AN INEXPENSIVE PHOTOGRAPHIC TECHNIQUE FOR IDENTIFYING NEST PREDATORS AT ACTIVE NESTS OF BIRDS

Change in rate of nest predation due to environmental modification is considered a major cause of population decline of many bird species. O ur ability to adequately understand and effectively manage this effect is limited by our ability to identify the relative roles of individua l nest predators. This is because nest predation is seldom witnessed d espite its high frequency. We describe and evaluate an inexpensive pho tographic technique for identifying nest predators at active nests. Ea ch camera unit (A$220) was triggered by circuitry (A$30), using a magn etic reed switch attached to a supplementary egg. A total of 51 nests of New Holland honeyeaters (Phylidonyris novaehollandiae) was monitore d with the equipment. Of these, 39 were preyed upon. Predation was nev er witnessed, but predators were captured on film for 72% of nests at which predation occurred.