Canada Jay ‘volunteering’ to be weighed

Canada Jays can be extremely friendly and eager to take handouts (one of their nicknames is the “camp robber”). We take advantage of this behaviour to weigh females regularly prior to breeding, which helps us to determine female condition and to identify when females are about to begin incubating. A piece of cheese is placed on a weight scale and the band combination of the bird and the weight output from the screen is videotaped using a simple digital camera. Using this method, we recently showed that females increase their body mass by 25% in preparation for nesting, an amazing feat considering that most or all of their bulking up is done by retrieving food that was stored 6-7 months prior to breeding (click here to view Sechley et al. 2014 paper). Photo by Peter Wolf.

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