DOI: 10.5061/dryad.q573n5thc
title: Evidence of nest material kleptoparasitism in Worm-eating Warblers (Helmitheros vermivorum) in east-central Arkansas, USA

description: Nest material kleptoparasitism likely evolved in birds to reduce the cost
 of searching for and collecting material themselves. Although nest
 material kleptoparasitism has been reported commonly in colonially nesting
 species, reports for solitary breeding species are infrequent, especially
 for neotropical migratory species. Here we report potential and actual
 nest material kleptoparasitism in the Worm-eating Warbler (Helmitheros
 vermivorum). We deployed video camera systems at passerine nests (n = 81)
 in east-central Arkansas during summers 2011–2012. In one video, we
 observed a Worm-eating Warbler stealing nesting material from a Hooded
 Warbler (Setophaga citrina) nest. One day later, we later observed a
 Worm-eating Warbler landing within 0.5 m of the same warbler nest when the
 female was incubating, which possibly deterred a second theft of nesting
 material. In a third video recording, we observed another Worm-eating
 Warbler landing within 1 m of an Indigo Bunting (Passerina cyanea) nest.
 As far as we could determine, neither of these latter two nest visits
 resulted in nest material kleptoparasitism. Potential benefits of nest
 material kleptoparasitism include reduced competition for limited nest
 materials, easy access to suitable material, reduced travel distance, and
 reduction of nest predation risk; however, costs include risk of attack by
 host or introducing parasites to one’s nest. Importantly, this behavior
 could ultimately affect the behavioral and life history evolution of a
 species. We suggest further work should be conducted to determine the
 prevalence of nest material kleptoparasitism in Worm-eating Warblers and
 other solitary breeding passerines, including efforts to quantify the
 benefits and costs of this behavior.
description: We recorded our Worm-eating Warbler observations while conducting
 an intensive study on the nesting ecology of passerines in bottomland
 hardwood forests. These observations were made at two study sites located
 in east-central Arkansas, USA: Saint Francis National Forest (N 34°
 38' 44.840", W 90° 40' 9.974") and Trusten Holder
 Wildlife Management Area (N 33° 59' 21.584", W 91° 20'
 53.917") (Fig. 1). Saint Francis is composed of over 8,500 ha of
 bottomland and upland forests (Benson et al. 2009) and Trusten Holder is
 comprised of over 4,000 ha of bottomland hardwood forest (AGFC 2020). In
 the larger research project (i.e., the intensive nesting ecology study),
 we established an approximately 72-ha grid at each site. We conducted nest
 searches for all understory passerine species from early May through late
 July 2011–2012 and deployed video camera systems recording 24 h/day at 81
 nests of 10 different species. Camera systems consisted of a Supercircuits
 mono-power infrared camera (PC177IR-1color, Liberty Hill, TX), a
 micro-digital video recorder (DVR; AKR-100S, Korea), and a 12-V deep-cycle
 marine battery. We reviewed approximately 13,500 hours (i.e., 562.5 days)
 of video with camera systems deployed between 1-13 days per
 nest.