PARENT SESSION

HABITAT ASSOCIATIONS OF SOUTHERN CALIFORNIA RODENTS BEFORE, DURING, AND AFTER AN ENSO EVENT. Jessica D. Braswell¹ and Douglas A. Kelt². ¹ San Diego State University, Department of Biology, 5500 Campanile Dr, San Diego, CA; ² University of California, Department of Wildlife, Fish, and Conservation Biology, One Shields Ave, Davis, CA.

ABSTRACT- Using data collected from a 4-year study in southern California, habitat associations of rodents were examined for vegetation characteristics in 4 habitat types: chaparral, coastal sage scrub, recently burned coastal sage scrub, and non-native grasslands. Canonical correspondence analysis was used to investigate associations between species including Peromyscus californicus, P. eremicus, P. maniculatus, Chaetodipus californicus, C. fallax, Neotoma fuscipes, N. lepida, Reithrodontomys megalotis, Microtus californicus and Dipodomys stephensi and habitat variables such as shrub cover, shrub height, bare ground cover, grass cover, litter cover, slope and aspect. Habitat associations before, during, and after the 1998 ENSO were compared. Some strong habitat associations, such as P. californicus with tall shrubs and D. stephensi with high grass cover, remained constant over all three periods. The relative importance of vegetation characteristics for species without such strong habitat preferences shifted in ENSO years. This may indicate that (1) some species have habitat associations that shift during ENSO events and (2) some species may be associated with certain habitats because of cover (P. californicus) or mobility constraints (D. stephensi), while others are more opportunistic and decide to use an area based on available food resources.

KEY WORDS: microhabitat associations, CCA, El Nino Southern Oscillation