Alpine birds: Climate change indicators?
OK. You’re a winter wren. A small brown songbird with a delightful song found in most parts of Canada. And it’s time to build your nest. Do you scout out a prime location in Vancouver’s Stanley Park, when the tulips are pushing through the ground in March?
Or do you fly far from the maddening crowd, seeking out extreme habitats on alpine slopes? Here you will have less time to reproduce and you will have fewer offspring, but just like your low-elevation counterparts, you still have to incubate your eggs at a steady 37 degrees, even when temperatures near your nest on the ground rise as high as 48 degrees by day and plunge to near freezing at night.
According to the University of British Columbia’s Dr. Kathy Martin, "If you look at it just on a seasonal basis, within one summer, it can never be an advantage to nest at the higher elevation." Yet this is precisely where some alpine-tolerant species choose to go. And she’d like to understand what draws these natural-born "survivors" to greater heights. Dr. Martin is also studying how songbirds cope with the harsh climatic conditions and how changes in weather and other environmental disturbances are affecting their survival.
For the past two summers, Dr. Martin has climbed the slopes of Hudson Bay Mountain, near Smithers, B.C. to collect data about nesting songbirds. "One of the challenges for an alpine ecologist is that if you go higher, you have to cope with bad weather too! And it can be extreme!
"In the alpine, it can snow five to eight centimetres pretty much any day of summer," Dr. Martin says. "But heavy snowfall and long rain events in spring and summer are increasing as a consequence of climate change. Extreme weather events make it very difficult for some birds to cope. Sometimes they are forced to abandon their nests to go and feed. Both summers, we’ve had a big snowstorm at the end of June, resulting in major breeding failure. Many young and many eggs died."
Dr. Martin’s theory about how alpine birds are "rewarded" for choosing to breed in a more difficult habitat is that they probably live longer. "For many songbirds breeding at low elevations, it’s a ‘live fast, die young,’ kind of lifestyle," she speculates. "At high elevation it may be a ‘live slow, die old,’ model."
Among Canada’s most understudied ecosystems, alpine environments share many similarities with the Arctic. However many alpine areas tend to be closer to manmade environmental stressors, such as air-borne contaminants from urban centres, nitrogen deposition from nearby farming areas, as well as recreational pressures from heli-skiing or backcountry camping.
Dr. Martin studies both alpine "specialists" – birds such as the ptarmigan or pipit that breed exclusively in alpine environments – and alpine-tolerant species, such as the savannah sparrow, the horned lark and the winter wren that can breed either in alpine areas or at lower elevations.
Experts at camouflage, alpine birds are very aware of their body colour and use this knowledge to blend in with the background of the wide open spaces. "A pair of ptarmigan will stay within a few metres of each other for several weeks in spring, but the male moults his white winter plumage sooner than the female, so he is brown, while she is white," Dr. Martin says. "The pair resolves this potential camouflage crisis by remaining near the edge of a snowfield: the male sits in the brown grass while the female sits on the snow.
"The ptarmigan are supreme alpine specialists and although they are going to be challenged by climate change, I feel it’s the songbirds that are going to be the canaries-in-the-mine for climate change," she says.
The former president of the Society of Canadian Ornithologists, Dr. Martin is the only scientist in Canada devoted to the study of alpine birds. She finds herself on a virtual "ornithological frontier," with only three other colleagues across North America who specialize in alpine birds, two of whom are retired.
Most researchers look for a niche to occupy. "These birds have just not been studied, especially in Canada, so it’s almost a vacant niche!" she says.
Whistler Naturalists Speaker Series: Getting By or Flying High — The Challenges of being an Alpine Animal with Dr. Kathy Martin. The University of British Columbia’s Dr. Martin is the only scientist in Canada devoted to the study of alpine birds (see above). Event will take place Thursday, April 22nd at 7:30 p.m. at MY Place (doors open at 7 p.m.). Admission by donation, children free.
Monthly Bird Walk: The next bird walk will take place Saturday, May 1st. Join Whistler experts in the monthly update of our feathered locals and migrants. For details, contact Michael Thompson.
Written by: NSERC Newsbureau Bulletin