Transient Responses of Avian Assemblages to Geothermal Drilling in Costa Rica

Due to their requirements, geothermal projects are often located near volcanic activity that, in the tropics, overlaps with or lies close to conservation areas. It is therefore important to assess the environmental impact of these projects on biodiversity. We evaluated the impacts of well-drilling activities on bird communities at a geothermal field in Costa Rica. We hypothesized that (i) disturbance generated during drilling caused a temporary decline in bird diversity and abundance, followed by recovery once drilling noise ceased, and (ii) responses were species-specific, ranging from a negative response to neutral tolerance. Linear transects were established, and birds were sampled before, during, and after well-drilling. Our study revealed a moderate and transient impact during drilling operations. Analysis of diversity metrics showed lower values during drilling in only one case, which returned to pre-drilling levels once operations concluded. Individual responses were shaped by specific ecological traits—species tolerant of human disturbance and those with loud vocalizations showed greater adaptability, whereas species sensitive to acoustic masking, particularly duetting songbirds, were most affected. Nonetheless, noise control should not be addressed in isolation, especially in landscapes where conservation-priority species depend on critical resources such as forest remnants and suitable nesting trees. Analysis of community abundance and most of diversity metrics showed lower, although not significantly different, values during drilling, both of which returned to pre-drilling levels once operations concluded.