Studies on the postnatal growth of free-ranging bats can be based on multiple recaptures of marked individuals of known age (longitudinal sampling) or derived from measurements of captured pups with unknown birth dates (cross-sectional sampling). We therefore used individuals of Geoffroy’s bat Myotis emarginatus in a case study to test the hypothesis that these two methods yield similar data on growth rates and growth derivatives. We followed postnatal growth in body mass, forearm length, and total epiphyseal gap in 24 tagged neonates sampled 10 times (via 143 cases of longitudinal sampling) and compared finding with those deriving from cross-sectional sampling carried out on the same occasions among 138 non-tagged neonates of the same colony. A generalized estimating equation relating to the first 3 weeks of postnatal growth indicated that initial values (y-intercepts) for forearm length and body mass did not differ significantly between groups sampled in the two ways (P > 0.05), while rates of growth characterized by these parameters were found to differ significantly (P < 0.05). In relation to the length of total epiphyseal gap obtained for days 12–40, tests for equal intercepts and parallelism confirmed significant differences between the two sampling methods at P < 0.05. Specifically, cross-sectional sampling of the three growth parameters resulted in significant overestimation of ages among the studied bats. However, given the greater logistical challenges with longitudinal sampling, our demonstration of the relative value of the two sampling methods, and of their dependence for accuracy on the amount of variation found in growth variables, allows us to persist in advocating cross-sectional sampling in postnatal studies on bats.

中文翻译：

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比较生长变量和年龄估计的纵向和横截面抽样方法：Geoffroy蝙蝠Myotis emarginatus产后生长的经验教训

自由放养的蝙蝠产后生长的研究可以基于已知年龄的有标记个体的多次捕获（纵向采样），或者可以通过对出生日期未知的捕获幼崽进行测量（横断面采样）得出。因此，我们使用了Geoffroy蝙蝠Myotis emarginatus的个体在一个案例研究中，检验了以下假设：这两种方法得出的增长率和生长导数相似的数据。我们追踪了24例标记新生儿的出生后体重，前臂长度和骨epi间隙的增长情况，这些样本均进行了10次采样（通过143例纵向采样），并与138例未进行过相同横截面采样的婴儿进行了比较标记的同一个殖民地的新生儿。与出生后前3周有关的广义估计方程表明，以两种方式采样的组之间前臂长度和体重的初始值（y-截距）差异不显着（P  > 0.05），通过这些参数发现差异显着（P <0.05）。关于在第12-40天获得的总骨epi间隙的长度，相等截距和平行度的测试证实了两种采样方法之间的显着差异（P  <0.05）。具体而言，对三个生长参数的横截面采样导致研究蝙蝠的年龄显着高估。但是，考虑到纵向采样在后勤方面面临的更大挑战，我们对两种采样方法的相对价值以及它们对准确性的依赖性（取决于生长变量中发现的变化量的依赖性）的证明，使我们能够继续主张采用横截面采样方法。蝙蝠的产后研究。