Bats in a fragmented landscape: Species composition, diversity and habitat interactions in savannas of Santarém, Central Amazonia, Brazil

Species response to forest fragmentation may strongly vary according to ecological requirements, shape, spatial configuration and connectivity of fragments, and the structure of the surrounding matrix. Bats are natural candidates for studies on forest fragmentation. However, the conclusions of such studies are often contradictory. We present the results of a study on the effects of forest fragmentation on bat communities in Alter do Chão, Santarém area, in Central Amazonia, Brazil, an area composed by forests and fragments surrounded by savanna-like vegetation. We compared the species composition between habitats, tested the effect of size, shape and density of trees of forested areas on the presence species and their relative frequency of captures, and investigated the savannas as an ecological barrier for the dispersion of bats. With an effort of 5678 mistnet-hours, we captured 3740 bats (64 species). Multidimensional Scaling indicated no strong separation between the habitats sampled, however, savanna sites were grouped distinctly of fragments and forest sites. Multiple linear regressions indicated no significant correlation between the number of bat species recorded and the size, shape or tree density in forest sites and fragments. There was a significant correlation between the number of captures and the variables tested, explained by the shape of the sites, but not by size or tree density. In general, sites with bigger shape indices had fewer captures. Ten of the 20 most captured species showed no significant difference between the three habitats. The bat communities in Alter do Chão were not strongly affected by forest fragmentation, and the savannas did not appear to act as an ecological barrier to bats.     

Sex differences in population genetics, home range size and habitat use of the parti-colored bat (Vespertilio murinus, Linnaeus 1758) in Switzerland and their consequences for conservation

When habitats are declining, niche segregation by demographic groups, such as the two sexes, can have a profound impact on the extinction risk of a species as a whole. Thus, differences in the requirements of demographic groups are of importance in conservation. We combined behavioural and genetic data to investigate whether the sexually segregated parti-colored bat (Vespertilio murinus) exhibits sex-specific niche partitioning. We use our data to evaluate implications for conservation of this potentially vulnerable species in Switzerland, the western boundary of its range. Using radio-telemetry, we found sex-specific differences in habitat use. Foraging females strongly relied on lakes while foraging males displayed more flexibility in their habitat use. Moreover, males covered significantly larger foraging areas than females. Sequencing 341 base pairs of the mitochondrial D-loop of 247 individuals revealed sex-specific differences in the genetic structure of colonies, but no such difference was observed for three nuclear micro-satellite markers. We found high mtDNA diversity in two Swiss male colonies and one German female colony, but low mtDNA diversity in two Swiss female colonies. Our genetic data suggest that considerable gene flow occurs via male dispersal and mating. At the same time immigration of females into the existing female colonies in Switzerland is rare compared to the immigration of new males into male colonies. Since we found the sexes in Vespertilio murinus to differ markedly in their ecology, population genetics, and behaviour, we conclude that sex-specific conservation plans are required to protect this species efficiently.     

Swarming of bats at underground sites in Britain—implications for conservation

We investigated the extent of visitation of underground sites during late summer and autumn (‘swarming’) by bats. Bats were captured at eight cave, mine and tunnel sites in southern England over 6 years (1995-2000). A total of 3077 bats representing 11 of Britain's 16 species was caught. Myotis bats predominated in autumn. At some sites these are rarely seen during winter hibernation counts. Myotis nattereri and M. daubentonii were most common. However, species composition changed seasonally. At one site, M. brandtii dominated early in the season and at all sites peak activity of M. daubentonii was earlier than in M. nattereri. Relatively high numbers of internationally vulnerable species such as M. bechsteinii and Barbastella barbastellus were recorded. There was a strong male bias in captures of swarming species. Swarming probably has an important reproductive function, most males are reproductively active at this time and such sites may be important for outbreeding. Due to this and the large number of individuals and species concerned, the conservation of ‘swarming sites’ is vitally important. Clearly swarming sites merit special consideration in conservation management strategies for cave-dwelling bats.     

An Ecophysiological Study of the Meiofauna of the Swartkops Estuary

Environmental correlations with mean, as well as seasonal, distribution and abundance of the meiofauna in two exposed beaches in the Swartkops Estuary, near Port Elizabeth, were elucidated. Population densities showed a direct relationship with particle size. Consequent on this, oxygen appeared to be the controlling factor although desiccation played a role in the intertidal distribution of meiofauna in sandy areas. Seasonal fluctuations in numbers were characterized by peaks occurring in spring and autumn. Variations of temperature and oxygen were found to be responsible for this pattern. The presence of the sand prawn Callianassa kraussi affected both vertical penetration and seasonal fluctuation of the meiofauna. Since fluctuation in nitrogen and chlorophyll a content of the substrate bore little relationship to the fluctuation of the meiofauna, it is concluded that food is not limiting in these areas. Biomass determinations revealed that nematodes, which were the dominant taxon, weighed 0,42 μg individual mean ash-free dry mass and harpacticoid copepods 0,47 μg. On this basis the standing crop biomass was 0,40 μm² in the sandy areas and 0,07 g/m² in the muddier areas, both to a depth of 20 cm.     

Book Review

Agricultural landscapes are typically associated with a decreased biodiversity, particularly when they extend across large spatial scales. Despite the fact that some African bat species seem to provide essential ecosystem services across landscapes, we only have a limited understanding of how intensive agricultural practices influence bat communities. This study investigated the effects of sugarcane monoculture on the composition of both bat species and functional groups across a conservation-agricultural matrix. Specifically, we wanted to understand changes in the bat communities within savannas and sugarcane plantations. We categorised bats into broad foraging (functional) groups based on their echolocation call structure: open-air; clutter-edge; and, clutter. To measure bat activity, we established twelve 25 ha grids randomly located in savanna and sugarcane vegetation. Within each grid we placed nine acoustic detectors, in 3 × 3 formation, 250 m apart; totalling 54 plots in each land use. We sampled each plot over four nights (two in the wet season and two in the dry season) during a one-year period. We did not observe a significant difference in species richness between savanna and sugarcane. However, there was a difference in functional group composition. Sugarcane negatively affected clutter foragers; this group was practically absent here despite occurring within neighbouring savannas. We observed distinct patterns of seasonality in bat activity, with activity of all functional groups being reduced in the dry season.     

Bats adjust temporal parameters of echolocation pulses but not those of communication calls in response to traffic noise

Many studies based on acute short‐term noise exposure have demonstrated that animals can adjust their vocalizations in response to ambient noise. However, the effects of chronic noise over a relatively long time scale of multiple days remain largely unclear. Bats rely mainly on acoustic signals for perception of environmental and social communication. Nearly all previous studies on noise‐induced vocal adjustments have focused on echolocation pulse sounds. Relatively little is known regarding the effects of noise on social communication calls. Here, we examined the dynamic changes in the temporal parameters of echolocation and communication vocalizations of Vespertilio sinensis when exposed to traffic noise over multiple days. We found that the bats started to modify their echolocation vocalizations on the fourth day of noise exposure, with an increase of 42–91% in the total number of pulse sequences per day. Under noisy conditions, the number of pulses within a pulse sequence decreased by an average of 17.2%, resulting in a significantly slower number of pulses/sequence (P < 0.001). However, there was little change in the duration of a pulse sequence. These parameters were not significantly adjusted in most communication vocalizations under the noise condition (all P > 0.05), except that the duration decreased and the number of syllables/sequences increased in 1 type of communicative vocalization (P < 0.05). This study suggests that bats routinely adjust temporal parameters of echolocation but rarely of communication vocalizations in response to noise condition.     

广东南岭自然保护区翼手类物种资源调查

2009年9月,对南岭自然保护区翼手类物种多样性进行了调查。采集蝙蝠标本9种36号,其中西南鼠耳蝠和中管鼻蝠为广东省蝙蝠新纪录。结合以往调查资料,得出该保护区共有翼手类25种,隶属5科12属,其物种多样性十分丰富。     

翼手目保护生物学研究中的MHC分子标记

主要组织相容性复合体(major histocompatibility complex,MHC)是脊椎动物基因组中多态性最高的基因座位之一,是动物免疫相关基因。MHC进化机制主要是病原体选择机制,MHC多态性能够反映动物种群生活史的适应性进化和生存能力,MHC基因作为非中性分子标记,在翼手目保护生物学研究中具有重要意义和应用前景。     

The distribution of cave-dwelling bats and conservation status of underground habitats in Northwestern Turkey

The distribution and abundance of cave-dwelling bats were investigated in the Thrace region of northwest Turkey. Data were collected in two periods, January-March and April-May 2001, from 32 underground sites, 25 of which had not been surveyed previously. Approximately 76,000 bats representing 13 species were recorded. The most abundant species were Miniopterus schreibersii, Rhinolophus euryale, Myotis myotis/blythii, Myotis capaccinii, and Rhinolophus ferrumequinum. The roosts were evaluated for their conservation importance. The most important sites in Turkish Thrace are Dupnisa and Koyunbaba. The Dupnisa Cave serves as a hibernaculum to approximately 28,000 bats representing five species. The Koyunbaba Cave is a nursery roost to approximately 23,000 bats of six species. Presently, none of the caves in the region has adequate protection and some bat populations are under serious threat.     

Bartonellae are Prevalent and Diverse in Costa Rican Bats and Bat Flies

Species in the bacterial genus, Bartonella, can cause disease in both humans and animals. Previous reports of Bartonella in bats and ectoparasitic bat flies suggest that bats could serve as mammalian hosts and bat flies as arthropod vectors. We compared the prevalence and genetic similarity of bartonellae in individual Costa Rican bats and their bat flies using molecular and sequencing methods targeting the citrate synthase gene (gltA). Bartonellae were more prevalent in bat flies than in bats, and genetic variants were sometimes, but not always, shared between bats and their bat flies. The detected bartonellae genetic variants were diverse, and some were similar to species known to cause disease in humans and other mammals. The high prevalence and sharing of bartonellae in bat flies and bats support a role for bat flies as a potential vector for Bartonella, while the genetic diversity and similarity to known species suggest that bartonellae could spill over into humans and animals sharing the landscape.