Individual differences in nest defense in the colonial breeding Black-tailed Gulls

Kentaro Kazama, Yutaka Watanuki

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Often in colonial seabirds, all colony members are believed to defend against nest predators and experience equal nest predation risk. However, the variation of defense behavior among members and its reproductive consequences are largely unknown. We investigated (1) individual variation in the nest defense of breeding Black-tailed Gulls Larus crassirostris against a natural egg predator, the Jungle Crow Corvus macrorhynchos and (2) how this behavioral variation affects an individual's own nest predation risk and that of their neighbors. Results were compared between 2 years where crow attack levels were manipulated to average 5 and 22 times normal rates ("low" and "high" predation risk years, respectively) by the placement of varying numbers of artificial nests containing unguarded eggs at the perimeter of the gull colony. In both years, 23-38% of parents, mostly males, showed "aggressive" defense behavior (strikes or chases) against crows and decoys. Other "non-aggressive" gulls showed no defense. In the year of low predation risk, intrusion rates by crows (landing within 0.5 m of an individual gull's nest) were similar for aggressive and non-aggressive gulls. In the year of high predation risk, however, the rates of intrusion for aggressive gulls (4%) and for non-aggressive gulls with an aggressive neighbor (37%) were significantly lower than for non-aggressive gulls without an aggressive neighbor (76%). These results indicate that aggressive individuals reduce nest predation risk for themselves and conspecific neighbors in a colonially breeding species.

Original languageEnglish
Pages (from-to)1239-1246
Number of pages8
JournalBehavioral Ecology and Sociobiology
Volume64
Issue number8
DOIs
Publication statusPublished - 2010 Mar 11
Externally publishedYes

Fingerprint

colonial breeding
predation risk
Laridae
nest
nests
crows
nest predation
predation
breeding
defense behavior
predator
egg
artificial nest
predators
individual variation
Corvus
seabird
defence
Larus crassirostris
seabirds

Keywords

  • Aggressiveness
  • Black-tailed Gull
  • Coloniality
  • Group living
  • Mobbing
  • Neighbor
  • Nest defense

ASJC Scopus subject areas

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

Cite this

Individual differences in nest defense in the colonial breeding Black-tailed Gulls. / Kazama, Kentaro; Watanuki, Yutaka.

In: Behavioral Ecology and Sociobiology, Vol. 64, No. 8, 11.03.2010, p. 1239-1246.

Research output: Contribution to journalArticle

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