State-wide volunteers have maintained the Christmas Bird Count for 122 years, allowing experts to track significant population decreases due to habitat loss.
Since 1900, counters have tallied birds at local Christmas Bird Counts and submitted observations to the National Audubon Society, a nonprofit conservation organization. Joe Attwater, conservation and education coordinator for the Roger Tory Peterson Estuary Center in Old Lyme, told CT Examiner that the volunteer-driven event gathered essential data more efficiently than one organization could on its own.
“We can use this data, and we don’t have to be the ones going out and collecting every single piece of data from all over the state,” Attwater said. “That’s key.”
By analyzing trends in the data, Attwater explained, Audubon could identify specific species facing habitat loss – the leading cause of population decline.
Additionally, Attwater said annual counts helped to inform national studies like 3 Billion Birds, which found 2.9 billion fewer North American breeding birds in 2019 than there were in 1970. According to the study, the largest declines were forest birds and grassland birds, with more than 1 billion and 720 million lost respectively.
Attwater verified the findings, saying both forest birds and grassland birds were diminishing in Connecticut.
“Those two groups are especially struggling, and grassland birds are ones we really want to keep an eye out,” Attwater said. “The state does as well – they monitor populations of those two different habitats and the species that utilize them.”
A Connecticut Wildlife Action Plan from 2015 detailed state conservation efforts and confirmed Attwater’s concern for grassland birds – of the 22 species that breed in grasslands, fields and field edges, 17 have experienced widespread declines.
Christmas Bird Counts of song sparrows, one of the 17 declining species, from 1900 until 2021 painted a similar picture. Following a significant sighting spike in 1947, counts remained considerably low. The state action plan pointed to farming trends to explain changes.
“This trend probably reflects the historical fact that habitat for these species expanded during the period of widespread farming and pasturing and then declined following agricultural abandonment and a return of the land to forest,” the plan said.
Both the state action plan and Audubon counts of yellow-rumped Warblers – often found migrating along the east coast – confirmed a changing forest bird population. These increases and decreases, according to the action plan and Attwater, were correlated with habitat fragmentation from state-wide development.
“You may have little parks and small bits of forest, but there's a lot of birds that need large tracts of wilderness,” Attwater explained. “And so by putting these subdivisions in cities and things, we're breaking up these large tracts of habitat that are really crucial.”
While both Attwater and the 3 Billion Birds study emphasized a need for grassland and forest bird conservation, the state plan also highlighted shrubland bird populations, as Connecticut was regionally responsible for numerous species. According to the state plan, the populations of more than 80 percent of shrubland birds in New England declined from 1966 to 2006, confirmed by Audubon counts of field sparrows in Connecticut.
But after national and state conservation efforts, some populations have rebounded. After the implementation of the Endangered Species Act of 1973, the 2019 study concluded that raptors including bald eagles and osprey made a rapid turnaround.
Based on Audubon counts of osprey, Connecticut’s turnaround began in 1979 after a period of decline. According to the state plan, the 1970s drop came “partly from the effects of DDT” – an insecticide once widely used in agriculture.
While state osprey populations have historically ebbed and flowed, recent sighting counts somewhat mirror the 1970s lull. Attwater said that since its emergence, the Christmas Bird Count had and would continue to provide an “important snapshot” of those changes.
The annual count was originally created to replace a holiday wildlife-harvesting competition known as the Christmas side hunt. Few Connecticut residents participated from the outset, with only one or two volunteers in each region. But for the 2021 count, about 76,880 residents joined.
Attwater highlighted a recent increase in volunteers, citing the pandemic.
“The pandemic got a lot of people involved with birding. It was something you could do outside, it was something you could do from your own backyard,” Attwater said. “And so, a lot of people the past couple of years have really gotten into that, and that's carried over.”
To participate, volunteers must count the birds they see or hear within 15-mile-wide circles across the state. This year, Connecticut counts began on Dec. 17 and end on Jan. 2. Upcoming events include a Guildford count on Dec. 30, New London on Dec. 31 and Old Lyme on Jan. 1.