Bird-watching is one of Ithaca’s most popular outdoor activities year-round, as migratory patterns mean hundreds of different bird species are present during different seasons throughout the year and provide the potential for a unique experience each trip.
Yet that activity, like so many other parts of our daily lives, has been touched by climate change. As weather trends change, bird populations are being impacted significantly, leaving less and less to be observed through a pair of binoculars on peaceful mornings around the area as time goes on.
Jody Enck, a member of the Cayuga Bird Club, lamented the loss of the “Dawn Chorus,” when birds of all species and sizes would greet the morning with songs. It’s one of the more noticeable changes Enck said he’s found over the last decade or so, which is symptomatic of the overall dissipation of bird population in the area. That may have been highlighted this month in the annual Christmas Bird Count, held on New Year’s Day, which saw lower numbers than normal, especially in comparison to a very high turnout in 2018.
“There’s all this activity, and it used to be that you could go out and it would be really loud,” Enck said. “But the last decade or so it’s been getting less and less and less. I’m talking mostly in the spring, when birds are really singing and defending territory. Now you can go out and you hear long periods of silence. Maybe you hear one or two birds like warblers over there, and then there’s silence. And then you hear a woodthrush. But before, you couldn’t even tell how many birds you were hearing because there were just so many.”
Enck said there’s a myriad of reasons for the population drop-off, but he cites three primary factors: the use of chemicals, like pesticides that diminish the amount of food birds are capable of feeding on; residential development that can often lead to habitat loss; and overall climate change. Specifically, climate change has caused something called a “mismatch,” according to John Fitzpatrick, the director of Cornell’s well-known Ornithology Lab. The mismatch means the explosion of new-born insects, which are normally the main food source for birds and their newly-hatching young, are actually being born too early due to warmer temperatures. By the time the birds get to their long-term location, the insects have matured, making them more difficult to catch and harder to digest for younger birds.
Enck added that moisture distribution shifts resulting from climate change can also contribute to habitat modification, making some locations less suitable for birds that would normally stay there. The birds’ instincts aren’t able to adjust as quickly as the environment is changing around them. Beyond that, rising shore tides have hurt some species who inhabit coastal settings.
One day of counting per year, like the New Year’s Day event, serves as a metric of sorts, but it’s not a greatly comprehensive statistic for measuring larger trends of birds, as it can be bumped up or down by something as simple as that day’s weather. For instance, Enck ascribes this year’s low numbers to the day’s relative mildness with high winds, particularly compared to 2018. Still, Enck said, the bad years like 2019 seem more significant to him than years with good figures, like 2018, because of the overall trends of decreasing populations that he has observed, and as has been researched extensively, “down” years seem more ominous. At this point, he said, it’s fair to say that there are fewer birds in the area, and it’s equally fair to wonder whether or not that can change.
“It concerns me when we have a bad year with the Christmas bird count,” Enck said. “It makes me more concerned and anxious for next year. Are things going to recover? Are we going to go back to normal or not?”
Plenty of research is being done to chart the long-term shifts of bird migratory patterns and how they might be impacted by rising temperatures globally. The most prominent example of this charting is eBird, a digital service offered by Cornell’s Ornithology Lab that diagrams population density of certain species throughout the year, showing movements and patterns during different seasons. Through the tool, which is publicly available, Fitzpatrick can see how different birds have already changed their seasonal behaviors, theoretically in response to changing temperatures along their normal routes.
Climate change has necessitated at least one change in how birds are studied and the way conservation is approached, Fitzpatrick noted, pushing a more complete method to the forefront to better understand what harms birds are facing as the climate deviates from its norms.
“What’s very clear in the field right now is that conservation of birds means paying attention to their full annual cycle,” Fitzpatrick said. “Not just where they breed, or where they winter, but what’s happening with migration as well.”
Fitzpatrick said at this time, climate change having some significant impact on bird populations and their behavior; the only question is determining what that impact will be, and how severe its effect will be. This points to Enck’s nervousness about diminished bird count numbers: one year could be just a fluke, but it likely portends something larger.
“There’s no question it’s going to affect bird numbers and bird distributions, we’re just now starting to see the edges of that,” Fitzpatrick said. “There’s a growing body of literature that is trying to project into the future what today’s community of birds is going to look like in 75 years, and some of those models predict it to be very different.”