Dietary composition and echolocation call design of three sympatric insectivorous bat species from China

Studying the diet of echolocating, insectivorous bats can provide important insights into their foraging behaviors and ecological constraints they are facing. By examining an extensive data set covering a period of 2 years, the present study identifies the dietary composition of three sympatric insectivorous bat species in rural areas of Beijing municipality. Each species clearly has different preferences for particular food items. Greater horseshoe bats, Rhinolophus ferrumequinum, preferred to catch nocturnal, actively flying insects, mostly moths (Lepidoptera), and to a lesser percentage flies (Diptera), beetles (Coleoptera), and flying ants and termites (Hymenoptera). Other nocturnal insects which do not exhibit any perceptible wing movements, such as true bugs (Homoptera), or strictly diurnal insects that hardly ever fly in the dark, such as grasshoppers (Orthoptera) and dragon- and damselflies (Odonata), were never found in droppings of horseshoe bats. Large mouse-eared bats, Myotis chinensis, preferentially glean relatively large terrestrial prey of the order Coleoptera (mostly carabid beetles) and Orthoptera, whereas greater tube-nosed bats, Murina leucogaster, consume predominantly smaller, diurnal Coleoptera (mostly soldier beetles, Cantharidae, and ladybugs, Coccinellidae). Our findings also indicate previously not described, significant spectro-temporal differences in the echolocation signals of M. chinensis and M. leucogaster. The results suggest that in our study area the dramatic differences in the dietary composition of these three bat species are mainly based upon differences in their foraging behaviors, including differences in their echolocation signal structure. The dietary data provide important background information for conservational efforts, such as habitat protection.     

Analysis of the diet of Natterer's bat Myotis nattereri and the common long-eared bat Plecotus auritus in the West of Ireland

The diets of Natterer's bat Myotis nattereri and the common long-eared bat Plecotus auritus were investigated at a nursery colony of each species by analysis of droppings collected monthly from May to September. Respectively, 68% and 42% of the diets comprised items presumed to have been gleaned from foliage or other surfaces: diurnal insects, insects which rarely fly, and non-flying arthropods. Such surfaces included the ground: centipedes were eaten by both bats, and the muscid, Scatophaga stercoraria , usually associated with cattle dung, was a common prey. Indeed, the prevalence of cattle-farming around both of the bat roosts almost certainly contributed indirectly, in the form of S. stercoraria , to a significant part of the Diptera consumed. The chief food of M. nattereri was the larger Diptera, but Trichoptera, Hymenoptera and Arachnida were also important. Lepidoptera, Coleoptera and Hemiptera were minor prey, with Dermaptera and Chilopoda taken occasionally. Diptera, closely followed by Lepidoptera, together accounted for nearly two-thirds of the diet of P. auritus. Also taken, in descending order of importance, were Trichoptera, Arachnida, Chilopoda, Coleoptera, Dermaptera, Hymenoptera and Hemiptera. Plecotus auritus , but not M. nattereri , was evidently able to take a few small insects such as aphids and lesser nematoceran Diptera.     

同地共栖三种鼠耳蝠食性差异及其生态位分化

2005年9—11月在贵州省安龙县笃山乡暗河村,分析了共栖同一山洞3种鼠耳蝠的形态特征和食性。在体型上,华南水鼠耳蝠体重为(4.46±0.53)g,前臂长为(34.63±1.45)mm;毛腿鼠耳蝠体重为(5.15±1.76)g,前臂长为(35.20±1.07)mm;西南鼠耳蝠体重为(10.94±0.87)g,前臂长为(45.21±1.15)mm。3种鼠耳蝠的体重两两之间差异显著,西南鼠耳蝠与另外2种鼠耳蝠的前臂长相比两两之间差异显著。在食物组成上,华南水鼠耳蝠主要捕食近水面活动的双翅目及其幼虫,体积百分比和频次百分比分别为79.7%和100%;毛腿鼠耳蝠主要捕食双翅目和小型鞘翅目,体积百分比分别占59.6%和28.8%,频次百分比分别为91.3%和80.1%;西南鼠耳蝠的食物组成主要为近地面或在地表活动的鞘翅目步甲科和埋葬虫科昆虫,体积百分比和频次百分比分别为80.8%和100%;3种鼠耳蝠食物组成存在显著差异。结果表明,同地共栖3种鼠耳蝠除了形态结构上出现差异,食物组成也存在明显的差异。据此,推测3种鼠耳蝠可能采取不同的捕食生境和捕食策略,从而导致捕食生态位分离,避免出现激烈竞争,使得3种近缘鼠耳蝠能够同地共栖。     

Molecular diet analysis finds an insectivorous desert bat community dominated by resource sharing despite diverse echolocation and foraging strategies

Interspecific differences in traits can alter the relative niche use of species within the same environment. Bats provide an excellent model to study niche use because they use a wide variety of behavioral, acoustic, and morphological traits that may lead to multi‐species, functional groups. Predatory bats have been classified by their foraging location (edge, clutter, open space), ability to use aerial hawking or substrate gleaning and echolocation call design and flexibility, all of which may dictate their prey use. For example, high frequency, broadband calls do not travel far but offer high object resolution while high intensity, low frequency calls travel further but provide lower resolution. Because these behaviors can be flexible, four behavioral categories have been proposed: (a) gleaning, (b) behaviorally flexible (gleaning and hawking), (c) clutter‐tolerant hawking, and (d) open space hawking. Many recent studies of diet in bats use molecular tools to identify prey but mainly focus on one or two species in isolation; few studies provide evidence for substantial differences in prey use despite the many behavioral, acoustic, and morphological differences. Here, we analyze the diet of 17 sympatric species in the Chihuahuan desert and test the hypothesis that peak echolocation frequency and behavioral categories are linked to differences in diet. We find no significant correlation between dietary richness and echolocation peak frequency though it spanned close to 100 kHz across species. Our data, however, suggest that bats which use both gleaning and hawking strategies have the broadest diets and are most differentiated from clutter‐tolerant aerial hawking species.     

Flight performance, foraging tactics and echolocation in the trawling insectivorous bat Myotis adversus (Chiroptera: Vespertilionidae)

The bat Myotis adversus hunts for prey by aerial hawking and by taking prey from the water surface with its feet (trawling). The flight performance and echolocation of this species were studied in Queensland, Australia, and comparisons were made with Myotis daubentoni , a bat filling a similar ecological niche in the Palaearctic Region. The bats foraged in very similar ways, using the same foraging tactics and feeding in similar habitats, yet they were not geometrically similar in shape. The slightly larger Myotis adversus had relatively larger wings than M. daubentoni , conferring a slightly lower wing-loading. Nevertheless, M. adversus flew faster than M. daubentoni during the searching phase of foraging. Myotis daubentoni turned in tighter circles than M. adversus . Both species used short frequency-modulated (FM) echolocation calls of a characteristic sigmoidal structure, and nulls typically observed in the calls were an observational artefact. Myotis adversus also adopted an unusual 'long'FM call while foraging. The relations between echolocation frequencies and body size were explored in male M. adversus . Specialized morphological and acoustic adaptations for prey capture by trawling in insectivorous bats are discussed.     

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.     

Studies on the prevalence of haematozoa of British bats

Bloodfilms were collected from 491 bats representing 12 of the 15 species of British bats, from a number of sites in England and Scotland, and examined for haematozoa. Trypanosoma (Schizotrypanum ) sp. were found in Pipistrelluspipistrellus, Nyctalus noctula, N. leisleri, Eptesicus serotinus and Myotis brandtii , and Trypanosoma (Megatrypanum) incertum was found in P. pipistrellus. Both subgenera of trypanosomes appear to be transmitted by the bat bug Cimex pipistrelli. Gametocytes of the haemoproteid Poly-chromophilus murinus were found in one-third of Myotis daubentonii examined, and stages of the parasite were found in the vector, the wingless blood-sucking fly, Nycteribia kolenatii , collected from these bats. The piroplasm Babesia vesperuginis was found in the blood of P. pipistrellus and Myotis mystacinus , and was the only parasite to show evidence of pathogenicity to bats.     

Analysis of the diet of Daubenton’s batMyotis daubentonii in Ireland

The diet of Daubenton’s batMyotis daubentonii (Kuhl, 1817), which takes prey by aerial hawking and from the surface of water, was investigated by analysis of faeces collected in summer at 7 roosts, all close to rivers in pastoral land, in three widely-separated districts in Ireland. Forty-seven categories of arthropod prey were identified; several were insect taxa found in and around water. Most categories were recovered at most roosts, but mainly in small amounts. The main categories were the same throughout, accounting for 82% of the diet by percentage frequency in droppings for pooled data: Chironomidae/Ceratopogonidae 24% (adults 14%, preadult stages 10%), other nematoceran Diptera 21%, other Diptera 10%, and Trichoptera 26% (adults 20%, preadult 6%). A quarter of the prey had evidently been obtained from the water’s surface (eg aquatic insects, their larvae and pupae). Although consumption of several food items varied significantly by month at one or more roosts, little of such variation was consistent between roosts.     

Analysis of the diet of the lesser horseshoe bat Rhinolophus hipposideros in the West of Ireland

The diet of the lesser horseshoe bat Rhinolophus hipposideros was investigated over one season by analysing faeces and discarded insect fragments collected on polythene sheets at eight roosts. Remains of 23 insect families from seven orders (Lepidoptera, Neuroptera, Trichoptera, Hymenoptera, Coleoptera, Diptera and Hemiptera) and of spiders (Araneae: Arachnida) were identified. Nematoceran Diptera were the chief prey but Lepidoptera, Trichoptera and Neuroptera were also important. Both locational and seasonal variation were demonstrated for some food categories. The predicted seasonal availability of the different insect taxa is broadly reflected in the results: the question of possible prey selection is discussed. The bat fed successfully on three families of Lepidoptera known to possess hearing organs sensitive to bat ultrasounds. The possible mechanisms by which R. hipposideros might catch such prey are reviewed.     

Trophic resource partitioning drives fine‐scale coexistence in cryptic bat species

Understanding the processes that enable species coexistence has important implications for assessing how ecological systems will respond to global change. Morphology and functional similarity increase the potential for competition, and therefore, co‐occurring morphologically similar but genetically unique species are a good model system for testing coexistence mechanisms. We used DNA metabarcoding and high‐throughput sequencing to characterize for the first time the trophic ecology of two recently described cryptic bat species with parapatric ranges, Myotis escalerai and Myotis crypticus. We collected fecal samples from allopatric and sympatric regions and from syntopic and allotopic locations within the sympatric region to describe the diets both taxonomically and functionally and compare prey consumption with prey availability. The two bat species had highly similar diets characterized by high arthropod diversity, particularly Lepidoptera, Diptera and Araneae, and a high proportion of prey that is not volant at night, which points to extensive use of gleaning. Diet overlap at the prey item level was lower in syntopic populations, supporting trophic shift under fine‐scale co‐occurrence. Furthermore, the diet of M. escalerai had a marginally lower proportion of not nocturnally volant prey in syntopic populations, suggesting that the shift in diet may be driven by a change in foraging mode. Our findings suggest that fine‐scale coexistence mechanisms can have implications for maintaining broad‐scale diversity patterns. This study highlights the importance of including both allopatric and sympatric populations and choosing meaningful spatial scales for detecting ecological patterns. We conclude that a combination of high taxonomic resolution with a functional approach helps identify patterns of niche shift.     

Use of foraging habitats by bats in a Mediterranean area determined by acoustic surveys: conservation implications

We determined habitat use by foraging bats by broad-band acoustic surveys in 10 habitat types from a Mediterranean area (southern Italy). We applied discriminant functions to identify time-expanded echolocation calls from free-flying bats.
Moon phase and cloud cover had no effect on bat activity. Only Hypsugo savii was influenced by temperature, and activity of Myotis daubentonii and Myotis capaccinii was reduced at higher wind speeds. Both total numbers of bat passes and feeding buzzes were highest over rivers and lakes. Pipistrellus kuhlii and H. savii were most frequently recorded. Pipistrellus kuhlii , Pipistrellus pipistrellus and Tadarida teniotis proved generalists in using foraging habitats.
Water sites and conifer plantations were respectively the most and the least used habitats by H. savii . Rivers were especially important to Myotis bats, Miniopterus schreibersii and Pipistrellus pygmaeus . Unlike P. kuhlii , P. pipistrellus was frequent in beech woodlands; P. pygmaeus made a considerable use of chestnut woodlands and Myotis spp. were moderately active in both these woodland types.
A large number of endangered or vulnerable species featured in riparian habitats, broadleaved woodlands and olive groves. Riparian and woodland habitats constitute an important target for conservation. Typical land use forms such as woodlands used for chestnut production and traditionally managed olive groves should be encouraged in conservation plans. The negative impact of urbanisation on bats might be counteracted by fostering trees, gardens and small cultivated patches. Farmland practices should encourage landscape complexity and limit the use of pesticides.     

The diets of two high-flying bats from Africa

The diets of two fast-flying, aerial-hawking bats from north-east Africa (Ethiopia) were investigated by means of faecal analysis. Otomops martiensseni (Molossidae; c. 35 g body mass), which is remarkably specialized morphologically with very long, narrow wings and large ears, and which uses low frequency echolocation (10kHz), feeds almost exclusively (97% by volume) on moths, mostly of large species. The smaller (20 g) Taphozous perforatus (Emballonuridae) also has long, narrow wings but short ears and is less morphologically extreme than Otomops. It feeds on moths (56%), but also on many other insect groups such as Isoptera (14%). Coleoptera (10o%), Orthoptera (8%), as well as Hemiptera, Neuroptera, Hymenoptera and Diptera. Otomops martiensseni , in particular, appears to be a highly specialized moth predator.     

东亚水鼠耳蝠形态描述与分类

水鼠耳蝠 Myotis daubentonii(Chiroptera,Vespertilionidae),广泛分布于欧洲和亚洲,亚种分化众多,在亚洲已报道有 M.d.ussuriensis,M.d.loukashkini,M.d.petax和M.d.laniger但其分类地位一直受到国内外学者的关注.中国的水鼠耳蝠长期以来被认为属于水鼠耳蝠M daubentonii亚种.最近有研究认为中国的水鼠耳蝠与欧洲的水鼠耳蝠M.daubentonii不同,并把"petax"提升为种.在中国境内相继采到17只鼠耳蝠标本,根据外形、头骨、牙齿、阴茎骨、线粒体DNA细胞色素b等特征,鉴定为东亚水鼠耳蝠Myotis petax,对中国水鼠耳蝠的种和亚种分类做一讨论.     

Diet and trophic groups of an aquatic insect community in a tropical stream.

The diet and trophic groups of an assemblage of aquatic insects were studied in a tropical stream. Genera of the orders Ephemeroptera, Odonata, Plecoptera, Lepidoptera, and Hemiptera showed feeding specialization. Others, such as Trichoptera, Coleoptera, and Diptera, showed great diet variation with genera of different trophic groups. Seasonal variation of insect diet, evident only for some genera of the orders Trichoptera, Lepidoptera, Coleoptera, and Diptera, was due to the differences observed in community composition and to generalist habits of these genera. However, the seasonal comparison of trophic groups showed no significant statistical differences. The great importance of organic matter, a non-limited resource, in the diet of Ribeir?o do Atalho aquatic insects may be the explanation for the trophic stability in this community organization.     

Habitat occurrence and feeding ecology of Crocidura montis and Lophuromys flavopunctatus on Mt. Elgon, Uganda

The distribution, habitat occurrence and feeding ecology of Crocidura montis and Lophuromys flavopunctatus coexisting in the afro‐alpine zone on Mt. Elgon, Uganda, are described. Crocidura montis was the only shrew species occupying the afro‐alpine zone, but was not found in forested habitats below 3200 m. While there was considerable overlap in habitat occurrence between the two species, C. montis was most abundant in the montane grassland and in drier sites while L. flavopunctatus occupied a wider range of habitats and wetter sites. C. montis ate a diversity of invertebrates, the most important being Coleoptera, Araneae and Lumbricidae. Invertebrates, mostly Diptera larvae, Lumbricidae and Coleoptera, formed a major component of the L. flavopunctatus diets, plus plant material (particularly Hepaticae and monocots). The arthropod components of the diets reflected their abundance in pitfall samples.     

Fruit sizes and the structure of frugivorous communities in a New Guinea lowland rainforest

A community of frugivorous insects was studied by rearing of 25 565 individual insects representing three orders (Coleoptera, Lepidoptera and Diptera except Drosophilidae) from 326 woody plant species in a lowland rainforest in Papua New Guinea. Fruits from 19.3% of plant species were not attacked by any insect order, 33.4% of plant species were attacked by a single order, 30% by two orders and 17.2% by all three orders. The likelihood of attack by individual orders was positively correlated so that a higher proportion of plant species than expected suffered either no attack at all or was attacked by all three insect orders. Fruits from most of the plant species exhibited low rates of attack and low densities of insects. One kilogram of fruit was attacked on average by 11 insects, including three to four Coleoptera, six Diptera and one Lepidoptera. Thus, we reared on average one insect from 10 fruits, including one Diptera from 14 fruits, one Coleoptera from 22 fruits and one Lepidoptera from 100 fruits. Only 72 out of the 326 plant species hosted more than one insect per 10 fruits, and only seven species supported a density of greater than one insect per fruit. Our results suggest that specialized insect seed predators are probably too rare to maintain the diversity of vegetation by density‐dependent mortality of seeds as suggested by the Janzen–Connell hypothesis. Fruit weight, fruit volume, mesocarp volume, seed volume and fleshiness had no significant effect on the probability that a fruit would be attacked by an insect frugivore. However, fruits attacked by Diptera were significantly larger and had larger volume of both mesocarp and seeds than fruits attacked by Coleoptera and Lepidoptera.     

Characteristics of echolocating bats’auditory stereocilia length, compared with other mammals

The stereocilia of the Organ of Corti in 4 different echolocating bats, Myotis adversus, Murina leuco-gaster, Nyctalus plancyi (Nyctalus velutinus), and Rhinolophus ferrumequinum were observed by using scanning electron microscopy (SEM). Stereocilia lengths were estimated for comparison with those of non-echolocating mammals. The specialized lengths of outer hair cells (OHC) stereocilia in echolocating bats were shorter than those of non-echolocating mammals. The specialized lengths of inner hair cells (IHC) stereocilia were longer than those of outer hair cells stereocilia in the Organ of Corti of echolocating bats. These characteristics of the auditory stereocilia length of echolocating bats represent the fine architecture of the electromotility process, helping to adapt to high frequency sound and echolocation.     

Food of the serotine bat, Eptesicus serotinus—is faecal analysis a valid qualitative and quantitative technique?

The diet of Epfesicus serotinus was investigated by faecal analysis and the validity of this technique as a means of obtaining reliable quantitative results was assessed. Knowledge of what the bats eat will allow predictions of which habitats contribute most prey. Three male serotines were kept in captivity during the months of July and August 1991 and fed known quantities of identified insects. With captive E. serotinus the remains of prey appeared within 33 min of first bite and continued to appear for up to 32 h after consumption. Scales from two Noctua pronuba moths consumed were contained in 59 subsequent droppings. Similarly, fragments of three beetles, Geotrupes stercorarius , were contained in 28 subsequent faeces.
Analysis of the faeces of free-living bats revealed insects from seven orders. Coleoptera were found to be present in 96.1% of the droppings examined; the next most frequently found order was Lepidoptera, occurring in 14.7%. The beetles were mostly associated with hay meadows ( Aphodius spp. and Melolontha spp.), or grazed pasture ( Aphodius spp. and Geotrupes spp.). Quantitative determination of prey eaten is not possible owing to the large number of the droppings shown to contain the remains of marker insects and the long period over which they are produced.