With the loss of farmland and the gain in forestland in the state since 1970, many birds that nest in meadows, such as eastern meadowlarks (left), are vanishing in the commonwealth, while many of those that nest in forests, such as Cooper’s hawks, have been on the rise, according to a recent report, “State of the Birds,” by the Massachusetts Audubon Society. (To download report in pdf format, click on the State of the Birds link).
The American kestrel, (right) the continent’s smallest falcon, thrived in local grasslands, hunting for grasshoppers, mice, and other prey in the state’s once-abundant farms. And the red-eyed eastern towhee long warbled in wooded areas while noisily raking the brush-covered grounds to forage for insects.
Those birds as well as many others are disappearing from Boston to the Berkshires, while wrens, woodpeckers, and other species from Southern states are mysteriously taking their place and surging throughout Massachusetts, according to a landmark report by Mass Audubon, which compiled more than four decades worth of data from three periodic birding surveys about the state’s birds from thousands of scientists and trained birders. The compiled data covered nearly 300 species that were followed, including wintering birds that do not nest in the state.
“We’re getting a lot right in Massachusetts,” said Joan M. Walsh, one of the principal authors of the report.
“We have nearly as much protected land as developed land in the state. And nearly 70 percent of our bird species are stable or increasing. Yes, there’s no doubt there are challenges ahead, but I think we can come out on the good side of them,” she said.
The report notes that the populations of a third or more of the species studied are declining, some precipitously. Habitat loss was the single biggest factor in the declines.
The report found nearly half of all the state’s breeding birds are declining, including many marshland and grassland species as well as more common birds such as blue jays (right) and swallows, raising questions about the health of the state’s wetlands and other ecosystems.
It also found that although the state has helped bring back endangered birds such as piping plovers, peregrine falcons, and bald eagles, 20 of the 28 birds listed under the Massachusetts Endangered Species Act remain vulnerable. An additional 34 birds that have been identified as of “conservation concern’’ were also found to be declining.
Among the other findings:
- More than a quarter of all wintering birds are in decline;
- the number of species that are increasing has fallen by half since 1980;
- and the number of ground-nesting birds and others that feed on insects are dropping.
The bird populations of Western Massachusetts have not been as affected as those of other regions because the change in habitat, such as development, has not been as pronounced as in eastern and central Massachusetts, according to Walsh.
The course of climate change will likely determine future changes to the state’s bird population, the report suggests.
If year-round temperatures continue to warm in the Northeast as they have (about a half-degree warmer per decade on average since 1970), for instance, birds with a more southern range will move in to the state while others, which prefer colder conditions, will move out.
In a letter introducing the report, famed Harvard biologist E.O. Wilson, a two-time Pulitzer Prize winner, said one of the “unmistakable markers” of climate change already is that “many historically southern species are now permanent residents.”
For instance, the Carolina wren (right) and red-bellied woodpecker (upper left) , primarily Southern birds, are becoming more common in Massachusetts.
By 2100, according to the report, “Winters in the Northeast U.S. may be 5 to 12 degrees Fahrenheit warmer and summers 3 to 14 degrees Fahrenheit warmer, giving Boston a climate similar to that of Baltimore, Maryland, or Charleston (S.C.).”
The report also notes that anticipated changes in vegetation and insects, due to warming temperatures, will affect birds dependent on them.
“Future projections suggest that the oak-pine forests that predominate in central and eastern Massachusetts will completely cover all of Massachusetts in the future,” the report said. “The northern hardwood forests (left) - dominated by sugar maple, American beech and yellow birch, common in central and Western Massachusetts - are also predicted to disappear,” it said.
Mass Live,"Massachusetts Audubon Society 'State of the Birds' report: Climate change affecting bird population", accessed October 11, 2011
Boston.Com Article Collection, "Study finds steep drop in Bay State’s native birds", accessed October 11, 2011