Chronic Degradation of Seasonally Dry Tropical Forests Increases the Incidence of Genotoxicity in Birds

Multiple studies have shown that exposure to pollutants can increase genotoxic damage in different taxa. However, to our knowledge, the effects of environmental stress have been explored little. In certain stressful ecosystems, such as seasonally dry tropical forests, the combined effects of anthropogenic activities and ongoing global changes can cause an increase in environmental stresses, in turn, may trigger physiological and genetic effects on biodiversity. The present aims to assess changes in the prevalence of genotoxic damage in birds within three states of forest degradation in the Tumbesian Region of Western Ecuador. We used blood samples from 50 bird species to determine the frequency of micronucleus and nuclear abnormalities in erythrocytes. Our results revealed a significant impact of forest degradation on the occurrence probability of micronucleus and nuclear abnormalities at the community level. Localities with higher levels of degradation exhibited higher levels of abnormalities. However, when analyzing the dominant species, we found contrasting responses. While Lepidocolaptes souleyetii showed a reduction in the proportion of nuclear abnormalities from the natural to shrub‐dominated localities Troglodytes aedon and Polioptila plumbea showed an increase for semi‐natural and shrub‐dominated respectively. We concluded that the degradation process of these tropical forests increases the stress of bird community generating genotoxic damage. Bird responses seem to be species‐specific, which could explain the differences in changes in bird composition reported in other studies. Plain Language Summary Many studies have shown that pollutants can cause changes in the characteristics of cells, specifically at the level of the nucleus. These changes are known as genotoxic damage and can have serious consequences for individuals. In addition to pollutants, other factors can cause genotoxic damage, such as water deficit or solar irradiation. The degradation of seasonally dry tropical forests can lead to changes in water availability and the amount of irradiation that organisms receive. We conducted a study to evaluate how the environmental changes caused by the degradation of these forests affect the level of genotoxic damage. We evaluated genotoxic damage in 50 bird species inhabiting areas with different levels of degradation. We found that the degradation of these forests increases the level of genotoxic damage at the community level, which could be c