INTRASPECIFIC NEST PARASITISM IN STARLINGS STURNUS-VULGARIS - EFFECTS OF DISTURBANCE ON LAYING FEMALES

Female Starlings Sturnus vulgaris that laid distinctive eggs at Worplesdon, Surrey, in 1988 and 1989 were made to desert their partially completed first clutches by removing their eggs part way through the laying sequence. Most of these Starlings continued to lay, but in other Starlings' nests, and most of them subsequently laid a replacement clutch that they reared themselves. Using estimates of the success of nests in the colony over 14 breeding seasons, it is concluded that intraspecific nest parasitism offers a means of maximizing annual chick production in the event of disturbance causing the loss of first-clutch eggs.