Egg pricking
Making a small hole in the shell of an egg, which eventually causes the death of the embryo. Egg pricking is practised in situations where the population of a particular species on a nature reserve is growing at the expense of one or more other species which are in need of special protection. The owners of the pricked eggs continue with their incubation, not realising that anything is amiss, and so they do not lay replacement eggs. On coastal reserves the numbers of Black-headed Gulls Larus ridibundus may be controlled in this way.From Peter Weaver's Birdwatcher's Dictionary
Copyright © 1981 by Peter Weaver