Artificial nests are commonly used in studies of nest predation. We de
veloped a simple device to determine the precise time and date of pred
atory events on artificial nests. The device enables investigators to
lengthen the interval between visits and to evaluate the assumption th
at predation rate is constant over the interval. Furthermore, when tim
e and date of each predatory event are known, patterns of predation ca
n be evaluated relative to diurnal period, to time since nests were pl
aced 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 smal
ler birds should be straightforward.