Testosterone and breeding behavior in male Black-tailed Gulls: An implant experiment

Kentaro Kazama*, Kentaro Q. Sakamoto, Yasuaki Niizuma, Yutaka Watanuki

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


Testosterone affects male sexual-, aggressive-, and parental-behaviors in bird species. To understand the breadth of the proximate contribution of testosterone to breeding behaviors in male Black-tailed Gulls Larus crassirostris, sexual behaviors, aggressive behaviors against egg-predators and conspecifics, and chick-provisioning behavior of five testosterone-implanted males (T-males) were observed and compared with those of three control males (placebo-implanted; C-males). T-males showed significantly higher levels of courtship and copulation behaviors than C-males. The levels of aggressiveness against egg-predators and against conspecifics, and the rate of feeding of chicks did not differ between T- and C-males. These results suggest that sexual and mating behaviors in male Black-tailed Gulls may be affected by testosterone, while aggressive- and feeding-behaviors are affected by certain ecological factors, such as individual age, or a necessity for high levels of feeding by males, rather than by testosterone.

Original languageEnglish
Pages (from-to)13-19
Number of pages7
JournalOrnithological Science
Issue number1
Publication statusPublished - 2011 Jun
Externally publishedYes


  • Aggressiveness
  • Behavioral endocrinology
  • Implant
  • Sexual behavior
  • Testosterone

ASJC Scopus subject areas

  • Animal Science and Zoology


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