Researchers used a model to identify when count trends of migrating raptors recorded at the Hawk Mountain Sanctuary in Pennsylvania shifted, and to assess the role of traits in driving these trends, over 73 years (1946-2018). Scientists discovered a breakpoint at the year 1974, where mean assemblage-wide count trends shifted from negative to positive. Diet and habitat specialization, both traits associated with resource use, were synchronously associated with count trends. Researchers found that a suite of additional factors such as decreased persecution pressure, acting together with release from DDT pressures, affected the recovery of species from pesticide‐linked declines. Trait-based frameworks have promise for testing generalized assumptions about drivers of population trajectories. 
 

Dumandan, P.T., Bildstein, K.L., Goodrich, L.J., Zaiats, A., Caughlin, T., Katzner, T.E., 2020, Shared functional traits explain synchronous changes in long-term count trends of migratory raptors: Global Ecology and Biogeography, https://doi.org/10.1111/geb.13242