Throughout North America, billions of birds, comprising more than 350 species, migrate thousands of kilometers each year in the spring and autumn. Some species, like the Arctic Tern, can travel as far as 80,000 kilometers, when making a roundtrip between their Arctic breeding grounds and Antarctic wintering grounds. These long journeys, however, pose serious risks for the birds. They face predation, starvation, and severe weather events. Yet, the risks are worth the reward of plentiful food supply, safe breeding grounds and secure wintering grounds. Alberta hosts 8 million migrant waterfowls each year that travel thousands of kilometers to breed and feast on the plentiful food supplies found all over the province. This transaction between migratory risk and reward, however, is much trickier than it appears. One single variable, i.e., timing, can turn the hard-earned bargain into a complete failure. Birds must arrive at the right time to harvest and maximize the resources, i.e., not too late as to lose their food supply and nesting ground to other birds, yet not too early in order to avoid cold weather and starvation due to low food supply. Over thousands of years, evolution has synchronized birds’ migration with the peak in the availability of food and habitat resources at their migratory destinations. Climate change, however, has started to impact this synchrony. In this blog we will explore the impacts of climate change on bird phenology by focusing on the latest research on Mountain Bluebirds published by the Ellis Bird Farm and the Beaverhill Bird Observatory.
Mountain Bluebirds are a medium size, short-distance migrant found in western North America. Their arrival often indicates the beginning of spring, including in Alberta. In early spring, Bluebirds migrate from their wintering grounds in the southwestern United States and central Mexico to their northern breeding grounds that extend from Alaska to western Canada and United States. In their breeding range they occupy grassland habitat and prefer to eat beetles, grasshoppers, and caterpillars while nesting in man-made bird boxes or cavities in trees left behind by woodpeckers.
Bluebird migration arrival dates in central Alberta, over the last 58 years, have advanced significantly in response to climate change as demonstrated in a study led by Myrna Pearman of the Ellis Bird Farm. Bird migration is stimulated by time of the year, local weather, change in sunlight, and temperature, according to Dr. Geoff Holroyd, a co-author of the study and chair of Beaverhill Bird Observatory. Their study found that, between 1961 and 2018, the first arrival date of Mountain Bluebirds in central Alberta have advanced by 19 days, meaning in the last 58 years, Mountain Bluebirds have been arriving earlier at the rate of 0.33 days per year. The Bluebirds are responding to increasing temperature and declining snow cover.
The mean temperature for the month of March has increased by 2.7 °C in 58 years, while the snow cover decreased by 3.6 cm. “Bluebirds are coming back earlier in response to early availability of arthropods (insects) caused by increasing temperatures and declining snow cover,” Holroyd said in a personal phone interview. This, however, is not necessarily good for the bluebirds. Extreme weather fluctuations are common in Alberta in early spring and April is one of the snowiest months of the year. “If the birds are coming back earlier, they are at risk of suffering from cold weather in April. They may also face starvation due to limited access to their food supply caused by deep snow cover on the ground,” Holroyd said. The advancing migration, therefore, could potentially jeopardize Mountain Bluebird population in Alberta. Holroyd thinks that the Mountain Bluebird could be a good indicator of what is happening to other species as well, particularly other short-distance migrants. These migrants tend to arrive in early spring, and therefore, are more vulnerable to extreme weather events compared to longdistance migrant which tend to arrive later in June.
The aviation industry is one of the biggest emitters of greenhouse gases. One round trip flight, between Edmonton and London, England can emit as much as 2.19 tons of carbon emissions straight into the atmosphere. We can help reduce our carbon footprint by reducing our air travel. Instead of vacationing overseas, consider travelling closer to home. Alberta offers many great destinations to explore, such as the Canadian Rocky Mountains in Banff National Park and Jasper National Park. There are the Badlands down south around Drumheller with dinosaur fossils and the Tyrell Museum. Lac Le Biche to the north has phenomenal fishing, hunting and bird watching getaway tours to allow people to reconnect with nature. In addition to numerous craft breweries located across the province, Alberta offers many other great touring opportunities. You can find more information about places to visit here: https://www.travelalberta.com/ca/
Tony Hisgett, accessed on January 21, 2020, [picture cropped] retrieved from https://commons.wikimedia.org/wiki/File:Mountain_Blue_Bird_4_(8045057780).jpg
Mountain Bluebird by IIP Photo Archive. 24 October 2018. https://commons.wikimedia.org/wiki/File:Mountain_Bluebird_(2).jpg
Mountain Bluebird by VJAnderson. 7 April 2019. https://commons.wikimedia.org/wiki/File:Mountain_Bluebird_5841vv.jpg
Myrna Pearman, Leo De Groot, Geoffrey l. Holroyd, and Stephanie Thunberg. Earlier Spring Arrival of the Mountain Bluebird in Central Alberta, Canada. accepted 19 December, 2019