Great Gray Owls

Burlington birders were abuzz this week with Tuesday’s exciting discovery of a Great Gray Owl at the home of Marshall and Sue London. Although nearly 100 people were lucky enough to see the bird, thanks to the Londons’ welcoming hospitality, its appearance was fleeting. Sometime during the overnight hours, the owl departed the London’s back yard. Whether or not it surfaces again in the area, this bird left an enduring mark on the humans who witnessed its stately presence.

Great Gray Owls are a bird of dense, northern boreal forests, rarely venturing south of Canada into the northeastern U.S. during winters when their rodent prey is scarce. Superficially similar to, and belonging to the same genus as, our common Barred Owl, this species is distinguished by its larger size, bright yellow eyes, and black-and-white “bow tie” below the gray facial disc. Southward invasions, or “irruptions”, occur sporadically and can involve substantial numbers of birds. In Vermont, only eight Great Gray Owls have been confirmed previous to this one, and three of those appeared during the winter of 1984. One bird remained in St. Johnsbury for almost seven weeks. An infamous Great Gray that lingered on a farm in Massachusetts for two months in 1973 attracted more than 3,000 birders!

Although the Great Gray Owl cuts an imposing and massive figure, its bulk is made up largely of feathers, which allow it to withstand the bitter cold of boreal winters. The species’ body mass is considerably smaller than that of two other large, northern owls—the Great Horned and Snowy. Preying primarily on voles in the eastern part of its range, the Great Gray uses its superior hearing to locate rodents beneath the snowpack, plunging through the surface to seize them. An apparent scarcity of red-backed voles in eastern Canada this winter probably accounts for the rare and unexpected appearance of this individual in Vermont, as well as the steady stream of Barred Owls that have been reported statewide in recent months.

Although a distant second to the Burlington owl, waterfowl and gulls also provided birding interest during the past week. Snow Geese have begun their return journey to Arctic nesting grounds, with reports of 100 off the mouth of Otter Creek, 515 in Cornwall, and 500 off Grand Isle. Canvasbacks continue to make an unusually good showing on Lake Champlain, with several flocks of up to 23 birds off Charlotte, Colchester, and the islands. Single Redheads were observed in Colchester and off Allen Point, while the male Tufted Duck remained off the Colchester Railroad Causeway, where it has been reliably present for several weeks.

Although gulls pose an identification nemesis for many birders, careful searching of Lake Champlain yielded three rare species last week. A third-winter Lesser Black-backed Gull in Kellogg Bay on March 22^nd was the most unusual. This European stray has only been confirmed in Vermont on six previous occasions, the last in January of 2001. More regular, but still noteworthy, were seven Iceland and two Glaucous Gulls between Kellogg Bay and Basin Harbor. These Arctic-breeding species are probably more common in winter than records indicate, but may be overlooked by many birders.

Other highlights included a remarkable concentration of 25 Bald Eagles scattered along the Lake Champlain ice and trees between Kellogg Bay and Basin Harbor on March 22^nd. American Woodcocks are now engaging in their spectacular aerial courtship displays, with the first report coming from Shelburne. The past week’s consistent north winds and cold temperatures kept most spring landbird migrants to our south, but the season’s first Eastern Phoebes appeared in Starksboro on the 18^th. The next push of southerly winds should bring a pulse of early migrants, but for now enjoy the lingering Bohemian Waxwings, Pine Grosbeaks and Common Redpolls that continue to be reported around Vermont.

You can explore all the birds reported last week in Vermont and add your own sightings at Vermont eBird.

-by Chris Rimmer

VCE Scientists in the News

Two news articles over the weekend highlighted VCE scientists. Roz Renfew's work in Bolivia working with Bobolinks was featured in a NY Times article on how to be a bird-friendly consumer. Dan Lambert was quoted in an article about the lights out campaign that took place Saturday from 8-9pm to bring attention to our energy use and light pollution that disorients migrating birds.

Great Gray Owl in Burlington, VT

A crowd armed with binoculars and cameras gathered on Summit Street in Burlington. Word spread quickly about an unusual visitor. "It's exceptionally rare," said Allan Strong, an Assistant Professor at UVM's Rubenstein School of Environment and Natural Resources. Perched high in a pine tree-- a great gray owl.

Read the rest of the story at WCAX...

View all the Great Gray Owl records on Vermont eBird.

Not Just Your Ordinary Chickadee

It is hard to imagine a bird feeding station anywhere in Vermont, or the Northeast for that matter, without a lively band of Black-capped Chickadees. Imagine, however, the surprised delight of a homeowner on the Newfane/Wardsboro town line, where a northern, brown-capped relative of our familiar species has regularly visited feeders throughout this winter.

The Boreal Chickadee that has graced this southern Vermont residence on a daily basis, in company with a flock of Black-cappeds, is a long way from home. This species is one of the few North American songbirds whose breeding range is almost entirely restricted to the cold coniferous forests of Canada and the adjacent U.S. In Vermont, no records of nesting are known outside the Northeast Kingdom.

Boreal Chickadees differ from their more common Black-capped relatives by a brown cap, bright chestnut sides, and browner back. Their call, while similar to the Black-cappeds, is a more wheezy, drawling chick-a-dee. Once learned, it is quite easy to distinguish the two species, which often forage together. Boreal Chickadees tend to be less vocal and more retiring than Black-cappeds, and less inquisitive to humans. They feed primarily on tree-infesting insects and spiders, their pupae and eggs, some fruit, and the seeds of conifers and birches. Like most chickadees, this species regularly hides food, principally insect larvae and seeds. Such storage is probably vital for winter survival in the harsh boreal environment. Nesting takes place in cavities excavated in a dead tree snag or stump, usually in May and June.

The appearance of a Boreal Chickadee in southern Vermont, while very unusual, is not without precedent. The species is known to undergo periodic southward migrations, or irruptions, which may be related to shortages of conifer seeds, a crucial winter food. The Newfane/Wardsboro bird is the third known record so far in this century – in late December of 2000, a Boreal Chickadee briefly visited a Brattleboro feeder, while during January of 2006 a bird regularly appeared at a Bennington feeding station. Birders should keep a watchful eye for these southern strays at feeders!

Other Sightings

Waterfowl dominated the past week’s birding highlights, as is usual in March. The Colchester railroad causeway continues to be a reliable spot, featuring thousands of diving ducks on the open water. Among these were two rarities – a male Barrow’s Goldeneye and the male Tufted Duck that has been present for several weeks. Also present were Canvasbacks, Redheads, Ring-necked Ducks, hundreds of Greater and Lesser Scaup, a single Long-tailed Duck, and many Bufflehead and Common Goldeneyes. Dabbling ducks are beginning to appear as well. Reports included Wood Ducks from scattered locations, Gadwalls, American Wigeon, Northern Pintail, and Green-winged Teal. Lake Champlain also hosted several early migrant Horned Grebes, with 7 off Charlotte on March 10^th and a single bird off Shelburne Point on the 13^th.

Mid-March is a transition time for landbirds in Vermont. Winter specialties are still present, as evidenced by numerous statewide reports of Northern Shrikes, Bohemian Waxwings, Pine Grosbeaks, and Common Redpolls. A month from now, these species will all likely have departed for their Canadian breeding grounds. They are joined here now by early spring migrants that are being pushed northward by lengthening days and southerly winds. Welcome returnees during the past week included American Kestrels, Killdeer, an American Woodcock in West Brattleboro, Eastern Bluebirds inspecting next boxes, and Song Sparrows at several locations.

You can explore all the birds reported last week in Vermont and add your own sightings at Vermont eBird.

-by Chris Rimmer

Wood Ducks

Despite the deep snow pack across much of Vermont, spring migration is chugging along. The open water on Lake Champlain is attracting rafts of waterfowl, with at least 18 species observed this week, including the year’s first Wood Ducks.

Considered by many to be the most beautiful North American waterfowl, the Wood Duck (Aix sponsa) is also one of the earlier nesting species in the Northeast. After wintering in the southern half of the U.S., this medium-sized duck returns to Vermont in mid-March, frequenting open water on larger lakes and rivers until their preferred swamps, beaver ponds, and slow-moving streams thaw. Most individuals pair up in January, which explains why spring sightings are typically of mated pairs already looking for suitable breeding sites.

Wood Ducks are one of the few North American waterfowl species to nest in trees. Nest sites include natural cavities, old Pileated Woodpecker holes, and nest boxes, usually within close proximity to water. Surprisingly, however, successful nests have been found up to one mile away from water bodies. Perhaps even more surprising is the height at which they will nest—from just a few feet above the water to as high as 200 feet above the forest floor. The female alone incubates from six to 15 eggs. Within a day of hatching, the chicks leap from their nest cavity and, if they haven’t landed in water, follow their mother to the nearest water source. Click here to view a remarkable video of a Wood Duck brood leaving their nest site and gently falling 35 feet to the forest floor.

Although Wood Ducks will readily use nest boxes, placing too many boxes in a single location frequently leads to “dump” nests. This is when many female Wood Ducks (and other cavity nesting waterfowl) deposit eggs in each other’s nests, often leading to clutches of up to 40 eggs that cannot be incubated successfully. To avoid creating this situation, place only one or two boxes per pond or wetland and locate them out of sight of each other.

Other Sightings
Waterfowl sightings dominated the bird reports this week, including a pair of Wood Ducks at the Colchester railroad causeway, along with Redheads. Tufted Duck, White-winged Scoter, Northern Pintail, Green-winged Teal, Greater and Lesser Scaup, Common Goldeneye, and Red-breasted Mergansers were observed at the South Hero causeway. Further south at the Charlotte Town Beach were a Common Loon and Horned Grebe. Other migrants included the first reports of Killdeer in Pownal and Brattleboro, and five American Woodcock in Bennington.

You can explore all the birds reported last week in Vermont and add your own sightings at VT eBird.

Harbingers of Spring: Turkey Vultures

While its face may be one only a mother could love, no North American bird can match a Turkey Vulture’s grace on the wing. Soaring serenely over forests and farmlands, the species is one of spring’s earliest harbingers, appearing with the south winds of late winter. Last week’s sighting of a single turkey vulture in North Westminster was a welcome sign that winter’s grip will eventually relax.

Formerly a very rare bird in New England, the species is now common and widespread, having expanded dramatically northward in the 20^th century. Its range expansion probably resulted from a combination of exploding deer populations, declines in human shooting and trapping practices, and reductions in organochlorine contamination.

Migrating northward from wintering areas in the southeastern U.S., Turkey Vultures spread out across Vermont to breed. The state’s first nesting record was confirmed in 1983, but precious few nests have ever been found. Although adaptable to human activity and changing landscapes overall, Turkey Vultures nest in inaccessible and well-concealed sites, including caves, cliff ledges, talus slopes, hollow logs or trees, dense brush piles, even abandoned buildings. As a result, surprisingly little is known about the species’ breeding biology or behavior.

Almost exclusively scavengers (their scientific name Cathartes means “purifier”), Turkey Vultures use a highly developed sense of smell to locate carrion in open areas or beneath the forest canopy. The part of their brain responsible for olfaction is particularly large compared to other birds. Vultures are one of the few birds with a developed sense of smell.

Turkey Vultures typically forage alone, but individuals attracted to other feeding vultures may gather together at carcasses. Communal roosting is common, especially in winter, when up to several thousand birds may congregate in trees. Birders in Vermont should also now be on the lookout for the smaller relative of this graceful, soaring species, the Black Vulture, which is expanding its range northward into the state.

Other Sightings

Birding highlights of the past week were concentrated on Lake Champlain, which hosted several uncommon diving ducks and gulls. Foremost among these was a Tufted Duck off South Hero, only Vermont’s 5^th record (all since 2000) of this European vagrant. Joining this rare bird were a female Canvasback and a pair of Barrow’s Goldeneyes. The Charlotte Town Beach, always a reliable spot, yielded 75 Ring-necked Ducks, two drake Redheads, and a second pair of Barrow’s Goldeneyes. Among five species of gulls on the Lake just south of Thompson’s Point were single first-winter Iceland and Glaucous Gulls.

While not reflected in the recent weather, spring’s advance was signaled by an adult Peregrine Falcon observed at its breeding cliffs on Mt. Horrid in Goshen. Other early signs of the northward migration included five Fox Sparrows in Rutland and the season’s first report of a Common Grackle in Waitsfield. Continuing this winter’s unprecedented trend of Barred Owl sightings, five individuals were seen along a five-mile stretch of road in Danby on February 28.

You can explore all the birds reported last week in Vermont and add your own sightings at Vermont eBird.

Vermont Fish & Wildlife Asks for Reports of Dead or Flying Bats

WATERBURY, VT -- State wildlife agencies continue to monitor the spread of the sickness known as white nose syndrome affecting hibernating bats in New York, Vermont and Massachusetts. The sickness has been documented in 16 caves or mines where an estimated 500,000 bats spend the winter.

In many instances, bats are flying out of the cave or mine and are now being observed by the public around residences. Vermont officials see this as a means of monitoring the locations of affected bat populations throughout the state and are now asking the public to report observations of flying or dead bats.

We are already receiving reports of bats flying around during the day in Arlington, Pownal and Brattleboro, said Scott Darling, bat biologist for the Vermont Fish & Wildlife Department. In some of these instances, this information is leading us to new caves or mines that have never been surveyed for hibernating bat populations, and this gives us additional sites to check for the sickness. The more we can determine the speed at which this ailment is spreading and the site conditions that this sickness can be found in, the better we can piece together what is causing this sickness and how is it being spread.

Vermont Fish & Wildlife has collaborated with USDA Wildlife Services so that public observations of dead or flying bats can be reported during March by calling the rabies hotline telephone number (1-800-472-2437). Information provided through the hotline number will allow biologists to follow up on reports, respond to public inquiries, and, if necessary, collect dead specimens. Bats normally leave their wintering areas as the weather starts to warm up, so reports of bat sightings after March are not needed.

While there is no evidence that the sickness afflicting bats can be transmitted to humans, do not touch sick or dead wild animals. People should not handle bats unless absolutely necessary. Any bats that must be handled should be picked up with gloves or other materials that would prevent bites or contact with the bat. Materials used in handling the bats should either be discarded or washed in hot water, detergent, and 10% bleach solution (1 ½ cups of bleach to 1 gallon of water).

We do not want to overstate the risk from this bat sickness, but we still do not know what it is that is causing these deaths, adds Darling.

Deforestation in Monarch Butterfly Reserve

Recently, scientists identified severe degradation of the forest habitat within the Monarch Butterfly Biosphere Reserve in central Mexico using imagery from the commercial Ikonos satellite. Check out the imagery and article at NASA Earth Observatory.

Monarch Eclosing
© Bryan Pfeiffer / Wings Photography

Searching for Bobolinks in Northern Argentina

We recently returned from a 3-week field excursion in eastern Formosa, Argentina in search of the Bobolink on its wintering grounds. The eastern portion of the province of Formosa, Argentina is characterized by a habitat type known as Humid Chaco. VCE biologist, Rosalind Renfrew has been working with Bobolinks in their wintering area in Bolivia and Paraguay since 2004 and this trip was a continuation of that research. The objective in 2008 was to find Bobolinks in natural habitats and capture some of them using mistnets in order to collect blood and feather samples. These samples will serve as a control for comparing samples from Bobolinks captured in Bolivia where the landscape is dominated by rice fields and pesticide use is common.

We encountered many flocks of Bobolinks. The majority of our sightings were in natural areas and were almost always in what is known as a “pirizal”, which is a wetland dominated by a plant named Piri in Spanish or Giant Flatsedge (Cyperus giganteus) in English. We often saw them feeding on grasses which occurred in small patches dispersed throughout the pirizal. We also observed them feeding on invertebrates in these areas.

Although we visited many “estancias” or ranches during the three weeks in late January and early February, all of the 45 Bobolinks we captured were at Santa Olga Lodge, a 17,000 ha cattle ranch. This is the site where we discovered a night roost as well as an active daytime feeding area. On multiple occasions, we observed the spectacular event of thousands of Bobolinks either leaving or entering the roost located in the middle of a very large pirizal. Once it seemed that most of the birds had arrived to the roost in the evening, looking with binoculars deep in to the pirizal, we could make out the thousands of birds fluttering about just above the vegetation and we could hear the sound made by the immense group (~5000-6000 individuals) at least 300 meters away.

Eastern Formosa is also known for its sweltering summers (austral) which bring frequent isolated downpours. One afternoon as we watched a dark and raining cloud close in on us, we thought it would be a good idea to close the nets. Apparently we underestimated the speed of the approaching cloud because just as we were walking out into the marsh, the rain came down and we finished the afternoon soaked to the bones. The soil in this area is almost pure clay, so when it does rain, it makes many of the dirt roads impassable.

Almost all of the individuals were starting to molt into their breeding plumage. We noticed that throughout the three weeks as the stage of molt became more advanced, they appeared more and more like they do when they arrive to Vermont to breed.

Sarah Frey and Juan Klavins
VCE field biologists