Effect of drought on demography of Pileated Finch (Coryphospingus pileatus: Thraupidae) in northeastern Brazil

- The annual survival of Pileated Finch varied little between regular dry intervals.
- In years with intense droughts the survival estimates were strongly affected.
- The physiognomy of the environment was an important factor in survival estimates.
- The distinction of transient birds from residents improved the understanding of demographic patterns.
- Frequent and intense droughts in the Caatinga will can affect demographic parameters of many species.

Information on the effects of stochastic weather events on the survival of tropical birds can improve the knowledge of life history adaptations, allowing better demographic projection models to examine species persistence in light of global climate change forecasts. With this in mind, we conducted a mark-recapture study on Coryphospingus pileatus in the Brazilian Caatinga. We applied Cormack-Jolly-Seber and Robust Design models to test the influence of sex, precipitation, drought and vegetation on demographic parameters. We found that the apparent annual survival of residents ranged from 31 to 49% in the first year and 65-77% in the second, depending on the area, sex and structure of the models used. Controlling for an effect of time since marking, survival was substantially lower in a year affected by a severe drought, and was higher at a site with more open vegetation structure. The results showed little variation in survival of the species during the regular annual dry season and a decline greater than 50% in apparent survival caused by severe drought. This suggest that in prolonged drought the drastic reduction of food directly affects the productivity, reducing in survival observed over time and projecting a critical perspective for endangered species that may disappear due to climate change.