Concerns over declining mule deer (Odocoileus hemionus) populations during the 1990s prompted research efforts to identify and understand key limiting factors of deer. Similar to past deer declines, a top priority of state wildlife agencies was to evaluate the relative importance of habitat and predation. We therefore evaluated the effect of enhanced nutrition of deer during winter and spring on fecundity and survival rates using a life table response experiment involving free‐ranging mule deer on the Uncompahgre Plateau in southwest Colorado, USA. The treatment represented an instantaneous increase in nutritional carrying capacity of a pinyon (Pinus edulis)—Utah juniper (Juniperus osteosperma) winter range and was intended to simulate optimum habitat quality. Prior studies on the Uncompahgre Plateau indicated predation and disease were the most common proximate causes of deer mortality. By manipulating nutrition and leaving natural predation unaltered, we determined whether habitat quality was ultimately a critical factor limiting the deer population. We measured annual survival and fecundity of adult females and survival of fawns, then estimated population rate of change as a function of enhanced nutrition. Pregnancy and fetal rates of adult females were high and did not vary in response to treatment. Fetal and neonatal survival rates increased in response to treatment, although the treatment effect on neonatal survival was marginal. Overwinter rates of fawn survival increased for treatment deer by 0.16–0.31 depending on year and fawn sex, and none of the 95% confidence intervals associated with the effects overlapped zero. Overwinter rates of fawn survival averaged 0.905 (SE = 0.026) for treatment deer and 0.684 (SE = 0.044) for control deer. Nutritional enhancement increased survival rates of fetuses to the yearling age class by 0.14–0.20 depending on year and fawn sex; 95% confidence intervals slightly overlapped zero. When averaging estimates across sexes and years, treatment caused fetal to yearling survival to increase by 0.177 (SE = 0.082, 95% CI: 0.016–0.337). Annual survival of adult females receiving treatment (Ś = 0.879, SE = 0.021) was higher than survival of control adult females (Ś = 0.833, SE = 0.025). Our estimate of the population rate of change (λ) was 1.165 (SE = 0.036) for treatment deer and 1.033 (SE = 0.038) for control deer. Increased production and survival of young (i.e., fetal, neonatal, and overwinter fawn survival) accounted for 64% of the overall increase in λ, whereas adult female survival accounted for 36% of the increase in λ. The effect of nutrition treatment on overwinter fawn survival alone accounted for 33% of the overall increase in λ.

中文翻译：

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营养增强对M鹿种群变化率的影响

在1990年代对m鹿（Odocoileus hemionus）种群数量下降的担忧促使人们进行了研究工作，以查明和了解鹿的关键限制因素。与过去的鹿存亡相似，州野生动植物保护机构的首要任务是评估栖息地和捕食的相对重要性。因此，我们使用生命表响应实验（包括在美国科罗拉多州西南部Uncompahgre高原上自由放养的m鹿）进行了生命表响应实验，评估了冬季和春季鹿营养增强对繁殖力和存活率的影响。该处理代表了松树（Pinus edulis）-犹他州杜松（Juniperus bonesperma）的营养承载力的瞬时增加。）冬季范围，目的是模拟最佳栖息地质量。先前关于Uncompahgre高原的研究表明，捕食和疾病是造成鹿死亡的最常见直接原因。通过控制营养并保持自然捕食不变，我们确定了栖息地质量最终是否是限制鹿种群的关键因素。我们测量了成年雌性的年生存率和繁殖力以及小鹿的生存率，然后估计了人口变化率与营养增强的关系。成年女性的妊娠率和胎儿率很高，并且没有因治疗而变化。尽管治疗对新生儿存活的影响很小，但胎儿和新生儿的存活率随治疗而增加。治疗鹿的越冬小鹿存活率提高了0.16-0。取决于年份和小鹿性别，则为31，而与影响相关的95％置信区间中没有一个重叠为零。小鹿的越冬存活率平均为0.905（SE = 0.026），对照鹿为0.684（SE = 0.044）。营养的提高使到一岁年龄组的胎儿存活率提高了0.14-0.20美元，具体取决于年岁和小鹿的性别。95％的置信区间略微重叠零。当按性别和年龄进行平均估计时，治疗可使胎儿至一岁的存活时间增加0.177（SE = 0.082，95％CI：0.016–0.337）。接受治疗的成年女性的年生存率（营养的提高使到一岁年龄组的胎儿的存活率提高了0.14-0.20，具体取决于年岁和小鹿的性别。95％的置信区间略微重叠零。当按性别和年龄进行平均估计时，治疗可使胎儿至一岁的存活时间增加0.177（SE = 0.082，95％CI：0.016–0.337）。接受治疗的成年女性的年生存率（营养的提高使到一岁年龄组的胎儿的存活率提高了0.14-0.20，具体取决于年岁和小鹿的性别。95％的置信区间略微重叠零。当按性别和年龄进行平均估计时，治疗可使胎儿至一岁的存活时间增加0.177（SE = 0.082，95％CI：0.016–0.337）。接受治疗的成年女性的年生存率（Ś = 0.879，SE = 0.021）高于对照组成年女性的存活率（Ś = 0.833，SE = 0.025）。我们估计治疗鹿的种群变化率（λ）为1.165（SE = 0.036），对照鹿为1.033（SE = 0.038）。年轻人的生产和生存增加（即胎儿，新生儿和越冬的小鹿生存）占λ总体增长的64％，而成年女性的生存占λ增长的36％。营养处理对越冬小鹿存活的影响仅占λ总体增加的33％。