DOES EXPOSURE TO HETEROSPECIFIC MALES AFFECT SEXUAL PREFERENCES OF FEMALE BUNTINGS (PASSERINA)

Indigo buntings, Passerina cyanea, and lazuli buntings, P. amoena, for m hybrid pairs during the breeding season, although the frequency of h ybrid pairs is less than expected if mating is at random. The antecede nt conditions leading to hybrid pairing are unknown. In the experiment reported here, adult female indigo and lazuli buntings from allopatri c populations were photostimulated and implanted-with oestradiol to at tain reproductive condition in the presence of heterospecific males. F emales were exposed for 25 days to vocal and visual displays of hetero specific males while developing reproductive physiology and behaviour. Females were then tested for their preferences, as indicated by copul ation solicitation displays, for conspecific versus heterospecific mal es and their vocalizations. Additionally, songs of several males were recorded before and after exposure to females and subsequently examine d for structural modifications that may have been caused by the exposu re to heterospecific females. Females of both species preferred conspe cific males and their vocalizations in tests following the heterospeci fic exposure treatments. Comparisons with previous experiments on fema le buntings suggested that the 25-day stimulation from heterospecific males was unable to alter female preference for conspecific males. Nor were male songs structurally altered as a consequence of exposure to heterospecific females.