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Prey selection by Rhinolophus hipposideros (Chiroptera, Rhinolophidae) in a modified forest in Southwest Europe

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Lino A. , Fonseca C. , Goiti U. , Pereira M. J. R.

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nr 1

EN

The knowledge of the diet of endangered species provides information on ecology and behaviour that is essential for the adequate management of their populations. Population decline may be indeed associated with diet specialization and unavailability of feeding resources, especially in modified environments. We studied the diet and prey selection of Rhinolophus hipposideros Borkhausen, 1797 in a modified Mediterranean landscape in Portugal, where this species is classified as vulnerable. Diet composition was evaluated by analyzing faecal pellets collected in a breeding colony of R. hipposideros, and the available arthropods were sampled using a light trap set outside the roost. The most consumed prey were Lepidoptera, Tipulidae (Diptera), Hymenoptera, Diptera and Neuroptera. Arthropod diversity remained fairly constant in the diet, but not in terms of prey availability. Our results show that R. hipposideros is a generalist species that feeds on a great number of prey species. However, our data suggest that, within the broad dietary niche, R. hipposideros is not opportunistic, actively selecting Diptera as a preferred food item. Despite the marked differences in foraging habitats, our results are closely match to those of studies done in Western and Central Europe, suggesting that R. hipposideros feeds on similar taxa all across Europe. However, as many studies indicate, this species selects broadleaved woodlands and riparian vegetation to forage, so conservation measures should take into account the protection of native forest and the maintenance of forest corridors among them, as R. hipposideros seems to avoid crossing open areas.

2

Availability of Food for frugivorous bats in lowland Amazonia: The influence of flooding and river banks

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Marques J. T. , Pereira M. J. R. , Palmeirim J. M.

Acta Chiropterologica

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2012

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tom 14

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nr 1

EN

In Neotropical forests fruits are key resources for a great diversity of vertebrates, including many frugivorous bats, but little is known about the factors that determine their availability. We studied forest inundation and river banks as determinants of the spatial variation in the availability of fruits for bats in lowland Amazonia. We sampled the bat assemblage composition, fruit availability, and bat diet in terra firme upland forest and in two types of flooded forest — várzea and igapó. Two distinct frugivore bat guilds were found in both terra firme and flooded forests: (1) canopy frugivores, feeding mainly on Ficus and Cecropia, and (2) understorey frugivores that feed mainly on Vismia and Piper. Fruits consumed by the canopy guild were more abundant in the flooded forests — particularly in the nutrient-rich várzea, but those dominating the understory guild diet were most abundant in terra firme. Availability of both fruit genera most consumed by the canopy guild was greater along river banks than in the forest matrix. For the understory guild, the greater abundance of Vismia along river banks was compensated for by a higher availability of Piper in the matrix. In conclusion, both factors influence the availability of fruits, although differently for the canopy and understory guilds. The resulting differences in fruit abundance may explain variations in bat assemblages of the different forest types. River banks play a particularly important role in providing food for bats of both guilds, but are under particularly heavy human pressure.

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Prey selection by Myotis myotis (Vespertilionidae) in a Mediterranean region

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Pereira M. J. R. , Rebelo H. , Rainho A. , Palmeirim J. M.

Acta Chiropterologica

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2002

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tom 04

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nr 2

EN

Seasonal variations in the diet composition and prey selection by Myotis myotis were studied in a Mediterranean region dominated by open stone oak woodlands, olive groves, and cereal steppes. The diet and food abundance were determined by faecal analysis and pitfall trapping, respectively. Overall, the diet (expressed as % frequency) was dominated by carabid beetles (Carabidae, 52%), crickets (Gryllidae, 43%), and spiders (Arachnida, 34%). Food was far more abundant in the spring than in the summer and autumn. The dietary composition varied significantly throughout the year. In the spring, it was dominated by carabids and crickets, and in the summer by spiders. These were then replaced by carabids, which became the most frequently eaten prey in autumn. The spring-summer switch to spiders coincided with a marked drop in food abundance. Some of the temporal variations in bats’ diet can be explained by parallel changes in prey abundance. In comparison to central European populations, our Mediterranean colony of M. myotis consumed much more crickets and spiders, which was balanced with a lower use of carabid beetles. Prey selection was tested using logistic regression models. The results suggest that, although carabids are the most consumed, crickets are preferred. Spiders seem to represent mostly a complement preyed upon at times of lower food abundance. It is not clear if the preference for crickets is simply due to their great conspicuousness, or to the choice based on energetic rewards or taste. Overall, our results are consistent with the predictions of the optimal foraging theory.