Study warns of possible future peril
Creatures not matching nesting with earlier food supply
A new international study out of the University of Edinburgh, with key input from Canadian researchers, has shown that seabirds are not adapting to warming sea surface temperatures caused by climate change.
The study, which was published in the scientific journal Nature Climate Change, looks at more than 60 species of seabirds from 145 populations around the world with data going back to the 1950s.
Although rising temperatures show food sources like plankton, insects and vegetation have been appearing earlier each year, seabird populations are not matching up their breeding and nesting patterns to adapt with this change.
“It’s one of those examples of what you can do when you match really technologically sound thinking with people who are willing to put all their data together to answer bigger questions,” Mark Mallory, a biology professor at Acadia University in Wolfville and the current Canada Fulbright Visiting Chair in Arctic Studies at the University of Washington in Seattle, told The Chronicle Herald.
Mallory’s research on seabird populations in Nunavut was used in the study. For seabirds, the most stressful time of the year is when they’re trying to rear their young — instead of having just themselves to feed, they have many other mouths to worry about.
“There’s a theory that has generally received good evidence and that is seabirds and all birds time their breeding so that their young are being raised when there are very high food supplies available,” Mallory said.
Most of those sources start growing when they get light and nutrients as temperatures rise in the spring, something Mallory said should be relatively predictable each year.
But as climate change occurs, scientists have noticed advanced warming of the ocean, break up of ice and progressively earlier food supplies.
“If you’re a top-of-the-foodchain type organism, like a seabird, you want to be nesting earlier so that your chicks are still hatching when that peak of food supply is out,” Mallory said.
But as this study shows, scientists don’t see seabirds changing their nesting dates to match up with that earlier food supply. Although some populations have adapted slightly, Mallory said, it’s not enough to keep up with the changes.
“This is very convincing proof that these birds are not that flexible at a global level as a group,” he said.
This lack of congruence between populations of animals and changing environments is known as the mismatch theory, Mallory said.
What does this mean for seabird populations?
According to Mallory, it doesn’t mean there will be a noticeable decline in seabirds, but it’s something that could have dire effects on populations over time, especially those that are already endangered or at risk.
“Any time you have a species that has adapted to an area and you change the conditions of that area, if the species can’t (adapt) it’s going to die out or greatly reduce its numbers and something else presumably will come in and replace it,” he said.
Seabirds are already facing many threats from other sources, such as negative interactions with fisheries, plastic contamination and other debris in our oceans, and pollution, and with climate change now added to that list, Mallory said we should be trying to do what we can to eliminate some of those other more immediate threats.
“It’s not a single issue. There are some threats we can deal with, luckily, and there’s some that are going to take a lot more political action, economic action, and are longer term.”