Shared Functional Traits Explain Synchronous Long-Term Trends in Counts of Migratory Raptors

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Assessing long-term trends in counts of species is important to understand the consequences of ongoing global environmental change. One approach to study drivers of species assemblage changes is to identify the traits, such as body mass or migratory behavior, associated with count trends among species. 

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, 

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Date published: November 6, 2017
Status: Active

Conservation Ecology and Monitoring of Raptors

Raptors, or birds of prey, are often used to indicate the state of an ecosystem, and monitoring their populations can help us to understand ecosystem processes. Raptors are particularly good animals for monitoring because they are big and therefore charismatic and easy to observe. Whether we’re monitoring nesting biology and reproductive output, counting individuals on roads, or setting up...

Contacts: Todd E Katzner