Christmas Bird Counts Survey Local Populations Amidst North American Declines

Jan 22, 2020

At dawn on the edge of Big Lagoon County Park, north of Arcata, California, Ken Burton is walking through the woods trying to rile up the nearby birds. As he scans the windswept cypress trees and leggy underbrush, he purses his lips and makes a plosive screech. It’s called “pishing.”

“I don’t’ think anyone really knows why it works,” Burton says. “Maybe it’s just an unfamiliar sound or close enough to an alarmed jay call.”

Burton is a seasonal wildlife biologist. He’s out early this morning for the Christmas Bird Count, which he’s been doing for the past 40 years. The goal: count as many birds as possible – rare and common alike – over the course of a day.

Peering through his telescope across the lagoon he spots a Black Phoebe, a few Ruddy Ducks, and several Grebes, among hundreds more in the distance. He enters each into an app on his phone called eBird.

But despite all the species he’s recording now, Burton is concerned about local bird populations. For the first time, researchers are able to accurately estimate dramatic declines of common bird species across North America. Burton says he’s seen it too.

A few years ago, he was revising the field guide he wrote called Common Birds of Northwest California, first published in 2012. While reviewing the eBird data between book editions he noticed the birds seemed to be disappearing.

“The differences were stark enough that they really kind of jumped out at me,” Burton says.

Burton scans the coast for birds during the 2019/20 Christmas Bird Count.
Credit Erik Neumann/JPR

In the span of just a few years, two thirds of the local species, including common birds like crows, jays, blackbirds and sparrows, appeared to have declined, many by more than ten percent.  

“The fact that there are such striking differences in such a short time really rings some alarm bells,” he says.  

Burton’s observations run parallel to a study that came out last year in the journal Science. Titled “Decline of the North American avifauna,” it shows there are nearly 30% fewer birds across North America today than there were in 1970. Researchers estimate the decline translates to nearly 3 billion fewer birds within a single lifetime.

“There’s a lot of rare species declining but they don’t really make up much of the abundance, so seeing these declines in these really common birds that are not threatened and endangered is really what’s new here,” says Ken Rosenberg, an applied conservation scientist at the Cornell Lab of Ornithology and the American Bird Conservancy.   

According to Rosenberg, the lead author of the paper, that term “abundance” is particularly important. Shrinking biodiversity is usually defined by extinctions of rare species. His paper shows it’s not just endangered species that are disappearing. In recent years, vast numbers of familiar birds have been declining right in front of us.

“The kinds of declines that we were seeing, even in very common species, if you weren’t really paying attention you might not notice them,” he says.  

Rosenberg calls the drivers behind bird declines “death by a thousand cuts.” Among the biggest are declines in insects that birds feed on due to pesticide use, loss of habitat, bird collisions with windows and being eaten by house cats, and climate change accelerating other factors.

It is important to be cautious when drawing connections between local bird populations and trends across an entire continent, Rosenberg and Burton both note. For example, what Burton noticed in Arcata is not necessarily what’s happening to the same species everywhere else.

But in the world of research, birds are unique. Because they’re such a charismatic species and are so easy to count, the sheer amount of data from both citizen scientists and professional researchers allows for refined study beyond that of most other animals. The eBird app alone has over 500,000 participants, according to the Cornell Lab of Ornithology, making it “the world’s largest biodiversity-related citizen science project.”

“We don’t have anything equivalent for salamanders and voles, and things like that,” Rosenberg says. “What we’re seeing with birds could likely mirror changes that are happening in these other animal groups that we’re not monitoring in the same way.”

In response to the alarming findings of their paper, Rosenberg and others created a website, 3Billionbirds, that includes a list of actions individuals can do to help protect and restore bird populations.

Big Lagoon County Park, one location during the 2019/20 Christmas Bird Count.
Credit Erik Neumann/JPR

Volunteers like Ken Burton taking part in the Christmas Bird Count are just one data source to help researchers get a better picture of what’s happening. This year, Burton’s sightings were good. By the end of the day, he and a several other volunteers counted 121 bird species across the 15-mile wide circle they crossed by car, foot and boat.

But it doesn’t stop him from worrying about the culmination of pressures unraveling the creature he loves the most. The condition of bird populations and the speed of their declines should be a concern to everyone, Burton says.  

“Whether you think you care or not, you really should care. Not necessarily about the birds themselves but about what that signifies.”