What do these two birds have in common? Left image: The Canada Jay is a boreal bird that was once very common in Algonquin Provincial Park. However, it is now seen there less frequently. Photo by Paul Nicholson. Right image: A domestic canary, a species that was historically used as a "sentinel animal" to alert miners to sudden changes in air quality in mines. Photo from Wikipedia
Wild birds today are similar in many ways to the canaries in the mineshaft. Bird scientists continue to demonstrate the effects of climate change, including the range changes of some of Ontario's bird species over the past decades.
Because of global warming, we have seen some bird populations shift either north or to higher elevations to adapt. Species including Red-bellied Woodpecker, Northern Mockingbird, Tufted Titmouse, and Blue-gray Gnatcatcher have expanded their ranges into Ontario. Local populations have also increased.
Selfishly, one might be quietly pleased with the opportunity to see more of these birds, but the calculus is complex of course. Some of our northerly species are now being forced further north. Boreal Chickadees, which used to be seen reliably in Algonquin Provincial Park, are now seen there infrequently.
Dr. Laura Coristine is a biologist who has studied temperature-related geographical shifts among songbirds. In a paper published in Ecology and Evolution, she confirmed that “climate change is causing widespread geographical range shifts.” She described a range squeeze. She found that for many birds, range gains to the north haven’t happened as quickly as range loss to the south. You can listen to Coristine speak about this with CBC Radio’s Bob McDonald in a 7-minute 2016 segment on Quirks & Quarks.
The ranges of some Ontario birds are shifting because of climate change. During an 18 year study period, the range of the Prairie Warbler was squeezed. It had moved north into Ontario by 16 km, but the species had lost 170 km at the south and of its range. Photo by Paul Nicholson
Citizen science data and ornithological studies have also shown that the ranges of some warbler species including Pine, Prothonotary, Hooded, and Cape May, have also shifted.
Another boreal forest bird, the iconic Canada Jay, is also having to cope with climate-induced changes. Populations of this bird – also known as the “camp robber” or the Whiskeyjack from the Algonquin Wisakedjak – have dropped in Algonquin Provincial Park. Sightings of this bird by park visitors are no longer assured.
Canada Jays are among the birds that cache perishable food so that they can retrieve it through the winter and during their early nesting season. Rising temperatures result in a significant freeze-thaw cycle that triggers spoilage of some of the cached food. Dan Strickland, a bird scientist who specialized in this bird, noticed a decreasing population trend in the 1970s. He wrote about climate change and "the demographic demise of a hoarding bird living on the edge."
Research published in Global Change Biology in December 2020 was consistent with the hypothesis that “warmer and more variable fall conditions accelerate the degradation of perishable stored food.” This in turn threatens regional populations of the Canada Jay. More recently, University of Guelph biologist Dr. Ryan Norris determined that spring 2021 was the Canada Jay’s worst reproductive season since data have been collected in Algonquin Park. Between 1970 and 2021, the Park’s estimated Canada Jay population has dropped by 67%. This contributes to a concern that the Algonquin population could become extirpated.
In a Nature Canada article titled “How climate change is affecting birds”, changes to bird populations apart from range shifts are described. These include nesting changes, migration changes, and a trophic mismatch when not enough food is available when young birds hatch. Ontario Breeding Bird Atlas data and birders’ entries into the eBird community science platform provide important resources for bird scientists who continue to study this issue. Data collected today may become fundamentally important in the future for understanding changes and conserving bird species affected by climate change.
Because of the complex connections that birds share with ecosystems throughout their ranges, changing environmental conditions brought on by global warming may have long-term effects for birds that scientists cannot predict with currently available data. It seems likely that changes in the distribution of species of plants and insects, two primary sources of food for birds, will drastically impact a great number of bird species in the coming decades. Habitat loss is already a leading contributor to the decline of birds and may be exacerbated by extreme weather under climate change, especially in equatorial regions where many of Ontario's migratory birds overwinter.
With many bird species expected to decline under climate change conditions, the numerous ecosystem services those birds provide will be significantly affected. Reductions in pollination and seed dispersal, and losses of birds' contributions to the food web, could theoretically have drastic consequences for ecosystems as we know them. Like those old-time canaries that warned miners of deadly threats, the shifting ranges and populations of some of Ontario's birds represent a similar omen that we ignore at our peril.
It has never been more important for people who care about birds to vote for leaders in government who listen to scientists and support conservation of biodiversity and species already listed as being at risk of extinction.