Swarming

Tendo em conta que o conhecimento geral da biologia e ecologia de muitas espécies e existentes em Portugal continental é ainda muito escasso, deixo aqui o resumo de um artigo recentemente publicado com o meu singelo trabalho, que basicamente põe em discussão a possibilidade de uma mina ser um sítio “swarming”, um dos comportamentos mais desconhecidos dos morcegos.

This study investigated the visitation of an underground site by bats during the “swarming” season (September and October) of 2009, 2011 and 2012, in a mine located in the Northeast Portugal (Vila Cova mine, 850 m a.s.l.). A total of 79 bats were captured, representing 12 of the 25 bat species identified in Portugal Continental. The Western Barbastelle (Barbastella barbastellus) was the most predominant species, with 31,6% of the captures. Although the relative low number of specimens captured, the species composition and their conservation status were significant due to the presence of Critical Endangered species (Rhinolophus euryale and Myotis blythii), Vulnerable species (Rhinolophus ferrumequinun, Rhinolophus hipposideros, Myotis myotis, Myotis escalerai and Miniopterus schreibersii) and species with Data Deficient (Barbastella barbastellus and Plecotus auritus). The peak of the nocturnal activity was 3-4 hours after sunset, with statistically significant differences between males and females in the third hour after sunset (P=0,002). In total, 75,9% of the specimens captured were males, representing a sex ratio of 3♂♂:1♀♀. In the specific case of B. barbastellus the ratio was of 2:1. The peak of captures between males and females was different along time, with females arriving later to the mine. This behavior was also verified to B. barbastellus. The differences regarding Body Condition Index (BCI) between sexes in B. barbastellus were statistically different, with females presenting higher BCI than males (P=0,015). Undoubtedly, the conservation value of “swarming” sites is of special concern for bats management strategies, especially when used by species such as B. barbastellus, characterized by high level of philopatry within their populations.

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