Spatial ecology of yellow-spotted goannas adjacent to a sea turtle nesting beach

Abstract

Nest predation is the main cause of hatch failure for many turtle populations. For loggerhead turtles (Caretta caretta) nesting at the Wreck Rock rookery, adjacent to Deepwater National Park in south-east Queensland, yellow-spotted goannas (Varanus panoptes) are the main nest predator. However, no studies have documented the space use of goannas in costal habitat adjacent to a sea turtle nesting beach. Here we used Global Positioning System data loggers to evaluate the spatial ecology of adult yellow-spotted goannas in order to discover their potential interaction with sea turtle nests. Male yellow-spotted goannas had larger home ranges, spent a greater proportion of their time in the beach dune area where sea turtles nest, and their home ranges overlapped with more sea turtle nests compared with females. Both males and females had a bimodal activity pattern, with peaks in activity in the early morning and mid to late afternoon. Examination of space-use patterns indicates that it is the larger male yellow-spotted goannas that are the main predators of sea turtle nests at the Wreck Rock beach-nesting aggregation. Hence, by inference, it is probable that large male yellow-spotted goannas are responsible for opening nests at other Australian mainland sea turtle beaches, and if a goanna-specific management strategy is implemented to control predation it is these large males that should be targeted.