TY - JOUR
T1 - Hot rocks or no hot rocks
T2 - Overnight retreat availability and selection by a diurnal lizard
AU - Sabo, John
N1 - Funding Information:
Acknowledgements This study was funded by NSF grant DEB-FD 97-00834 to J. L. S. and Mary E. Power and two Graduate Research Grants from the Department of Integrative of Biology, University of California Berkeley. I am extremely grateful for the help of M. Ku and A. Su for long hours behind the radio receiver. I thank the Museum of Vertebrate Zoology and M. Power for supplying the radio receiver and outdoor weather logger, respectively. G. Gilchrist, H. Greene, R. Huey, S. Kupferberg, W. Porter, D. Roberts, J. Rodriguez, V. Vredenburg and K. Zamudio helped with the conceptual development of this project. J. Finlay, R. Huey, S. Kuchta, D. Miles, M. Power, W. Sousa ,W. Getz and three anonymous reviewers provided comments that improved earlier drafts of this paper. Finally, I thank P. Steele and the California Natural Reserve System for providing and maintaining a protected research site at the Angelo Coast Range Preserve.
PY - 2003/8
Y1 - 2003/8
N2 - I used radio telemetry to determine the effects of substrate size and composition on overnight retreat site selection by western fence lizards (Sceloporus occidentalis). In watersheds of northern California (USA), these lizards occupy two habitat types differing in substrate characteristics: rocky cobble bars found in the dry, active channels of rivers and grassy upland meadows. Rocky substrates, found almost exclusively on cobble bars, provided warmer potential retreat sites than all available retreat sites on meadows during the first 5 h of inactivity. Only cobble and sand substrates provided retreats with temperatures within the preferred daily active range (32-36°C) during the inactive period for these lizards (1900-0900 hours). Females on a cobble bar used rocks as retreats on >90% of nights during the breeding season whereas females on a meadow used wood (>70% of nights) and burrows (>25% of nights). In contrast to females, cobble bar males used rocks significantly less frequently (<70%) and slept in the open air significantly more frequently (25% vs. <1%). Cobble bar females further, showed a significant preference for cobbles 15 cm thick, whereas the rocks used by males did not differ significantly in thickness from those measured in randomly placed transects. Rocks 15 cm thick were the warmest retreats commonly available on this habitat type. Thus, thermal microenvironments available to and chosen by gravid female lizards differ considerably between river and non-river habitats.
AB - I used radio telemetry to determine the effects of substrate size and composition on overnight retreat site selection by western fence lizards (Sceloporus occidentalis). In watersheds of northern California (USA), these lizards occupy two habitat types differing in substrate characteristics: rocky cobble bars found in the dry, active channels of rivers and grassy upland meadows. Rocky substrates, found almost exclusively on cobble bars, provided warmer potential retreat sites than all available retreat sites on meadows during the first 5 h of inactivity. Only cobble and sand substrates provided retreats with temperatures within the preferred daily active range (32-36°C) during the inactive period for these lizards (1900-0900 hours). Females on a cobble bar used rocks as retreats on >90% of nights during the breeding season whereas females on a meadow used wood (>70% of nights) and burrows (>25% of nights). In contrast to females, cobble bar males used rocks significantly less frequently (<70%) and slept in the open air significantly more frequently (25% vs. <1%). Cobble bar females further, showed a significant preference for cobbles 15 cm thick, whereas the rocks used by males did not differ significantly in thickness from those measured in randomly placed transects. Rocks 15 cm thick were the warmest retreats commonly available on this habitat type. Thus, thermal microenvironments available to and chosen by gravid female lizards differ considerably between river and non-river habitats.
KW - Habitat selection
KW - Retreat site
KW - Riparian
KW - Sceloporus occidentalis
KW - Thermoregulation
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U2 - 10.1007/s00442-003-1292-6
DO - 10.1007/s00442-003-1292-6
M3 - Article
C2 - 12802672
AN - SCOPUS:0041695559
SN - 0029-8549
VL - 136
SP - 329
EP - 335
JO - Oecologia
JF - Oecologia
IS - 3
ER -