The island nation of Madagascar is home to three endemic species of Old World fruit bat in the family Pteropodidae: Pteropus rufus, Eidolon dupreanum, and Rousettus madagascariensis, all three of which are IUCN Red Listed under some category of threat. Delineation of seasonal limits in the reproductive calendar for threatened mammals can inform conservation efforts by clarifying parameters used in population viability models, as well as elucidate understanding of the mechanisms underpinning pathogen persistence in host populations. Here, we define the seasonal limits of a staggered annual birth pulse across the three species of endemic Madagascar fruit bat, known reservoirs for viruses of high zoonotic potential. Our field studies indicate that this annual birth pulse takes place in September/October for P. rufus, November for E. dupreanum, and December for R. madagascariensis in central-eastern Madagascar where the bulk of our research was concentrated. Juvenile development periods vary across the three Malagasy pteropodids, resulting in near-synchronous weaning of pups for all species in late January–February at the height of the fruiting season for this region. We here document the size range in morphological traits for the three Malagasy fruit bat species, with P. rufus and E. dupreanum among the larger of pteropodids globally and R. madagascariensis among the smaller. All three species demonstrate subtle sexual dimorphism with males being larger than females. We explore seasonal variation in adult body condition by comparing observed body mass with body mass predicted by forearm length, demonstrating that pregnant females add weight during staggered gestation periods and males lose weight during the nutritionally deficit Malagasy winter. Finally, we quantify forearm, tibia, and ear length growth rates in juvenile bats, demonstrating both faster growth and more protracted development times for P. rufus as compared with E. dupreanum and R. madagascariensis. The longer development period for the already-threatened P. rufus further undermines the conservation status of this species as human hunting is particularly detrimental to population viability during reproductive periods. Our work highlights the importance of longitudinal field studies in collecting critical data for mammalian conservation efforts and human public health alike.

中文翻译：

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三只马达加斯加果蝠的繁殖、季节形态和幼年生长

岛国马达加斯加是翼足科（Pteropodidae）中三种旧世界果蝠的特有物种的家园：Pteropus rufus、Eidolon dupreanum 和 Rousettus madagascariensis，这三种蝙蝠均被列入 IUCN 红色名录，属于某种威胁类别。划定受威胁哺乳动物的繁殖日历中的季节限制可以通过澄清种群生存力模型中使用的参数来为保护工作提供信息，并阐明对宿主种群中病原体持久存在的机制的理解。在这里，我们定义了马达加斯加特有的三种果蝠的交错年度出生脉冲的季节限制，这三种果蝠是已知的高人畜共患病病毒的储存库。我们的实地研究表明，在马达加斯加中东部地区，P. rufus 每年的出生脉冲发生在 9 月/10 月，E. dupreanum 发生在 11 月，R. madagascariensis 发生在 12 月，我们的大部分研究都集中在那里。三种马达加斯加翼足类的幼体发育时期各不相同，导致所有物种的幼崽几乎同步地在 1 月下旬至 2 月该地区结果季节的高峰期断奶。我们在这里记录了三种马达加斯加果蝠物种的形态特征的大小范围，其中 P. rufus 和 E. dupreanum 属于全球较大的翼足类动物，R. madagascariensis 属于较小的。这三个物种都表现出微妙的性别二态性，雄性比雌性更大。我们通过比较观察到的体重与通过前臂长度预测的体重来探索成人身体状况的季节性变化，证明怀孕的女性在交错的妊娠期期间体重增加，而男性在营养不足的马达加斯加冬季体重减轻。最后，我们量化了幼年蝙蝠的前臂、胫骨和耳朵长度的生长速度，结果表明，与 E. dupreanum 和 R. madagascariensis 相比，P. rufus 的生长速度更快，发育时间也更长。已经受到威胁的红腹雉的发育期较长，进一步破坏了该物种的保护状况，因为人类狩猎对繁殖期种群的生存能力尤其不利。我们的工作强调了纵向实地研究在收集哺乳动物保护工作和人类公共卫生等关键数据方面的重要性。