Abstract: Abstract:Animal reproductive activities are constrained by trade-offs between different natural selection pressures and their physiological limitations. Many abiotic factors including climate (temperature,photoperiod and rainfall)and abundance of plant species affect the reproductive activities of bats. We studied the effect of rainfall and the degree of food availability on the parturition timing of Cynopterus sphinx by measuring food resource availability and conducting marking-recapture on bats in Xishuangbanna. We found that average precipitation gradually increased from March to August (19. 82 - 41.13 kg /m2 ),and plant species fed on by bats increased (4 - 9 species)at the same time. There was a significant positive relationship between the number of captured sub-adult bats and the degree of food availbility (r = 0. 94, P = 0. 01). Although having the capacity of polyestrous and parturition twice a year,most of them were monoestrous and parturition once a year,which only occurred from March to May. The timing that sub-adults become volant and learn to forage corresponds to the peak phase of fruit availability,which facilitates to improve survival fitness of sub-adults.

Key words: Cynopterus sphinx, Precipitation, The timing of parturition, The degree of food availability

摘要： 繁殖是动物权衡不同自然选择压力和自身生理限制的结果。蝙蝠的繁殖受气候(温度、光周期和降雨量)和食物资源等非生物因素影响。本文通过野外调查犬蝠食物资源、设网捕捉和标志重捕的方法研究西双版纳地区降雨、食物资源可获得程度对犬蝠分娩时机的影响。研究发现,随着3 - 8 月降雨量逐渐增加(19.82 -41.13 kg/ m2 ),犬蝠取食的植物种类呈明显的增加趋势(4 - 9 种)。幼蝠捕捉量与植物资源可获得程度呈显著正相关关系(r = 0. 94,P = 0.01)。西双版纳犬蝠虽然具有一年两次动情和分娩的能力,但是绝大多数个体一年只分娩一次,且集中于3 -5 月。犬蝠分娩时机的选择使得幼蝠飞行学习和捕食时间与食物资源可获得程度高峰期相吻合,有利于提高幼体的生存适合度。

关键词: 生殖时机, 食物资源可获得程度, 降雨量, 犬蝠