Tag: Brown-headed Cowbird

Brown-headed Cowbird and their Impact on Songbirds

Brown-headed Cowbird (Molothrus ater) Science Article 17 abstract In recent decades, many environmental organizations, conservationists, and biologists have argued that the Brown-headed cowbirds are a major threat to migratory songbirds population. Therefore, I discuss broad aspects about the Brown-headed cowbirds, including nesting andbreeding ranges, nurture, and scientific classification. Jabber M. Al-jabber, unknown Download article download […]

Female brown-headed cowbirds’ (Molothrus ater)social assortment changes in response to male song:a potential source of public information

Brown-headed Cowbird (Molothrus ater) Science Article 5 abstract In many species, females’ behavior appears to be influenced by that of other females, particularly regarding mate choice. Females theoretically can reduce the costs associated with independent male assessment by observing conspecifics. Studies of brown-headed cowbirds suggest that females pay attention to other females’ behavior. Group-housed females […]

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 […]

UNSUITABILITY OF TREE SWALLOWS AS HOSTS TO BROWN-HEADED COWBIRDS

Brown-headed Cowbird (Molothrus ater) Science Article 21 abstract Swallows are parasitized rarely by Brown-headed Cowbirds (Molothrus ater). I added cowbird eggs to 15 Tree Swallow (Tachycineta bicolor) nests. One egg disappeared and seven failed to hatch whereas 63 of 66 host eggs hatched. The seven cowbird hatchlings died in 3-12 (mean = 6.3) d, whereas […]

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 […]