DOI 10.1007/s00442-008-0961-xBEHAVIORAL ECOLOGY- ORIGINAL PAPER Heterogeneity in individual quality overrides costs of reproduction in female reindeer

Abstract Reproductive allocation at one age is predicted to reduce the probability of surviving to the next year or to lead to a decrease in future reproduction. This prediction assumes that reproduction involves Wtness costs. However, few empir-ical studies have assessed whether such costs may vary with the age at primiparity or might be overridden by heterogene-ities in individual quality. We used data from 35 years ’ mon-itoring of individually marked semi-domestic reindeer females to investigate Wtness costs of reproduction. Using multi-state statistical models, we compared age-speciWc sur-vival and reproduction among four reproductive states (never reproduced, experienced non-breeders, reproduced but did not wean oVspring, and reproduced and weaned oVspring) and among contrasted age at primiparity. We assessed whether reproductive costs occurred, resulting in a trade-o