Demographic data show many populations of Rocky Mountain (Cervus elaphus nelsoni) and Roosevelt (Cervus elaphus roosevelti) elk have been declining over the last few decades. Recent work suggests that forage quality and associated animal nutritional condition, particularly in late summer and early autumn, influence reproduction and survival in elk. Therefore, we estimated seasonal nutritional condition of 861 female elk in 2,114 capture events from 21 herds in Washington, Oregon, Wyoming, Colorado, and South Dakota from 1998 to 2007. We estimated ingesta-free body fat and body mass, and determined age, pregnancy status, and lactation status. We obtained estimates for most herds in both late winter-early spring (late Feb-early Apr) and in autumn (Nov-early Dec) to identify changes in nutritional condition of individuals across seasons.Body fat levels of lactating females in autumn were consistently lower than their non-lactating counterparts, and herd averages of lactating elk ranged from 5.5% to 12.4%. These levels were 30-75% of those documented for captive lactating elk fed high-quality diets during summer and autumn. Body fat levels were generally lowest in the coastal and inland northwest regions and highest along the west-slope of the northern Cascades. Adult females in most herds lost an average of 30.7 kg (range: 5-62 kg), or about 13% (range: 2.6-25%) of their autumn mass during winter, indicating nutritional deficiencies. However, we found no significant relationships between spring body fat or change in body fat over winter with winter weather, region, or herd, despite markedly different winter weather among herds and regions. Instead, body fat levels in spring were primarily a function of fat levels the previous autumn. Thinner females in autumn lost less body fat and body mass over winter than did fatter females, a compensatory response, but still ended the season with less body fat than the fatter elk.Body fat levels of lactating females in autumn varied among herds but were unrelated to their body fat levels the previous spring. Within herds, thinner females exhibited a compensatory response during summer and accrued more fat than their fatter counterparts over summer, resulting in similar body fat levels among lactating elk in autumn despite considerable differences in their fat levels the previous spring. Level of body fat achieved by lactating females in autumn varied 2-fold among herds, undoubtedly because of differences in summer nutrition. Thus, summer nutrition set limits to rates of body fat accrual of lactating females that in turn limited body condition across the annual cycle.Pregnancy rates of 2-to 14-year-old females ranged from 68% to 100% in coastal populations of Washington, 69% to 98% in Cascade populations of Washington and Oregon, 84% to 94% in inland northwestern populations of Washington and Oregon, and 78% to 93% in Rocky Mountain populations. We found evidence of late breeding, even in herds with comparatively high pregnancy rates. Mean body mass of calves (n ¼ 242) in 3 popul...

Because they do not require sacrificing animals, body condition scores (BCS), thickness of rump fat (MAXFAT), and other similar predictors of body fat have advanced estimating nutritional condition of ungulates and their use has proliferated in North America in the last decade. However, initial testing of these predictors was too limited to assess their reliability among diverse habitats, ecotypes, subspecies, and populations across the continent. With data collected from mule deer (Odocoileus hemionus), elk (Cervus elaphus), and moose (Alces alces) during initial model development and data collected subsequently from free-ranging mule deer and elk herds across much of the western United States, we evaluated reliability across a broader range of conditions than were initially available. First, to more rigorously test reliability of the MAXFAT index, we evaluated its robustness across the 3 species, using an allometric scaling function to adjust for differences in animal size. We then evaluated MAXFAT, rump body condition score (rBCS), rLIVINDEX (an arithmetic combination of MAXFAT and rBCS), and our new allometrically scaled rump-fat thickness index using data from 815 free-ranging female Roosevelt and Rocky Mountain elk (C. e. roosevelti and C. e. nelsoni) from 19 populations encompassing 4 geographic regions and 250 free-ranging female mule deer from 7 populations and 2 regions. We tested for effects of subspecies, geographic region, and captive versus free-ranging existence. Rump-fat thickness, when scaled allometrically with body mass, was related to ingesta-free body fat over a 38-522-kg range of body mass (r 2 5 0.87; P , 0.001), indicating the technique is remarkably robust among at least the 3 cervid species of our analysis. However, we found an underscoring bias with the rBCS for elk that had .12% body fat. This bias translated into a difference between subspecies, because Rocky Mountain elk tended to be fatter than Roosevelt elk in our sample. Effects of observer error with the rBCS also existed for mule deer with moderate to high levels of body fat, and deer body size significantly affected accuracy of the MAXFAT predictor. Our analyses confirm robustness of the rump-fat index for these 3 species but highlight the potential for bias due to differences in body size and to observer error with BCS scoring. We present alternative LIVINDEX equations where potential bias from rBCS and bias due to body size are eliminated or reduced. These modifications improve the accuracy of estimating body fat for projects intended to monitor nutritional status of herds or to evaluate nutrition's influence on population demographics.

Recent declines in black‐tailed deer (Odocoileus hemionus columbianus) populations in Washington have been attributed partly to low recruitment. However, sparse information exists regarding fawn survival and factors affecting recruitment. During 2006–2009, we captured 228 fawns on the Olympic Peninsula, Washington, USA, to determine sources of fawn mortality, estimate survival rates, identify factors influencing survival rates, assess the influence of hair loss syndrome (HLS) on winter survival, and estimate population growth. We used known fate modeling in Program MARK to estimate survival rates to age 50 weeks and to 9 weeks by developing 2 candidate a priori model sets. We recorded 129 mortalities; predation was the leading cause (74%). Mountain lions (Puma concolor) and bobcats (Lynx rufus) were the most common predators. The survival rate to 50 weeks was 0.33 (95% CI = 0.24–0.43); survival differed between capture years and was age dependent, with fawns being most vulnerable to mortality during the first 9 weeks then again during the winter. The survival rate to 9 weeks was 0.65 (95% CI = 0.60–0.68), and our results suggested that an interaction between age and birth mass influenced survival. A posteriori modeling indicated that greater body mass and earlier birth date also influenced survival over the first 9 weeks of life. Fawns afflicted with HLS had lower survival rates than non‐afflicted fawns (P = 0.018) during winter. Poor body condition, based on femur marrow assessment, was a factor in 89% of fawns that died over winter. We estimated the growth of the population to be stationary at λ = 1.0. Estimates of lambda increased 3% when survival was modified to assume HLS was not a factor. We conclude that fawn mortality during the first 9 weeks followed by a significant increase in winter mortality, exacerbated by HLS, combine to limit black‐tailed deer population growth. Inherent nutritional limitations in summer forage may have influenced survival of many fawns, pre‐disposing them to mortality during the summer and winter. Wildlife managers can use this information to improve population modeling and management of black‐tailed deer populations afflicted with HLS. © 2014 The Wildlife Society.