Saturday, December 22, 2007
The High Elevation Landbird Program monitors Bicknell’s Thrush and other birds breeding at high elevations in Nova Scotia. Funding from the Species At Risk fund will help BSC to produce a Best Conservation and Stewardship Practices guide for Bicknell’s Thrush in Nova Scotia, and to conduct high elevation bird surveys in June 2008. For more information on the Bicknell’s Thrush, visit BSC’s High Elevation Landbird Program site as well as the website of the newly formed International Bicknell’s Thrush Conservation Group.
The Piping Plover and Bicknell’s Thrush are both federally and provincially listed Species At Risk. Select this link for more information on the Nova Scotia Species At Risk fund.
Friday, December 21, 2007
Harlequin Ducks occupy a unique ecological niche among North American waterfowl. Breeding on fast-flowing rivers of Quebec, Labrador, Newfoundland, and New Brunswick, the species winters along rocky coastlines from Nova Scotia to as far south as Virginia. In both habitats, birds show an unmatched ability to negotiate turbulent waters, as they dive for invertebrate prey. The East Coast population of Harlequin Duck numbers fewer than 2,000 individuals and has decreased in recent decades. The causes of this decline are not entirely clear, but this rare species ranks as a high conservation priority.
The season of Christmas Bird Counts (CBCs) is upon us, and there are sure to be some intriguing avian finds across the state during the next two weeks. Hundreds of birders are taking to the woods and watching feeders during this 108th annual CBC, which features 19 separate counts spread across Vermont. The season runs from Dec. 14 Jan. 5, and hardy participants are always welcome. You can view the list of Vermont CBCs and coordinators at http://ebird.org/content/vt/news/cbc.html.
Birding highlights from the past week included two unusual raptors: an adult Golden Eagle observed in flight over Thetford Center on Dec. 12 and a second-hand report of a very rare Northern Hawk-Owl in Richford on Dec. 9. Out-of-season woodpeckers included a Northern Flicker in Ferrisburgh and Yellow-bellied Sapsuckers in Brattleboro (1) and Saxton's River (4). Remarkable outside its normal Vermont range in spruce-fir forests of the Northeast Kingdom was a Boreal Chickadee found at a Shelburne feeder during the Burlington CBC on Sunday. A lingering Pine Warbler continued to visit a suet feeder in Middlebury, but much more extraordinary was a well-documented immature Prairie Warbler on the Green Mountain College campus in Poultney. This bird, most of whose relatives are now comfortably ensconced in dry forests on Caribbean islands, survived over several cold and snowy days between the Dec. 7-10.
You can explore all the birds reported last week in Vermont and add your own sightings at Vermont eBird.
Friday, December 14, 2007
Take for example the Gyrfalcon sighted on December 4 in
Gyrfalcons are larger than Peregrine Falcons, weighing twice as much, in fact. Gyrfalcons lack the clear mustache of Peregrines and have broader, blunter wings. In most years, a handful of these birds show up in the northern
Other rare winter visitors include Great Gray Owls and Northern Hawk Owls. Both owls feed on small rodents in the boreal forests, which undergo four year population cycles. The last major irruption of Great Gray Owls occurred in the winter of 2004-2005, with many reports of these large, tame birds along our northern border. A crash in the vole population occurred this past fall and already several of these large owls have been sighted in southern
Short-eared Owls and Rough-legged Hawks are regular winter residents in
I’d be remiss if I didn’t mention perhaps the most well-known example of an irruptive raptor, the Snowy Owl, popularized by Harry Potter. It undergoes sharp population changes following the cycle of lemmings approximately every four years. It is usually found during the day in open fields sitting on the ground or a low perch. Casual and avid birdwatchers alike are thrilled to watch these ghosts from the north.
You can explore all the birds reported last week in
Monday, December 10, 2007
In the eyes of the federal government, the tiny Bicknell's thrush isn't endangered or threatened, but experts say its numbers are dwindling and its habitat -- breeding grounds in the mountaintops of the northeastern U.S. and Canada and wintering grounds in the Caribbean -- is disappearing or being threatened by pollution.
"It's a canary in the coal mine for the higher elevations," said Kent McFarland, a biologist with the brand-new Vermont Center for Ecostudies.Boston Globe, United States -
By Wilson Ring Associated Press Writer
Read more at the Boston Globe...
Friday, December 07, 2007
Raptor migration in November can be huge. Not in numbers, but in size. At 14 pounds with a seven foot wingspan, the rare golden eagle is on the move.
In late fall they begin their migration southward. Using updrafts along ridgelines and warm air rising from valley floors, they can fly up to 50 miles a day to reach their wintering territory that can be found anywhere from the mid-Atlantic states and southward.
Historical nesting has been confirmed throughout the Northeast. But now, most of the eastern population breeds in northern Quebec. This small population is geographically and genetically isolated from the much larger western population.
Golden eagles reproduce very slowly. Breeding territories range from 10-20 square miles and most do not acquire one until they are at least 4 years old. They raise an average of only one young per year and up to 15 young over a lifetime. Pairs commonly refrain from laying eggs in some years, particularly when prey is scarce.
Humans cause over 70% of recorded deaths, directly or indirectly. Accidental trauma (collisions with vehicles, power lines, or other structures) is the leading cause of death (27%), followed by electrocution (25%), gunshot (15%), and poisoning (6%).
The National Aviary in Pittsburgh and the Ministère des Ressources naturelles et de la Faune in Quebec, have embarked on a program to study the migration patterns of golden eagles in eastern North America to identify areas of potential conflict that migrating eagles face from the developing wind energy program.
In late 2006 they began to outfit eagles with satellite transmitters. These new devices are solar powered and can last up to 3 years. The transmitters record locations and flight elevation every hour during the day using GPS and then transmit the data to a satellite. The satellite periodically transmits the data back to earth.
Golden eagle number 62 was captured on August 7th in the Gaspésie National Park, Quebec and outfitted with a transmitter. It was a 7 pound adult male. At the end of October, he headed southward. On November 11th he stopped for three days near Fairlee, Vermont before heading southwestward. You can check in on his and others fate here.
The irruption of northern species into the region continues to delight birdwatchers. Pine grosbeaks and Bohemian waxwings were observed across the region. Look for them in crab apple trees. There were over 70 sightings of common redpolls this week, ranging from Manchester Center to Canaan in the north. Two red crossbills were spotted in Manchester Center on December 2nd. Three white-winged crossbills were seen at Moose Bog on November 30th. Northern shrikes were found in Waitsfield, Johnson, Canaan, Post Mills, Charlotte and Shelburne.
A greater white-fronted goose was still at Minard's Pond in Bellows Falls on November 30th. A drake harlequin duck was in Shelburne on December 2nd. One was last seen at this site on November 24th. A gadwall was observed at Brattleboro Retreat Meadows on November 30th.
Two Lapland longspurs were seen in Vernon on December 1-2.
You can explore all the birds reported last week in Vermont and add your own sightings at Vermont eBird.
Tuesday, December 04, 2007
In winter, White-breasted Nuthatches often join mixed foraging flocks led by chickadees and Tufted Titmice. These loosely associated flocks, that may include small numbers of Golden-crowned Kinglets, Red-breasted Nuthatches, and Downy and Hairy woodpeckers, apparently gain protection from predators due to the vigilance of the assembled birds. This safety-in-numbers theory is supported by at least one study which found that if titmice were removed from a flock, nuthatches became more wary and reluctant to forage at exposed bird feeders.
Normally territorial throughout the year, White-breasted Nuthatch pairs typically stay together year-round, often foraging together. Like most birds, male White-breasted Nuthatches tend to be more vigilant when foraging alone than with a female. The opposite is true for the female, however. In danger of having the more dominant male displace her from feeding sites, the female White-breasted Nuthatch is more vigilant when her mate is around than when foraging alone.
Their characteristic upside-down posture and acrobatic foraging behavior are enhanced by their specialized, “scansorial” (adapted for climbing) feet. Similar to woodpeckers and woodcreepers, nuthatches have short, strong legs with extremely long, hook-shaped claws that permit them to move dexterously around tree trunks, limbs, bird feeders, and other surfaces.
White-breasted Nuthatches appear to be thriving across much of their range. Not only are they are widespread and abundant, but their population trends appear to be increasing most everywhere. Data from the Vermont Forest Bird Monitoring Program, a long-term project of the Vermont Center for Ecostudies, indicates that between 1989 and 2006, White-breasted Nuthatch populations increased in Vermont forests at a rate of nearly 10% per year.
With plenty of open water on the larger lakes and rivers, waterfowl sightings dominated many of the reports this week. These included a Gadwall observed at Brattleboro Retreat Meadows at the mouth of the West River on 11/25, along with the following Lake Champlain sightings – a Tundra Swan seen from the shores of Charlotte on 11/23, a male Harlequin Duck observed from Shelburne on 11/24, and 2,500 Snow Geese, 35 Gadwall, 800 American Black Ducks, 2,760 Mallards, 8 Northern Shovelers, 93 Green-winged Teal And 1 Surf Scoter observed during a day-long survey on 11/23. You can explore all the birds reported last week in Vermont and add your own sightings at Vermont eBird.
Monday, December 03, 2007
If you had been visiting the hut (and it had existed) 5,000 years ago, however, you wouldn't have had any view because the hut would have been surrounded by a balsam fir forest. Scientists have determined this by examining the pollen, seeds, twigs and other debris that has settled to the bottom of a nearby lake, accumulating year after year since the end of the last ice age. The sediments form layers, and by taking core samples down through the layers, the scientists have recreated the floral history of the Lakes of the Clouds area since the end of the last ice age.
The record shows that the treeline moved upward on Mount Washington beginning about 7,500 years ago, as the overall climate warmed. Around 2,500 years ago, the treeline moved back downslope, as a period of neoglacial cooling set in.
The warming period, called the Holocene Climatic Optimum, occurred worldwide, and it appears to have been characterized primarily by warming summer temperatures in the northern hemisphere. On Mount Washington, the treeline responded to the warmer climate by moving up. Given this history, what is likely to happen to the current fir forest on the mountain now that rapid climatic change is underway?
Bicknell's thrush is a rare mountain bird species with a fluty song and fascinating breeding ecology. It nests only in high-elevation "islands" of balsam fir across the Northeast and eastern Canada. For over 15 years, the thrush and its montane habitat have been studied by the Vermont Center for Ecostudies.
Since 1992, citizen science volunteers working with the VCE biologists have strapped on their backpacks each June to count birds on mountaintops from the Catskills in New York to Mount Katahdin in Maine and the Green and White Mountains in between. Using this information, coupled with aerial photographs that help determine the acreage of fir forest across New York, Vermont, New Hampshire, and Maine, the biologists created a map of Bicknell's thrush habitat in the Northeast.
The biologists then compared their habitat map to the mean July temperature map for the region, using a computer model called ClimCalc, which was developed by scientists at the University of New Hampshire from weather station data gathered throughout the Northeast between 1950 and 1980. Nearly all of Bicknell's habitat was located in a narrow temperature band between 49 degrees F (the average July temperature at the highest elevations near the treeline) down to 60 degrees (the average temperature where the forest begins to change from softwoods to hardwoods).
The researchers then used their computer model to recreate warming like the Holocene Climatic Optimum, slowly warming the mountain slopes and moving the temperature boundaries upward to predict the future location of the fir forest where Bicknell's thrush nests.
A warming of just 2 degrees F reduced potential Bicknell's thrush habitat in the Northeast by more than half, and an increase of 4 degrees was enough to eliminate all the habitat from the Catskill Mountains of New York and most of the habitat in Vermont, leaving the highest peaks of New Hampshire's Presidential Range as the only substantial breeding ground remaining.
A warming of at least 2 degrees to 4 degrees, meanwhile, is widely accepted as likely to occur in the Northeast before the end of this century. Indeed, summer temperatures locally are projected to rise an average of 5 degrees under a reduced-CO2-emissions scenario and as much as 11 degrees under a business-as-usual, higher-emissions scenario. At this upper end, possible by late in this century, the model shows that suitable habitat for Bicknell's thrush will disappear entirely from the Northeast.
Fortunately for the thrush, the actual treeline will take longer than this to move upslope because the movement of trees does not take place instantaneously. It is highly likely that shifts in forest composition will lag at least decades behind temperature changes. These lag times may even be as long as centuries. Such lags occur due to slowly changing soil characteristics, interactions among tree species, and the disturbance required for one habitat type to invade and replace an adjacent one under variable climate conditions.
During the Holocene Climatic Optimum, the treeline may have reached an elevation of 5,575 feet on Mount Washington, about 700 feet shy of the summit. But this change occurred over a period of 4,000 years. Under our current rate of global warming, the change is predicted to be far faster – perhaps within just a few hundred years – because the temperature change will be so much greater. We may well see drastic changes in mountain forests that are completely unpredictable.
You can read the scientific paper published on this material at http://www.northeastclimateimpacts.org/pdf/miti/rodenhouse_et_al.pdf