Effects of brood parasitism by brown-headed cowbirds may persist in the post fledging period

Wilson Journal of Ornithology
By: , and 



Brood parasitism by Brown-headed Cowbirds (Molothrus ater) typically decreases the number of host juveniles that fledge: however, little information exists regarding the effect of cowbird parasitism during the post-fledging period. We monitored 115 Ovenbird (Seiurus aurocapilla) nests in 2006–2008 in northcentral Minnesota, six of which were parasitized. We used radiotelemetry to monitor movements of 36 Ovenbird fledglings (nine additional fledglings depredated <24 hrs after fledging were excluded from the movement analysis) from non-parasitized nests and one fledgling from a parasitized nest. Clutch sizes and productivity were lower in parasitized Ovenbird nests than non-parasitized nests, similar to populations at other locations. The fledgling we tracked from a parasitized nest (in 2008) died after 26 days. It was the only fledgling in our study that died (n  =  20) with no sign of predation and an empty stomach. That fledgling took 12 days to travel >50 m from its nest and 25 days to travel >100 m from its nest. Fledglings from non-parasitized broods tracked for ≥25 days during 2008 (n  =  16) took 4.1 ± 0.71 and 9.5 ± 1.14 days to travel the same distances. Our observations suggest that negative effects of brood parasitism may persist into the post-fledging period, possibly confirming observations of cowbird-only survival compiled from the literature.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Effects of brood parasitism by brown-headed cowbirds may persist in the post fledging period
Series title Wilson Journal of Ornithology
DOI 10.1676/11-050.1
Volume 124
Issue 1
Year Published 2012
Language English
Publisher Wilson Ornithological Society
Publisher location Lawrence, KS
Contributing office(s) Coop Res Unit Leetown
Description 5 p.
First page 179
Last page 183
Country United States
State Minnesota
Online Only (Y/N) N
Additional Online Files (Y/N) N
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