Tracking fantastic flying machines with technology

Technology gave Dr. Keith Hobson, a research scientist in the Wildlife and Landscape Science Directorate of Environment and Climate Change Canada, an unexpected window into bird migration. It also helped his Colombian graduate students, Ana-Maria Gonzalez and Camila Gomez.

Last year, they used recycled radio transmitter tags the size of a dime and weighing half a gram to track the migration of 19 grey-cheeked and Swainson’s thrushes from their wintering grounds to Canada’s boreal region.  

The study was originally intended to find out where these thrushes stop over and winter in Colombia. However, it resulted in unexpected information on the movements of these birds far beyond these sites.

“Numbers of recoveries from banding have been inadequate to give us much of a picture of their migration,” said Dr. Hobson. In more than a century of banding, only a few thrushes have been re-sighted. Given the odds, Dr. Hobson and his students did not expect any information beyond the movements of birds at their Colombian study site.

When the thrushes flew into North America, their tags were detected on the MOTUS towers operated by Bird Studies Canada. Even more surprising, Dr. Hobson had a 50 per cent re-sighting rate from all tags put on the grey-cheeked thrushes.

“These are iconic long-distance migrants. If you don’t know where they are going, it’s difficult to conserve them,” said Dr. Hobson.  “If we can conserve their habitat in Colombia, and we know they stop there to eat fruits and berries near shade coffee plantations, we can take steps to help these fantastic flying machines.”

Photo: Thrush with a radio transmitter tag

Dr. Hobson