Strategy-switching in the gaffing bat

Foraging in Daubenton's bats Myotis daubentonii , at two altitudinal locations along a river gradient in North Wales was investigated in relation to aerial insect density and to the density of prey on the water surface. Prey capture in Daubenton's bats consisted of aerial hawking, where prey was taken in the air, and trawling, where bats gaffed invertebrates from the water surface. Aerial hawking accounted for 86% of all prey capture attempts, despite aerial insect availability falling close to zero for much of the night. Conversely, prey density on the water surface was an order of magnitude higher than aerial prey density and increased through the night due to aquatic invertebrate drift. At the higher altitude site, M. daubentonii switched prey capture strategy to gaffing, possibly to reflect this change in prey availability on the water's surface, but at the lower altitude site, they maintained aerial hawking as the preferred strategy. The switch to gaffing may be inhibited by the significant downstream accumulation of large numbers of inedible exuviae of caddis flies, Trichoptera, at the low-altitude site, which form both acoustic clutter and increase the probability of capturing inedible prey, making foraging less efficient. These small altitudinal differences in foraging strategy should be factored into the design of future altitudinal bat foraging studies and if found to be a widespread strategy, taken into consideration by conservation planners when reviewing the habitat requirements of Daubenton's bats in river valleys within the United Kingdom.     

毛腿鼠耳蝠(Myotis fimbriarus)血液的研究

本文对毛腿鼠耳蝠血液的有形成分和百分比等项正常数值进行了测定,并对各类血细胞的主要形态作了描述。 所测的各项数值与前人报道的数据比较,其红细胞数目和血红素含量都高于同属的其他种,也较其他哺乳动物为高。毛腿鼠耳蝠与该属有些种类的淋巴细胞数目占全部白细胞的百分数最高,也明显高于其他哺乳动物。     

Mitochondrial DNA (mtDNA) reveals that female Bechstein's bats live in closed societies

We present a microgeographic analysis of mitochondrial DNA (mtDNA) in Bechstein's bats using three sources of control region sequence variability, including a novel mtDNA microsatellite, to assess individual relatedness both within and among 10 maternity colonies. Comparison of marker variability among 268 adult females revealed little genetic variability within each colony. However, most colonies were clearly distinguished by colony-specific mitochondrial haplotypes (total n = 28). Low intracolony variability and strong haplotype segregation among colonies, was reflected by an extraordinary high FST of 0.68, indicating a very low intercolony dispersal rate of approximately one female in five generations. Haplotype distribution among 18 solitary males showed that males frequently disperse between colony locations, indicating the absence of dispersal barriers. Bechstein's bat maternity colonies are thus closed groups that comprise 20-40 females probably belonging to only one or, at most, two matrilines. The genetic population structure of Bechstein's bats is in agreement with the hypothesis that females seek familiar and, at least, partially related cooperation partners for raising their young. Alternatively strong philopatry might reflect the importance of profound roost or habitat knowledge for successful reproduction in female Bechstein's bats.     

Extreme sex-biased dispersal in the communally breeding,nonmigratory Bechstein's bat (Myotis bechsteinii)

Maternity colonies of the communally breeding, nonmigratory Bechstein's bat consist of closely related females that live together with unrelated females, and average colony relatedness is low despite the absence of immigration. We compared the genetic structure of both nuclear and mitochondrial microsatellites in order to quantify sex-specific dispersal rates. More specifically, we aimed at testing whether male dispersal is able to balance the genetic effect of strong (absolute) female philopatry. Absolute female philopatry, indicated by an extreme mitochondrial DNA population differentiation of 96%, was indeed opposed by strong (possibly complete) male dispersal. Based on our knowledge of the biology of Myotis bechsteinii, we conclude that inbreeding avoidance is likely to be the crucial factor driving male dispersal in this species.     

Genetic population structure of Natterer's bats explained by mating at swarming sites and philopatry

During autumn 'swarming', large numbers of temperate bats chase each other in and around underground sites. Swarming has been proposed to be a mating event, allowing interbreeding between bats from otherwise isolated summer colonies. We studied the population structure of the Natterer's bat (Myotis nattereri), a swarming species in northern England, by sampling bats at seven sites in two swarming areas and at 11 summer colonies. Analysis of molecular variance (amova) and genetic assignment analyses showed that the swarming areas (60 km apart) support significantly different populations. A negative correlation was found between the distance of a summer colony from a swarming area and the assignment of bats to that area. High gene diversity was found at all sites (HE = 0.79) suggesting high gene flow. This was supported by a low FST (0.017) among summer colonies and the absence of isolation by distance or substructure among colonies which visit one swarming area. The FST, although low, was significantly different from zero, which could be explained by a combination of female philopatry and male-mediated gene flow through mating at swarming sites with bats from other colonies. Modelling suggested that if effective size of the summer colonies (Ne) was low to moderate (10-30), all mating must occur at the swarming sites to account for the observed FST. If the Ne was higher (50), in addition to random mating during swarming, there may be nonrandom mating at swarming sites or some within-colony mating. Conservation of swarming sites that support potentially large populations is discussed.     

湖南长沙发现霍氏鼠耳蝠

2021年8月分别在湖南省长沙市天心区大托站立交桥底和昭华湘江大桥底捕获2只鼠耳蝠（2♂,标本号211521和211540）,经鉴定为霍氏鼠耳蝠（Myotis horsfieldii）,为湖南省蝙蝠分布新记录物种。本次捕获标本体型中等偏小,前臂长分别为36.1 mm（211521）和33.1 mm（211540）,头体长为44.0 mm和41.2 mm,后足长（10.5 mm和10.4 mm）超过胫骨长（16.4 mm和16.2 mm）的一半,耳屏长（5.1 mm和3.8 mm）不及耳长（12.5 mm和10.0 mm）的一半;头骨狭长,颅全长15.5 mm和15.0 mm,脑颅宽7.8 mm和7.5 mm,颅骨纤弱,额骨处有明显倾斜,脑颅高于上颌骨,颧弓较细。与来自泰国和印度尼西亚的霍氏鼠耳蝠标本相比,前臂长、头体长和尾长测量数据偏小,但头骨测量数据接近。基于Cyt b基因序列的系统发育分析表明,此次捕获的鼠耳蝠标本与霍氏鼠耳蝠聚类在一起,与来自香港的霍氏鼠耳蝠样本遗传距离仅为0.9%,故确定该物种为霍氏鼠耳蝠。标本保存于广东省科学院动物研究所。     

Environmental information from guano palynology of insectivorous bats of the central part of the United States of America

Bat droppings accumulate in caves, and the resultant guano contains a stratigraphic record of the environment analogous to the record from lake sediment and peat. The bats forage at night for insects; they return to the cave during the day to sleep and care for their young. They attach themselves to suitable perches in the cave ceiling, and their excrement accumulates on the floor below. Flying requires a lot of energy, and bats of temperate regions consume large numbers of night-flying insects. In some situations the guano can reach a depth of meters in hundreds to thousands of years, and it has a valuable chronostratigraphy. The bat scats occur as small pellets that represent the non-digestible portion of the animal's diet in the preceding few hours; hence the diet provides information about the time of the year the feeding occurred. Bat guano contains, among other things, insect fragments, hair, pollen, and mineral matter. Night-flying insects do not normally visit flowers for the pollen; many species do not eat during the flying phase of their life cycle, and those that do generally are nectar feeders. Although the insects are not after the pollen, they do fly through a pollen-laden environment, and the pollen and dust adheres to their bodies. The insects essentially act as living traps for airborne debris. The bats also are furry pollen traps; during grooming they ingest pollen and dust enmeshed in their fur, and this also is excreted. The pollen in an individual scat contains a record of the atmospheric pollen during a single day in the past. This kind of detail is rarely available from lake sediment. Chemical analysis of individual bat scats in a time series can chart the changing environment caused by agriculture, industry, volcanic dust, and a host of other details that depend only on the cleverness of the researcher. Careful ¹⁴C analysis can isolate the times when bats did not use the cave, and that may be useful in interpreting past conditions. If the insect types in the guano change over time, that may provide evidence of changing climate. Pollen was analyzed from guano samples taken from Tumbling Creek Cave near Protem, Missouri, USA. The cave contains a maternal colony of the Grey Bat (Myotis grisescens) that occupies the cave for a short time each year. Scats collected from the base of a 70 cm thick cone of guano yielded an AMS ¹⁴C date of 2810 ± 40 yr BP. The fecal material has a crumbly structure below the surface; it was of mahogany color (7.5 YR 2/1 to 3/2) and had no noticeable odor. Guano can be processed like normal sediment, but simple washing in a weak detergent solution followed by acetolysis appears adequate.