Abstract
IT is surprisingly seldom that one comes across telling examples of the activity of birds as destroyers of harmful insects. F. Bradshaw records an interesting experience in Canada, on the west side of Last Moun tain Lake, east of Liberty, Saskatchewan (Canadian Naturalist, 48, 68, April 1934). On June 18, 1933, he observed there what in the distance appeared to be a cloud of smoke, but on nearer approach turned out to be enormous flocks of the black-headed Franklin's gull. They alighted in column formation and gorged upon an army of grasshoppers. The number of birds present could not be estimated closely, but the column of close-set birds was a mile in extent and sixty birds in width, and two miles to the south-west an even larger cloud of gulls was seen. Estimates suggest that a Franklin's gull might devour 500 grasshoppers daily; the protective value of a flock, which at a very conservative estimate numbered more than a million, is, therefore, of considerable moment.
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Gulls Destroy Grasshoppers. Nature 134, 566 (1934). https://doi.org/10.1038/134566c0
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DOI: https://doi.org/10.1038/134566c0