A SIMPLE DEVICE FOR MEASURING SURVIVAL-TIME OF ARTIFICIAL NESTS

Artificial nests are commonly used in studies of nest predation. We developed a simple device to determine the precise time and date of predatory events on artificial nests. The device enables investigators to lengthen the interval between visits and to evaluate the assumption that predation rate is constant over the interval. Furthermore, when time and date of each predatory event are known, patterns of predation can be evaluated relative to diurnal period, to time since nests were placed or visited, and to spatial relationships among nests. We recorded time and date for 105 predatory events during 234 10-day field trials. Accuracy of the device was within 1 minute over a 10-day period. The device was developed and tested on nests mimicking those of dabbling ducks (Anatinae), but further miniaturization for applications to smaller birds should be straightforward.