Planet of Birds

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 […]

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 […]

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) 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 […]

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 […]

Brown-headed Cowbird (Molothrus ater) Science Article 16 abstract Brown-headed Cowbirds (Molothrus ater) have parasitized at least 220 species of birds, of DONALD H. WOLFE, Wilson Bull., 106(4), 1994, pp. 764-766 Download article download full text (pdf)

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 […]

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 […]

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 […]

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 […]