Capture and monitoring
We captured adult female (> 1.5-year-old) white-tailed deer via helicopter net guns (Native Range Capture Service, Elko, NV, USA). We then affixed very high frequency (VHF) radio-collars (model M2610B, Advanced Telemetry Systems, Inc., Isanti, MN) to individuals and inserted Vaginal Implant Transmitters (103 females; Advanced Telemetry Systems, Inc., Isanti, MN, USA) to aid in neonate capture (Bowman & Jacobson, 1998; Carstensen, DelGuidice & Sampson, 2003; Swanson et al., 2008).
We captured neonates from 23 May to 23 June in Dunn and Grant Counties, North Dakota, and in Perkins County, South Dakota, during 2014 and 2015. We searched for white-tailed deer neonates near expelled VITs, in areas of known parturition habitat, and near females who showed postpartum behavior such as isolation or fleeing short distances when approached (Rohm, Nielsen & Woolf, 2007; Grovenburg et al., 2010). We then captured neonates by hand or net once we located them. We restrained and blindfolded neonates upon capture, determined sex, recorded body mass (kg), and fitted individuals with a M4210 expandable breakaway radio-collar (Advanced Telemetry Systems, Isanti, MN, USA). We wore sterile rubber gloves, used no-scent spray, stored radio-collars and other equipment in natural vegetation, and kept handling time under five minutes when possible to reduce capture-related mortality. We only determined sex of radio-collared neonates if individuals were wet from rain or afterbirth or were too large to fit in the weighing bag. All handling methods followed the American Society of Mammalogists guidelines for mammal care and use (Sikes et al., 2016) and were approved by the South Dakota State University Institutional Animal Care and Use Committee (Approval No. 13-091A).