Urtzi Goiti

Habitat selection in sympatric Rhinolophus mehelyi and R. euryale (Mammalia: Chiroptera)

Habitat selection was studied in two rhinolophid (Chiroptera) species,Rhinolophusmehelyi andR.euryale, breeding in the same roost in south-west Spain. The first analysis of habitat selection by R. mehelyi is provided, and the hypothesis explored that despite their close relatedness, in sympatry the two bat species showed different habitat preferences. For both species, the least preferred habitats were open habitats such as scrubland, grassland and arable land. As found elsewhere, R. euryale preferred broadleaved woodland. In addition, R. mehelyi also foraged in habitats characterized by loose trees, such as the ‘dehesa’, a semi-natural oak savanna. The progressive disappearance of the dehesa, jeopardized by land-use change, may not harm R. euryale, but could represent a threat to R. mehelyi, which would then be restricted to dense woodland, possibly competing with other bat species, includingR.euryale. To conserve both species, the maintenance of a variety of wooded habitats of differing density is recommended.

Influence of Habitat on the Foraging Behaviour of the Mediterranean Horseshoe Bat, Rhinolophus euryale

In a previous study on habitat use by Rhinolophus euryale in an Atlantic area (Northern Iberian Peninsula), this bat species foraged exclusively in woodland, including both native deciduous woodland and exotic plantations. As the study was carried out in a landscape that was profoundly altered by industrial forestry, we predicted that in a better preserved landscape this species would select smaller feeding areas located at closer distances from the roost, according to the optimal foraging theory, and would use almost exclusively the preferred habitat, i.e., native deciduous woodland. To test these hypotheses, we radiotracked 14 R. euryale from the largest known breeding colony of northern Iberian Peninsula and determined their habitat selection, spatial foraging pattern, and hunting behaviour. Our predictions on habitat selection, as well as on the foraging site size and on commuting range were confirmed. Rhinolophus euryale used almost exclusively native deciduous woodland, and hedgerows were positively selected. We suggest that the richness of tree species in hedgerows provides a high prey availability sustained in time and space. Our findings show that habitat disturbance constitutes a major cause of decline for R. euryale in the study area.

FORAGING BY MEDITERRANEAN HORSESHOE BATS (RHINOLOPHUS EURYALE) IN RELATION TO PREY DISTRIBUTION AND EDGE HABITAT

Abstract We studied the effect of habitat type and prey availability on the foraging decisions of the Mediterranean horseshoe bat (Rhinolophus euryale), a species specialized for cluttered environments. We modeled seasonal habitat selection using radiotelemetry in relation to prey availability in a heterogeneous landscape, determined seasonal diet and prey selection, and used geographic information system data to characterize the landscape surrounding 10 breeding colonies in order to assess the radiotracking results at the population level. Although R. euryale typically has been associated with woodland, our results suggest that the existence of edge habitat, created by semicluttered structures such as hedgerows and woodland edges, was a significant factor in the choice of foraging areas by these bats. Edge habitat was associated with meadows and pastures, creating a landscape highly suited to moths, the preferred prey of R. euryale. In the study area, however, moths were evenly distributed among habitat types; therefore, distribution of moths cannot explain the preference of these bats for semicluttered habitats. The results of our study are consistent with the presumed origin of R. euryale in an edge-rich ecosystem (i.e., the savannahs of northern Africa) and establish a new paradigm for how this species uses habitat. This new paradigm, which might also apply to other members of the genus in Europe, should prompt reconsideration of the presumed habitat requirements for this species, and should be incorporated into the conservation policies for the Mediterranean horseshoe bat.

Diet and prey selection in the Mediterranean horseshoe bat Rhinolophus euryale (Chiroptera, Rhinolophidae) during the pre-breeding season

In May 2001 we collected droppings of Rhinolophus euryale from a colony located in the Basque Country (souhtwestern Europe). Simultaneously, we used Malaise traps to determine prey availability in different habitats, weighting it according to the habitat use of bats. Prey categories found in droppings were then compared to availability to perform the selection analysis. The main consumed prey were by far small lepidopterans (5-11 mm long), followed by tipulids, and scarabaeid beetles (entirely Rhizotrogus sp.). Moths and beetles were selected positively, whereas the other categories were underrepresented in the diet. These results suggest the importance of small moths in the pre-breeding diet of this species, although other items might seasonally play an important role.

Seasonal foraging by Rhinolophus euryale (Rhinolophidae) in an Atlantic rural landscape in northern Iberian Peninsula

ABSTRACT We investigated the foraging behaviour of the Mediterranean horseshoe bat (Rhinolophus euryale) in an Atlantic mosaic-like landscape consisting predominantly of meadows and broadleaved tree structures, and containing the largest known breeding colony in northern Iberian Peninsula. We radio-tracked a total of 46 individuals during pre-breeding, lactation and post-lactation periods. Bats were divided into different classes based on season, sex, reproductive condition or age. Significant differences between classes were apparent in the distances travelled to foraging areas. During pre-breeding foraging occurred on average within 1.3 km, and at most 4.2 km from the roost. Contrary to our predictions, lactating females extended mean foraging distances to 4.3 km, and covered the widest range with a maximum individual distance from the roost of 9.2 km. Males in the same period foraged closer (mean 1.9 km), but with lower fidelity to the main roost. The foraging distances of adult bats during post-lactation did not differ from that of lactating females (mean 4.6 km). Newly volant juveniles flew on average 2.6 km, though showed a varied behaviour. No seasonal effect was found on the size of individual foraging home ranges, as great variation was recorded within all groups. We conclude that the increase in foraging distances is the consequence of higher density as colony size increased by 55% from pre-breeding into the lactation period on. Our results show another aspect of the scale of foraging movements of R. euryale and highlight the need to take these into account when formulating conservation policy, especially during such crucial periods as lactation and juvenile dispersal.

Evidences of piscivory by Myotis capaccinii (Bonaparte, 1837) in Southern Iberian Peninsula

Faeces of Myotis capaccinii were collected from four individuals netted in a spring colony in Denia, Alicante (south-eastern Iberian Peninsula). Faecal analysis revealed the presence of fish scales and bones in all droppings examined (two pellets for each individual, i.e., n = 8), with volumes ranging 6-82.5 % of prey remains. Remains of Diptera and Trichoptera were also found. These data provide the first evidence of piscivory in M. capaccinii, and reveal that this may be an important feeding behaviour in this species, at least locally and/or seasonally.

Diet and prey selection in Kuhl’s pipistrellePipistrellus kuhlii (Chiroptera: Vespertilionidae) in south-western Europe

The trophic ecology of Kuhl’s pipistrellePipistrellus kuhlii (Kuhl, 1817) was investigated monthly from May to October 1999. Nine insect and two arachnid orders were identified in faeces and classified in 24 different categories. The most frequently occurring prey categories were Culicidae, Lepidoptera, Chironomidae/Ceratopogonidae, Hymenoptera, unidentified Brachycera, Tipulidae and unidentified Coleoptera in decreasing order. Other categories exhibited seasonal importance, such as the coleopteranRhizotrogus sp. Prey availability was evaluated monthly using Malaise traps in known feeding areas. Bats preyed selectively through a temporarily changing pattern. Some taxa constituted an important part of the diet and were positively selected either monthly or in most of the months. Many of them were the largest prey featuring in the diet and changes of their relative profitability across time would determine their selection index. The small size of some prey categories as well asP.kuhlii’s morphofunctional constraints relative to flight and echolocation could explain their underexploitation or rejection. Our results suggest thatP. kuhlii could be regarded as a ‘selective opportunist’ species.

Presence of Plecotus macrobullaris (Chiroptera: Vespertilionidae) in the Pyrenees

In July 2002, several bats of the genus Plecotus (Geoffroy, 1818) were captured at two localities of ‘Ordesa y Monte Perdido’ National Park (Central Pyrenees, Spain). They showed external characters that appeared intermediate between those of P. auritus and P. austriacus. Morphometric and genetic analysis have revealed that these long-eared bats should be ascribed to the recently recognized species P. macrobullaris. This study extends the distribution of this new species, whose western limit was considered, until now, to lie in the Alps, and adds a new mammal species to the Iberian fauna.

Fishing behaviour in the long-fingered bat Myotis capaccinii (Bonaparte, 1837): an experimental approach

Abstract To study the fishing behaviour of Myotis capaccinii, we performed an experiment in a flight tent containing an artificial pond. We recorded the behaviour of two groups of bats — eight individuals from two different roosts — using IR video camcorders and ultrasound detectors, and evaluated diet by analyzing faeces. Nightly, increasing amounts of fish were released in the pond. Our data show that M. capaccinii is able to exhibit fishing behaviour when fish occur in high densities in shallow waters, gaffing live fish from the water using their hind feet. They were attracted neither by dead fish floating, nor by ripples made by fishes feeding on the water surface. Bats showed a specific fishing behaviour with two main foraging patterns: A) long series of circular flights, skimming along the water and dipping in softly twice or three times in each roundabout; B) long figure-eight loops with bats flying faster and higher, swooping down on the centre of the pond, where they snapped their hind feet hard into the water. Compared with the echolocation calls used to catch insects from the waters surface in the wild, terminal buzzes were incomplete during the dips made to fish. Buzz II were always lacking, and buzz I had much longer inter-pulse intervals. This suggests that they were not pursuing specific targets but dipping randomly. We propose a scenario in which fishing behaviour occurs in the wild, linked to the seasonal drought of small ponds, marshes, or channels where large numbers of small fish become readily available and thus a profitable resource.

What mechanism of niche segregation allows the coexistence of sympatric sibling rhinolophid bats

IntroductionOur purpose was to assess how pairs of sibling horseshoe bats coexists when their morphology and echolocation are almost identical. We collected data on echolocation, wing morphology, diet, and habitat use of sympatric Rhinolophus mehelyi and R. euryale. We compared our results with literature data collected in allopatry with similar protocols and at the same time of the year (breeding season).ResultsEcholocation frequencies recorded in sympatry for R. mehelyi (mean = 106.8 kHz) and R. euryale (105.1 kHz) were similar to those reported in allopatry (R. mehelyi 105–111 kHz; R. euryale 101–109 kHz). Wing parameters were larger in R. mehelyi than R. euryale for both sympatric and allopatric conditions. Moths constitute the bulk of the diet of both species in sympatry and allopatry, with minor variation in the amounts of other prey. There were no inter-specific differences in the use of foraging habitats in allopatry in terms of structural complexity, however we found inter-specific differences between sympatric populations: R. mehelyi foraged in less complex habitats. The subtle inter-specific differences in echolocation frequency seems to be unlikely to facilitate dietary niche partitioning; overall divergences observed in diet may be explained as a consequence of differential prey availability among foraging habitats. Inter-specific differences in the use of foraging habitats in sympatry seems to be the main dimension for niche partitioning between R. mehelyi and R. euryale, probably due to letter differences in wing morphology.ConclusionsCoexistence between sympatric sibling horseshoe bats is likely allowed by a displacement in spatial niche dimension, presumably due to the wing morphology of each species, and shifts the niche domains that minimise competition. Effective measures for conservation of sibling/similar horseshoe bats should guarantee structural diversity of foraging habitats.