A Welcome Song From The Pines

High atop the tallest white pines, a breezy, musical trilling signals the true arrival of spring and the long-awaited flood of songbird migration in Vermont. The Pine Warbler is often the earliest warbler to return from its winter quarters, and its song joins that of the similar-sounding juncos and Chipping Sparrows in mid- to late April.

Rarely found outside stands of its namesake tree, it is one of the few wood-warblers whose breeding and wintering ranges lie almost entirely within the U.S. and Canada. Although resident subspecies occur on Hispaniola and in the Bahamas, Pine Warblers nesting in forests of southeastern Canada and the Northeast join those from southeastern states in winter, where they can be surprisingly abundant, with as many as 50-100 birds joining mixed-species foraging flocks.

The Pine Warbler is far more often heard than seen in Vermont, where it rarely ventures below the canopy of mature white and red pines. Consequently, it is one of the least well-studied North American breeding warblers. Nests are typically located near the ends of horizontal limbs, often more than 50 feet above ground, and eggs may be laid as early as the first week of May. Although primarily an insect eater, this species is the only wood-warbler known to regularly consume seeds, especially in fall and winter. Pine Warblers occasionally delight birders by visiting feeders during winter, taking both seeds and suet. Their digestive system is able to compensate for this seasonal dietary shift by modulating enzyme production.

Other Sightings

For Vermont birders, waterfowl have ceased to dominate the highlight reels, as the recent warm southerly air flow has brought a diverse push of early migrants. Vermont’s only pair of Sandhill Cranes returned for a fourth year to Bristol Pond, where observers are urged to use caution and respect in viewing them. Among wading birds reported during the past week were a Great Egret in Shelburne, three Black-crowned Night-Herons at Delta Park in Winooski, and a Virginia Rail at the West Rutland Marsh. Shorebirds included four reports of Greater Yellowlegs, one Lesser Yellowlegs at Brattleboro Retreat Meadows, a Spotted Sandpiper in Ludlow, and an Upland Sandpiper in West Brattleboro. Two Caspian Terns were observed along Lewis Creek in Addison and a single bird on Shelburne Bay.

Among landbirds, Broad-winged Hawks returned to the state en masse, while a Merlin was sighted in Proctor. Well ahead of its normal spring migration schedule was a Common Nighthawk at Brattleboro Retreat Meadows on April 19th. Also early was an Eastern Kingbird at the North Branch Nature Center in Montpelier on the 14^th. An intriguing report of a Red-headed Woodpecker from Castleton on the 16^th lends hope that this declining species, which has all but disappeared from Vermont, may still breed within the state. Purple Martins, Northern Rough-winged Swallows, and Bank Swallows all returned within the past week, while new songbird arrivals included Blue-headed Vireos, Brown Thrashers, Palm Warblers, Louisiana Waterthrush, Common Yellowthroat, Eastern Towhees, and an early Indigo Bunting.

Avian hold-outs from the still-retreating winter season included single Northern Shrikes in Essex Junction and Windsor, BoBunting in Berlin, and numerous Common Redpoll flocks in the northern half of Vermont.

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

-Chris Rimmer

Yellow-bellied Sapsucker: An Ecological Keystone

Each spring, the end of the maple sugar season is marked by the return of one of nature’s own sap harvesters – the Yellow-bellied Sapsucker. While its name may seem more fitting as an insult that Homer Simpson might sling at a co-worker, it is an apt description of this small woodpecker. Moreover, the ecological contributions this species provides are worthy of such a memorable name.

Most conservation biologists consider sapsuckers to be a keystone species – one whose existence is vital for the maintenance of a community, and whose loss would have a significant effect on other species’ populations or on ecosystem function. Common examples of keystone species include the beaver (for creating wetlands), starfish (as a predator of sea urchins and shellfish that have few, if any other, natural predators), and prairie dogs (for creating burrows that are utilized by many other species).

The Yellow-bellied Sapsucker plays two vital roles in woodland communities. Like all woodpeckers, they excavate new nest cavities each year that subsequently are used by a wide variety of animals, from other birds to squirrels and spiders. Sapsuckers also drill sap wells from which other animals obtain nutritious sap, as well as the insects that are attracted to it. Hummingbirds, which are particularly reliant on sapsuckers, often nest near sap wells and have been observed following sapsuckers, presumably to locate sap wells. In addition, it is thought that Ruby-throated, and possibly Rufous hummingbirds, time their spring arrival in northern New England and Canada to coincide with peak sapsucker activity, and that the northern limit of their breeding ranges is determined by the presence of this woodpecker.

Sapsucker feeding behavior is the most distinctive feature of their ecology. Although sap itself makes up only about 20% of their overall diet, most of their foraging time is spent creating, maintaining, inspecting, and feeding from sap wells. Sap is consumed for its sugar, which varies in content by tree species and season. Sap wells are usually excavated into phloem tissues (which are closer to the surface) during early spring. These shallow wells begin as slits, are gradually widened into squares, and must be maintained continually for the sap to flow. Sapsuckers also drill through the phloem to reach the underlying xylem tissues which have higher sugar content (to fuel leaf growth). Xylem wells can be recognized as neat, round holes. Sapsuckers vigorously defend their wells against other birds, and even many insects that might be considered food under other circumstances. The remainder of their diet consists primarily of insects, especially ants, which are exposed by flaking off bark or collected directly from sap wells.

Like all woodpeckers, the Yellow-bellied Sapsucker drums to defend a territory and advertise its presence to a mate. This drumming is easily recognizable, thanks to the Morse code-like quality that noticeably slows down at the end. Listen for it this week at a woodlot near you.

Sightings of Yellow-bellied Sapsuckers were widespread this week, with reports from Brandon, Woodbury, Huntington, and Strafford. Other notable reports include a Sandhill Crane in South Burlington, a Snowy Egret at Bristol Pond, Fox Sparrows in Montpelier, Monkton and Brownington, a Tree Swallow in Burlington, and 4 Red-necked Grebes, 2 Common Loons, and a Barn Swallow on Grand Isle.

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

National Geographic's Wild Chronicles Features VCE on PBS

The Vermont Center for Ecostudies' research on songbirds in the mountains of the Dominican Republic will be featured on National Geographic’s Wild Chronicles television show on Sunday, April 20th on PBS.

Filmed this past February, the segment highlights VCE's long-term studies of Bicknell's Thrush and other migrant and resident species on Hispaniola. The feature includes vivid footage of several of Hispaniola's 31 endemic species, some of which are among the most rare and threatened of Caribbean birds.

"The tropical environment of the Dominican Republic is a long way from home for National Geographic grantee Chris Rimmer,” according to National Geographic, which has helped to fund VCE’s work on Hispaniola. “Like the birds he studies, Rimmer migrates to this biologically rich island to conduct his research. The goal of Rimmer's pioneering research on the island is to compile a comprehensive database of both migrant and resident bird species that will lead to sound conservation practices."

On Vermont Public Television, the segment is scheduled to run on Sunday, April 20, at 1:00 pm. For broadcast times in other areas, check your local listings.

Vermont Weekly Bird Notes: Ospreys Rise

Osprey numbers declined drastically beginning in the 1950s. Breeding ospreys disappeared from Vermont after 1971 due to the pesticide DDT, which caused weakened eggshells and massive nest failures. Ospreys returned to Vermont in the late 1980s, and today there are nearly 100 osprey nests throughout the state. Osprey was removed from the state endangered species list in 2005, the culmination of a true conservation success story.

When intensive monitoring and management began in 1988 Vermont ospreys produced less than a handful of young. That number has steadily grown and in 2006 there were 82 nesting Osprey in the state. High productivity of ospreys in recent years has occurred due to the efforts of the Vermont Fish and Wildlife Department and other cooperators.

Artificial nesting platforms have been critical to the osprey recovery due to the lack of suitable nesting sites. Central Vermont Public Service (CVPS) has helped to build and install many nesting platforms in strategic areas identified by biologists. Many of these are now used by ospreys to build nests and raise young.

Osprey is a fish-eating specialist, with live fish accounting for nearly its entire diet. Barbed pads on the soles of its feet help it grip slippery fish. You can often see them carrying whole fish to a nest headfirst to make the load as aerodynamic as possible. These birds can be sensitive to human intrusion when nesting. It is fun to watch them, but biologists recommend that you to stay at least 300 feet from any nesting area.

This week five pairs of osprey were busy constructing nests at Sandbar Wildlife Management Area on Lake Champlain. If you observe any nesting activity, especially at natural tree sites, please report them and help monitor the Vermont Osprey recovery.

Check out the Osprey reports on Vermont eBird...

Other Sightings

The sounds of spring are returning to Vermont. Ruffed grouse have begun to drum their wings, Wilson’s snipe are displaying with the winnowing sound of their outstretched tail feathers, and the nasal “peent” of woodcocks have been widely reported around the state.

Tree swallows have been reported throughout the state. Two barn swallows were observed on Lake Bomoseen on April 3. A field sparrow was found at Red Rocks Park in Burlington and a yellow-rumped warbler was spotted on Thompson’s Point in Charlotte on April 6

Northern finches continue to linger. Thirteen pine grosbeaks were seen in Eden on April 1. A hoary redpoll has been visiting a feeder in Waitsfield and common redpolls have been reported throughout the state. Many flocks of Bohemian waxwings were reported. A large flock of 235 was found at the South Burlington Technology Park on March 31.

A Barrow’s goldeneye was seen in Grand Isle on April 1. A drake canvasback was spotted at Delta Park in Colchester on April 4.

Merlins were seen in East Dorset on April 2 and Dead Creek WMA on April 6. A pair of Peregrine falcons was observed their Bolton Notch aerie on April 6.

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

- Kent McFarland

Sightings Needed: Report Rusty Blackbirds

WANTED: a few good birders to track the migratory movements of a rapidly declining North American songbird. Rusty Blackbirds have declined by as much as 98% in the last four decades, making them among the most threatened species on the continent. Help scientists save this species by reporting your sightings to eBird.

Such is the plea that just went out to birdwatchers around the country. Rusty Blackbirds were once an abundant species, one of those species we hear about that formed massive flocks that blackened the skies. These stories are hard to believe for most of us, and it seems especially hard to believe for this species. Rusty Blackbirds are literally disappearing before our eyes. Now, birdwatchers get excited when they see 15 of these birds together, a far cry from the thousands upon thousands that delighted our ancestors.

Unfortunately, very little is known about this species. Rusty Blackbirds disperse widely on their breeding grounds in remote wooded swamps and bogs in the boreal forest, a habitat that is hard to access and undesirable for many people. Recent studies have been initiated in Maine and Alaska to learn more about their breeding requirements. In the winter months, they congregate in similar wet wooded areas in the southeastern U.S. to feed on nuts and seeds.

Migration is still a big black box for this species. How often are they joining flocks with other blackbirds? What habitats are they using in migration? Are they suffering from blackbird control measures? Most importantly, are threats during the migration season contributing to the species’ rapid decline?

This is where birdwatchers like you can help. As you witness flocks of blackbirds and grackles staging in your yard or favorite birding location, inspect them for the presence of a Rusty Blackbird. Note how many males and females you observe, their behavior, what other birds are around, and the habitat. Lastly, submit your observations to eBird.

Rusty Blackbirds are most easily identified by their song, widely described as sounding like a rusty door hinge. Males are black with a yellow eye. They are distinguished from male grackles by their shorter tail, smaller bill, and lack of iridescence. Female Rusty Blackbirds have a mottled appearance of rust, brown, and black, and lack the streaking on the belly of female Red-winged Blackbirds.

Other Sightings

Blackbirds and grackles continue to move through Vermont, as do large numbers of geese and other waterfowl. A few more Eastern Phoebes have shown up, most recently in Norwich and South Newfane. An Eastern Meadowlark was singing in South Burlington on April 1. Migrant raptors are slowly starting to return, like Red-shouldered Hawk, American Kestrel, and Merlin. Sparrows, often among the first migrants to return to Vermont, are being reported in increasing numbers, with Song, White-throated, Fox, American Tree, Chipping, and Dark-eyed Junco observed in the past week. The lingering snow has made for some interesting juxtapositions between winter and spring bird icons, with American Woodcock on display as Common Redpolls visit the feeders.

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

-Julie Hart