Tag: Brown-headed Cowbird

GEOGRAPHIC VARIATION IN BROWN-HEADED COWBIRD(MOLOTHRUS ATER) PARASITISM ON DICKCISSELS(SPIZA AMERICANA) IN GREAT PLAINS TALLGRASS PRAIRIE

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 […]

A role of her own: female cowbirds, Molothrus ater, influence thedevelopment and outcome of song learning

Brown-headed Cowbird (Molothrus ater) Science Article 3 abstract Previous work has shown that captive female cowbirds, Molothrus ater, can influence the outcome of malesong development by affecting retention or deletion of song elements and by stimulating improvization.Here we looked for evidence of female influence during the process of learning, as males progress fromsubsong to plastic […]

BREEDING BIOLOGY OF BROOD PARASITIC BROWN-HEADEDCOWBIRDS (MOLOTHRUS ATER) CHARACTERIZED BY PARENT-OFFSPRING AND SIBLING-GROUP RECONSTRUCTION

Brown-headed Cowbird (Molothrus ater) Science Article 11 abstract We characterized several equivocal aspects of the breeding biology of the broodparasitic Brown-headed Cowbird (Molothrus ater) at a study site in northeastern Illinois. Atotal of 175 offspring and a partial sample of parents were sampled and genotyped at sixmicrosatellite loci. A combination of sibling-group and parentage assignment […]

THE BREEDING SEASON OF A PARASITIC BIRD, THE BROWN-HEADED COWBIRD, IN CENTRAL CALIFORNIA

Brown-headed Cowbird (Molothrus ater) Science Article 18 abstract The breeding seasons of birds are usually timed so that the young are reared during aperiod of abundant food. At high latitudes nearly all small birds may nest within a weekor two of each other. In warmer temperate climates where plants grow and insects areactive for several […]

BROWN-HEADED COWBIRD (MOLOTHRUS ATER) PARASITISM ON WARBLING VIREOS (VIREO GILVUS)IN SOUTHWEST COLORADO

Brown-headed Cowbird (Molothrus ater) Science Article 9 abstract From May through July, 1993-1998 and 2001, effects of Brown-headed Cowbird (Molothrus ater) parasitism on 36 Warbling Vireo (Vireo gilvus) nests were documented in southwest Colorado. Overall parasitism was 75.0% and was the major source of nest failure. Among vireo nests that were not depredated, a significantly […]

Females have a larger hippocampus than males in the brood-parasitic brown-headed cowbird

Brown-headed Cowbird (Molothrus ater) Science Article 20 abstract Females of the brood-parasitic brown-headed cowbird (Molothrus ater) search for host nests in which to lay their eggs. Females normally return to lay a singe egg from one to several days after first locating a potential host nest and lay up to 40 eggs in a breeding […]

RESPONSES OF BELL’S VIREOS TO BROOD PARASITISM BY THEBROWN-HEADED COWBIRD IN KANSAS

Brown-headed Cowbird (Molothrus ater) Science Article 15 abstract I studied patterns of cowbird parasitism and responses to this parasitism by Bell’s Vireos (Vireo bellii) in Kansas. Bell’s Vireos abandoned parasitized nests at a significantly higher rate than unparasitized nests. Lower probability of brood parasitism later in the season may help make abandonment followed by renesting […]

HOW DO BROWN-HEADED COWBIRDS (MOLOTHRUS ATER)CAUSE NEST FAILURES IN SONG SPARROWS (MELOSPIZAMELODIA)? A REMOVAL EXPERIMENT

Brown-headed Cowbird (Molothrus ater) Science Article 8 abstract A removal experiment was conducted to measure how much and by whatmechanisms brood parasitic Brown-headed Cowbirds (Molothrus ater) cause nest failures in acommonly used host, the Song Sparrow (Melospiza melodia). When numbers of female cowbirdswere reduced experimentally, nest failures fell from 65.0% (n = 663 nests) to […]