P.T. Gregory’s scientific contributions

Many reptiles have different habitat requirements for different activities (e.g., hibernation and nesting/gestation) that may not be satisfied by a single location. Suitable habitat may not only be limited, but also fragmented, making it difficult for animals to move between sites. In this study, we examine habitat use and movement patterns of Northern Alligator Lizards (Elgaria coerulea) and Western Skinks (Eumeces skiltonianus). In particular we determine the characteristics of hibernation and summer sites for both species and the extent of movement in both species, particularly whether migration occurs between summer and winter habitats. We used mark-recapture (PIT-tags and toe-clips) to do this. Both species coexisted at many of the same study sites, although some sites had only one of the species, and individuals were found in approximately the same locations in spring, summer, and fall. Thus, hibernation apparently occurs in the same habitat where lizards are active during the summer and no seasonal migration occurs. In fact, individuals of either species were recaptured on average within 10 m of a previous capture. Both species were rarely found in the open and more often under rocks than in vegetation or under logs; they also remained close to shrubs and forest edges. Roads apparently are not a major hazard for either species because they have high site-fidelity and do not make long-distance movements between hibernation or summer sites. Their requirement for cover means that any disturbance or removal of rocks from their habitats would be detrimental to both species.