Barn Swallow is one of several common insectivorous species experiencing declines and the cause is the subject of much debate. It remains unclear whether habitat change, insect distribution, abundance and phenology, or climate are at the root of these declines. Barn Swallow began declining in the mid 1980s; however, their present population is still generally considered to be higher in Canada now than before Europeans altered the landscape so drastically. Furthermore, the sources of the data available to assess swallow declines reveal biases and needs to taken with a large grain of salt. It will be interesting to watch the reaction to this listing both in Canada and in the international scientific community. This and several other recent COSEWIC decisions; for example, the recent listing of Bobolink and other species where COSEWIC's assessment differed radically from Birdlife International despite relying on largely the same data sets, have the potential to result in a tarnishing of our reputation… or perhaps provoking a wider discussion on what it means to call a species "Threatened"!
Barn Swallows perch just outside the entrance to Oak Hammock Marsh Interpretative Centre, Manitoba (perhaps to greet Peter Pyle or other visitors on the day)…
Barn Swallows, threatened? What a joke!
ReplyDeleteWhile I don't necessarily dispute the decision of COSEWIC to list the Barn Swallow, I think there are two other species of swallow, Cliff Swallow & Purple Martin, in far more trouble. All the colonies of both I see are either shadows of their former numbers or gone altogether. While Barn Swallows have certainly disappeared as a breeding species in my immediate neighborhood, they are still found widely in good numbers whereas the declines of the others are much more widespread.
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