January 22-28, 2019 (Week 4 of 52): Most of Our Summer Birds Survive Winter Through Mass Migration

The vast majority of our summer birds survive winter by escaping the Buffalo-Niagara Region, migrating to warmer climes well to the south. The longest distance migrants fly 1,500 – 3,000 miles or more to spend winters in the West Indies, Mexico, Central America, and/or South America. These birds are often referred to as neotropical migrants. Shorter distance migrants travel more modest distances of 300 – 1,500 miles to over-winter in the southeastern United States. Migration demands a large investment of energy and poses substantial risks to migrants such as predation, competition with other animals that already occupy wintering areas, exhaustion and death from drowning while crossing large waterbodies, and collisions with buildings and other objects. Regardless, migration has evolved to be the most common strategy for winter survival of birds that nest in the Buffalo-Niagara Region.

Adult and young-of-the-year neotropical migrant songbirds typically depart the Buffalo-Niagara Region in late August and September, in anticipation of the upcoming scarcity of insect prey. This group of birds includes hummingbirds, flycatchers, vireos, thrushes, about 20 species of warblers, and several miscellaneous other species. Most reach their wintering destinations by late September and October, clad in relatively drab plumage (compared to their colorful breeding plumage). Ruby-throated hummingbirds, the smallest bird in our Region, trek as far south as Costa Rica and Panama often including a flight across the Gulf of Mexico of 600 miles or more. Wood thrushes also over-winter in that area, but the veery (another species of thrush) migrates considerably further south – to Brazil and beyond. One of the relatively common warblers that nests in our region, the American redstart, is currently residing in the West Indies and from southern Mexico south to Ecuador and Guyana. The Blackburnian warbler travels even further south, with some reaching Venezuela, Colombia, and Peru. Our beloved Baltimore orioles over-winter primarily from southern Mexico to Colombia. Many scarlet tanagers travel well into South America, as far south as Peru and Bolivia. Still, bobolinks take the prize for furthest songbird migration with some traveling 4,000 miles to winter as far south as Paraguay and Argentina. It is noteworthy that neotropical migrant birds spend more months in their wintering areas than in their breeding areas (such as our Region), so it is irrational to claim them as “our” birds.

Shorter-distance migrants, most of which are destined for southeastern United States, typically linger in our Region well into fall. This group includes many of the ducks and rails that nest in our area, as well as some shorebirds and hawks. While many of our nesting songbirds are neotropical migrants, a handful of species winter within the continental United States, including northern flicker, eastern phoebe, tree swallow, eastern bluebird, American robin, eastern towhee, song sparrow, and red-winged blackbird.   Most of the above-listed species are currently spending winter months in areas from Arkansas to Virginia and south to the Gulf of Mexico.

While most of our summer birds migrate south for winter, a fair number remain in the Region as year-round residents, migrating little if any. Examples include wild turkey, red-tailed hawk (although some individuals migrate), mourning dove, eastern screech owl, downy woodpecker, black-capped chickadee, and northern cardinal. These year-round residents are joined by winter visitants that include several species of ducks, tundra swans, over a dozen species of gulls, several winter raptor species, northern shrikes, horned larks, snow buntings, red-breasted nuthatches, American tree sparrows, and dark-eyed juncos. In some years, large numbers of “winter finches” and other irruptive species (e.g., pine siskins, common redpolls, evening grosbeaks, white-winged and red crossbills) join the mix.

These over-wintering birds exhibit a variety of adaptations that help them survive food scarcity and cold temperatures during western New York winters. They must produce enough metabolic heat from food or fat reserves to offset heat and energy lost to their cold surroundings. That is particularly challenging for small-bodied songbirds that are especially prone to heat loss. Fortunately, feathers provide these and other birds with an excellent layer of insulation. Species that over-winter in northern latitudes, such as the black-capped chickadee and American tree sparrow, may add up to 50 percent more feather mass during their fall molt. Birds also fluff out their feathers when cold, which bolsters their insulating value by trapping air in tiny pockets near the skin. The legs of snowy owls and rough-legged hawks are feathered all the way down to their talons to provide extra insulation. Some wintering birds will draw up one leg beneath their feathers when perched to reduce exposure. In addition, some species add considerable body fat before winter sets in by feeding heavily when food is abundant during fall. That extra layer of fat affords additional insulation and provides essential energy reserves to help maintain body temperature.

On the surface, one might think that ducks and other waterbirds which spend much of the winter exposed to near-freezing water temperatures would be at severe risk of frostbite to their exposed legs and feet, and of losing excessive amounts of body heat to the cold water. Fortunately, these birds suffer no ill effect as they are well adapted to those harsh conditions. The exposed parts of their legs, from the knees down, consist mostly of resilient bones and tendons protected by thick scales. Furthermore, these birds have an outstanding physiologic adaptation that helps to minimize heat loss through legs and feet. They utilize countercurrent blood flow associated with dense networks of veins that are in close contact with arteries going out to the legs. Warm blood going out to the legs heats cold blood coming in from the legs and returning to the animal’s core. Cold blood coming in from the legs cools warm blood going out to the legs. In this way, legs and feet are constantly cold but warm enough to keep tissues alive. Moreover, less body heat is lost by reducing the temperature gradient between blood in the veins and cold water temperatures.

One the most remarkable winter bird survival adaptations is the ability of black-capped chickadees and a few other species to lower their body temperatures at night by up to 20° F in a controlled state of torpor, sometimes called regulated hypothermia. In that state, they become temporarily unconscious but recoup a considerable energy savings. At dawn, chickadees raise their body temperature back to normal and regain consciousness so that they can feed. Other songbird species, such as the American goldfinch, shiver constantly as they sleep to generate body warmth. While effective at generating body heat, that approach uses considerably more precious energy.

The most common adaptations exhibited by over-wintering birds are behavioral changes focused on improving feeding efficiently and conserving energy. Some of these behavioral adjustments start in autumn, with most birds feeding actively during that period of abundant food resources to build up fat reserves. In addition, some species cache food for consumption during lean winter months. For example, white-breasted nuthatches, red-headed woodpeckers, and blue jays cache seeds and other foods in crevices and under loose bark. Great horned owls cache unfinished prey for later consumption. Once cold weather sets in, the most important thing for a bird to do is to consume enough food during the day to maintain fat reserves. As soon as dawn breaks, birds begin searching for energy-rich foods such as fruits and seeds. Some birds flock together to optimize their search efforts for food. Large flocks of wild turkeys forage for seeds and fruits in agricultural fields and other areas. Mourning doves and dark-eyed juncos often travel in small to medium sized flocks. Mixed species flocks of chickadees, nuthatches, tufted titmice, and woodpeckers search for insect prey, in egg or pupa stage. Large flocks of snow buntings, sometimes consisting of 100 or more birds, can be seen foraging within open fields. Winter waterfowl, such as common mergansers and common goldeneye, feed on fish, mollusks, crustaceans, and aquatic plants in open water areas such as the Niagara River. Bald eagles hunt fish in those same open water areas.

To conserve energy, over-wintering birds seek sheltered areas for use as night-time roosts, such as conifers and other evergreens (lone trees and groves), tree cavities, bird houses, and dense thickets. Such areas provide greater thermal shelter from wind-chill and are often located close to feeding areas, further helping these birds conserve critical energy reserves. Woodpeckers excavate cavities in late autumn that serve as winter roost sites. Some songbirds (e.g., eastern bluebirds, black-capped chickadees, white-breasted nuthatches, tufted titmice) roost together in tree cavities, woodpecker holes, and bird houses to capitalize on shared body heat. During frigid weather, ruffed grouse and snow buntings are known to fly into snow drifts to take advantage of the insulative values of snow. On sunny winter days, birds will often perch in exposed areas to capitalize on solar warming.

One way that people can help over-wintering birds survive the challenges of food scarcity and cold temperatures during Buffalo-Niagara winters is to establish bird feeding stations. Bird feeders, when properly maintained, can help individual birds survive and can raise the songbird carrying capacity (i.e., the number of individuals that can be supported) in the immediate area around the feeding station. It is best to provide a good variety of seed types, as well as energy-rich suet and water (ideally using a heated bird bath). Black oil sunflower and nyjer (AKA thistle) are the best seeds for attracting winter finches, evening grosbeaks, and red-breasted nuthatches. Consider placing white millet or other small seeds on the ground to attract ground-feeding birds such as dark-eyed juncos, American tree sparrows, and mourning doves. In addition to helping birds survive, bird feeding is a great way to attract a diversity and abundance of songbirds for close observation and enjoyment (including species in your neighborhood that you might otherwise not see).  It helps to bring them out of the woodwork, so to speak, especially during cold and snowy weather. If a feeding station is not a good option for you, visit a local nature center (see the 2nd to last column in the tables of nature viewing sites found under the “B-N Region & Sites” tab on this web page).

Below are highlights of what you can expect to find outdoors in the Buffalo-Niagara Region this week. Those in bold/italics are new or substantially revised highlights to watch for this week. Check out the list of 300 publicly accessible sites at https://bnnatureblog.com/nature-sites/site-lists/alphabetical-list/ to find areas to explore in your neighborhood and throughout the Buffalo-Niagara Region.

Average Sunrise/Sunset (Day Length):

  • 7:37 AM/5:18 PM EST (9 Hours, 41 Minutes)
  • 0 Hours, 40 minutes of daylight longer than at Winter Solstice

Typical Weather:

  • Normal High Temperature: 30.9° F  Normal Low Temperature: 17.9° F
  • On average, the lowest normal temperature of the year occurs during this week.

Lake, Pond, Stream & Wetland Conditions:

  • The Lake Erie water temperature off Buffalo cooled to 32°F and the Lake Ontario water temperature off Greece (Monroe County) cooled to 36°F as of January 25, 2019.
  • Water levels in most interior wetlands and vernal pools are near seasonal highs after a long period of normal or better precipitation and greatly reduced evapotranspiration rates.
  • Similarly, water levels in most ponds are close to seasonal highs.
  • Inland ponds, wetlands, and vernal pools are mostly ice-covered.
  • Streams are mostly ice and snow-covered.

Fungi:

  • With the onset of winter, most fungal fruiting bodies (e.g., mushrooms, bracket fungi) have been extinguished. The fungal “roots” (mycelium network) will survive the winter and produce new fruiting bodies during the appropriate season next year. Interestingly, fruiting bodies of some species of fungi (e.g., oyster mushrooms) remain viable during the winter and may disseminate spores during warm periods or in early spring.

Ferns and Grasses/Sedges/Rushes:

  • Freezing temperatures during late autumn killed remnant grass, sedge, and rush stems. The roots of these perennial plants will survive and sprout next spring.

Wildflowers:

  • Wildflower stems died back following late fall freezing temperatures. Roots and rhizomes of perennial wildflowers will survive and sprout next spring. Seeds of annual wildflowers will do the same.

Trees and Shrubs:

  • Some American beech trees will hold their dead leaves over most of the winter.
  • A few native shrubs and vines continue to provide fruit (soft mast) that is an important winter food source for a variety of birds and mammals: cranberry viburnum, staghorn sumac, and swamp rose.
  • In addition, one non-native species, multiflora rose, provides fruit consumed by wildlife.

Insects & Other Invertebrates:

  • Freezing temperatures during late autumn killed most adult insects and other invertebrates that have not migrated or entered hibernation. The vast majority of insect species in our Region over-winter as eggs or larvae/nymphs, although some species over-winter as adults.

Fish:

  • Steelhead continue to occur in Great Lakes tributaries and the Lower Niagara River at this time. Spawning does not occur until late winter and early spring. Steelhead are an anadromous form of rainbow trout that spawn in streams but live most of their lives in Lakes Erie and Ontario. All forms of rainbow trout are native to Pacific coast watersheds.
  • Brown trout continue to occur in Great Lakes tributaries and the Lower Niagara River. Spawning typically occurs from late October to December in these tributaries. Brown trout were introduced from Europe.

Amphibians & Reptiles:

  • With the onset of winter weather, essentially all amphibians and reptiles are now hibernating.

Water & Shore Birds, Gulls & Terns:

  • The annual buildup of “sea ducks” and similar waterbirds that over-winter in the Great Lakes and Niagara River is near its peak with impressive numbers of greater scaup, lesser scaup, canvasback, redhead, common goldeneye, bufflehead, white-winged scoter, surf scoter, black scoter, long-tailed duck, common merganser, and red-breasted merganser.
  • Watch for winter resident tundra swans congregating in open waters along the upper Niagara River (especially off Beaver Island, Buckhorn, and Niagara Falls State Parks).
  • This continues to be a good time to look for purple sandpipers feeding in rocky habitats above Niagara Falls.
  • This continues to be an excellent time to watch for rare species of gulls such as Franklin’s, little, black-headed, California, Iceland, Thayer’s, lesser black-backed, Glaucous, Sabine’s, and black-legged kittiwake among more common species such as Bonaparte’s and greater black-backed gulls. Such rarities add to the remarkable diversity of gull species – 19 species total – that have been observed along the Niagara River and bordering Great Lakes. The peak time is typically between mid-November and mid-January.

Birds of Prey:

  • Bald eagles can be found along the upper and lower Niagara River where good numbers are over-wintering.
  • Winter resident raptors will continue to occur in the region, especially in areas with extensive open grassland habitat, including northern harriers, rough-legged hawks, snowy owls, short-eared owls, and long-eared owls.
  • Snowy owls are frequently found along Great Lakes shorelines, such as the Buffalo waterfront, where they feed on ducks and other waterbirds.
  • Great horned owls have started to pair-up, form pair bonds, and establish nesting territories. Listen for their vocalizations, especially near sunset and sunrise, including duets consisting of a female and male singing nearly in unison (with male calls noticeably lower in pitch than those of the female).

Upland Game Birds:

  • Watch for wild turkey flocks in farm fields, along forest edges, and near bird feeders.

Songbirds:

  • Watch bird feeders for the following songbird species that are part of this year’s “winter finch” irruption: purple finch, red crossbill, white-winged crossbill, common redpoll, hoary redpoll, pine siskin, evening grosbeak, and red-breasted nuthatch. Nyjer (AKA thistle) and black oil sunflower are the best seeds for attracting these species.
  • Bird feeders are also excellent locations to watch for arrivals of more typical migrant and over-wintering feeder birds such as dark-eyed junco, white-throated sparrow, song sparrow, and American tree sparrow.   Place seed such as white millet in ground feeders or directly on the ground to attract many of these migrants.
  • Bird feeders will continue to be active with year-round resident birds such as mourning dove, downy woodpecker, hairy woodpecker, red-bellied woodpecker, black-capped chickadee, tufted titmouse, white-breasted nuthatch, blue jay, northern cardinal, house finch, and American goldfinch.
  • Good tips for feeding birds are available from the Cornell Lab of Ornithology, online at http://www.birds.cornell.edu/AllAboutBirds/notes/BirdNote01_WinterFeeding.pdf
  • If you don’t have a feeder of your own, consider visiting a local nature center (see the 2nd to last column in the tables of nature viewing sites found under the “B-N Region & Sites” tab on this web page).
  • The northern shrike, a predatory passerine that breeds in Canada and Alaska, will continue to occur in the Region. Watch for them on prominent perches overlooking open and brushy habitats.
  • While most American robins have migrated south, small to medium sized flocks may still be encountered.
  • Small flocks of horned larks and Lapland longspurs and large flocks of snow buntings can be found in open farmland and other tundra-like habitats by snow buntings.
  • To stay abreast of bird sightings in the region, consult eBird, Genesee Birds, and Dial-a-Bird (see the “Resources” tab on this web page for more details).

Mammals:

  • Resident species of cave bats (big brown, little brown, and eastern pipistrelle [tri-colored] bats), woodchucks, and meadow & woodland jumping mice continue to hibernate. These species are true hibernators.
  • False hibernators such as the raccoon and striped skunk are mostly dormant, other than occasional feeding forays during relatively warm weather. In contrast, Virginia opossums stay active all winter other than brief denning during particularly cold weather.
  • Most eastern chipmunks are in a state of torpor. In this condition, which is not a true form of hibernation, chipmunks sleep but arouse frequently to feed on hoarded food. They may forage aboveground during mild weather.
  • Gray squirrels and southern flying squirrels continue to actively forage for cached acorns and other available food, other than during extremely cold periods. Similarly, red squirrels feed from middens of pine and spruce cones.
  • Watch bird feeders after dark for nocturnal visits by southern flying squirrels.
  • Some white-footed mice and deer mice spend the winter in nests they built in woodpecker holes, bird houses, and squirrel leaf-nests. Some rehab old bird nests by adding a roof and insulation.
  • Beavers continue to feed on cut branches they cached in shallow water near their lodges during the fall, and muskrats do the same with herbaceous vegetation cached near their lodges.
  • Ermine (AKA short-tailed weasel) have molted from brown to white pelage for winter months.
  • Black bears, an uncommon species in the Buffalo-Niagara Region but increasingly common to our south, are in carnivorous lethargy. In this state, which is not a true form of hibernation, a bear’s heart rate is significantly lowered but body temperature falls only about 10°F (substantially smaller drop than for true hibernators).
  • White-tailed deer bucks typically shed antlers between mid December and mid February in the Buffalo-Niagara Region.

Be sure to find an opportunity to get outside this week to discover signs of the season.

Chuck Rosenburg

One thought on “January 22-28, 2019 (Week 4 of 52): Most of Our Summer Birds Survive Winter Through Mass Migration

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