An inexpensive photographic technique for identifying nest predators at active nests of birds.

Abstract

Change in rate of nest predation due to environmental modification is considered a major cause of population decline of many bird species. Our ability to adequately understand and effectively manage this effect is limited by our ability to identify the relative roles of individual nest predators. This is because nest predation is seldom witnessed despite its high frequency. We describe and evaluate an inexpensive photographic technique for identifying nest predators at active nests. Each camera unit (A$220) was triggered by circuitry (A$30), using a magnetic reed switch attached to a supplementary egg. A total of 51 nests of New Holland honeyeaters (Phylidonyris novaehollandiae) was monitored with the equipment. Of these, 39 were preyed upon. Predation was never witnessed, but predators were captured on film for 72% of nests at which predation occurred.