EFFECTS OF REPEATED CAPTURES ON BODY MASS AND SURVIVAL OF DUSKY-FOOTED WOODRATS IN A CALIFORNIA OAK WOODLAND

Abstract Trapping sessions consisting of repeated captures are routinely used to assess demography, social organization, and habitat associations of small mammals. Some capture-recapture analyses require a high number of trapping occasions for precise estimates, but repeatedly capturing an animal may have adverse effects on individuals and populations. During 2002–2006, we examined patterns of capture, changes in body mass, and longer-term survival in a population of dusky-footed woodrats (Neotoma fuscipes). During 10 trapping sessions of 3 nights each, we captured 1,824 woodrats 4,705 times. Captures per individual averaged 1.6/trapping session. Nearly all woodrats (91%) lost mass at a rate of 3.5%/capture. Mass loss was cumulative over consecutive days, averaging ca. 3.5% of body mass after the second capture and 6.8% after the third capture. Woodrats lost slightly more mass during trapping sessions in the fall than during sessions in the spring. Percentage of change in mass was not associated with age ...