GOYMANN, W*; MUCK, C; SCHWABL, I; Max Planck Institute for Ornithology: Blocking androgen and estrogen action does not affect territorial behaviour of sex-role reversed female black coucals Centropus grillii

In male birds, territorial behavior and song during the breeding season is commonly modulated by androgens. In classically polyandrous bird species, the sex roles are reversed, i.e. females aggressively defend territories or partners and vocalize, whereas males provide all parental care. Are androgens involved in the regulation of territorial and singing behavior in these females as well? The classically polyandrous bird species that have been investigated so far do not show a reversal in sex steroid levels. However, androgens may act at low concentrations if the sensitivity of the target tissues in the brain of females is increased. To test this, we implanted free-ranging female black coucals, a classically polyandrous bird, with an androgen receptor blocker and an aromatase inhibitor to prevent androgen action through the androgen receptor and conversion to estrogens. We investigated territorial and vocalization behavior of experimental and control implanted females. Experimental and control biirds did not differ in territorial aggression (latency to respond, vocalization rate, closest approach) towards a simulated territorial intrusion with a stuffed dummy and playback of black coucal territorial vocalizations. Also territory size and passive vocalization rate during a three week period after implantation did not differ between experimental and control birds. It seems as if androgen action via the androgen and estrogen receptors is not involved in the immediate control of territorial behavior in female black coucals. However, we cannot exclude non-genomic action of androgens that are not mediated via the intracellular receptors. Also, androgens may be only required for the activation of these behaviors at the beginning of the breeding season.