COS 123-3 - Habitat conversion to agriculture reduces avian reproductive behavior in Northwest Costa Rica

Background/Question/Methods

Behavioral changes are often an animal’s first response to human-induced environmental changes, and variation in behavior across different environments (e.g., differences in reproductive and foraging behavior) can have cascading implications for individual fitness and population persistence. Here, we investigated how bird communities vary in abundance and behavior between land-use types, and how patterns in species’ abundances relate to patterns in their behaviors. We hypothesized that land-use change is pernicious beyond its apparent effect on numbers of organisms, because it decreases habitat quality such that species might be able to pass through, but not fulfill their full life history. We analyzed over 14,000 behavioral observations of 55 bird species in Northwest Costa Rica to understand how land-use affects species and the likelihood of exhibiting reproductive, foraging, and passive behaviors. We expanded a modeling framework to quantify differences in behaviors in an avian community between farms, privately-owned forest patches, and formal nature reserves, after accounting for variation in detection probability between species, habitats, and behaviors.

Results/Conclusions

On average, we found that Costa Rican bird species were both more abundant and more likely to perform reproductive behaviors in forest than in agriculture. Species were also more likely to perform reproductive behaviors in protected forest than in privately-owned forest, despite there being no significant differences in average abundance between these land tenures. Our hypothesis that differences in abundance between habitats would be associated with differences in behaviors was not supported - species’ abundance responses were not entirely consistent with their behavioral responses to land use. Given that abundance and behavioral responses were not always consistent, our results highlight the importance of behavioral analyses for elucidating the conservation value of alternative habitat types.