Reproduction and growth in a Neotropical arboreal mouse: Oecomys rutilus (Sigmodontinae: Cricetidae) in French Guiana

Abstract: Postnatal growth and development of the small Neotropical mouse Oecomys rutilus (Sigmodontinae: Cricetidae) were investigated from birth to day 143, in the laboratory. Morphometric measurements at age of 3 days, of both sexes combined, revealed body weight to be 3.4 ± 0.3 g, mean tail length as 27.4 ± 1.1 mm, and mean hind foot length as 9.3 ± 0.7 mm. Body weight was found to increase steadily until at least 69 days, whereas the instantaneous growth rates of other measurements declined earlier: the daily growth of hind foot length declined to a minimum at age of 24 days, and the growth of tail and of ear declined by the age of 33 days. Average litter size for 12 captive births was 2.5, ranging from 2 to 3. The preserved eye crystalline lens was weighted in 23 captive-born animals of known age, allowing a rough estimate of the age of reproduction in wild-caught animals. Based on the inferred relation between eye-lens weight and age, the youngest reproductive (pregnant) wild-caught females had an estimated age of 90 and 95 days.

摘要：本研究于实验室环境下，针对新热带区小型小鼠红拟稻鼠（Oecomys rutilus，棉鼠亚科：仓鼠科）开展了从出生至143日龄的产后生长发育观测。对3日龄雌雄混合样本的形态学测量结果显示，其平均体重为3.4±0.3克，平均尾长为27.4±1.1毫米，平均后足长为9.3±0.7毫米。研究发现，体重至少在69日龄前均呈稳步增长态势，而其余形态指标的瞬时生长速率则更早出现下降：后足长的日生长量在24日龄时降至最低，尾长与耳长的生长速率则在33日龄时已显著降低。12例圈养产仔的平均胎仔数为2.5只，胎仔数范围为2至3只。本研究对23只已知日龄的圈养新生个体的眼晶状体进行称重，借此可粗略估算野生捕获个体的繁殖日龄。基于眼晶状体重量与日龄的推断关联，野生捕获的最年轻怀孕繁殖雌性个体的估算日龄分别为90日龄与95日龄。