Egoitz Salsamendi

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.

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.

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.

Detection of rhabdovirus viral RNA in oropharyngeal swabs and ectoparasites of spanish bats

Rhabdoviruses infect a variety of hosts, including mammals, birds, reptiles, fish, insects and plants. As bats are the natural host for most members of the genus Lyssavirus, the specificity of the amplification methods used for active surveillance is usually restricted to lyssaviruses. However, the presence of other rhabdoviruses in bats has also been reported. In order to broaden the scope of such methods, a new RT-PCR, able to detect a diverse range of rhabdoviruses, was designed. The method detected 81 of 86 different rhabdoviruses. In total, 1488 oropharyngeal bat swabs and 38 nycteribiid samples were analysed, and 17 unique rhabdovirus-related sequences were detected. Phylogenetic analysis suggested that those sequences detected in bats did not constitute a monophyletic group, even when originating from the same bat species. However, all of the sequences detected in nycteribiids and one sequence obtained from a bat did constitute a monophyletic group with Drosophila melanogaster sigma rhabdovirus.

Highly diversified coronaviruses in neotropical bats

Bats host a broad diversity of coronaviruses (CoVs), including close relatives of human pathogens. There is only limited data on neotropical bat CoVs. We analysed faecal, blood and intestine specimens from 1562 bats sampled in Costa Rica, Panama, Ecuador and Brazil for CoVs by broad-range PCR. CoV RNA was detected in 50 bats representing nine different species, both frugivorous and insectivorous. These bat CoVs were unrelated to known human or animal pathogens, indicating an absence of recent zoonotic spill-over events. Based on RNA-dependent RNA polymerase (RdRp)-based grouping units (RGUs) as a surrogate for CoV species identification, the 50 viruses represented five different alphacoronavirus RGUs and two betacoronavirus RGUs. Closely related alphacoronaviruses were detected in Carollia perspicillata and C. brevicauda across a geographical distance exceeding 5600 km. Our study expands the knowledge on CoV diversity in neotropical bats and emphasizes the association of distinct CoVs and bat host genera.

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.

Foraging Ecology in Mehely's Horseshoe Bats: Influence of Habitat Structure and Water Availability

The climate in Mediterranean ecosystems is characterised by aestival hot temperatures and water shortages which may affect the behaviour of bats living in these environments. We evaluated the influence of habitat type, habitat structure, and water availability on the foraging behaviour of the Mehelys horseshoe bats (Rhinolophus mehelyi) using classification and regression tree (CART) analysis. Twenty-five individuals were successively radio-tracked during May and June in two colonies (Marias and Aurora) of south-western Spain. Twelve females were tracked in Marias and 13 males in Aurora. Both localities differed in the availability of habitat types: in Marias savannah-like oak woodland dominated the landscape (81% of the study area), whereas in Aurora pasture were dominant (64% of the area). Rhinolophus mehelyi always foraged in woodland; preferentially in cluttered spaces, but also in less-cluttered/more-open ones, while open spaces were completely avoided. Bats foraged close to water bodies, preferentially at distances below 500 m, where they may readily have access to drinking water or may encounter higher insect abundances. The similarity between sexes on the preferences of habitat structure and distance to water suggest that the disparity in the habitat types used by males in Aurora and females in Marias may be due to local availability. Riparian forest is an important habitat for foraging and commuting, and should be scrupulously protected. Conservation strategies should also include the protection of woodland of diverse structure and linear landscape elements. We recommend the creation of water bodies in woodlands to enhance the suitability of foraging sites that might be underused.

Geoffroy's bat, Myotis emarginatus, preys preferentially on spiders in multistratified dense habitats: a study of foraging bats in the Mediterranean

Abstract. In a Geoffroys bat Myotis emarginatus colony in central Iberia, we investigated the foraging behaviour of six lactating females by means of radio-tracking and the diet of 23 individuals by faecal analysis. The bats preferred to forage mainly in pine plantations, riparian woodland, and scrubland, whereas native dehesa (a loose semi-natural oak Quercus rotundifolia and Q. suber woodland) was not exploited as expected. By far the most important prey type for this bat in the Mediterranean were spiders. We conclude that Geoffroys bat prefers to forage in multistratified dense habitats, even if these include nonnative plantations. The vertical structuring and especially high cover, along with the combination of both parameters are important for this highly manoeuvrable, clutter-tolerant bat. This is valid even when the vertical component is much reduced as occurs in scrubland, in the first succession steps to woodland creation, and in degraded conditions. Under such circumstances, aerial weaving spiders might be detected and captured when lying in their webs. It is likely that dehesa is too loosely wooded to offer suitable characteristics for orb-weaving aerial spiders to build webs, and thus it may not be as attractive for M. emarginatus as more dense habitats.

Hierarchical patch choice by an insectivorous bat through prey availability components

Food availability does not only refer to the abundance of edible items; accessibility and detectability of food are also essential components of the availability concept. Constraints imposed by a habitat’s physical structure on the accessibility and detectability of food have been seldom treated simultaneously to the abundance of prey at the foraging patch level in observational studies. We designed a research that allowed decoupling the effects of microhabitat structure and prey abundance on foraging patch selection of the trawling insectivorous long-fingered bat (Myotis capaccinii). The use of different patches of river was surveyed by radiotelemetry during three periods of the bat’s annual cycle, and prey abundance was accordingly measured in and out of the hunting grounds of the tracked bats by insect traps emulating the species’ foraging. Bats preferentially used river stretches characterised by an open course and smooth water surfaces, i.e. they used the most suitable patches in terms of prey accessibility and detectability, respectively. In addition, prey abundance in the selected river stretches was higher than in others where bat activity was not recorded, although the latter also offered good access and prey detection possibilities. Bats also shifted foraging stretches seasonally, likely following the spatiotemporal dynamics of prey production over the watershed. We suggest that the decisions of bats during the patch choice process fitted a hierarchical sequence driven first by the species’ morphological specialisations and ability to hunt in unobstructed spaces, then by the detectability of prey on water surfaces and, finally, by the relative abundance of prey.