Avian response to prolonged drought in drylands: The case of two dove species in Brazil's semi-arid region

摘要

In view of the scenario of global warming, understanding how individuals disperse and populations fluctuate in response to climatic extremes is becoming increasingly important. Thereby, we used a capture-mark-recapture approach on Columbina minuta and Columbina picui in two Caatinga physiognomies (shrubby-woodland and savanna) during and following a prolonged drought in northeastern Brazil. We evaluated three hypotheses: density is higher in the savanna, doves are more abundant during the rainy season, and doves are able to undertake regional movements in response to drought. We used Huggins closed population models to estimate detection rates and population size. The results revealed low capture and recapture rates, greater abundance in the savanna, a higher density of C. minuta in both study areas, and a higher density of both species in the rainy season. We also observed that the prolonged drought has negatively impacted on doves density. The recovery of banded individuals at other sites indicates that nomadism may be the principal strategy adopted by doves to endure periods of drought. Our findings show that conservation units in the Caatinga are important to conservation of granivorous birds and contribute to understanding the birds' strategies to face seasonality and severely dry periods in semiarid areas.