Movement and nutritional data of mule deer in Western Wyoming (December 2013–December 2021)

Animal Capture and Handling In March 2013, we captured 70 adult, female mule deer using helicopter net gunning. Each year following that initial capture event, we recaptured surviving individuals and captured new individuals to maintain a sample size of 70 animals in mid-March (i.e., spring) and early December (i.e., autumn) until December 2021. At the initial capture of any new animal, we extracted one incisiform canine to estimate age using cementum annuli (LaSharr et al. 2023a). At each capture event, we collected data on nutritional condition, measured body mass, and fit all animals with a GPS radiocollar programmed to take satellite fixes every 2 hours (Advanced Telemetry Systems, Isanti, Minnesota, USA, Telonics, Mesa, Arizona, USA, and Vectronic Aerospace, Berlin, Germany). GPS radiocollars weighed ≤ 2 kg (~3.0% of adult body mass in spring and ~2.6% of adult body mass in autumn).We measured nutritional condition using protocols for mule deer which include measuring subcutaneous rump fat via ultrasonography and body palpation to estimate a body condition score (Stephenson et al. 2002; Cook et al. 2007). Using body mass, body condition score, and maximum thickness of rump fat via ultrasonography, we then estimated ingesta-free body fat (hereafter, ‘body fat’; Cook et al. 2010). We calculated over-summer change in fat by subtracting the body fat of each animal in autumn from their body fat in spring. Each spring capture, we determined pregnancy and fetal number of each animal via ultrasonography (Aikens et al. 2021). All capture and handling were done under compliance with a protocol approved by an Institutional Animal Care and Use Committee at the University of Wyoming (Wyoming Range 20131111KM00040, 20151204KM00135, 20170215KM00260, 20200305KM00412), and were in accordance with guidelines of the American Society of Mammologists (Sikes 2016). Survival and Recruitment Monitoring To account for the energetic cost of raising offspring, we determined recruitment status of radiomarked females each autumn. We determined presence and number of dependent young for collared females each autumn (mid – late November). In 2013 and 2014, all recruitment was evaluated using visual observations. We watched marked females for 5–10 minutes using binoculars or spotting scopes to identify recruitment status based on maternal behavior (Monteith et al. 2014). Maternal behaviors included close association, suckling or attempted suckling, and any other evidence of maternal care. Each observation was classified with a confidence level of “low,” “medium,” or “high” based on evidence of maternal behaviors and group dynamics. For observations considered “low” or “medium” confidence, we returned to the site at a later day to make additional observations until the confidence level was “high”. No “low” or “medium” observations were included in our analyses. Additionally, during autumn captures, we validated our observational data by confirming evidence of lactation by palpating the udder (Monteith et al. 2014, Stephenson et al. 2020). During 2015 – 2021, we collared neonates of collared females each spring as an additional component of the long-term research project. Detailed methodology on capture and handling of neonates can be found elsewhere (Aikens et al. 2021). In instances where all neonates of a marked female were captured and collared (i.e., if a female was pregnant with 2 fetuses and 2 neonates were captured and collared), we used known fate from the juvenile collars to determine recruitment status of adult females each autumn. For any animals in which we were not successful in capturing all neonates in a litter, we used the aforementioned protocol to determine recruitment status. Environmental Covariates and Population Estimates To determine the role of population density and habitat on accumulation of capital over summer, we evaluated the influence of moisture, vegetative biomass, and metrics of greenness from NDVI. First, we estimated seasonal home ranges of each animal using Brownian Bridge movement models (Sawyer et al. 2009). We estimated 95% summer home ranges for each animal in each summer from 1 June to 30 August.