Flocks of volunteers seek out changing habitat of state's birds

MASHPEE - Stalking breeding birds is not always a walk in the woods.

So here's Mary Keleher scrambling through a worksite where bulldozers are carving yet another parking lot for Cape Cod. She gains a vantage point overlooking a vast electronics emporium and focuses her high-powered telescope in tight.

Bingo!

There's a killdeer snuggled in a new nest, nearly invisible on the gravel and tar roof of the big box store. The habitat approximates the pebbly flats where the spindly legged shorebirds typically bear offspring.

"You check out birds where you find them," said Keleher, one of the more tenacious volunteers in an ambitious five-year study of all feathery species that breed from Nantucket to North Adams. "It could be a wetland. It could be a shopping strip or suburban yard."

This is no ordinary bird watch.

The study, the Breeding Bird Atlas, marks the first time since the 1970s that the Massachusetts Audubon Society has sought to exhaustively determine what species of birds reproduce in the Bay State, as well as the extent and nature of their breeding grounds.

One striking discovery, so far, is that increasing numbers of southern birds are settling into Massachusetts for mating season. Climatic warming may be the spur. Meanwhile, some longtime native species are faring poorly, although lost habitat and, possibly, pesticides are suspected culprits - not climate change.

Entering its second season, the study has found that 47 of about 170 species known to be breeding in the state have declined by at least 10 percent over the past three decades.

The American kestrel is among the birds whose numbers are dropping sharply and unexpectedly. No one is sure why the small falcon is in such big trouble. Suburban sprawl may be part of the reason, but the state is also losing farmland to forest. Since kestrels thrive in open fields and pastures, the rise of dense woods means no more mice, grasshoppers, and other meadow prey.

"Birds are tricky, and the reasons for population losses or gains aren't necessarily the obvious ones," said Joan Walsh, an ornithologist and director of the project. "It isn't always because of 'bad' bulldozers ripping away nature. Farms go down, fallow fields grow up, and birds that require open land disappear. The flip side? Birds that like woodier habitats may move in."

The Cooper's hawk, for example, is proliferating in older suburbs like Concord and Lincoln that are now thickly timbered.

"Each bird has its own story," Walsh said.

Mass Audubon has divided the state into 1,055 blocks, each covering 10 square miles, and has recruited volunteers to identify all the breeding species in each block. The lookers are interested only in birds actively courting, mating, and hatching chicks. These are the birds that count as native species, as opposed to migrants that might tarry a few days or weeks en route to other breeding grounds.

"Protecting birds is really about protecting their ability to reproduce and raise healthy young," Walsh said in an interview at the conservation group's headquarters in Lincoln. "For that you need good and highly local intelligence."

The completed atlas will be published online in 2011 and will serve as the foundation for conservation programs and ornithological research for decades to come.

The kestrel, the American black duck, the eastern meadowlark, and other troubled species are still breeding robustly enough for a comeback with aggressive conservation programs, according to ornithologists.

Other birds are basically goners. The golden-winged warbler and short-eared owl, for example, are "for all intents and purposes extinct as breeding birds in Massachusetts," Walsh said.

The declines reflect regional trends, not just state problems, and ornithologists say the causes are largely a mystery. Habitat loss is cited, but so, too, is the propensity of some birds to mate with highly similar species and thus disappear into other flocks over time.

On another front, the South is rising. Species associated with more gentle climes are becoming Bay State regulars, perhaps another signal of climate change - although ornithologists caution against fast judgments.

Nonetheless, the red-bellied woodpecker - once an exotic sojourner in these parts - is now a familiar face. In 1979, when the last atlas was completed, red-bellieds were found in only two blocks statewide; the new study, which has covered only a third of the state, found the species nesting (or at least drumming for a mate) in 263 grid sections, an explosive increase.

American oystercatchers and blue-gray gnatcatchers are among other southerly birds setting up shop in Massachusetts. If the inflow continues, joked Audubon field ornithologist Simon Perkins, the black-capped chickadee might one day be replaced as Massachusetts state bird by the Carolina chickadee. "Not that anyone would notice," he said of the innocuous little fluffer.

Mass Audubon completed America's first breeding bird survey in 1974-79. The effort, together with similar work in Great Britain, became the model for studies in most states and Canadian provinces. Vermont just completed its second breeding bird atlas; ditto New York.

The grunt work of the Massachusetts study is carried out by seasoned volunteers; Mass Audubon has 600 "citizen scientists" beating the bushes, slogging through swamps, clambering steep slopes, and checking out urban birdscapes.

Keleher, a 39-year old office worker, isn't missing a trick.

An ardent amateur birdwatcher, she's also coordinator for two breeding blocks in the Mashpee area and spends chunks of her free time on the prowl. The other day she had binoculars fixed on a battery of outdoor lights looming over the tennis courts at Mashpee High School. A pair of ospreys recently built a spectacularly messy nest atop the fixtures.

"Look," Keleher cried. "They are copulating."

It was literally one for the record: Using Audubon codes, Keleher entered the romantic raptors as a "probable-C" - a potential breeding pair showing signs of courtship. Later this season, she hopes to spy chicks squawking in the nest, at which point she will classify the family as "confirmed-NY," for nest-with-young.

Next stop, a culvert in Cotuit.

Keleher slashed the dimness with a flashlight's beam. Eastern phoebes had been known to nest herein. But no joy. Give it a couple weeks, Keleher said, they'll show.

In a stand of pines, a barred owl snoozed on a branch. Mark him "p" for a possible breeder. His mate might be nesting in a nearby trunk cavity, over which he seemed to be keeping bleary guard. But Keleher couldn't be sure.

A few miles away, there was no doubt motherhood loomed for the mourning dove occupying a fine-woven nest on a spruce in a suburban front yard. Keleher first spied the dove and her male bringing twigs to the site days earlier. Now the dove was incubating eggs.

"This isn't just about checking a bird off a list," said Keleher. "We're watching, we're learning, we're trying to understand more about birds breeding in our Commonwealth."