One Bird or Two?

The recent discovery atop Stratton Mountain of an apparent hybrid of a Bicknell’s Thrush and Veery, two closely related species in the genus Catharus, has generated some buzz in birding circles. The bird was discovered by field biologists with the Vermont Center for Ecostudies, in the course of their long-term research on high elevation bird populations. The first clue to this individual’s possible hybrid origin was provided by its song, which combined elements of both Bicknell’s Thrush and Veery. In-hand examination following a mist net capture revealed that the bird (a male) had plumage characters of both species, though it appeared more Veery-like overall.

VCE collected small amounts of blood and feathers, which will be subjected to mitochondrial DNA analysis to document the bird’s maternal roots. This will provide insight (although not conclusive proof) into whether in fact its parents crossed species boundaries and mated. It seems likely that the father was a Veery, the mother a Bicknell’s Thrush. This would help explain the bird’s song, which was predominantly that of a Veery (young birds learn songs in part by imprinting while in the nest).

Assuming the bird is a hybrid, the question naturally arises as to how these individuals of two ecologically separate species found one another. The two do not typically overlap in habitat use. Bicknell’s Thrush is specialized on spruce-fir forests that grow only on mountaintops above ~3000 feet elevation in the northeastern US, Quebec, and Canadian Maritimes. Veery is a species of lowland hardwoods forests, primarily second growth and floodplain. Does occupancy of mountaintop forests by a Veery signal the upslope creep of deciduous forests due to climate change, as has been shown by recent UVM research? Possibly, but it is far too early to make that case. It is but one of several possible explanations for why a Veery and Bicknell’s Thrush might have paired up.

The most reasonable explanation for this presumed hybrid mating is one of serendipity. Birds are mobile creatures, and these two species are, after all, closely related, with similar plumage and vocalizations. Hybridization among birds is widespread, although uncommon, having been recorded in more than 2,000 unique species pairs. Blue- and Golden-winged Warblers provide a familiar example of two species that regularly interbreed and produce offspring that themselves may be fertile. In fact, introgression of Blue-winged Warbler genes into Golden-winged Warbler populations has been implicated as a cause of Blue-wingeds’ range expansion at the expense of Golden-wingeds. Most avian hybrids, however, show reduced or no fertility, such that hybridization is rarely significant in a biological or evolutionary sense. In the case of the Stratton “thrush”, it is best viewed as a scientific curiosity for now.

Other Sightings

Recent birding reports have been dominated by accounts of juveniles and family groups. As always in mid-late summer, fledglings abound and are quite conspicuous as they beg from their parents. These young, often unwary birds can provide great opportunities for close-up viewing and becoming familiar with the short-lived juvenile plumage. Many songbirds are now feeding fledged young, and the early migrants (e.g., some flycatchers and warblers) will soon be dispersing southward. The vanguards of shorebird migration have begun to appear en route south from their arctic and subarctic breeding grounds—a Greater Yellowlegs was observed in South hero on July 20^th and a Least Sandpiper in West Swanton on the same date.

Two breeding species recently removed from Vermont’s Endangered and Threatened Species List continue their strong recoveries this summer. Common Loons, once down to a mere eight breeding pairs statewide in the mid-1980s, matched 2007’s record population level, with 62 pairs attempting to nest. That number may well increase as additional pairs with chicks are discovered. Vermont’s Peregrine Falcon population also maintained its upward trajectory, with a record 36 territorial pairs statewide, of which at least 25 nested successfully. The rebound of these two species is testament to the diligent efforts of a legion of committed amateur and professional conservationists throughout Vermont.

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

-by Chris Rimmer

The King of Fishing

Hot summer days and river walking go hand-in-hand for many Vermonters. What better way is there to get some exercise, see some beautiful places, and keep cool? For one bird, this is their year-round habit. Indeed, it’s hard not to notice Belted Kingfishers if you spend time along a Vermont waterway.

Belted Kingfishers are highly territorial and we often hear their dry rattle well before we see them darting along a river or lake edge in search of fish. It’s always a thrill to watch these fishing masters hover 20 feet above the water, plunge beneath the surface, and then fly to a nearby branch with a good-sized fish in its bill. If you watch closely, you can see them flip the fish around so that it goes down head first with the direction of the scales.

Kingfishers have an unusual plumage or coloring. In most bird species, the male is the more brightly colored individual, but Belted Kingfisher females are more colorful than their male counterparts. All individuals have a blue crest, back, and band across a white chest. Females are the ones with the additional rusty band across the belly. Careful observers will also notice that kingfishers have a small white patch in front of their eye, which helps to cut down on glare from the water.

Belted Kingfishers are found breeding throughout the United States and into far northern Canada wherever open water for foraging and sandy banks for nesting are found. They burrow into banks anywhere from one to eight feet to create their nest. The tunnel is usually built at an upward angle, which may help prevent water from entering the nest.

Human disturbance has aided the expansion of kingfishers into some areas, with sand and gravel pits, road cuts, landfills, and ditches providing additional breeding sites. Other human impacts have not been so beneficial. Kingfishers rank up there with Common Loon, Bald Eagle, Peregrine Falcon, and Atlantic Puffin in the level of contaminants found in their blood. Researchers with the Biodiversity Research Institute in Maine have documented that birds that eat insects and small fish tend to have lower contaminant levels than birds that eat larger fish and other birds. Mercury exposure also varies with habitat, with kingfishers living along lakes exposed to four times as much methylmercury than those living in a marine environment.

Keen-eyed river walkers may run into a few families of Belted Kingfishers this time of year. This is the time of year when most of the breeding birds in Vermont are fledging young. Other cavity-nesting fledglings you might encounter, especially if you have bird boxes in your neighborhood, include Eastern Bluebird, Black-capped Chickadee, Tree Swallow, Bank Swallow, and House Wren. Fledglings often leave the nest before they are fully capable of sustained flight, so if you are fortunate enough to encounter a young bird on the ground, please keep your distance and do not pick them up. The parents are still feeding and caring for the young.

You can explore all the birds reported last week in Vermont and add your own sightings at www.ebird.org/content/vt.

-Julie Hart

Mount Washington Butterflies Added to State Endangered List

The New Hampshire endangered and threatened species lists are due for updates, and more animals may be added than subtracted.

A total of 25 species would change status if the updated list is approved by a joint legislative committee, according to Steve Weber, chief of New Hampshire Fish and Game's wildlife division.

The White Mountain Arctic will be listed as threatened and the White Mountain Fritillary will be listed as endangered. Both of these are new editions to the list. The Vermont Center for Ecostudies has been designing a population survey for both of these species with funding from the Waterman Fund and the White Mountain National Forest.

You can view a past status report to the White Mountain National Forest for these two species, here.

A Shorebird that Doesn't Do Shores

“Sandpiper” might conjure up an image of a bird walking along a shoreline, probing the mud for prey. Or a beach scene might come to mind, with small shorebirds called sanderlings chasing a retreating wave, frantically snatching invertebrates from the sand before the next oncoming wave. But a few shorebirds have nothing to do with “shores,” and the upland sandpiper gives itself away with its name.

Long legs and a long neck are distinctive traits that make the upland sandpiper stand out in agricultural and fallow grasslands where it breeds. It nests in medium-height grasses, and escorts its precocial chicks, who leave the nest right after hatching, to shorter grasses for feeding.

The upland’s “wolf whistle” song is like no other. It is named after the whistle boys used to give girls in the 1940’s (and may still be heard emanating from construction sites). It is more drawn-out: “whooooleeeeeee, wheeeelooooo-oooo.”

During European settlement the upland sandpiper suffered massive declines in its native prairie habitat. But forest clearing for agriculture in the east was a boon to the bird. Its breeding range expanded east, and by the late 1800’s it was locally common in Vermont. But in the 1900’s, development replaced agriculture and row crops replaced hayfields and pastures, and the upland sandpiper diminished.

Today only remnant populations of the upland sandpiper remain in Vermont. The first survey for this species was carried out in 1989-1992, and documented 126 individuals at 47 locations. In 1999 only 28 individuals were found at 15 locations. The Vermont Breeding Bird Atlas surveyed the state for all bird species for five years (2003-2007), and found upland sandpipers at 19 locations. The species is quickly disappearing as the large, open grasslands that it needs become scarcer. The pattern is part of a larger, downward trend throughout its range over the last 25 years.

The upland sandpiper makes an incredible 12,000-15,000 mile round-trip migration to South America each winter, and population declines could be attributable in part to threats at migration stopovers or on the wintering grounds. The application of pesticides was cited as one possible problem, but recent research in Argentina found no evidence to support this idea. The loss of grasslands to crops may be a more likely culprit.

Other Bird Sightings

A horned lark, a grassland species that prefers sparse vegetation, was found in Panton. A clay-colored sparrow was spotted in Charlotte, and last week a pair was seen feeding young in South Burlington. Black-billed cuckoos were reported from several locations throughout the state, and a yellow-billed cuckoo was seen in the Aiken State Forest. An Orchard Oriole, an uncommon breeder in Vermont that occurs mainly in the Champlain Valley, was seen at Dead Creek.

-Rosalind Renfrew

VT Weekly Bird Notes: Coffee, Birds and Ants

The army of coffee drinkers could be helping the army of ants and our native songbirds. Army ants in colonies of over one million individuals marching through the Central American rain forest, or in this case, the coffee plantation.

Army ants swarm through plantations in lines up to 75 feet across the ground and up tree trunks searching for food. Their prey is anything alive and small enough to subdue and carry back to the colony. Most insects, spiders and centipedes don’t have a chance. Even some small frogs and snakes can be taken. Prey scatters while attempting to escape the marching troops.

Some songbirds get their meals by perching on a low branch in front of the marching ants and catching the fleeing insects. The relationship is so close that some species of birds are never found far from ant swarms.

So what does all of this have to do with coffee?

Sun coffee plantations have become the dominate way to produce coffee. Sun coffee is a hybrid coffee that shuns the shade. The forest is cut down and the coffee is planted in neat rows. The ground cleaned of all weeds and chemical fertilizers are added. This type of coffee can’t be grown without chemicals. Production is high and so are the ecological costs to ants, birds and the local people.

Coffee is naturally an understory shrub that loves the deep shade. Traditionally, small farmers grow it under a thick canopy, usually without the use of chemicals. They have the feel of a natural forest with thick leaf litter covering the soil, humid and cool air, and army ants and birds. Scientists have found that shade coffee plantations have 90 percent more bird species than sun coffee.

Scientists from the Smithsonian Migratory Bird Center studied army ants and the birds that follow them in natural forests, shade coffee and sun coffee plantations in Chiriqui Province, Panama near the border of Costa Rica. The Ruddy Woodcreeper, a small brown bird that often clings to tree trunks like a woodpecker, and the Gray-headed Tanager, about the size of an Eastern Bluebird with a gray head and a bright yellow chest and belly, were only found near the swarming ant colonies. They found 124 species of other birds that were most often found near troops of ants.

Many of the birds were migratory and return to Vermont each spring to grace us with beautiful song and dine on insects. One of the principle scientists on the study, Dina Roberts, said, “One of the most vivid accounts of bird attendance at the swarms, especially by a migratory species, were Swainson's thrush. Comparatively small numbers of these birds wintered at our sites and at any particular swarm, one would detect between 1 and 3 Swainson's thrushes. However, during the northward migration in April, on several different occasions I came upon ant swarms or detected a swarm raid by the thrush calls. It was common to see over ten thrushes foraging above one swarm. Once I saw 23 Swainson's thrushes at a swarm. They would forage on insects and then often flew to shade tree to eat fruit.”

They never found army ants or the attending birds in the sun coffee plantations. So what can that cup of coffee in your hand do? If it is a cup of shade-grown organic coffee it could help promote a market, a group of traditional family farmers, an army of ants and a beautiful spring song. Drink wisely.
Recent Noteworthy Bird Sightings

A female black-backed woodpecker was spotted in Bear Swamp in Wolcott on June 25th.

A blue-winged warbler was found in Brandon on June 28th. A hybrid Lawrence’s warbler was seen in Saxton's River on June 27th. A Tennessee warbler was found on Mt. Ascutney on June 25th. And a northern parula was singing in downtown Woodstock on June 29th.

On June 23rd two orchard orioles were found in Colchester. Five days later two nesting pairs were observed. One pair had two nestlings and the other pair was feeding one young.

You can explore all the birds reported last week in Vermont and add your own sightings at www.ebird.org/content/vt.

Field Report: White Mountain Arctic Monitoring

VCE biologists were in the alpine zone yesterday in the Presidential Range testing different population monitoring methods for the White Mountain Arctic butterfly. As usual, the weather was a factor on Mount Washington with sun, hail (It hurts when it hits you! Those white dots on the ground next to the boots are hail.), rain, and deep fog.

When it was sort of sunny, we did observe about 20 arctics. We even found this pair in the photo copulating! We'll be working more with this species and other alpine butterflies to determine there population status over the coming years.

Would you like to know more about their natural history? Check out our report about their status for the White Mountain National Forest.

Kent McFarland