Influence of Recruitment Age on Lifetime Reproductive Success of the Cooperatively Breeding Florida Scrub-Jay Erin L. Hewett 1, Reed Bowman 1, Glen E. Woolfenden 1 and John W. Fitzpatrick 2 1 Archbold Biological Station, Lake Placid, Florida, USA; and 2 Cornell Laboratory of Ornithology, Cornell University, Ithaca, New York, USA Discussion Age of first breeding affects LRS in females more than in males Female jays that first breed at age two do better than those that first breed at three; in males age at recruitment makes no difference. Although the patterns were not significant, females that recruit at age two appear to have higher annual fecundity than females that recruit at age three; in males it does not make a difference. In both sexes, breeding lifespan is more important to LRS than annual fecundity. For jays that recruit at age two in both sexes, breeding experience increases fecundity. In males (but not females), delaying breeding to age three increases fecundity during the first year of breeding. Sex-specific differences in recruitment behavior help explain these patterns. Thanks to the Archbold Biological Station internship program, and the ABS Bird Lab. Special thanks to R. Boughton for statistical help and the 2006 demography tract crew: T. Beck, A. Shipley and L. Riopelle. Woolfenden, G. E, and J. W. Fitzpatrick Florida Scrub-Jay (Aphelocoma coerulescens). In The Birds of North America, No. 228 (A. Poole and F. Gill, eds.). The Academy of Natural Sciences, Philadelphia, and the American Ornithologists’ Union, Washington, D. C. Figure 4: More males recruit at older ages than females (Χ 2 =13.4, P=0.004). Components of lifetime reproductive success Figure 2: Breeding lifespan explained 71% (females) and 78% (males) of the variation in LRS. When annual fecundity was added to the model, R 2 increased to 83% (females) and 89% (males). Breeding vs. helping experience A. B. C. Figure 3: A. Females that recruited at age two or three produced the same number of fledglings during their first year of breeding. During their second year of breeding, females that recruited at age two produced more fledglings (P=0.02) than third-year recruits. B. Males that recruited at age two produced fewer fledglings during their first year of breeding than males that recruited at age three (P=0.03). During their second year of breeding, fledgling production was similar. Figure 1: A. Lifetime reproductive success (total fledglings) was lower for females recruiting at age three (Z=-1.85, P=0.064). Males show a similar trend but the difference was not significant. B. Trends exist for females that recruit at age two and males that recruit at age three to have higher annual fecundity, but the differences were not significant. C. Trends exist for females and males that recruit at age two to breed longer, but the differences were not significant. A A A B A,C B B B,C P=0.064 P=0.803 P=0.125 P=0.108 P=0.444 P=0.265 A. B. Introduction The Florida Scrub-Jay (Aphelocoma coerulescens) is a long-lived cooperative breeder with specific habitat requirements and limited breeding opportunities. Breeding usually is delayed, the young remaining as helpers at their natal territory for one or more years post-hatching. Age at first breeding (recruitment age) is an important factor in understanding variation in lifetime reproductive success (LRS). LRS is influenced by both annual fitness (the number of fledglings per year) and breeding lifespan (number of years spent as a breeder). Delaying breeding may benefit future reproductive attempts. Males are more likely than females to gain a breeding opportunity by inheriting or budding from the natal territory; this may affect recruitment strategies and the possible benefits of delayed breeding. Methods Demographic data analyzed on 349 breeding Florida Scrub-Jays (173 female, 176 male; ) from the long-term data set at Archbold Biological Station, Lake Placid, Florida (Woolfenden and Fitzpatrick 1996). Only known-age birds that produced eggs at least once were considered breeders. Questions 1. Does LRS vary between jays of each sex recruiting at different ages? 2. Does annual fecundity or longevity as a breeder more strongly influence LRS? 3. How does previous helping or breeding experience influence fitness, and does the pattern differ among birds recruiting at different ages? Acknowledgments and Literature Cited