Do Birds Alter Levels of Parental Investment Based on Nest-Site Habitat Features?

Loren Merrill, Elizabeth M. Baehl, Kaitlyn E. Ripple, Thomas J. Benson

Research output: Contribution to journalArticlepeer-review


Many habitats have undergone rapid changes over the past century as a result of anthropogenic activities. Organisms can respond to changes in their environment in many ways, including how much they invest in a given reproductive bout. Optimality theory and life history theory together have provided a framework for understanding how individuals make decisions about the risks and rewards of investing high levels of resources into their offspring within the context of current vs. future reproduction. Shrubland birds in the United States often breed in habitat that has been impacted by humans to varying degrees and provide an ideal system for examining whether organisms alter their levels of parental investment based on the habitat around the nest site. In this study, we assessed levels of nest-defense behavior during a simulated nest predation event in four shrubland birds: American robins (Turdus migratorius), gray catbirds (Dumetella carolinensis), brown thrashers (Toxostoma rufum), and northern cardinals (Cardinalis cardinalis). We found that thrashers and catbirds exhibited significantly higher levels of nest defense compared to robins and cardinals and that birds with larger broods acted more aggressively in defending them. We also found that thrashers acted less aggressively as the proportion of shrubland around the nest increased and as the proportion of developed land around the nest decreased and that cardinals acted less aggressively as the proportion of developed land around the nest increased. These patterns suggest that nest-defense behavior can covary with features of the landscape surrounding the nest, but that the factors shaping that behavior can differ by species.

Original languageEnglish (US)
Pages (from-to)859-868
Number of pages10
Issue number11
StatePublished - Nov 1 2016


  • environmental cues
  • habitat gradient
  • nest defense
  • nest predation
  • parental investment
  • shrubland

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Animal Science and Zoology


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