Habitat density, dispersal ability and migratory behaviour modulate body mass-extinction risk relationship in birds

Rapidly changing environments pose a greater extinction risk for some species than others. Increasingly, predictive conservation studies are investigating behaviour, life history and ecology to identify predictors of species extinction risk. Most studies predict species with larger body masses are at a higher risk of extinction. However, this relationship is known to be mediated by species' life histories and ecology. We investigated their role in explaining variation in the body mass-extinction risk relationship of bird species at the regional scale. We compiled data and constructed phylogenetic generalized linear models for 1213 bird species native to India to test hypotheses to predict extinction risk based on the International Union for Conservation of Nature (IUCN) Red List threatened status. We assessed potential predictors of extinction probability, including birds' survival and reproductive life-history traits, ecology and their interactions with body mass. We found habitat density preference, hand-wing index or wing pointedness that indicates dispersal ability and migratory behaviour modulated the positive body mass-extinction risk relationship. Small clutch size was also a predictor of high extinction risk. Our findings highlight the importance of assessing interaction between predictor variables to increase the precision of predictive conservation. We discuss the need for similar taxa-specific and regional studies to prioritize conservation efforts.