Data from: Re-evaluating neonatal-age models for ungulates: does model choice affect survival estimates?

New-hoof growth is regarded as the most reliable metric for predicting age of newborn ungulates, but variation in estimated age among hoof-growth equations that have been developed may affect estimates of survival in staggered-entry models. We used known-age newborns to evaluate variation in age estimates among existing hoof-growth equations and to determine the consequences of that variation on survival estimates. During 2001–2009, we captured and radiocollared 174 newborn (≤24-hrs old) ungulates: 76 white-tailed deer (Odocoileus virginianus) in Minnesota and South Dakota, 61 mule deer (O. hemionus) in California, and 37 pronghorn (Antilocapra americana) in South Dakota. Estimated age of known-age newborns differed among hoof-growth models and varied by >15 days for white-tailed deer, >20 days for mule deer, and >10 days for pronghorn. Accuracy (i.e., the proportion of neonates assigned to the correct age) in aging newborns using published equations ranged from 0.0% to 39.4% in white-tailed deer, 0.0% to 3.3% in mule deer, and was 0.0% for pronghorns. Results of survival modeling indicated that variability in estimates of age-at-capture affected short-term estimates of survival (i.e., 30 days) for white-tailed deer and mule deer, and survival estimates over a longer time frame (i.e., 120 days) for mule deer. Conversely, survival estimates for pronghorn were not affected by estimates of age. Our analyses indicate that modeling survival in daily intervals is too fine a temporal scale when age-at-capture is unknown given the potential inaccuracies among equations used to estimate age of neonates. Instead, weekly survival intervals are more appropriate because most models accurately predicted ages within 1 week of the known age. Variation among results of neonatal-age models on short- and long-term estimates of survival for known-age young emphasizes the importance of selecting an appropriate hoof-growth equation and appropriately defining intervals (i.e., weekly versus daily) for estimating survival.新生有蹄类动物的蹄部新生生长量被视为预测其日龄最可靠的指标，但已开发的各类蹄部生长方程所得到的年龄估计值存在差异，这可能会影响交错进入模型中的生存估计结果。本研究利用已知日龄的新生有蹄类动物，评估现有蹄部生长方程间的年龄估计差异，并明确该差异对生存估计结果的影响。2001年至2009年间，我们共捕获并为174只日龄≤24小时的新生有蹄类动物佩戴了无线电项圈：其中明尼苏达州与南达科他州的白尾鹿（Odocoileus virginianus）76只、加利福尼亚州的骡鹿（O. hemionus）61只，以及南达科他州的叉角羚（Antilocapra americana）37只。不同蹄部生长模型对已知日龄新生个体的年龄估计存在差异：白尾鹿的估计差值超过15天，骡鹿超过20天，叉角羚则超过10天。利用已发表的方程进行新生个体日龄判定时，其准确率（即被分配至正确日龄的幼崽占比）表现为：白尾鹿为0.0%至39.4%，骡鹿为0.0%至3.3%，叉角羚则为0.0%。生存模型分析结果显示，捕获时年龄估计的偏差对白尾鹿和骡鹿的短期（30天）生存估计存在影响，同时也会影响骡鹿的长期（120天）生存估计结果。与之相反，叉角羚的生存估计并未受到年龄估计值的影响。本研究分析表明，鉴于用于估算幼崽日龄的各类方程存在潜在偏差，当捕获时的年龄未知时，以日为间隔构建生存模型的时间尺度过于精细。相较之下，以周为间隔的生存模型更为合适，因为多数模型能够在已知日龄前后1周的范围内准确预测个体年龄。针对已知日龄幼崽，不同日龄模型得到的短期与长期生存估计结果存在差异，这凸显了选择合适的蹄部生长方程，并合理定义生存估计的时间间隔（即周间隔vs日间隔）的重要性。