SURVIVAL AND REPRODUCTION OF RESIDENT AND IMMIGRANT FEMALE ROOT VOLES(MICROTUS-OECONOMUS)

Many spatially explicit population models assume that residents and im migrants have equal vital rates (survival and reproduction). We tested this assumption by using root vole (Microtus oeconomus) populations i n an experimental setting where habitat patches were embedded in an un inhabitable transition habitat. Place of birth and matrilineal relatio ns were known for all animals in 12 different populations. Females wer e classified as residents or immigrants depending on whether they stay ed and reproduced in their natal patch or settled and reproduced in a foreign patch. We compared survival probabilities, derived from the Jo lly-Seber-Cormack model, and reproductive parameters between resident and immigrant root vole females. We found no difference between reside nts and immigrants for any of the parameters examined. Nor did we find any significant difference in net reproductive rate (R-0) derived fro m Leslie models utilizing estimated demographic parameters for residen ts and immigrants. We conclude that the assumption of equal vital rate s may be justified, at least at the spatial scale considered in this s tudy.