By Pamela Doan
Some birds are generalists and other birds are specialists. The generalists, crows are one example, adapt to different conditions more easily. They can find food, shelter and breeding sites in many places. Specialists aren’t that versatile. They exist in a certain place because it has the right food, landscape and habitat. These requirements are so specific that some specialist birds can only live in a handful of places in the world. Their diet may consist of a certain berry or nut that only comes from a tree that itself can only live within its own narrow range.
Specialists are in trouble and so are some more common birds. A recent report, The State of Birds, issued annually by the U.S. North American Bird Conservation Initiative Committee details the changes in bird populations throughout America. The NABCI is a group of federal and state agencies along with private conservation groups and the data is gathered from several large-scale bird counts, including the Audubon Christmas Bird Count. The report summarizes the overall health of bird populations categorized by their habitat.
Locally, Philipstown includes two main bird habitats, forest and wetlands. We also have many species that migrate through here. Our diverse geography encompasses many features for birds.
Overall, the report isn’t cheery, which isn’t surprising given the many environmental challenges wildlife face. There are 230 species of birds that are endangered or are on the brink of becoming endangered unless some action is taken.
An additional 33 species of common birds have lost more than half their global population and are in rapid decline. About half of the common birds that are suffering mass losses are found in our area. They include the field sparrows, eastern meadowlarks, bank swallows, and pine siskins, among others.
Factors contributing to the population losses include habitat loss, fragmentation of habitat by development, invasive species, pesticides, and climate change. Cats are another big factor, as are tall buildings that are lighted at night along migration routes.
Locally, Eric Lind, the center director at Constitution Marsh Audubon Center and Sanctuary, said that cats are one of the main threats. “We can modify our actions to benefits birds,” Lind said. “Keeping cats indoors is something we have control over that can really help.” He also commented: “Nothing is cut and dry in nature. Many birds here are migratory and conservation efforts have to be much larger in scope. Rarely is it only one cause impacting populations. It’s a combination of factors.”
Bird sanctuaries like Constitution Marsh, which was founded in 1970 and includes 270 acres on the Cold Spring and Garrison waterfront, have been the saving grace for birds and the State of Birds report highlights public and private partnerships as critical to the survival rates for other populations. We can’t set aside all the land, though. Birds will only be saved if people that own land privately pay attention to the landscapes that they control, too. In next week’s column, I’ll detail ways to create bird-friendly habitats in a home yard.
Lind noted two significant changes in local bird populations. Bald eagles, on the endangered list 25 to 30 years ago, have made a population recovery thanks to intervention efforts and decades of work. There are local nests here in Philipstown. Bluebirds are another success story he mentioned. “People started maintaining boxes for nesting and it created habitat for them.”
Swallows, which used to be seen in great numbers in Constitution Marsh 20 years ago, are in steep decline. Lind said, “In later summer through the first cold snap, we would literally see hundreds of thousands of swallows, swirling in enormous flocks in the marsh, staging for their migration. Now we might see a couple hundred. We don’t know why. They aren’t on the verge of extinction, but they are certainly in decline. Pesticides might be a problem. The big thing on everybody’s mind is climate change.”
For the marsh itself, sea level rise as a result of global warming is already happening. They have documented a rise of about one inch every 10 years so far and climate models anticipate that seas will rise more rapidly in the future. Lind says that means plants in the marsh that provide habitat and food might not be able to survive in higher water levels. Conditions will continually change. In spite of the challenges, Lind is optimistic. “A lot of these things are in our control and simple actions can help,” he said. “People have the capacity to turn things around.”
The State of Birds report is available at stateofthebirds.org.
Tree swallow photo courtesy Constitution Marsh Audubon Center and Sanctuary