Temporal resource partitioning by bats at water holes


Rick A. Adams, Department of Biological Sciences, University of Northern Colorado, Greeley, CO 80639, USA. Tel: 970-351-2057; Fax: 970-351-2335
Email: battings@yahoo.com


The temporal axis of niche (temporally based resource partitioning) is an understudied mechanism for resource partitioning in mammals even though it provides a potential means for species coexistence. Herein we evaluate species-specific use curves based upon capture times during the overlapping activity of bat species at two water holes in an arid environment where bats likely suffer high levels of evaporative water loss during roosting. During the first 75 min after sunset, intense bat activity at each water hole ensued and, although visitation times overlapped, there was a significant difference among species use curves. In addition, pairwise comparisons showed high similarity in temporal visitation patterns across sites for species in which capture numbers were comparable, whereas other species shifted to significantly earlier arrival times when their capture numbers were higher. There were no significant differences in mean roost site emergence times among species, nor in distance of roost sites from water holes. Our data provide one of the few statistically verified examples of fine-grain temporal partitioning by mammals simultaneously using the same resource. We conclude that temporal partitioning helps facilitate bat species coexistence in water-stressed environments.