Tag: Molothrus ater

Developmental Origins of Sociality in Brown-Headed Cowbirds(Molothrus ater)

Brown-headed Cowbird (Molothrus ater) Science Article 19 abstract Five variables were studied relating to the emergence of sociality in hand-reared cowbirds (Molothrus ater): proximity, sex assortment, reactions to adults, head-down displays, and vocalizations. The authors were especially interested in female sociality because adult female birds influence male courtship, song content, and use through proximity, attention, […]

Demography, mating system and reproductive success ofthe Brown-headed Cowbird (Molothrus ater) at Delta Marsh,Manitoba

Brown-headed Cowbird (Molothrus ater) Science Article 13 abstract The Brown-headed Cowbird (Molothrus ater) is anative North American icterid and the most commonobligate interspecific brood parasite in North America.Brood parasites lay their eggs in the nests of other birdspecies and all parental care, including incubation andfeeding is provided by the host species. The matingsystem of the […]

The cultural transmission of courtship patterns in cowbirds,Molothrus ater

Brown-headed Cowbird (Molothrus ater) Science Article 4 abstract In this study, I tested whether the courtship behaviours that facilitate patterns of assortative pairing andmating could be culturally transmitted across generations of brown-headed cowbirds. In an earlier study,I housed a first generation of young South Dakota cowbirds in one of two cultural backgrounds: (1) withadult social […]


Brown-headed Cowbird (Molothrus ater) Science Article 10 abstract The incidence of brood parasitism by Brown-headed Cowbirds(Molothrus ater; herea er ‘cowbirds’) within host species typically refl ects thecontinental pa ern in cowbird abundance across North America, where parasitismis heaviest in the Great Plains. However, we found considerable variation incowbird parasitism on Dickcissel (Spiza americana) nests within […]

First Record of Brown-headed Cowbird Egg in a Lesser Scaup Nest

Brown-headed Cowbird (Molothrus ater) Science Article 14 abstract On 16 June 1999, I found a Lesser Scaup (Aythya affinis) nest parasitized by a BrownheadedCowbird (Molothrus ater). On 22 June the female scaup had begun incubating the 10 scaup eggs but the cowbird egg was missing, presumably ejected by the female scaup. David N. Koons, Wilson […]

Female brown-headed cowbirds’, Molothrus ater, organization andbehaviour reflects male social dynamics

Brown-headed Cowbird (Molothrus ater) Science Article 2 abstract In four large aviaries, we studied social assortment and reproductive behaviour of female brown-headedcowbirds housed with males differing in age class and in corresponding levels of intrasexual interaction.Juvenile and adult females resided with either (1) adult males, (2) juvenile males, (3) adult and juvenilemales, or (4) no […]

A future cost of misdirected parental care for brood parasitic young?

Brown-headed Cowbird (Molothrus ater) Science Article 1 abstract Parental care is advantageous because it typically increases the survival ofgenetically related young. In contrast, parental care given to unrelated young incurs no benefit.A further cost of parental investment is that it reduces the future reproductive potential of thecaregiver. I examined whether eastern phoebes’ Sayornis phoebe future […]

Variation in growth of Brown-headed Cowbird(Molothrus ater) nestlings and energetic impactson their host parents

Brown-headed Cowbird (Molothrus ater) Science Article 6 abstract I tested several hypotheses about the plasticity of avian growth by comparing growth of Brown-headedCowbird (Molothrus ater) nestlings in 20 different host species. Growth of cowbird nestlings was not strongly correlatedwith host adult mass and nearly all hosts were able to provision cowbirds with enough food to […]

Retaliatory mafia behavior by a parasitic cowbirdfavors host acceptance of parasitic eggs

Brown-headed Cowbird (Molothrus ater) Science Article 12 abstract Why do many hosts accept costly avian brood parasitism evenwhen parasitic eggs and nestlings differ dramatically in appearancefrom their own? Scientists argue that evolutionary lag orequilibrium can explain this evolutionary enigma. Few, however,consider the potential of parasitic birds to enforce acceptance bydestroying eggs or nestlings of hosts […]

Host use strategies of individual female brown-headed cowbirdsMolothrus ater in a diverse avian community

Brown-headed Cowbird (Molothrus ater) Science Article 7 abstract Although it is well established that brown-headed cowbirds Molothrus ater are hostgeneralists, the parasitism strategies of individual females are not well documented.Here we use microsatellite genotyping to characterize host use by individual femalecowbirds. Of 205 offspring sampled at a site in northeastern Illinois during onebreeding season, we […]