DOI: 10.5061/dryad.j3tx95xjs
title: Nutritional condition and net body weight for adult female mule deer (Nov 2017–Mar 2018), Wyoming, USA

description: Many temperate and polar animals have developed physiological and
 behavioral adaptations to survive the challenging conditions of winter.
 Some animals hibernate to reduce energetic expenditure while other
 animals, including ungulates, migrate to avoid cold temperatures and deep
 snow. Despite moving vast distances between seasonal ranges, many
 migratory ungulates are unable to escape the energetic challenges of
 winter and often rely on reserves of fat to withstand food scarcity and a
 negative energy balance. The mobilization of fat for ungulates often is
 dependent on nutritional condition, yet the fine-scale rate at which
 ungulates mobilize fat throughout winter remains unclear. We took
 advantage of three sampling periods during the winter of 2017–18 on a
 population of mule deer that spends the winter in the Red Desert of
 south-central Wyoming, USA to investigate the fine-scale expenditure of
 fat from mid-autumn through late winter (November–March). Although the
 full effects of winter on forage were still minimal in mid-autumn, mule
 deer mobilized fat reserves 2.5 times faster in mid-autumn
 (November–December) than in late winter (December–March). The mobilization
 of fat strongly depended on nutritional condition with mule deer that
 entered a season with higher nutritional condition expending more fat than
 those of lower nutritional condition (P &lt; 0.001). Adjusting
 mobilization of fat based on nutritional condition may allow temperate
 ungulates to survive winter without completely exhausting fat reserves and
 risking malnutrition.
description: On 5 November 2017, we captured n = 30 adult female mule deer
 (&gt; 1-yr-old) in the Red Desert near Rock Springs, WY, USA
 (41°35’09” N, 109°12’15” W). During 8–10 December 2017, we recaptured n =
 20 deer that were captured in November 2017. Then, during 11–13 March
 2018, we recaptured all deer (n = 17) that survived the winter and that
 were captured in November 2017 and December 2017. All mule deer were
 captured via helicopter net-gunning (Ortega et al. 2020) and outfitted
 with store-on-board GPS collars programmed to collect locations every two
 hours (LOTEK Wireless Inc, New Market, Ontario, CAN). During captures, we
 used an electronic platform scale (±0.1 kg; WeighSouth, Asheville, NC) to
 measure net body mass (kg). We measured depth of rump fat via
 ultrasonography (Ibex Pro, E.I. Medical Imaging, Loveland, CO) and
 accompanied it with a body-condition score following standardized
 protocols to estimate scaled, ingesta-free body fat for mule deer (Cook et
 al. 2010). Ingesta-free body fat is a scaled representation of percent
 body fat and is a reliable measure of nutritional condition for live
 animals (Cook et al. 2010). We calculated ingesta-free body mass following
 methods from Cook et al. (2007) to determine a scaled representation of
 body mass. All animal capture and handling protocols were approved by the
 Wyoming Game and Fish Department (Chapter 33-937) and an Institutional
 Animal Care and Use Committee at the University of Wyoming (Protocol
 #20170215KM00260). References: Cook,
 R. C., T. R. Stephenson, W. L. Myers, J. G. Cook, and L. A. Shipley. 2007.
 Validating predictive models of nutritional condition for mule deer.
 Journal of Wildlife Management 71:1934–1943. Cook, R.
 C., J. G. Cook, T. R. Stephenson, W. L. Myers, S. M. McCorquodale, D. J.
 Vales, L. L. Irwin, P. B. Hall, R. D. Spencer, S. L. Murphie, K. A.
 Schoenecker, and P. J. Miller. 2010. Revisions of rump fat and body
 scoring indices for deer, elk, and moose. Journal of Wildlife Management
 74:880-896. Ortega, A. C., S. P. Dwinnell, T. N.
 LaSharr, R. P. Jakopak, K. Denryter, K. S. Huggler, M. M. Hayes, E. O.
 Aikens, T. L. Verzuh, A. B. May, M. J. Kauffman, and K. L. Monteith. 2020.
 Effectiveness of partial sedation to reduce stress in captured mule deer.
 Journal of Wildlife Management 84:1445–1456.