Presence of female cowbirds (Molothrus ater ater) affects vocal imitation and improvisation in males.

Abstract

In this article we report that imitation and improvisation of tutor songs by eastern male cowbirds (Molothrus ater ater) differs when they are housed with conspecific females as opposed to nonconspecifics. When males, tutored with 12 different song types, were individually housed with females, they developed repertoires composed primarily of improvised and original song types, whereas the repertoires of males housed with canaries were composed entirely of copies of the tutor songs. Song preferences of the female companions for individual tutor songs were unaffected by social housing. The potency of the males' repertoires, as tested by playback to females, appeared to be related to the song responsiveness of their female companions. The results add further evidence that suggests that male cowbirds configure their song repertoire by attending to social signals from companions.In this experiment we asked three questions. First, do male cowbirds (Molothrus ater ater) housed with females show different patterns of vocal imitation than males housed with canaries? Second, is the males' imitative behavior related to differences in song responsiveness of females? Third, are females' song preferences affected by the vocal behavior of the males? Different forms of social stimulation have different effects on vocal development in songbirds (Pepperberg, 1985; Petri novich, 1988). White-crowned sparrows (Zonotrichia leuco phrys), for example, can learn heterospecific songs after 50 days of age when exposed to live male tutors but not when exposed to tape recordings (Baptista & Petrinovich, 1984;Petrinovich, 1985). So too, red-winged blackbirds (Agelaius phoeniceus) copy less heterospecific song when in the presence of female, as opposed to male, conspecifics (Marler, Mundin ger, Waser, & Lutjen, 1972). Thus, social stimulation, as well as acoustic stimulation, appears to mediate vocal learning, although how these sources of stimulation are integrated remains to be specified.Because female cowbirds do not sing, they provide an opportunity to study the effects of social stimulation in the absence of species-typical song stimulation. Several lines of evidence suggest that females exert discernible effects on males' vocal ontogeny. First, although juvenile eastern males learned nonnative song variants when housed with males from a second cowbird subspecies, M. a. obscurus, adult eastern males copied nonnative variants only when housed with males and females of the second subspecies (West, King, & Harrocks, 1983 subspecies. The structural differences in the males' songs involved acoustic elements used by females to discriminate between songs of the, two subspecies (King & West, 1983b, 1983cWest & King, 1985). Third, the subsongs and plastic songs of yearling males displayed different characteristics when eastern males were housed with M. a. ater rather than M. a. obscurus females, which suggests that the females' presence had effects early in ontogeny (King & West, 1988b). Thus, the aim of this investigation was to study the ...

Alimentary epigenetics: A developmental psychobiological systems view of the perception of hunger, thirst and satiety☆

“…As another example, the Brown-headed cowbird ( Molothrus ater ) is a brood parasitic species (that lays its eggs in the nests of other species, which then raise its hatchlings as their own) that has long been thought to have innate capacities of species-recognition and species-typical song production. (e.g., West and King 1985, 1988; King & West, 1983, 1989) have, however, elaborated the non-obvious influence on male song repertoire of subtle movements made by female cowbirds—movements hardly visible to the unaided human eye—that have the effect of shaping juvenile male song production. The deliberate study of such non-obvious factors, often driven by the dogged investigation of otherwise unusual or unexpected results, has shown that much of what has traditionally been categorized as simply genetic or innate turns out, on closer examination, to be the product of normally occurring experience within a normally occurring, species-typical developmental system or rearing environment (cf.…”

Cultural transmission of vocal traditions in cowbirds (Molothrus ater) influences courtship patterns and mate preferences.

“…King and West used diacepts to describe populational differences in females' preferences and selectivities for males' songs in cowbirds. During 2 decades of study with this species, researchers have found that the development of male song is influenced by the social environment (King, Freeberg, & West, 1996;West & King, 1996a, 1996bWest, King, & Freeberg, 1997;West, King, & Harrocks, 1983) and that females from different populations can shape male song development on the basis of their populational preferences (King & West, 1989;Smith, King, & West, 2000;West & King, 1988).…”

Communicating about communicating: When innate is not enough

“…We were able to segregate the effects of social and acoustic stimulation in the male's environment by studying the nature of vocal development in naive males housed with female cowbirds, which cannot sing. The studies show that although females cannot serve as fellow performers or models, they can serve as social critics and co-composers West & King, 1985;King & West, 1989).…”