fig Buttercup. In early April it blankets stream banks throughout the lower Susquehanna region. If you don’t remember seeing it growing like that when you were younger, there’s a reason. Lesser Celandine is an escape from cultivation that has become invasive. While the appearance is tolerable; it’s the palatability that ruins everything. It’s poisonous if eaten by people or livestock.
The Eastern Spring Beauty (Claytonia virginica) is a dainty native wildflower of riparian forests and other woodlands throughout the lower Susquehanna valley.
The Trout Lily (Erythronium americanum) is beginning to bloom now. It’s a native of the region’s damp forests.
Virginia Bluebells (Mertensia virginica) is not native to the Susquehanna watershed, but neither is it considered invasive. It creates colorful patches in riparian forests.
Dutchman’s Breeches (Dicentra cucullaria) is a strikingly beautiful native wildflower that grows on undisturbed forested slopes throughout the Susquehanna valley.
Wasn’t that refreshing? Now go take a walk.