VOLUME 16 - N. 2

Abstract:

I review population changes from 1976 to 1992 in the Audouin's Gull colonies of Chafarinas Islands National Game Sanctuary. Earlier studies showed that after increasing rapidly between 1976 and 1983, the Audouin's Gull population stabilized, and breeding success decreased until 1985. This decrease was linked to a rapid increase in Yellow-Iegged Gulls over the same period, and was attributed to predation and to limited nesting sites. Yellow-Iegged Gulls have been controlled since 1987 by narcotizing adults and sterilizing eggs. After 6 years culling, the Yellow-Iegged Gull population and the breeding success of Audouin's Gulls were similar to those of 1983, but the breeding Audouin's Gull pairs had doubled during the same periodo It is suggested that immigration of Yellow-Iegged Gulls reduces the effectiveness of culling. The rat population may also limit the breeding success of the Audouin's Gull.