Researchers listen to birds for answers why their numbers are so low
Collection of nature recordings would take 2½ human lifetimes to listen to
Alberta researchers are using hundreds of audio recording devices as they seek to understand why bird populations are declining.
A University of Alberta professor says a study published last year that suggested North America had lost billions of birds ruffled a lot of feathers in the scientific community.
"The basic premise that we have lost three billion birds, it is probably conservative, is my guess," Erin Bayne told Radio-Canada.
"That, in fact, the number is larger than that. That's what we are trying to figure out. How much more? What are some of the things we can do to reduce that loss and perhaps restore and recover some of it?"
Bayne said it's the job of researchers like him to strengthen those numbers, and one way of doing that is by simply listening.
They are using autonomous recording units (ARUs), about 1,000 of them in Western Canada, to create soundscape recordings of birds and other natural elements.
"Human noise affects wildlife," Bayne said. "We have shown very conclusively that traffic noise and noise from industrial sites reduces the quality of otherwise perfectly good habitat. Animals just avoid being there.
"Vocal communication is so important to those animals, that's how they communicate with each other. When we add our noise in, it makes it harder for that signal to be properly interpreted," he said.
"We are seeing over time less and less birds who make the sounds that make a soundscape such a beautiful thing to listen to."
A study in the journal Science from last fall pointed to a loss of 2.9 billion birds in North America since 1970, including an "overlooked biodiversity crisis."
Bayne says there are three main culprits: cats, windows and industrial development.
Keeping your kitty cat inside would be a huge help, as would the use of tools to reduce bird collisions with windows on homes and office buildings, such as tinting or the addition of a film coating.
"The biggest thing we have to do is balance our need for the resources from habitats like this," Bayne explained.
"If we take away too much of any given habitat, those birds are not going to be able to recover. That is the biggest one. If we don't manage our habitat well, we are going to be in serious trouble."
And measuring where we are is where the ARUs come in.
They programmable audio recording units can capture as much data as is desired.
"We have roughly 700 terabytes of soundscape recordings from across Western Canada — probably one of the largest sets of audio files of nature anywhere in the world."
He said it would take 2½ human lifetimes to listen to all of those recordings.
"With this equipment, we are much better able to track exactly how many individuals there are, when they are there, when they are arriving. That is all through sound. Most animals make a very unique sound you can track," he said.
Artificial light can have an impact, too.
And that's where student Carrie Ann Adams comes in.
"We are studying how all sorts of human development impacts wildlife. I am looking at the effects of artificial light on birds," Adams said.
"I am seeing the species that are present, and how often they are using this site changes when there is artificial light. Artificial light is growing at a rapid rate worldwide and yet it could be one of the most easily controlled pollutants."
Adams says night birds and their food source is currently on her radar.
"I am interested in seeing how nocturnal birds respond to artificial light because they are active at a time when artificial light is more visible in the environment and they prey on insects that are also active at night," she said.
"In the future, we will likely study bats, and using ARUs we can also do that."
There's a group in Calgary that is looking at the role office buildings play in bird populations.
The Calgary Migratory Species Response Team says minor changes can make a big difference.
"It could be related to turning lights down at a certain time, it may be something just on the glass that's not going to affect the appearance of the building but may help birds and bats to avoid collisions in the future," Kathleen Johnson told CBC News in November.
It's estimated 25 million birds die each year from striking buildings in Canada.
Meanwhile, researcher Bayne says some bird species are at greater risk than others.
"The aerial insectivores are birds you would regularly see in farms and over your fields. They eat flying insects. Some of them have declined 90 per cent," Bayne said.
"When I was a kid, my farm had barn swallows absolutely everywhere," he said. "They have declined 90 to 95 per cent over the past 20 to 30 years and our assumption is that it's primarily due to the loss of the insect food supply. Insects across the board are declining.
"There is also a new class of pesticides called neonicotinoids which are thought to be having a fairly substantive effect on insect food supplies, particularly in agricultural areas."
With files from Radio-Canada’s Vincent Bonnay