Apparent Annual Survival Estimates of Four Passerine Birds with Diverse Life History Traits in Subtropical Brazil

Survival in passerine birds varies across latitudes, with survival typically greater in tropical species compared to their temperate counterparts. However, understanding of survival patterns in subtropical latitudes is limited. In this study, we provide the first apparent annual survival estimates for four sympatric passerines with different life-histories in southern and subtropical Brazil: the Star-throated Antwren Rhopias gularis, the White-rumped Swallow Tachycineta leucorrhoa, the Green-headed Tanager Tangara seledon, and the Golden-crowned Warbler Basileuterus culicivorus. We used mark-recapture and resighting data from 3–5 years of intensive population monitoring to estimate survival. We tested for potential survival trade-offs with clutch size and body weight, and whether convergence in survival rates (as predicted by the latitudinal concept of life history traits) occurs. We show important differences in apparent adult annual survival rates, rather than convergence, among the studied species. The Star-throated Antwren, with the smallest clutch size, had the greatest survival rate (0.77/yr), while the White-rumped Swallow, with the largest clutch size, had the lowest (0.49/yr), with the remaining species having intermediate clutch sizes and intermediate survival rates (0.54–0.64/yr). Our results show that survival rates of subtropical passerines differ among species, and the estimates seem to be inversely related to their clutch size. Furthermore, the observed intermediate life history traits of subtropical species compared with tropical and temperate extremes, suggests that much of this pattern may be due to local adaptation to subtropical conditions, which confound understanding in macro-scale analysis.