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Effects of Exogenous Androgen and Antiandrogen on Territorial and Nonterritorial Red‐winged Blackbirds (Aves: Icterinae)
Author(s) -
Beletsky Les D.,
Orians Gordon H.,
Wingfield John C.
Publication year - 1990
Publication title -
ethology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.739
H-Index - 74
eISSN - 1439-0310
pISSN - 0179-1613
DOI - 10.1111/j.1439-0310.1990.tb00386.x
Subject(s) - territoriality , flutamide , testosterone (patch) , biology , androgen , ecology , zoology , endocrinology , androgen receptor , prostate cancer , hormone , genetics , cancer
We investigated the role of testosterone (T) in territory establishment and maintenance in male red‐winged blackbirds ( Agelaius phoeniceus ) by implanting exogenous T or pharmacological agents that block the action of T in nonterritorial floaters and territory owners. Floaters with artificially elevated plasma T levels were unable to obtain territories. Territory owners implanted with T did not expand their territories, although they engaged in more aggressive behavior than did control males. Flutamide, which binds to T receptors in target areas, had no effect on territoriality. However, most territory owners given a combination of flutamide and ATD, an aromatization blocker, lost portions of their territories even though they actively defended them. Our results 1) suggest that, although T influences aggressive behavior, elevated plasma levels alone are insufficient to overcome previously‐established social relationships between territory owners or between owners and floaters; 2) indicate that impairing the action of T leads to reduced abilities of territory owners to maintain territories against vigorous challenges: and 3) support recent findings that T acts on reproductive behavior in birds through both androgenic and estrogenic metabolites.