Humidity effects on avian blood parasites in the Caatinga of Brazil

Abstract

The Caatinga is an ecologically diverse region encompassing a variety of environments. Given the influence of the environment on parasite–host systems, the goals of this study were to investigate the presence of hemoparasites in birds from different Caatinga physiognomies, both for comparison among them and between the Caatinga and other documented biomes. For this, we collected blood samples from 59 birds in three Caatinga physiognomies from the state of Pernambuco, Brazil. In comparison with previous studies in other biomes, the frequency of hemoparasites in the different environments of the Caatinga (20%) is higher than that of the Cerrado (7%), and the same as obtained for the Atlantic Forest (20%). The Caatinga physiognomy that revealed the highest hemoparasitism index is known as Brejo de Altitude (high-altitude humid area). Brejos de Altitude occurs between ca. 500 and 1100 m a.s.l., where orographic rains result in levels of rainfall that can reach 1200 mm/year. The coincidence of frequencies of hemoparasites for Caatinga and Atlantic Forest may arise from the detected high frequency of parasitized individuals in the Brejo de Altitude. The blood samples from this region were responsible for 60% of the parasitized samples of our study. This could be attributable to higher humidity, facilitating higher reproductive success of the parasite vectors.