Tree Swallows Have Winter of Discontent

Canadian Tree swallows are losing weight, probably because of inadequate food on their southern wintering grounds.

Many species of birds that feed on airborne insects are in decline.  Not only are their numbers diminishing, but the size of the remaining birds, particularly breeding females, has also been shrinking. Dr. Sebastien Rioux Paquette, a post-doctoral researcher in the Department of Biology at the University of Sherbrooke, has been studying one of these birds, the tree swallow, in its summer habitat in Quebec.  He's found that summer forage doesn't seem to be a problem for the swallows.  The issue seems to be declines in their insect prey in their wintering ground in the US and Mexico.  Pesticides and shrinking habitat for insects due to agricultural intensification is depleting the swallows' winter food, and the birds are suffering as a result.

Related Links

• Paper in Royal Society Proceedings B: