Escaping drought: Seasonality effects on home range, movement patterns and habitat selection of the Guatemalan Beaded Lizard

Abstract

The relative contribution of extrinsic and intrinsic factors affecting lizard movement patterns have rarely been examined. We were interested in understanding the effects of extrinsic factors such as seasonality and forest cover, along with the intrinsic factor of body length on home range size, coarse-scale movement patterns and habitat selection of the endangered Guatemalan Beaded Lizard (Heloderma charlesbogerti). We predict that home ranges, core areas and movement patterns will be reduced in the dry season compared to those of the wet season. Twelve individuals (five males and seven females) were radio tracked for 4–9 months from April 2007 to April 2008. We used minimum convex polygon for home range comparison with other helodermatid studies. Guatemalan Beaded Lizards showed larger home ranges than other helodermatids. We determined annual and seasonal home range size and core areas using kernel density estimators. Turning angles and step lengths were also determined to assess the effect of the extrinsic and intrinsic factors on the movement patterns of the lizards. Dry season home ranges and core areas were substantially smaller and its associated lizard movement patterns showed shorter step lengths and smaller turning angles than those of the wet season. Larger lizards also presented larger home ranges. When estimating dry forest selection within their home ranges, lizards with larger annual home range size and more forest cover within their home range showed higher selection for dry forest habitat. These findings showed the differential response of Guatemalan Beaded Lizards to seasonality and highlights the relevance of the conservation of the remnants of well-preserved dry forest on the ability of this species to cope with drought and habitat destruction.