Distribution of cave-dwelling bats and conservation status of underground habitats in the Istanbul area

Populations of cave-dwelling bat species were investigated in the transitory region between the Eastern Thrace and the Western Pontus. Data were collected during 30 surveys in 13 underground sites, 10 of which had not been surveyed previously by bat researchers, between March 1999 and March 2000. Approximately 20 000 bats representing eight species were recorded. Grouping the sites according to their ecological resemblance, by means of cluster and correspondence analyses, yielded different results for the summer and winter data. In summer, there was a partial separation of the sites by their location in biogeographic regions. In winter, no regional grouping was observed. It was concluded that in the transitory region, species distribution does not differ considerably between the Eastern Thracian and Western Pontic ecosystems. In addition, a conservation scoring system is proposed for those sites investigated, their status is evaluated, and the most important local roosts are identified.     

太行山南段洞栖蝙蝠的分布及栖息地重要性分析

2009年8月至2010年9月,对太行山南段的洞栖蝙蝠及栖息地进行了调查,共调查洞穴38个,其中28个洞穴为首次调查,共观察到蝙蝠约17000只,隶属2科4属9种,其中分布最广、数量最多的是马铁菊头蝠。测量洞穴的总水平长度、最大宽度和最大高度,并以洞穴内蝙蝠的种群数量(Ai)与根据物种生存状态赋值的权重(Mi)乘积之和评估洞穴重要性。在调查的洞穴中,最重要的洞穴是黄楝树水渠,有8种约2500只蝙蝠在此繁殖和冬眠;其次是涧河洞,有5种约2100只蝙蝠在此繁殖和冬眠。基于洞栖蝙蝠种类和洞穴测量数据的聚类及主成分分析,探讨了太行山南段东西两侧洞栖蝙蝠的分布状况、不同类型栖息地之间的差异以及洞栖蝙蝠对栖息地的选择。太行山南段东西两侧洞栖蝙蝠的种类和种群数量差异不显著。冬眠洞穴的总水平长度、最大宽度、最大高度、郁闭度均显著大于非冬眠洞穴。影响蝙蝠栖息地选择的主要因子有地形因子、隐蔽因子和干扰因子,这3个主成分的累计贡献率达到85.96%。目前,这些洞穴的保护现状均不理想,一些洞穴已经或正在被开发成旅游景点,这使该地区洞栖蝙蝠面临严重的生存危机。本研究结果以期能为决策者在制定开发旅游策略时提供参考和依据。     

Thermoregulation and roost selection by reproductive female big brown bats (Eptesicus fuscus) roosting in rock crevices

A free-ranging maternity colony of big brown bats Eptesicus fuscus roosting in rock crevices along the South Saskatchewan River in south-eastern Alberta, Canada, was studied to understand better the discrepancy that exists in the literature regarding torpor use by reproductive female bats. Using radio-telemetry, thermoregulatory patterns and roost microclimate were recorded for pregnant, lactating and post-lactating females. Relative torpor use is described in several ways: the proportion of days on which torpor was used, depth, minimum body temperature, time spent in torpor, and a comprehensive torpor unit (degree-min). Pregnant and lactating female E. fuscus used torpor to the same extent overall (degree-min), but pregnant bats used torpor less frequently and with more time in deep torpor. Torpor was used to the greatest extent after weaning (post-lactation). Evidence is presented that the cost:benefit ratio for deep and prolonged periods of torpor may be highest during lactation. Microclimates of rock-crevice roosts mirrored the use of torpor throughout reproduction by bats. Lactation roosts (deeper, larger opening size) were more thermally stable and remained warmer at night compared to the shallow roosts used by pregnant and post-lactating females. It is shown that conclusions about relative use of torpor can differ depending on the units of comparison, necessitating measurement of all aspects of torpor (depth, duration and frequency). Comprehensive measurements, individual-based normothermic temperatures, and a definition of torpor that accounts for all energy savings, allow a more accurate depiction of patterns and facilitates inter-study comparisons.     

Roost Structure,Modification, and Availability in the White‐throated Round‐eared Bat,Lophostoma silvicolum (Phyllostomidae) Living in Active Termite Nests1

We studied roost structure, modification, and availability in Lophostoma silvicolum (Phyllostomidae), an insectivorous gleaning bat, on Barro Colorado Island (BCI), Panamá. Collection of nest material beneath termitaria and infrared video filming indicated that males of L. silvicolum excavate and maintain cavities inside active termite nests. A binary logistic regression analysis showed that to be suitable as roosts, termite nests have to be larger than 30 cm in diameter and taller than 30 cm, well shaded, with few transecting branches, and freely accessible from below. Use of active termite nests as roosts may provide several benefits to L. silvicolum, including reduction of competition for roost sites with sympatric bat species, reduced parasite load and a suitable microclimate. A comparison of number of all termite nests in selected forest plots with number of termite nests that are potentially suited as bat roosts and number of termite nests that are actually used by bats suggests that L. silvicolum may not be roost‐limited on BCI in spite of its highly specialized roost choice.     

洞穴型蝙蝠的栖息环境选择、生态作用及保护

多数蝙蝠为洞穴型。在野外调查的基础上,结合前人调查的结果,对洞穴型蝙蝠的栖息环境选择及其在洞穴生态系统中的特殊生态作用进行了探讨。针对目前随着人类活动的增加,洞穴型蝙蝠的生存环境遭到日益严重的干扰、破坏和污染而导致蝙蝠的物种多样性降低,加之国内对洞穴型蝙蝠研究不足的现状,提出了加强对洞穴型蝙蝠的栖息和捕食环境进行保护、对蝙蝠的多样性进行调查的建议。     

Distribution of ground-dwelling beetles in fragmented tropical habitats

The conservation of biodiversity is increasingly dependent on human-altered habitats. In a fragmented forest landscape in northern Costa Rica within the Mesoamerican Biological Corridor, an area of great conservation importance, we compared the diversity and composition of ground-dwelling beetle communities in five habitat types along a gradient of increasing disturbance: primary forest, logged forest, secondary forest, plantation (Gmelina arborea) and pasture. Using pitfall trapping we captured a total of 1,877 beetles (Coleoptera), comprising 422 morphospecies in 26 families. The plantation sites had the lowest number of species followed by secondary forest and pasture. Multivariate analysis separated the beetle fauna according to land use, and suggested that only the logged forest maintains a similar species assemblage to primary forest. However, each habitat harboured a number of unique species indicating the conservation value of the mosaic of habitats found in fragmented landscapes. Our results suggest that to maintain forest beetle species diversity it is essential that areas of natural forest are conserved. However, other land uses also provide beetle habitats and in fragmented areas active management to maintain a mosaic of land uses will contribute to the conservation of beetle diversity.     

Birth size and postnatal growth in cave- and bridge-roosting Brazilian free-tailed bats

As the human population continues to expand, increased encroachment on natural landscapes and wildlife habitats is expected. Organisms able to acclimate to human-altered environments should have a selective advantage over those unable to do so. Over the past two decades, bats have increasingly begun to roost and raise offspring in spaces beneath pre-cast concrete bridges. Few studies have examined the health or fitness of individuals living in these anthropogenic sites. In the present study, we examined birth size and postnatal growth, as surrogates of reproductive success, in Brazilian free-tailed bat pups born at a natural and a human-made roost. Based on putative stress-related conditions (noise from vehicular traffic, chemical pollutants and a modified social environment) present at bridges, we predicted that bats at these sites would have reduced reproductive success. Contrary to our prediction, pups born at a bridge site were on average heavier and larger at birth and grew faster than those born at a cave site. Also, both birth size and growth rates of pups differ between years. We attribute observed differences to a combination of roost-related conditions (i.e. roost temperature and proximity to foraging areas), climate and maternal effects with larger mothers raising larger pups. Thus, some bridge roosts, at least in the short term, are suitable, and in some cases may provide better conditions, for raising young bat pups than cave roosts.     

The evolution of flight and echolocation in bats: another leap in the dark

The earliest known complete bats, from the Eocene (49–53 Mya), were already capable of flapping flight and echolocation. In the absence of direct fossil evidence there have been many speculative scenarios advanced to explain the evolution of these behaviours and their distributions in extant bats. Theories assuming chiropteran monophyly have generally presumed the ancestral pre‐bat was nocturnal, arboreal and insectivorous. Following this assumption hypotheses can be divided into the echolocation first, flight first and tandem development hypotheses, all of which assume that flight evolved only once in the lineage. In contrast, the chiropteran diphyly hypothesis suggests that flight evolved twice. Evidence supporting and refuting the different hypotheses are reviewed. It is concluded that there are significant problems attached to all the current models. A novel hypothesis is advanced, which starts from the assumption that bats are monophyletic and the ancestral pre‐bat was arboreal, but diurnal and frugivorous. After the evolution of flight it is suggested that these animals were driven into the nocturnal niche by the evolution of raptorial birds, and different groups evolved either specialised nocturnal vision (megachiropterans) or echolocation (microchiropterans). A block on sensory modality transfer has retained this distribution of perceptual capabilities ever since, despite some Megachiroptera evolving rudimentary echolocation, and the dietary convergence of some Microchiroptera with the Megachiroptera. The new hypothesis overcomes many of the problems identified in previous treatments.     

Foraging habitats of bats in southern Finland

We determined the foraging habitats of the northern batEptesicus nilssonii (Keyserling et Blasius, 1839), Brandt’s batMyotis brandtii (Eversmann, 1845), whiskered batMyotis mystacinus (Kuhl, 1819), Daubenton’s batMyotis daubentonii (Kuhl, 1819) and brown long-eared batPlecotus auritus (Linnaeus, 1758) in southern Finland. Among these species, we compared the diversities of foraging habitats, linear feature preference and the bats’ tendencies to forage simultaneously.Eptesicus nilssonii was the most opportunistic, foraging in a wide range of habitats.Myotis daubentonii (94%) foraged mainly on water habitats, whileM. brandtii/mystacinus (89%) andP. auritus (66%) foraged mainly in forest habitats. The diversities of foraging habitats used byE. nilssonii andP. auritus were higher than those ofM. brandtii/mystacinus andM. daubentonii. Both E.nilssonii andP. auritus foraged mostly alone or in small numbers, whileM. brandtii/mystacinus tended to gather in large numbers to forage in the same habitat. Half ofE. nilssonii and 46% ofM. daubentonii foraged over linear features, while other species did not use linear features to such an extent. Management and conservation of foraging habitats are needed especially forM. brandtii/mystacinus andM. daubentonii, which are more specialized thanE. nilssonii and P. auritus.     

Rainfall, food abundance and timing of parturition in African bats

We used published results from studies in Africa to test the hypothesis that the timing of parturition in the Chiroptera is constrained by rainfall. Comparison of year-round rainfall and insect data at various latitudes showed that insect abundance peaks approximately a month after peak rainfall. A similar comparison of parturition time to rainfall showed that with the possible exception of the molossids, the Microchiroptera commonly give birth a month before peak rainfall. With an average 6-week lactation period in the Microchiroptera, the timing of parturition is such that young bats are weaned just before the period of maximum insect abundance. We suggest that the needs of the young in this post-weaning period may be more important than the energetic demands of lactation on the mother in determining the timing of parturition on an evolutionary scale. A similar conclusion is implied for the African Megachiroptera, but there is insufficient information on their reproduction to adequately test the main hypothesis for these bats. Received: 4 October 1996 / Accepted: 14 March 1997     

Nectarivorous feeding mechanisms in bats

Cranio-dental characteristics are quantified between micro- and megachiropteran nectarivores and compared with microchiropteran animalivores, frugivores, and megachiropteran frugivores. Microchiropteran nectarivores share many characteristics with megachiropteran nectarivores and frugivores, but differ in having a long, narrow head. Megachiropterans have wide zygomata, which would allow for more jaw musculature. Diminutive cheekteeth are characteristic of nectarivory in both suborders, but both have relatively large canines. Teeth in nectarivores can occupy as little as a tenth of the palatal area compared to nearly two-thirds in microchiropteran animalivores. The proportion that the dilambdodont stylar shelf occupies of molars in microchiropteran nectarivores can be as much as that in microchiropteran animalivores (insectivorous and carnivorous bats) or as little as that in microchiropteran frugivores but not as extreme as either. In addition to dimunitive teeth, nectarivores have fused mandibles and upper canines that are worn from contact with the lower canines (thegosis). These characteristics may be necessary for the lower jaw to support an elongated, mobile tongue. While microchiropteran nectarivory, frugivory, and carnivory probably evolved independently from an insectivorous microchiropteran ancestor, megachiropteran nectarivory probably evolved from megachiropteran frugivory or the reverse.     

Plasma leptin decreases during lactation in insectivorous bats

We previously demonstrated high leptin levels during late pregnancy in little brown bats (Myotis lucifugus). We now extend these observations to a second species, the big brown bat (Eptesicus fuscus), and also report that leptin increases after the first trimester of pregnancy. Leptin decreased to baseline 1 week following parturition, with a half-time decay of 2 days. During lactation, leptin was significantly correlated with body mass in E. fuscus, but not in M. lucifugus. No circadian pattern of leptin was observed in M. lucifugus. The decrease in post-partum leptin in bats may be partly explained by loss of putative placental leptin. The continued decrease may reflect depletion of body fat during this energy demanding period, at least in Eptesicus. Changes in leptin during lactation appeared to be independent of circadian effects and time of sampling. Our study provides additional evidence that leptin increases during pregnancy and declines during lactation in a free-ranging mammal, supporting the hypothesis that leptin plays important but yet undetermined roles in reproduction. Accepted: 4 October 1998     

Ethanol ingestion affects flight performance and echolocation in Egyptian fruit bats

Ethanol, a potential toxin for vertebrates, is present in all fleshy fruits and its content increases as the fruit ripens. Previously, we found that the marginal value of food for Egyptian fruit bats, Rousettus aegyptiacus, decreases when its ethanol content exceeds 1%. Therefore, we hypothesized that, if ingested, food containing >1% ethanol is toxic to these bats, probably causing inebriation that will affect flight and echolocation skills. We tested this hypothesis by flying Egyptian fruit bats in an indoor corridor and found that after ingesting ethanol-rich food bats flew significantly slower than when fed ethanol-free food. Also, the ingestion of ethanol significantly affected several variables of the bats’ echolocation calls and behavior. We concluded that ethanol can be toxic to fruit bats; not only does it reduce the marginal value of food, but it also has negative physiological effects on their ability to fly competently and on their calling ability.