Brood parasitic birds often remove an egg from host nests. At least one previous author interpreted single-egg removal from a nest as a sign of Brown-headed Cowbird (Molothrus ater) activity. Partial clutch reduction, however, cannot be taken as a clear indication of brood parasitic activity at natural or artificial nests because egg predators may also cause partial clutch reduction by pecking and removing some but not all eggs. Video-taping at an artificial nest baited with plastic eggs showed that the Gray Catbird (Dumetella carolinensis), a known egg-predator, was responsible for a single-egg removal event, even though it also pecked other eggs in the nest. Thus, partial clutch reduction in general, and single-egg removal in particular, cannot be interpreted as clear signs of either brood parasitism or egg predation. In addition, the use of plastic eggs, however convenient and realistic they may seem, is inappropriate to distinguish between the activities of brood parasites and egg predators.
|Original language||English (US)|
|Number of pages||4|
|State||Published - Sep 1 1998|
ASJC Scopus subject areas
- Animal Science and Zoology