Scores of bird species could disappear due to climate change, study finds
Not even the state bird appears to be safe from climate change.
The black-capped chickadee, which inhabits nearly every corner of Massachusetts, is among scores of birds that are likely to disappear from parts or all of the state by 2050 as temperatures continue to warm, according to a new report by Mass Audubon, a conservation group.
Of the state’s 143 most common breeding species, 43 percent are considered “highly vulnerable” to climate change by the middle of the century, the researchers found. An additional 22 percent are considered “likely vulnerable.”
“There is no credible doubt that the Earth’s changing climate and its living inhabitants are now on a collision course,” Christopher Leahy, a field ornithologist at Mass Audubon, wrote in the report.
Birds, like canaries in coal mines, have long served as warnings to environmental threats, he noted.
“Losses for birds due to climate change presage losses in the quality of human life,” he wrote. “When Tweety starts wobbling on his perch, it’s time to take corrective action in the name of survival.”
As humans pump carbon dioxide into the atmosphere, Massachusetts in the coming decades will probably experience warmer temperatures, higher seas, greater precipitation, and more acidic oceans.
Those changes, while gradual, are likely to impact the avian world, affecting a range of species from Boston to the Berkshires, the report found.
They’re expected to alter food sources for many fish-eating birds, and will probably affect when trees produce leaves, flowers bloom, and insects emerge, potentially killing flocks of migratory birds that arrive at their breeding grounds in time for the peak supply of their food.
Rising seas and the more powerful storms expected from climate change are likely to reduce nesting areas for birds that live along the coast or in salt marshes. Ocean acidification, which occurs when the ocean absorbs carbon dioxide, is likely to reduce stocks of shellfish, which many birds rely on.
The report classified 70 percent of species that nest in salt marshes as highly vulnerable to climate change, along with more than half of coastal-nesting species that were surveyed.
Another 30 species of forest-breeding birds — half of those assessed by the report — are also considered highly vulnerable.
Birds at the greatest risk include species now common throughout the state, including the yellow-bellied sapsucker, ruffed grouse, purple finch, magnolia warbler, and white-throated sparrow.
Other birds, those used to warmer climates further south, are likely to increase in abundance and compete for food, such as the eastern kingbird, American robin, and ruby-throated hummingbird.
“That we are likely already seeing disruption of so many different species, even relatively common species, is an indicator that we face a profound challenge,” said Daniel Brown, climate change program coordinator at Mass Audubon. “The projections for the future are chaotic and dire, but they are avoidable if we act quickly to address climate change and reduce existing stressors on birds.”
The report is the third “State of the Birds” assessment the group has produced since 2011, when their researchers found that nearly half of all the state’s breeding birds were declining in number, from marshland and grassland species to more common birds such as blue jays and swallows.
Climate change is only one factor endangering birds. Many at-risk species are also threatened by the loss of agricultural lands to development, the use of toxic chemicals such as pesticides, and feral cats and other predators.
In the latest report, the authors based the conclusions on models that rely on preferred climates of various species and projections for how those climates are likely to change. Because some species can breed in several habitats, they are included in multiple lists.
The authors relied on estimates that average temperatures in the region — without aggressive action to reduce emissions — are likely to increase several degrees by 2050, with significantly more days of extreme heat and fewer cold snaps. They also used estimates that annual precipitation would increase by 15 percent and seas in the region could rise between 7 inches and 1.5 feet during the same period, which they said would produce significantly more coastal flooding.
Chris Elphic, an ornithologist at the University of Connecticut Storrs who was not involved in producing the report, called its methodology “a common approach” to make predictions such as how certain crops will grow or where diseases are likely to emerge in the future.
“The general patterns that emerge from this study line up closely both with other predictive studies from around the world and with changes we see in the field,” he said.
One limitation of the report, he noted, is it assumes that climate change will exclusively determine the future distribution of species. The actual affects could be more dire, he said.
“As the authors point out, things are more complicated; changes are happening rapidly and species will only be able to move into areas with suitable climates if the habitat also changes,” Elphic said. “Both ecological and human factors mean that this may not happen fast enough for many species.”
For example, coastal marshes along Long Island Sound that he has studied are not moving inland fast enough to keep up with rising sea levels.
“In other words, dire as this report’s predictions may seem, without concerted efforts by the conservation community, there’s a good chance that the report underestimates how badly the state’s birds might be affected,” he said.
By 2050, the likelihood that a bird-watcher would encounter a black-capped chickadee is projected to decline by more than 30 percent. In some areas, such as from Cape Cod to Newburyport, the birds are likely to all but disappear, according to the report.
The songbirds, now common in forests and suburban yards, had been rising in number over recent decades. But warming temperatures are likely to push them further north.
“That [loss] speaks to the chaotic future that will surely have unpredictably negative outcomes for our farms, fisheries, and families in Massachusetts,” said Joan Walsh, an ornithologist at Mass Audubon.