Resumo Os morcegos Phyllostomidae apresentam diferentes padrões reprodutivos no Neotropico e a estratégia adotada depende do clima regional. Neste trabalho nós estudamos a biologia reprodutiva de A. fimbriatus no Brasil, na região que determina o limite sul de sua distribuição geográfica, onde não há estação chuvosa e o clima é caracterizado por variações na temperatura e fotoperíodo. Nós examinamos 129 fêmeas de A. fimbriatus e utilizamos procedimentos histológicos, quando necessário, para classificar as fêmeas como prenhe ao longo dos meses. As fêmeas exibem um longo período reprodutivo e estão grávidas de junho até fevereiro. Nossos resultados mostram que as fêmeas de A. fimbriatus apresentam uma estratégia reprodutiva que é dependente da sazonalidade com os nascimentos ocorrendo quando os dias são mais longos e a temperatura é maior (primavera e verão), no limite sul de sua distribuição geográfica.

Abstract Bats of the Phyllostomidae family exhibit different reproductive patterns in Neotropical regions and the strategy adopted depends on the regional climate. Here we studied the reproductive biology of Artibeus fimbriatus at the southern limit of their distribution in Brazil. This region has no rainy season, and the climate is characterized by high temperatures and variable photoperiods. We examined 129 A. fimbriatus females over several months, and used histological procedures where necessary in order to determine whether bats were pregnant. Females exhibited a long reproductive period and were pregnant from June until February. The reproduction events were found to be dependent on the photoperiod, but independent of annual accumulated precipitation. Our results show that at the southern limit of their distribution, A. fimbriatus exhibit seasonal-dependent reproductive patterns, with parturition events occurring during spring and summer, in which the days are longer and temperature is warmer.

Chrotopterus auritus (Peters, 1856) (Phyllostomidae, Chiroptera) é a única espécie carnívora de morcego registrada para o estado do Rio Grande do Sul. Neste trabalho a dieta e o uso de abrigos diurnos foram estudados. Sete cavernas foram monitoradas, a cada quinze dias, no período de maio/2002 a abril/2003, nos municípios de Machadinho e Barracáo, Rio Grande do Sul, Brasil. A dieta foi estudada por meio da análise das fezes (n=67) e restos alimentares (n=63) coletados quinzenalmente em cada abrigo. Mamíferos, aves e artrópodes constituíram a base alimentar de C. auritus. O resultado do exame das fezes não evidencia a preferência por presas como mamíferos, aves ou artrópodes, pois não há diferença significativa na freqüéncia de ocorréncia dos mesmos. O mesmo resultado foi obtido na comparacáo dos itens alimentares constantes ñas fezes entre as estacóes do ano. Dentre os mamíferos consumidos predominaram os roedores; dentre as aves, os passeriformes e dentre os artrópodes, os coleópteros. Frutos foram consumidos em menor freqüéncia, cerca de 5.9% do total das amostras. C. auritus esteve presente durante todo o período de estudo em cavernas, variando em número de indivíduos e abrigos ocupados. Observouse coabitacáo com Desmodus rotundus e Myotis nigricans.

Chrotopterus auritus (Peters, 1856) (Phyllostomidae, Chiroptera) is the only species of carnivorous bat recorded in Rio Grande do Sul state. In this work we identified the diet Ítems and observed their spatial distribution within roosting sites at daytime. We monitored seven caves, every fifteen days, from may/2002 to april/2003, in Machadinho and Barracáo counties, Rio Grande do Sul state, Brazil. The diet was inferred from fecal samples (n=67) and food remains (n=63). Mammals, birds and arthropods, composed the diet of the C. auritus. C. auritus did not show preference by food Ítems, such as mammals, birds or arthropods, because there were no significant differences among them in fecal samples. The result was similar when comparing the presence of these Ítems between seasons. Rodents, Passeriformes and Coleopterans were the prevailing Ítems in the diet of the C. auritus. Fruits were consumed occasionally, about 5.9% of the total of the samples. C. auritus was, during the whole study period, present in the studied caves, varying in number of individuáis and shelters. Cohabitation with Desmodus rotundus and Myotis nigricans was observed.

A study has been made on the geographical distribution and comparative external and cranial morphological analysis of Artibeus lituratus Olfers, 1818 and Artibeus fimbriatus Gray, 1838 (Chiroptera, Phyllostomidae) in the state of Rio Grande do Sul, Brazil. A. lituratus and A. fimbriatus were found to be sympatric in the state north to the "Planície Costeira", in the "Depressão Central", in the hillsides of "Serra Geral", and in the northern region of the state, areas previously covered by forests. The southernmost point for Artibeus Leach, 1821 distribution is 30º South, and A. lituratus and A. fimbriatus are the two species found more to the south. The two species studied do not show sexual dimorphism as to external characteristics. Cranial measurements revealed significant differences between males and females of A. lituratus in mandible length, which was significantly larger in females(p<5%), and between males and females of A. fimbriatus, in the length of the set of lower teeth and in the external width between the cingula of canine teeth, which were significantly larger in males (p<5%). No further morphological cranial differences were found between genders of both species. A. lituratus and A. fimbriatus can be externally distinguished by size, for A. lituratus is larger than A. fimbriatus as concerns all external dimensions analysed except for the tibia length (p<5%). The two species can also be differentiated by pelage colour, hair length, and facial stripes appearance. In the skull, a number of differences were found in rostrum format, in the developmental degree of supraorbital and post-orbital crests and pre-orbital and post-orbital processes, and in several cranial dimensions analysed.

Study of 179 specimens of Molossus molossus in Ceará, Brazil, showed morphological and functional ovarian asymmetry in adult females, with the right side more developed. Blastocyst implantation occurred also in the right uterine horn. Active male testicles were bigger (x = 5,38mm) than inactive ones (x = 3,25mm). Pregnancy with subsequent offspring was found in March-April and November, during the wet season.