Individual species and populations can have varying responses to changes in climate. Scientists investigated the association between annual variation in seasonal temperature and precipitation and relative abundances of breeding-bird species in southern California, using the North American Breeding Bird Survey which contains data from 1968 through 2013 at local and regional levels. The investigators also used this data to examine whether the responses to climate varied between species groups that occupied similar land-cover or had similar nesting locations and migratory patterns.  

At the outset of the study, researchers had hypothesized that breeding-bird abundance would be positively related to precipitation and negatively related to temperature in this region. However, they found that results varied. Species that live in arid scrublands or that nest on the ground consistently supported the hypotheses, while species that live in coniferous forests or that nest in cavities did not support the hypothesis. The correlations for other trait-based groups varied widely, where some species and trait-based groups seemed to benefit from the variations in temperature and precipitation and others did not. These results suggest that management of breeding-bird species should be considered at a local or regional level, and consider each species individually, because even similar species within a single region can differ widely in their response to climate variation.  

This study was funded by the SW CASC project “Improving Understanding of Climate Extremes in the Southwestern United States”.