Adult Yellow-crowned Night-herons face in opposite directions at the nest

Michelle E. Afkhami, Joan E. Strassmann

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Vigilance is especially important in colonial socially monogamous birds during the nesting season as nest materials, offspring, and mates are vulnerable to theft, depredation, and extra-pair copulations, respectively. We found that when both members of a mated pair of Yellow-crowned Night-herons (Nyctanassa violacea) were at the nest they faced in opposite directions in 73% of observations, which was significantly more often than would be expected by chance (P < 0.0001, χ21 = 33.3). This behavior may improve vigilance against intruders from all directions. When an extra-pair conspecific was present at the nest of a mated pair, members of the pair were significantly more likely to orient in the same direction towards the conspecific rather than face opposite directions. In 95% of all cases in which an extra-pair conspecific was present, at least one member of the mated pair faced it, indicating that extra-pair conspecifics are perceived as threats by nesting pairs.

Original languageEnglish (US)
Pages (from-to)747-749
Number of pages3
JournalWilson Journal of Ornithology
Issue number4
StatePublished - Dec 1 2007
Externally publishedYes

ASJC Scopus subject areas

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


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