Changes in the apparent survival of a tropical bird in response to the El Niño Southern Oscillation in mature and young forest in Costa Rica.

Abstract

The effects of habitat alteration and climatic instability have resulted in the loss of bird populations throughout the globe. Tropical birds in particular may be sensitive to climate and habitat change because of their niche specialization, often sedentary nature, and unique life-cycle phenologies. Despite the potential influence of habitat and climatic interactions on tropical birds, we lack comparisons of avian demographics from variably aged forests subject to different climatic phenomena. Here, we measured relationships between forest type and climatic perturbations on White-collared Manakin (Manacus candei), a frugivorous tropical bird, by using 12 years of capture data in young and mature forests in northeastern Costa Rica. We used Cormack-Jolly-Seber models and an analysis of deviance to contrast the influence of the El Niño Southern Oscillation (ENSO) on manakin survival. We found that ENSO had little effect on manakin survival in mature forests. Conversely, in young forests, ENSO explained 79% of the variation where dry El Niño events negatively influenced manikin survival. We believe mature forest mitigated negative effects of dry El Niño periods and can serve as refugia for some species by buffering birds from climatic instability. Our results represent the first published documentation that ENSO influences the survival of a resident Neotropic landbird.