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Please use this identifier to cite or link to this item: http://hdl.handle.net/1993/3023

Title: Genetic elucidation of host use by individual sympatric bronzed cowbirds (Molothrus aeneus) and brown-headed cowbirds (M-ater)
Authors: Ellison, K
Sealy, SG
Gibbs, HL
Keywords: AVIAN BROOD PARASITISM
MICROSATELLITE DNA MARKERS
CUCKOO CUCULUS-CANORUS
SHINY COWBIRD
COMMON CUCKOO
SCREAMING COWBIRD
REPRODUCTIVE SUCCESS
POPULATION-DYNAMICS
NATURAL-POPULATIONS
TEMPORAL PATTERNS
Issue Date: 30-Sep-2006
Citation: 0008-4301; CAN J ZOOL, SEP 2006, vol. 84, no. 9, p.1269 to 1280.
Abstract: Species of avian brood parasites that use one or several species of hosts are called host specialists and generalists, respectively. To determine host use of individual bronzed cowbirds, Molothrus aeneus (Wagler, 1829), and brown-headed cowbirds, Molothrus ater (Boddaert, 1783), we assigned maternity to eggs using microsatellite DNA markers. We measured patterns of host use by individual sympatric cowbirds. This allowed us to determine whether these species competed for host nests and the number of females laying at nests that were already parasitized by conspecifics. We monitored 1447 nests of 42 potential host species and found that each species of cowbird used primarily four host species, with minimal overlap in the species used, yet at least some individuals acted as generalists. Individual cowbirds tended to avoid laying again at nests each had already parasitized, and multiple parasitism was frequently due to same-day laying by more than one female (19% and 44% of 27 and 39 cases for brown-headed and bronzed cowbirds, respectively). Our results suggest that both cowbirds can differentially parasitize host species; however, host use does not appear to be refined, as many eggs were laid in already-parasitized nests when unparasitized nests of other suitable host species were available.
URI: http://hdl.handle.net/1993/3023
DOI: http://dx.doi.org/10.1139/z06-091
Appears in Collection(s):Research Publications (UofM Student, Faculty and Staff only access)

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