Platypus, Ornithorhynchus anatinus, Movement Data from The Duckmaloi Weir Pool: Poisson Regression Models.

Abstract

McLeod (1993) monitored the movement of platypuses (Ornithorhynchus anatinus) using telemetric devices, recording the number of times animals were found in predetermined grid positions in a pool impounded behind the Duckmaloi Weir near Oberon, New South Wales, and the number of times they were discovered in numerous burrows on the periphery of the weir pool. The aim of this program was to identify the predictive variables that accounted for platypus movement from among those measured such as water depth, and from among known factors such as age. A Poisson regression model is described together with the results for these data. The potential benefits of Poisson regression models for these data over log transformation models, such as handling zeros and catering for overdispersion, are expounded. The analyses indicate that the use of areas of the weir pool were related to water depth, with there being greater use of shallow depths in the channel than in other locations in the pool. There was also differential usage of burrows in the banks of the pool related to different degrees of foliage density from one side of the weir pool to the other.