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Keywords:

  • overabundance;
  • songbirds;
  • trophic cascades;
  • understory;
  • ungulate

Abstract

Aim

We evaluate the possible link between increasing deer populations and declines in woodland birds.

Location

North American continent.

Methods

We used a group of 73 forest bird species that had been tested for their sensitivity to the impact of overabundant deer on forest understory. We used Breeding Bird Survey data to assess population trends for these 73 songbird species between 1966 and 2009, a period of marked continent-wide increases in white-tailed (Odocoileus virginianus) and mule or black-tailed (Odocoileus hemionus) deer.

Results

We show a continent-wide link between increase in deer populations and declines in forest–songbird species-dependent on understory for nesting and/or foraging.

Main conclusions

Increasing deer populations may actually play an important and underestimated role in the decline of North American songbirds.