These brightly-coloured songbirds look like they would be easy to spot against the deep green of the boreal forest, but looks can be deceiving. Canada Warblers are a shrub-loving species, and spend much of their time either foraging for insects in dense hazelnut bushes, or singing ten metres up in a tall aspen, defending their territory from intruding strangers. In addition, when good habitat is available, birds can be clustered very close together. So they are not only difficult to find, but it is nearly impossible to tell individuals apart. This can pose challenges to studying habitat use and breeding success of these birds throughout the season, as individuals must be located and correctly identified on multiple visits.
Luckily for researchers such as myself, there are several “name tag” tools that help us distinguish who’s who, and let us track the birds more effectively. Firstly, we attach tiny coloured bands to their lower leg, with a different colour combination for each individual. A glimpse of these distinct combinations through our binoculars helps us differentiate Tom, Dick, and Harry. Another method is to attach miniature radio transmitters to the birds’ backs. Each bird gets a transmitter that emits a distinct frequency, which we can detect using a handheld receiver and antenna. Along with distinguishing individuals, this technique allows us to hone in on the birds’ locations from greater distances. This makes it possible to detect and locate birds even when they have strayed from their usual hangouts, providing valuable information on habitat use and home range size.
So why does this matter? Canada Warblers are defined as a threatened species in Canada, and are listed as special concern in Alberta. To protect and recover populations of at risk species, it is important that we know details about the habitat they require to make a home and raise their young. We know from previous studies that Canada Warblers are found in old-growth forest dominated by aspen trees. However, little is known about what they select under the forest canopy. Factors such as shrub density and terrain could have a large influence on where Canada Warblers live and breed successfully. My research involves investigating the microhabitats and breeding success of these threatened birds within areas extensively managed by forestry companies. This information could inform forest management strategies to ensure preservation of important Canada Warbler habitat. This research would not be possible without the valuable collaborative work and resources contributed by Alberta-Pacific Forest Industries (ALPAC) and the Lesser Slave Lake Bird Observatory (LSLBO).
Written by Anjolene Hunt