DOI: 10.5061/dryad.6wwpzgn5c
title: Digital records of Brown-headed Cowbirds removing eggs and nestlings from nests of grassland passerine birds in southwest Wisconsin

description: We present digital recordings from video surveillance systems at nests of
 grassland birds. Video surveillance systems were used as part of grassland
 bird studies done in southwestern Wisconsin. Study sites were clustered
 near Mt. Horeb (43.0167°N, 89.7500°W). Four grassy field types were
 studied: continuously-grazed pasture, prairie, and cool- and warm-season
 grass fields. The digital recordings archived here were used to document
 egg and nestling destruction by the Brown-headed Cowbird (Molothrus ater).
description: We used video surveillance systems at nests to identify the nest
 predators in all the studies. We prioritized putting video surveillance
 systems on nests of obligate grassland birds, followed by facultative
 grassland birds, and finally generalist birds that occurred in the
 grasslands. In general, we used cameras with infrared light-emitting
 diodes (LEDs) that facilitated recording quality images under low-light
 conditions. We distributed cameras among fields to avoid clustering and we
 set up cameras at nests during or soon after the egg-laying stage ended to
 lower the chance for abandonment. Recording systems were attached to
 cameras with 25-m cables (following the protocol established by Renfrew
 and Ribic 2003). Each camera was mounted on a wooden dowel 3 – 38 cm above
 the ground. Cameras were 64 cm<sup>3</sup> and placed 12 –25
 cm from the nest, depending on the nest structure and surrounding
 vegetation. The field of view at these distances ranged from 414 to 1,320
 cm<sup>3</sup>. Cameras were typically placed at or below the
 height of surrounding vegetation to avoid creating a potential visual cue
 for potential predators. As part of data analysis for
 each study, we watched the digital recordings of all nests to document
 nest fate as well as any other events that resulted in loss of an egg or
 nestling and compiled this information in a master data file.  We watched
 the digital recordings using VideoLAN VLC Media Player or DivX Player. For
 this study, we used any event (partial or complete nest predations,
 scavenging of unhatched eggs) from this master file that involved a
 Brown-headed Cowbird. 
description: # Digital records of Brown-headed Cowbirds removing eggs and nestlings
 from nests of grassland passerine birds in southwest Wisconsin --- We
 present digital recordings from video surveillance systems at nests of
 grassland birds. Video surveillance systems were used as part of grassland
 bird studies done in southwestern Wisconsin. The digital recordings
 archived here were used to document egg and nestling destruction by the
 Brown-headed Cowbird (Molothrus ater). Study sites were clustered near Mt.
 Horeb (43.0167°N, 89.7500°W). Four grassy field types were studied:
 continuously-grazed pasture, prairie, and cool- and warm-season grass
 fields. We used video surveillance systems at nests to identify the nest
 predators in all the studies. We prioritized putting video surveillance
 systems on nests of obligate grassland birds, followed by facultative
 grassland birds, and finally generalist birds that occurred in the
 grasslands. In general, we used cameras with infrared light-emitting
 diodes (LEDs) that facilitated recording quality images under low-light
 conditions. We distributed cameras among fields to avoid clustering and we
 set up cameras at nests during or soon after the egg-laying stage ended to
 lower the chance for abandonment. Recording systems were attached to
 cameras with 25-m cables (following the protocol established by Renfrew
 and Ribic 2003). Each camera was mounted on a wooden dowel 3 – 38 cm above
 the ground. Cameras were 64 cm3 and placed 12 –25 cm from the nest,
 depending on the nest structure and surrounding vegetation. The field of
 view at these distances ranged from 414 to 1,320 cm3. Cameras were
 typically placed at or below the height of surrounding vegetation to avoid
 creating a potential visual cue for potential predators. As part of data
 analysis for each study, we watched the digital recordings of all nests to
 document nest fate as well as any other events that resulted in loss of an
 egg or nestling and compiled this information in a master data file. We
 watched the digital recordings using VideoLAN VLC Media Player or DivX
 Player. For this study, we used any event (partial or complete nest
 predations, scavenging of unhatched eggs) from this master file that
 involved a Brown-headed Cowbird. ## Description of the data and file
 structure There are 7 video files with female Brown-headed Cowbirds
 removing eggs and/or nestlings from passerine birds nests. Each file name
 has the date of the event, species of passerine bird, and a short
 description of the event. ## Sharing/Access information Data were derived
 from the following sources: * Byers, C. M., C. A. Ribic, D. W. Sample., J.
 D. Dadisman, and M. R. Guttery. 2017. Grassland bird productivity in warm
 season grass fields in southwest Wisconsin. American Midland Naturalist
 178:47–63. * Ellison, K. S., C. A. Ribic, D. W. Sample, M. J. Fawcett, and
 J. D. Dadisman. 2013. Impacts of tree rows on grassland birds and
 potential nest predators: a removal experiment. PLoS ONE 8(4):e59151.
 . * Renfrew, R. B., C.
 A. Ribic, and J. L. Nack. 2005. Edge avoidance by nesting grassland birds:
 a futile strategy in a fragmented landscape. The Auk 122:618–636. * Ribic,
 C. A., M. J. Guzy, T. A. Anderson, D. W. Sample, and J. L. Nack. 2012.
 Bird productivity and nest predation in agricultural grasslands. Studies
 in Avian Biology 43:119-134.