Open AccessPower lines, roads, and avian nest survival: effects on predator identity and predation intensity
Author(s) -
DeGregorio Brett A.,
Weatherhead Patrick J.,
Sperry Jinelle H.
Publication year - 2014
Publication title -
ecology and evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.17
H-Index - 63
ISSN - 2045-7758
DOI - 10.1002/ece3.1049
Subject(s) - predation , predator , nest (protein structural motif) , intensity (physics) , ecology , identity (music) , power (physics) , biology , art , physics , biochemistry , quantum mechanics , aesthetics
Anthropogenic alteration of landscapes can affect avian nest success by influencing the abundance, distribution, and behavior of predators. Understanding avian nest predation risk necessitates understanding how landscapes affect predator distribution and behavior. From a sample of 463 nests of 17 songbird species, we evaluated how landscape features (distance to forest edge, unpaved roads, and power lines) influenced daily nest survival. We also used video cameras to identify nest predators at 137 nest predation events and evaluated how landscape features influenced predator identity. Finally, we determined the abundance and distribution of several of the principal predators using surveys and radiotelemetry. Distance to power lines was the best predictor of predator identity: predation by brown‐headed cowbirds ( M olothrus ater ) , corvids ( C orvus sp . and C yanocitta cristata ) , racers ( C oluber constrictor ), and coachwhips ( M asticophis flagellum ) increased with proximity to power lines, whereas predation by rat snakes ( E laphe obsoleta ) and raptors decreased. In some cases, predator density may reliably indicate nest predation risk because racers, corvids, and cowbirds frequently used power line right‐of‐ways. Of five bird species with enough nests to analyze individually, daily nest survival of only indigo buntings ( P asserina cyanea ) decreased with proximity to power lines, despite predation by most predators at our site being positively associated with power lines. For all nesting species combined, distance to unpaved road was the model that most influenced daily nest survival. This pattern is likely a consequence of rat snakes, the locally dominant nest predator (28% of predation events), rarely using power lines and associated areas. Instead, rat snakes were frequently associated with road edges, indicating that not all edges are functionally similar. Our results suggest that interactions between predators and landscape features are likely to be specific to both the local predators and landscape. Thus, predicting how anthropogenic changes to landscapes affect nesting birds requires that we know more about how landscape changes affect the behavior of nest predators and which nest predators are locally important.