<b>Repeated parasitism of individual female Dark-eyed Juncos (</b><b><i>Junco hyemalis)</i></b><b><i> </i></b><b>by Brown-headed Cowbirds (</b><b><i>Molothrus ater)</i></b><b><i> </i></b><b>over two decades</b>

Dark-eyed Juncos (<i>Junco hyemalis</i>) are a common host that accepts and raises offspring of obligate brood parasitic Brown-headed Cowbirds (<i>Molothrus ater</i>). The Ketterson-Nolan lab at Indiana University has collected long-term, publicly available data on this host-parasite system in Virginia, USA, which allowed us to examine the occurrence and effect of repeated cowbird parasitism on color-banded individuals of a host species across twenty-two years.

Based on previous data collected elsewhere on this and other cowbird hosts, we hypothesized that some individual juncos in this system would experience repeated parasitism within and between breeding years and that the likelihood of repeated parasitism would be negatively related to the reproductive success of the host. We did not detect a statistical pattern of repeated parasitism of female juncos within the same breeding year.