A Method for Trapping Breeding Adult Gulls

Many thousands of flightless young Herring Gulls (Larus argentatus) have been banded, and recoveries of these birds have furnished a wealth of data on the biology of the species.In recent studies, however, it has become apparent that knowledge of parental behavior with respect to reproductive success is lacking.Such information can best be obtained by studying a banded population of breeding adults.In order to band a great many gulls on their territories, but at the same time cause as little disturbance as possible to the nesting birds, several methods of trapping were considered, including cannon-netting (Dill and Thornsberry, 1950; Thompson and DeLong, 1967), the use of padded muskrat traps and clap-net traps at the nest (Kadlec and Drury, 1969), and the use of soporific drugs (Smith, 1967; Kadlec and Drury, 1969).Cannon-netting and muskrat and clap-net traps could not be used because of their high disturbance effect.A soporific that rendered a gull immobile at its nest without any preliminary flopping (which would alarm adjacent gulls), had no risk of mortality, and had a short recovery time had not been developed at the time of this study.The method of trapping finally used was developed by John C. Coulson of the University of Durham, Durham, England.It was utilized because of its comparatively low disturbance effect, and because it allowed banding of birds at their nests.