Abstract Semiaquatic habits evolved in several Sigmodontinae rodent species, but this issue remains poorly studied. The marsh rat Holochilus vulpinus (Brants, 1827) has been associated with palustrine wetland environments and exhibits several morphological traits related to the semiaquatic habit. However, its swimming behavior and the way its morphological specializations contribute to it have not been evaluated so far in this species. This note focuses on describing and quantifying the swimming behavior and swimming performance of H. vulpinus. In order to address these issues, five individuals of H. vulpinus, four adults and one subadult, were filmed while swimming and their performance was quantified. The obtained results indicate that the swimming mode is bipedal paddling, alternating the stroke of the hind feet. The quantitative indicators also qualify H. vulpinus as a good swimmer compared to other terrestrial and semiaquatic mammals.

中文翻译：

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沼泽鼠 Holochilus vulpinus (Brants, 1827) (Cricetidae, Sigmodontinae) 的游泳行为和表现

摘要 几种 Sigmodontinae 啮齿动物物种进化出半水生习性，但这个问题仍然缺乏研究。沼泽鼠 Holochilus vulpinus (Brants, 1827) 与沼泽湿地环境有关，并表现出与半水生习性相关的几种形态特征。然而，迄今为止，尚未在该物种中对其游泳行为及其形态特化对其做出贡献的方式进行评估。本说明侧重于描述和量化狐猴的游泳行为和游泳性能。为了解决这些问题，在游泳时拍摄了五只狐狸犬，四只成虫和一只亚成虫，并对它们的表现进行了量化。获得的结果表明游泳模式是双足划桨，交替后脚划水。