Bird migration - talk about global connections!!

Sean Boyd

By Sean Boyd
Environment Canada's Migratory Bird Ecologist

What is it that fascinates us so much about bird migration? Distances traveled? Routes taken? Why birds migrate in the first place? And... how do they actually navigate? I have been intrigued by these questions ever since learning about the incredible 15,000 km migration performed by the small Arctic tern.

My name is Sean Boyd and I am a research scientist with the Canadian Wildlife Service on the west coast of British Columbia, Canada. For the past 15 years I have been fortunate to be able to study the migration ecology of a number of different bird species with the aid of a new technology, ‘satellite telemetry'. Biologists are using this technology to track the large-scale movements of many wildlife species, from polar bears to whales to Arctic geese.

My first experience with satellite tracking was with snow geese nesting on Wrangel Island, in Russian Siberia. The project, lead by Dr. John Takekawa of the US Geological Service, was the first one in which Arctic geese were marked with satellite radios. In July 1991, we ‘tagged' 30 birds with small transmitters mounted on neck-bands. During the entire next year, the radios transmitted signals to satellites orbiting 100s of km overhead and the location data for the geese were downloaded and plotted. We learned things about their fall migration that were never known before; for example, that they stopped at St. Lawrence Island in the middle of the Bering Sea, that most birds flew down the Pacific coast to reach their winter areas but some actually migrated to the prairies and then south, and that many of the birds intending to winter in California stopped at the Fraser River delta (in B.C.) and Skagit River deltas (in Washington) for several weeks.

My next experience with satellite tracking involved Brant Geese. A small population of Grey-belly Brant (5000 - 10,000 birds) spends the winter in the northern Puget Sound area of Washington state (just south of Vancouver). These birds are almost impossible to capture in winter so we traveled to their Arctic nesting grounds in the summer of 2005. We tagged the birds by implanting the transmitters into their bellies, which has proven to be a good technique for marking long-distant migrants. Over the next year we tracked the birds on an almost daily basis (view maps of the routes taken in the fall and spring ). We learned that:

• in fall, all birds migrated south along the coast from breeding grounds (Melville Island) to Izembek Lagoon on the Alaskan Peninsula
• they staged (stopped) at Izembek Lagoon for several weeks (likely building body reserves to fuel the next leg of their journey)
• they then migrated out over the Pacific Ocean (not via the coastline) to reach their winter area
• they spent the entire winter in a very small part of the northern Puget Sound area and remained there until May
• they migrated north to Alaska along the coast in spring and some birds then flew along the Alaskan coast but others flew overland to Liverpool Bay (Northwest Territories)
• and the final leg to Melville Island

Some parts of this migration story were unknown until this study and the information generated will help management agencies establish conservation priorities. Another project, related to the one above, involved marking ‘Irish' geese nesting on Bathurst Island with satellite transmitters. Visit the Wildfowl & Wetlands Trust (WWT) website to learn more about the international Brant project.

Now, onto sea ducks (as you can see, I enjoy studying the migration of different species). In 2003 and 2004, we captured all three species of scoters (surf, white-winged and black scoters) wintering in coastal B.C. Scoters are sea ducks which means that they spend most of their lives on the ocean. (If you were to walk the Stanley Park seawall in Vancouver during the winter, you would see large flocks of scoters). The intent of our research was to determine where these species nested and how they moved between winter and summer ranges. These species have been declining for some years now, the cause for the declines are unknown, and migration information is needed to help delineate and manage specific populations. Up until now, biologists could only speculate on the connections between their winter and breeding grounds. The satellite information we have been able to gather to date suggests that the surf and white-winged scoters wintering in the Strait of Georgia breed over a large area in Canada's Northwest Territories whereas the black scoters breed only in southwestern Alaska. The data also suggest that the northeast tip of the Queen Charlotte Islands is an important staging area for black and white-winged scoters in spring, where the birds likely build nutrient reserves for migration and nesting. This is important information as there is a proposal for a large wind farm in the area that could have negative effects on wintering and migrating birds. Visit the Sea Duck Joint Venture website to view the migration maps.

Finally, in May 2006 we marked another sea duck species, Barrow's goldeneye, with satellite transmitters. We tagged 20 adult males near Williams Lake, B.C. and have been following their movements ever since. This project has already generated a lot of information on their moult migration (i.e., where birds travel after the breeding season to replace their flight and body feathers). All birds migrated north from Williams Lake in south central B.C., with some flying to northern B.C and northern Alberta, some to the Northwest Territories between Great Bear Lake and Great Slave Lake, and even some birds all the way to northern Northwest Territories, near the Beaufort Sea! Why do these birds migrate so far north, in the opposite direction to most birds at this time of the year? There must be a good reason, perhaps to do with the increasing number of daylight hours to feed, higher abundance of foods, fewer predators, or...?? Studies like this often generate more questions than they answer.

Migration is a fascinating topic. There is so much about this subject we don't know but our knowledge bank is growing as more and more species are being tagged and as transmitters become smaller and smaller. Many of B.C.'s species are migratory. Some, like the species I have described, breed in the north and winter further south in temperate areas, but some species travel as far south as Central or South America to spend the winter and at least one migrates as far as Antarctica. Satellite projects produce important information on connections and movements but they also generate data that can be used to determine the importance of specific sites needed for resting and accumulating nutrient reserves. Such habitats are critical in the annual life cycle of many bird species. We need to ensure that these habitats are protected, not only here in North America, but all along their migration routes.