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Biotic and abiotic factors can act as filters for determining the species composition of biological communities. We aimed to identify abiotic factors driving the assembly of bat communities in Eastern Mediterranean pine plantations along a north–south climatic gradient, as they are crucial forest habitats for the assessment and conservation of these communities. We expected that bat communities are predominantly shaped by environmental filtering. We conducted acoustic sampling in 35 pine plantations in Israel and analyzed recordings for species identification. We used the ESLTP analysis, an extension of the three‐table ordination (RLQ analysis), to explore relationships between environmental characteristics, species occurrences, and functional traits of species while accounting for phylogenetic relationships between species and spatial distribution of the communities. Communities showed phylogenetic and trait clustering. Climatic conditions and forest vegetation composition shaped communities of bats, affecting the distribution of traits related to foraging behaviors, vegetation clutter, and the ability of bats to maneuver in it. Maneuverable species were associated with the northern Mediterranean climatic zone, with a scarce cover of drought‐tolerant small shrubs and grassland. Fast flyers were associated with the center‐south semi‐arid area, with abundant drought‐tolerant small shrubs and grassland. These forces might have a predominant role in the assembly of these communities, presumably due to the stressful climatic conditions of the study area. The ESLTP approach can be extended to other taxa and environments to predict species responses to disturbance and environmental changes and give insights into environmental management. [ABSTRACT FROM AUTHOR]

Insectivorous bats may play a significant role in regulating populations of agricultural pests. Currently, few methods are available to enhance the activity of bats in agroecosystems. We asked whether synthetic sex pheromones, used in integrated pest management (IPM) to impede the mating success of major moth pests in vineyards and apple orchards, could also enhance the activity and richness of insectivorous bats, their natural enemies. We hypothesized that applying concentrated sex pheromones of pest moths will alter the movement patterns of male moths, indirectly affecting bat richness and activity. We compared the effect of sex pheromones on bats under two different agricultural management systems: conventional farming and IPM. We used synthetic sex pheromones of Lobesia botrana or Cydia pomonella; both are among the most destructive moth pests in vineyards and apple orchards, respectively. Using passive acoustic monitoring, we compared species richness and bat activity in plots without and with additional pheromones. In both IPM vineyards and IPM apple orchards, total bat activity and species richness significantly increased after applying the pheromone treatment, with a positive correlation between total bat activity and the numbers of moth pests in the vineyards. In conventional vineyards, bat species richness increased significantly, but not total bat activity. IPM vineyards had significantly higher species richness than conventional vineyards, both before and after the pheromone treatment. Our study shows that moth pheromone lures, commonly used as a pest control method, may also attract insectivorous bats, which in turn may further suppress the pests. These findings highlight the potential of insectivorous bats as pest control agents and call for further research directed at integrating them in IPM practices. [ABSTRACT FROM AUTHOR]

Over 40% of the Earth's surface has been converted to agricultural use and agroecosystems have become important habitats for wildlife. In arid regions, intensive agriculture creates artificial oasis-like habitats due to their high irrigation inputs. Date production is one of the primary agricultural practices in the deserts of the Middle East and North Africa. Insectivorous bats are known to use agricultural areas, but the role of date plantations as their foraging habits and the importance of insectivorous bats as date bio-pest control agents are still unknown. We assessed the role of date plantations as foraging habitats for local desert bat species by acoustically recording bat activity in conventional and organic date plantations in the southern Arava Valley, Israel. In addition, we captured bats in the plantations and collected feces for DNA metabarcoding analysis to investigate the presence of pest species in their diets. We found that 12 out of the 16 known species of bats in this region frequently used both conventional and organic date plantations as foraging habitats. Species richness was highest in the organic plantation with complex ground vegetation cover. Foraging activity was not affected by plantation type or management. However, bat species richness and activity increased in all plantations during summer date harvesting. Molecular analysis confirmed that bats feed on a variety of important date pests, but the particular pests consumed and the extent of consumption varied among bat species. Our results highlight a win–win situation, whereby date plantations are an important foraging habitat for desert bats, while bats provide bio-pest control services that benefit the date plantations. Therefore, date farmers interested in bio-pest control should manage their plantations to support local desert bat populations. [ABSTRACT FROM AUTHOR]

Bats are primarily forest mammals and forest structure may affect their communities through the level of vegetation clutter. Pine plantations are typically even-aged managed forests that lack structural complexity. However, an understory layer can enhance the heterogeneity of these forests, making them suitable for several animal taxa. We hypothesized that species composition, richness, and foraging activity of insectivorous bats in pine plantations vary according to forest structure, specifically with the density of the understory. We measured pine density, Diameter at Breast Height (DBH), canopy closure, and vegetation cover of 29 pine (Pinus halepensis) plantations of the Judean Lowlands, Israel, and collected acoustic data on resident bats. We found that bat species richness and total activity increased in forests with large tree DBH and dense shrubs. Cluttered-habitat species foraged preferentially in forests with large tree DBH and high pine density, while open-habitat species preferred forests with well-developed canopies and dense shrubs. Pipistrellus pipistrellus and Eptesicus serotinus foraged in mature forests with well-developed bushes and these species are endangered in Israel. We conclude that mature planted pine forests with a well-developed under-canopy are suitable foraging grounds for insectivorous bats. Management plans for planted pine forests should consider our findings to support bat populations, including rare and endangered species. [ABSTRACT FROM AUTHOR]

The maintenance of water balance in arid environments might represent a formidable challenge for Chiroptera, since they have high surface-to-volume ratios. In deserts, bats conserve water, for example, using daily torpor, but they also might experience episodic heat bouts, when they may need to increase total evaporative water loss (TEWL) to thermoregulate. We hypothesized that in bats, habitat aridity and its variability determine a trade-off between water conservation and thermoregulation via evaporative means. To test this hypothesis, we collated data from the literature of 22 species of bats on TEWL, body temperature and resting metabolic rate, in torpor and euthermy. We also collected data on ambient temperature (Ta) and precipitation of the locations where bats were captured, calculated an aridity index, and built an index of variability of the environment. After correcting for phylogeny, we found that, as aridity and variability of the environment increased, bats had lower values of TEWL, but the rate at which TEWL increases with Ta was higher, supporting our hypothesis. These results suggest that at high Ta there is a trade-off between water conservation and evaporative heat loss in bats. The evolution of physiological mechanisms that allow water conservation and tolerance to conditions of high Ta without access to free water might thus be crucial to explain the distribution of desert bats. [ABSTRACT FROM AUTHOR]

Conservation biological control (CBC) seeks to minimize the deleterious effects of agricultural pests by enhancing the efficiency of natural enemies. Despite the documented potential of insectivorous bats to consume pests, many synanthropic bat species are still underappreciated as beneficial species. We investigated the diet of Kuhl's pipistrelle (Pipistrellus kuhlii), a common synanthropic insectivorous bat that forages in urban and agricultural areas, to determine whether it may function as a natural enemy in CBC. Faecal samples of P. kuhlii were collected throughout the cotton‐growing season from five roost sites near cotton fields located in a Mediterranean agroecosystem, Israel, and analyzed using DNA metabarcoding. Additionally, data on estimated abundance of major cotton pests were collected. We found that the diet of P. kuhlii significantly varied according to sites and dates and comprised 27 species of agricultural pests that were found in 77.2% of the samples, including pests of key economic concern. The dominant prey was the widespread cotton pest, the pink bollworm, Pectinophora gossypiella, found in 31% of the samples and in all the roosts. Pink bollworm abundance was positively correlated with its occurrence in the bat diet. Furthermore, the bats' dietary breadth narrowed, while temporal dietary overlap increased, in relation to increasing frequencies of pink bollworms in the diet. This suggests that P. kuhlii exploits pink bollworm irruptions by opportunistic feeding. We suggest that synanthropic bats provide important pest suppression services, may function as CBC agents of cotton pests and potentially contribute to suppress additional deleterious arthropods found in their diet in high frequencies. [ABSTRACT FROM AUTHOR]

The acoustic arms race between insectivorous bats and their invertebrate prey has led to the convergent evolution of ultrasound hearing in seven orders of nocturnal insects. Upon hearing the echolocation calls of an approaching bat, such insects take defensive action. Here, we document a previously unknown sense of ultrasound hearing and phonotactic flight behaviour in the neuropteran family Myrmeleontidae (antlions). The antlion Myrmeleon hyalinus was presented with sound pulses at ultrasonic frequencies used by echolocating bats and its response thresholds in tethered flight determined. Behaviours included abdominal twitches, wing flicks, brief pauses in flight and flight cessation. Such behaviours create erratic evasive flight manoeuvres in other eared insects, particularly mantids and lacewings. Antlions responded best to ultrasound between 60 and 80 kHz (75 dB peSPL at 80 kHz), showing response thresholds similar to those of the related lacewings (Neuroptera, Chrysopidae). Yet, at lower ultrasonic frequencies (20-50 kHz), antlions were far less sensitive than lacewings. Based on calculated response distances, we conclude that antlions respond only after having been detected by bats rather than using early evasive flights. We argue that the high response threshold for lowfrequency ultrasound is adaptive for an insect that is mainly active close to and within vegetation, because a behavioural response to the lower ultrasonic frequencies used by high-flying bats would result in evasive action in the absence of actual predation risk. [ABSTRACT FROM AUTHOR]

Aim: Desert ecosystems, with their harsh environmental conditions, hold the key to understanding the responses of biodiversity to climate change. As desert community structure is influenced by processes acting at different spatial scales, studies combining multiple scales are essential for understanding the conservation requirements of desert biota. We investigated the role of environmental variables and biotic interactions in shaping broad and fine‐scale patterns of diversity and distribution of bats in arid environments to understand how the expansion of nondesert species can affect the long‐term conservation of desert biodiversity. Location: Levant, Eastern Mediterranean. Methods: We combine species distribution modelling and niche overlap statistics with a statistical model selection approach to integrate interspecific interactions into broadscale distribution models and fine‐scale analysis of ecological requirements. We focus on competition between desert bats and mesic species that recently expanded their distribution into arid environment following anthropogenic land‐use changes. Results: We show that both climate and water availability limit bat distributions and diversity across spatial scales. The broadscale distribution of bats was determined by proximity to water and high temperatures, although the latter did not affect the distribution of mesic species. At the fine‐scale, high levels of bat activity and diversity were associated with increased water availability and warmer periods. Desert species were strongly associated with warmer and drier desert types. Range and niche overlap were high among potential competitors, but coexistence was facilitated through fine‐scale spatial partitioning of water resources. Main conclusions: Adaptations to drier and warmer conditions allow desert‐obligate species to prevail in more arid environments. However, this competitive advantage may disappear as anthropogenic activities encroach further into desert habitats. We conclude that reduced water availability in arid environments under future climate change projections pose a major threat to desert wildlife because it can affect survival and reproductive success and may increase competition over remaining water resources. [ABSTRACT FROM AUTHOR]

We examined the effects of sex, age, and reproductive state of the insectivorous bat Pipistrellus kuhlii on the abundance and prevalence of arthropod ectoparasites (Macronyssidae and Cimicidae) in habitats with either sewage-polluted or natural bodies of water, in the Negev Desert, Israel. We chose water pollution as an environmental factor because of the importance of water availability in desert environments, particularly for P. kuhlii, which needs to drink on a daily basis. We predicted that parasite infestation rates would be affected by both environment and demographic cohort of the host. We found that female bats in the polluted site harbored significantly more mites than female bats in the natural site and that juveniles in the polluted site harbored significantly more cimicid individuals than juveniles in the natural site. We further found that age and sex (host-related factors) affected ectoparasite prevalence and intensity (i.e., the abundance of parasites) in the polluted site. Our results may suggest that the interaction between host-related and environment-related factors affected parasite infestations, with females and young bats being more susceptible to ectoparasites when foraging over polluted water. This effect may be particularly important for bats that must drink or forage above water for other wildlife that depend on drinking water for survival. [ABSTRACT FROM AUTHOR]

The water vapour permeability barrier of mammals and birds resides in the stratum corneum (SC), the outermost layer of the epidermis. The molar ratio and molecular arrangement of lipid classes in the SC determine the integrity of this barrier. Increased chain length and polarity of ceramides, the most abundant lipid class in mammalian SC, contribute to tighter packing and thus to reduced cutaneous evaporative water loss (CEWL). However, tighter lipid packing also causes low SC hydration, making it brittle, whereas high hydration softens the skin at the cost of increasing CEWL. Cerebrosides are not present in the mammalian SC; their pathological accumulation occurs in Gaucher's disease, which leads to a dramatic increase in CEWL. However, cerebrosides occur normally in the SC of birds. We tested the hypothesis that cerebrosides are also present in the SC of bats, because they are probably necessary to confer pliability to the skin, a quality needed for flight.We examined the SC lipid composition of four sympatric bat species and found that, as in birds, their SC has substantial cerebroside contents, not associated with a pathological state, indicating convergent evolution between bats and birds. [ABSTRACT FROM AUTHOR]

Bats broadcast rapid sequences of echolocation calls, named 'drinking buzzes', when they approach water to drink on the wing. So far this phenomenon has received little attention. We recorded echolocation sequences of drinking bats for 12 species, for 11 of which we also recorded feeding buzzes. Based on the different sensorial tasks faced by feeding and drinking bats, we hypothesize that the drinking buzz structure will differ from that of feeding buzzes since unlike the latter drinking buzzes are not designed to detect and track mobile prey. We demonstrated that drinking buzzes are structurally different from feeding buzzes. We show that the buzz- II phase common in feeding buzzes is absent in drinking buzzes; that is, call frequency is not lowered to broaden sonar beam since the task of drinking does not imply tracking fast-moving targets. This finding indirectly confirms the role of buzz II in feeding buzzes. Pulse rate in drinking buzzes is also lower than in feeding buzzes, as predicted since the high pulse rate typical of feeding buzzes is important to update rapidly the relative location of moving targets. The most likely function of drinking buzzes is to guide a safe drinking manoeuvre, similar to 'landing buzzes' broadcast when bats land on the ground. [ABSTRACT FROM AUTHOR]

Echolocating bats have historically been classified as either loud aerial hawkers or whispering gleaners. Some bat species can forage in multiple ways and others have demonstrated limited flexibility in the amplitude of their echolocation calls. The desert long-eared bat, Otonycteris hemprichii, has been said to be a passive gleaning whispering bat preying on terrestrial arthropods such as scorpions. Using an acoustic tracking system, we recorded individuals flying at foraging and drinking sites and compared their flight height, flight speed, call duration, pulse interval and source levels with those of gleaning individuals previously recorded using the same setup. We found differences in all variables with the strongest difference in source levels, where bats called at a mean of 119 dB peSPL (compared with 75 dB peSPL when gleaning). Bat faecal analysis indicated that their diet differed from previous studies and that prey species were capable of flight. We conclude that the bats switched from passive gleaning to capturing airborne insects (aerial hawking). Although whispering bats have been known to opportunistically catch insects on the wing, in the present study we show a full bimodal switch between foraging guilds with the respective changes in source level to those typical of a true aerial hawker. [ABSTRACT FROM AUTHOR]

We studied the epiphytic yeast species of the plants of the Negev Desert and the Dead Sea region, Israel, which are considered one of the most extreme hyper-arid lands in the world. For this purpose, we developed isolation protocols; we performed morphological, cultural and molecular identification tests and compared yeast diversity between the locations and the plants. The composition of the yeast populations present in the study's plants underwent seasonal fluctuations, whereas differences in community compositions were significant within sites. The maximum number of species of yeast occurred in autumn and C ryptococcus spp. were predominant year round. The isolated yeast strains showed an unusual tolerance to extreme growth conditions, such as high temperatures (up to 72% viability at 50° C), lethal hydrogen peroxide and NaCl concentrations. These results suggest that epiphytic yeasts inhabit the plants of the Dead Sea region and the Negev Desert have a community structure that is unique to the plant species and have a high tolerance to the harsh conditions that enables them to adapt to an arid ecosystem. [ABSTRACT FROM AUTHOR]

The controlled adjustment of body temperature ( Tb) by animals in relation to ambient temperature ( Ta), or heterothermy, is a phenomenon that has a clear adaptive value. Heterothermy results in a substantial reduction in energy expenditure and water loss, but it also incurs costs, such as the energy cost required for rewarming, energy cost of excretion of metabolic wastes, delayed development of offspring and fitness costs of increased vulnerability to predators. A general index quantifying heterothermy would be useful, since heterothermy is often correlated with important physiological variables that determine fitness., We used metabolic rate ( MR), Tb and Ta to develop a thermoregulatory index ( TRi), a continuous variable that describes the thermoregulatory effort of animals. TRi is expressed by an equation with two terms: the deviation of actual heat gain/dissipation to heat gain/dissipation predicted by first principles and the temperature dependence of metabolic reactions., TRi can be interpreted as a measure of the amount of time an animal needs to generate an amount of heat, estimated from physical principles, to reach a certain Tb along a temperature gradient., TRi eliminates the need to define a threshold for Tb and can be used to compare positions of animals along a thermoregulatory continuum within and among species of diverse taxonomic affiliation. In addition, TRi unveils the relationship between the energy expended for thermoregulation and important physiological variables that determine survival and reproduction. TRi requires knowledge of MR, which may be a disadvantage since information on MR for free-living animals may be difficult to obtain. However, with the advent of methods to measure field metabolism, this impediment may be surmountable in many species. [ABSTRACT FROM AUTHOR]

Bats hibernate to cope with low ambient temperatures (Ta) and low food availability during winter. However, hibernation is frequently interrupted by arousals, when bats increase body temperature (Tb) and metabolic rate (MR) to normothermic levels. Arousals account for more than 85% of a bat's winter energy expenditure. This has been associated with variation in Tb, Ta or both, leading to a single testable prediction, i.e. that torpor bout length (TBL) is negatively correlated with Ta and Tb. Ta and Tb were both found to be correlated with TBL, but correlations alone cannot establish a causal link between arousal and Tb or Ta. Because hydration state has also been implicated in arousals from hibernation, we hypothesized that water loss during hibernation creates the need in bats to arouse to drink. We measured TBL of bats (Pipistrellus kuhlii) at the same Ta but under different conditions of humidity, and found an inverse relationship between TBL and total evaporative water loss, independent of metabolic rate, which directly supports the hypothesis that hydration state is a cue to arousal in bats. [ABSTRACT FROM AUTHOR]

Anthropogenic habitat modification often has a profound negative impact on the flora and fauna of an ecosystem. In parts of the Middle East, ephemeral rivers (wadis) are characterised by stands of acacia trees. Green, flourishing assemblages of these trees are in decline in several countries, most likely due to human-induced water stress and habitat changes. We examined the importance of healthy acacia stands for bats and their arthropod prey in comparison to other natural and artificial habitats available in the Arava desert of Israel. We assessed bat activity and species richness through acoustic monitoring for entire nights and concurrently collected arthropods using light and pit traps. Dense green stands of acacia trees were the most important natural desert habitat for insectivorous bats. Irrigated gardens and parks in villages and fields of date palms had high arthropod levels but only village sites rivalled acacia trees in bat activity level. We confirmed up to 13 bat species around a single patch of acacia trees; one of the richest sites in any natural desert habitat in Israel. Some bat species utilised artificial sites; others were found almost exclusively in natural habitats. Two rare species (Barbastella leucomelas and Nycteris thebaica) were identified solely around acacia trees. We provide strong evidence that acacia trees are of unique importance to the community of insectivorous desert-dwelling bats, and that the health of the trees is crucial to their value as a foraging resource. Consequently, conservation efforts for acacia habitats, and in particular for the green more densely packed stands of trees, need to increase to protect this vital habitat for an entire community of protected bats. [ABSTRACT FROM AUTHOR]

Total evaporative water loss is the sum of respiratory water loss (RWL) and cutaneous water loss (CWL) and constitutes the main avenue of water loss in bats. Because bats fly and have large surface-to-volume ratios, they potentially have high rates of RWL and CWL. Most species of small insectivorous bats have the ability to reduce their body temperature (Tb) at rest, which substantially reduces energy expenditure and water loss. We hypothesized that bats reduce evaporative water loss during bouts of deep hypothermia (torpor) by decreasing RWL and CWL. We measured Tb, RWL, CWL, and resting metabolic rate (RMR) in Kuhl's pipistrelle Pipistrellus kuhlii, a small insectivorous bat. In support of our hypothesis, we found that RWL decreased with decreasing RMR. We found that CWL was lower in torpid individuals than in normothermic bats; however, bats in deep torpor had similar or higher CWL than bats in shallow torpor, suggesting that they exert a less effective physiological control over CWL when in deep torpor. Because insectivorous bats spend most of their lives in torpor or hibernation, the regulation of CWL in different heterothermic states has relevant ecological and evolutionary consequences. [ABSTRACT FROM AUTHOR]

Environmental conditions, including anthropogenic disturbance, can significantly alter host and parasite communities. Yet, our current knowledge is based mainly on endoparasites, while ectoparasites remain little studied. We studied the indirect effects of anthropogenic disturbance (human population density) and climate (temperature, precipitation and elevation) on abundance of highly host-specific bat flies in four Neotropical bat species across 43 localities in Venezuela. We formulated a set of 11 a priori hypotheses that included a combination of the two effectors and host species. Statistically, each of these hypotheses was represented by a zero-inflated negative binomial mixture model, allowing us to control for excess zeros in the data. The best model was selected using Akaike's information criteria. Fly abundance was affected by anthropogenic disturbance in Artibeus planirostris, Carollia perspicillata and Pteronotus parnellii, but not Desmodus rotundus. Climate affected fly abundance in all bat species, suggesting mediation of these effects via the host or by direct effects on flies. We conclude that human disturbance may play a role in shaping bat-bat fly interactions. Different processes could determine fly abundance in the different bat species. [ABSTRACT FROM AUTHOR]

Summary 1. Nutrients are a critical resource for plant growth, but the elements limiting growth in tropical forests have rarely been determined. 2. We investigated the influence of nitrogen (N), phosphorus (P), potassium (K) and micronutrients on seedling biomass and nutrient allocation in a factorial nutrient fertilization experiment in lowland tropical forest at the Barro Colorado Nature Monument, Panama. We also measured 8 years of herbivory and growth for 1800 seedlings. We sought to determine the identity of limiting elements and possible nutrient interactions. 3. The five study species were Alseis blackiana, Desmopsis panamensis, Heisteria concinna, Sorocea affinis and Tetragastris panamensis. Plants grew in deeply shaded understorey with a mean canopy openness of 4.9% (±0.7%; 1 SE). 4. Tissue N concentration increased by 11% with N addition. Tissue P concentration increased by 16% with P addition. Tissue K increased by 4% with K addition. K addition reduced root-to-shoot biomass ratio. There was no significant effect of fertilization on specific leaf area or leaf area ratio. 5. The proportion of leaves damaged and the mean level of damage by herbivory increased with P and K addition and showed a significant P × K interaction. 6.7ensp;Across all species and years, relative growth rate of height increased with K addition and with N and P in combination. Relative growth rate of leaf count trended 8.5% higher with K addition ( P = 0.076). 7. We also added micronutrients in a parallel experiment. There was no effect of micronutrient addition on any seedling parameter. 8. Synthesis. K addition affected seedlings by enhancing tissue nutrient concentration, increasing herbivory, reducing root-to-shoot biomass ratio and increasing height growth. Additional effects of N or P on tissue chemistry, herbivory and growth offer support for the multiple limiting resources hypothesis. Our results suggest that seedling growth is limited by nutrients, especially K, even under highly shaded conditions in this lowland tropical forest. [ABSTRACT FROM AUTHOR]

Bodies of water are a key foraging habitat for insectivorous bats. Since water is a scarce and limiting resource in arid environments, bodies of open water may have a structuring effect on desert bat communities, resulting in temporal or spatial partitioning of bat activity. Using acoustic monitoring, we studied the spatial and temporal activity patterns of insectivorous bats over desert ponds, and hypothesised that sympatric bat species partition the foraging space above ponds based on interspecific competitive interactions. We used indirect measures of competition (niche overlap and competition coefficients from the regression method) and tested for differences in pond habitat selection and peak activity time over ponds. We examined the effect of changes in the activity of bat species on their potential competitors. We found that interspecific competition affects bat community structure and activity patterns. Competing species partitioned their use of ponds spatially, whereby each species was associated with different pond size and hydroperiod (the number of months a pond holds water) categories, as well as temporally, whereby their activity peaked at different hours of the night. The drying out of temporary ponds increased temporal partitioning over permanent ponds. Differences in the activity of species over ponds in response to the presence or absence of their competitors lend further support to the role of interspecific competition in structuring desert bat communities. We suggest that habitat use and night activity pattern of insectivorous bats in arid environments reflect the trade-offs between selection of preferred pond type or activity time and constraints posed by competitive interactions. [ABSTRACT FROM AUTHOR]

Since mammalian frugivores generally choose to eat ripe fruit in which ethanol concentration ([EtOH]) increases as the fruit ripens, we asked whether ethanol acts as an appetitive stimulant in the Egyptian fruit bat, Rousettus aegyptiacus, and also studied the effects of ethanol on their skin temperature (Ts). We hypothesized that the responses of fruit bats to dietary ethanol are concentration dependent and tested the predictions that the bats’ response is positive, i.e., they eat more when [EtOH] in the food is in the range found in naturally ripe fruit, while it negatively affects them at higher concentrations. We also tested the prediction that in winter, even when availability of fruit is low and thermoregulatory costs are high, ingestion of ethanol by fruit bats is low because assimilated ethanol reduces shivering thermogenesis and peripheral vasodilation; these, alone or together, are detrimental to the maintenance of body temperature (Tb). In summer, captive bats offered food containing 0.1% ethanol significantly increased consumption over food with no ethanol; they did not change consumption when food contained 0.01, 0.3, or 0.5% ethanol; but significantly decreased consumption at higher levels of ethanol [EtOH], i.e., 1 and 2%. In winter, captive bats ate significantly less when their food contained 0.1% ethanol than when it contained 0, 0.3, or 0.5%. During summer, freshly caught bats ate significantly more ethanol-containing food than freshly caught bats in winter. Skin temperature (Ts) in Egyptian fruit bats decreased significantly at an ambient temperature (Ta) of 12°C (winter conditions) after gavage with liquid food containing 1% ethanol. The effect was clearly temperature-dependent, since ethanol did not have the same effect on bats gavaged with food containing 1% or no ethanol at a Ta of 25°C (summer conditions). In conclusion, ethanol may act as an appetitive stimulant for Egyptian fruit bats at low concentrations, but only in summer. Bats are deterred by food containing [EtOH] corresponding to that in overripe, unpalatable fruit (1 and 2%). Furthermore, during winter, Egyptian fruit bats are deterred by ethanol-rich fruit, possibly due to the potential thermoregulatory consequences of ethanol consumption. [ABSTRACT FROM AUTHOR]

Over 70% of the droppings of the gleaning bat Otonycteris hemprichii can contain scorpion fragments. Yet, some scorpions found in its desert habitat possess venom of the highest known toxicity, rendering them a very dangerous prey. In this study, we describe how O. hemprichii catches and handles scorpions, quantify its flight and echolocation behaviour in the field, investigate what sensory modality it uses to detect scorpions, and test whether it selects scorpions according to their size or toxicity. We confirmed that O. hemprichi is a whispering bat (approx. 80 dB peSPL) with short, multi-harmonic calls. In a flight room we also confirmed that O. hemprichii detects scorpions by their walking noises. Amplitudes of such noises were measured and they reach the flying bat at or below the level of echoes of the loess substrate. Bats dropped straight onto moving scorpions and were stung frequently even straight in their face. Stings did not change the bats' behaviour and caused no signs of poisoning. Scorpions were eaten including poison gland and stinger. Bats showed no preference neither for any of the scorpion species nor their size suggesting they are generalist predators with regard to scorpions. [ABSTRACT FROM AUTHOR]

We investigated the patterns of torpor use and body temperature (Tb) in reproductive Hemprich's long-eared bats (Otonycteris hemprichii; body mass ~20 g) in the central Negev Desert highlands. We hypothesized that Tb regulation in female O. hemprichii during reproduction is shaped by a trade-off between the energy and temperature requirements of embryo and pup growth and the mother's own need to use torpor and passive rewarming to save energy and water. We predicted that patterns of torpor use change during pregnancy but change little if at all during nursing. We used radio telemetry to track, find the roosts of, and measure the skin temperatures of eight pregnant and 15 nursing bats during the years 2002-2004; we measured roost temperature (Tr) using temperature data loggers. Before field data collection, we simultaneously measured skin temperature and Tb in three female bats in the laboratory and derived field body temperatures (Tbf) from these data. Female bats often used both deep and shallow daily torpor during the first two trimesters of pregnancy, with Tbf frequently dropping as low as 15°C. Pregnant females used only shallow torpor during the last trimester of pregnancy, perhaps to permit faster growth of the embryo. During nursing, the bats used only shallow torpor, with Tbf always 129°C, possibly to facilitate milk production. Tbf of pregnant and nursing bats varied with daily oscillations in Tr. Passive rewarming was not evident before the animals exited their roosts to forage. [ABSTRACT FROM AUTHOR]

1. Understanding the causes and consequences of animal flight speed has long been a challenge in biology. Aerodynamic theory is used to predict the most economical flight speeds, minimizing energy expenditure either per distance (maximal range speed, Vmr) or per time (minimal power speed, Vmp). When foraging in flight, flight speed also affects prey encounter and energy intake rates. According to optimal flight speed theory, such effects may shift the energetically optimal foraging speed to above Vmp. 2. Therefore, we predicted that if energetic considerations indeed have a substantial effect on flight speed of aerial-hawking bats, they will use high speed (close to Vmr) to commute from their daily roost to the foraging sites, while a slower speed (but still above Vmp) will be preferred during foraging. To test these predictions, echolocation calls of commuting and foraging Pipistrellus kuhlii were recorded and their flight tracks were reconstructed using an acoustic flight path tracking system. 3. Confirming our qualitative prediction, commuting flight was found to be significantly faster than foraging flight (9·3 vs. 6·7 m s−1), even when controlling for its lower tortuosity. 4. In order to examine our quantitative prediction, we compared observed flight speeds with Vmp and Vmr values generated for the study population using two alternative aerodynamic models, based on mass and wing morphology variables measured from bats we captured while commuting. The Vmp and Vmr values generated by one of the models were much lower than our measured flight speed. According to the other model used, however, measured foraging flight was faster than Vmp and commuting flight slightly slower than Vmr, which is in agreement with the predictions of optimal flight speed theory. 5. Thus, the second aerodynamic model we used seems to be a reasonable predictor of the different flight speeds used by the bats while foraging and while commuting. This supports the hypothesis that bats fly at a context-dependent, energetically optimal flight speed. [ABSTRACT FROM AUTHOR]

Natural forests are composed of a heterogeneous mixture of plant architectures that change temporally and spatially. In addition, variation in ridges, tree falls, natural clearing, logs and animal or man-made paths results in a topographic complexity which is likely to have a profound effect on the movements of animals within the forest. [ABSTRACT FROM PUBLISHER]

We used nitrogen isotope analysis from pectoral muscle of the Egyptian fruit bat Rousettus aegyptiacus (Chiroptera: Pteropodidae) to determine intrapopulation variation in sources of dietary protein throughout the year in northern Israel. In Mediterranean climates, winter and summer are stable seasons, whereas spring and fall are transitional seasons. Number of species of fruit-bearing plants is higher during the transitional periods, and we therefore predicted that intrapopulation variation would be higher during spring than in winter and summer; we made no prediction for fall because sample size was small. We also reconstructed sources of dietary protein for each individual using nitrogen isotope ratios (δ15N) to determine whether individuals foraged on the same sources of food within each season. Intrapopulation variation in δ15N was significantly higher in spring (δ15N range: 9.7-17.5‰) compared to winter (8.8-11.1‰) and summer (9.5 -11.2‰), suggesting that individuals during this period varied more in their use of protein sources. Dietary reconstruction revealed intrapopulation partitioning among the bats in the use of plant food items, and interspecific partitioning among plants in their dependence on dispersal by bats. [ABSTRACT FROM AUTHOR]

Food resources are complementary for a forager if their contribution to fitness is higher when consumed together than when consumed independently, e.g. ingesting one may reduce the toxic effects of another. The concentration of potentially toxic ethanol, [EtOH], in fleshy fruit increases during ripening and affects food choices by Egyptian fruit bats, becoming deterrent at high concentrations (⩾1%). However, ethanol toxicity is apparently reduced when ingested along with some sugars; more with fructose than with sucrose or glucose. We predicted (1) that ingested ethanol is eliminated faster by bats eating fructose than by bats eating sucrose or glucose, (2) that the marginal value of fructose-containing food (food+fructose) increases with increasing [EtOH] more than the marginal value of sucrose- or glucose-containing food (food+sucrose, food+glucose), and (3) that by increasing [EtOH] the marginal value of food+sucose is incremented more than that of food+glucose. Ethanol in bat breath declined faster after they ate fructose than after eating sucrose or glucose. When food [EtOH] increased, the marginal value of food+fructose increased relative to food+glucose. However, the marginal value of food+sucrose increased with increasing [EtOH] more than food+fructose or food+glucose. Although fructose enhanced the rate at which ethanol declined in Egyptian fruit bat breath more than the other sugars, the bats treated both fructose and sucrose as complementary to ethanol. This suggests that in the wild, the amount of ethanol-containing fruit consumed or rejected by Egyptian fruit bats may be related to the fruit's own sugar content and composition, and/or the near-by availability of other sucrose- and fructose-containing fruits. [ABSTRACT FROM AUTHOR]

Two decades ago D. J. Keegan reported results on Egyptian fruit bats (Rousettus aegyptiacus, Megachiroptera) that were strangely at odds with the prevailing understanding of how glucose is absorbed in the mammalian intestine. Keegan's in vitro tests for glucose transport against a concentration gradient and with phloridzin inhibition in fruit bat intestine were all negative, although he used several different tissue preparations and had positive control results with laboratory rats. Because glucose absorption by fruit bats is nonetheless efficient, Keegan postulated that the rapid glucose absorption from the fruit bat intestine is not through the enterocytes, but must occur via spaces between the cells. Thus, we hypothesized that absorption of water-soluble compounds that are not actively transported would be extensive in these bats, and would decline with increasing molecular mass in accord with sieve-like paracellular absorption. We did not presume from Keegan's studies that there is no Na+-coupled, mediated sugar transport in these bats, and our study was not designed to rule it out, but rather to quantify the level of possible non-mediated absorption. Using a standard pharmacokinetic technique, we fed, or injected intraperitonealy, the metabolically inert carbohydrates L- rhamnose (molecular mass=164 Da) and cellobiose (molecular mass=342 Da), which are absorbed by paracellular uptake, and 3-O-methyl-D-glucose (3OMD- glucose), a D-glucose analog that is absorbed via both mediated (active) and paracellular uptake. As predicted, the bioavailability of paracellular probes declined with increasing molecular mass (rhamnose, 62±4%; cellobiose, 22±4%) and was significantly higher in bats than has been reported for rats and other mammals. In addition, fractional absorption of 3OMn-glucose was high (91±2%). We estimated that Egyptian fruit bats rely on passive, paracellular absorption for the majority of their glucose absorption (at least 55% of 3OMD-glucose absorption), much more than in non-flying mammals. [ABSTRACT FROM AUTHOR]

We examined the responses of moths to an auditory stimulus in the field with respect to moth size, moth activity state (at rest or flying), whether it responded, and response type. Moths most commonly responded by changing flight direction. Flying moths responded significantly more often to the auditory stimulus than did resting moths; small- and medium-sized moths responded significantly more often than larger ones. We found no differences in use of response types between size classes. We suggest that these behavioral responses to the auditory stimulus are likely due to evolved induced responses to detection of predatory bats. [ABSTRACT FROM AUTHOR]

The diets of frugivorous and nectarivorous vertebrates contain much water and generally have high energy but low protein contents. Therefore, we tested the prediction that to save energy under conditions of high energy demands and high water intake, frugivorous Egyptian fruit bats (Rousettus aegyptiacus)will increase both the absolute quantity and the proportion of ammonia in their urine. We also examined whether such changes occur when protein intake is low and water intake is high. We did three feeding trials. In trials 1 and 2, bats were fed one of four liquid diets containing constant soy protein concentrations but varying in sucrose concentration and were kept at ambient temperatures (Ta) of 30°C and 12°C, respectively. In trial 3, bats were kept at Ta = 12°C and fed one of four liquid diets with equal sucrose concentrations but varying protein concentrations. In trial 1, food intake at a sucrose concentration of 256 mmol/kg H2O was initially high but decreased to a constant rate with further increases in sucrose concentration, while in trial 2, food intake decreased exponentially with increasing sucrose concentration. As predicted, at 12°C with varying sucrose concentration, both the absolute quantity and the fraction of ammonia in the bats' urine increased significantly with food intake (P<0.02), while the absolute quantity of urea and the fraction of urea nitrogen excreted decreased significantly with food intake (P<0.03). Varying sucrose concentration had no significant effect on nitrogen excretion at Ta = 30°C Varying protein concentration had no significant effect on nitrogen excretion at Ta = 12°C. We suggest that Egyptian fruit bats can increase ammonia excretion in response to increased energetic demands, and we calculate that they can save energy equal to #x223C;2% of their daily metabolic rate by doing so. [ABSTRACT FROM AUTHOR]

We compared the thermoregulatory abilities of two insectivorous bat species, Tadarida teniotis (mean body mass 32 g) and Otonycteris hemprichii (mean body mass 25 g), that are of different phylogenetic origins and zoogeographic distributions but are sympatric in the Negev Desert. At night, both were normothermic. By day, both were torpid when exposed to ambient temperatures (Ta) below 25°C, with concomitant adjustments in metabolic rate (MR). Otonycteris hemprichii entered torpor at higher Ta than T. teniotis, and, when torpid, their body temperatures (Tb) were 1°–2°C and 5°–8°C above Ta, respectively; MR was correspondingly reduced. At night, the lower critical temperature of T. teniotis was 31.5°C, and that of O. hemprichii was 33°C. Mean nocturnal thermoneutral MR of T. teniotis was 37% greater than that of O. hemprichii. At high Ta, evaporative water loss (EWL) increased markedly in both species, but it was significantly higher in T. teniotis above 38°C. In both species, the dry heat transfer coefficient (thermal conductance) followed the expected pattern for small mammals, by day and by night. Total EWL was notably low in normothermic and torpid animals of both species, much lower than values reported for other bats, indicating efficient water conservation mechanisms in the study species. Comparing thermoregulatory abilities suggests that O. hemprichii is better adapted to hot, arid environments than T. teniotis, which may explain its wider desert distribution. By both standard and phylogenetically informed ANCOVA, we found no differences in basal metabolic rate (BMR) between desert and nondesert species of insectivorous bats, substantiating previous studies suggesting that low BMR is a characteristic common to insectivorous bats in general. [ABSTRACT FROM AUTHOR]

We studied the role of echolocation and other sensory cues in two small frugivorous New World leaf-nosed bats (Phyllostomidae: Artibeus watsoni and Vampyressa pusilla) feeding on different types of fig fruit. To test which cues the bats need to find these fruit, we conducted behavioral experiments in a flight cage with ripe and similar-sized figs where we selectively excluded vision, olfaction, and echolocation cues from the bats. In another series of experiments, we tested the discrimination abilities of the bats and presented sets of fruits that differed in ripeness (ripe, unripe), size (small, large), and quality (intact(infested with caterpillars). We monitored the bats' foraging and echolocation behavior simultaneously. In flight, both bat species continuously emitted short (<2 ms), multi-harmonic, and steep frequency-modulated (FM) calls of high frequencies, large bandwidth, and very low amplitude. Foraging behavior of bats was composed of two distinct stages: search or orienting flight followed by approach behavior consisting of exploration flights, multiple approaches of a selected fruit, and final acquisition of ripe figs in flight or in a brief landing. Both bat species continuously emitted echolocation calls. Structure and pattern of signals changed predictably when the bats switched from search or orienting calls to approach calls. We did not record a terminal phase before final acquisition of a fruit, as it is typical for aerial insectivorous bats prior to capture. Both bat species selected ripe over unripe fruit and non-infested over infested fruit. Artibeus watsoni preferred larger over smaller fruit. We conclude from our experiments, that the bats used a combination of odor-guided detection together with echolocation for localization in order to find ripe fruit and to discriminate among them. [ABSTRACT FROM AUTHOR]

Aerial hawking bats use intense echolocation calls to search for insect prey. Their calls have evolved into the most intense airborne animal vocalisations. Yet our knowledge about call intensities in the field is restricted to a small number of species. We describe a novel stereo videogrammetry method used to study flight and echolocation behaviour, and to measure call source levels of the aerial hawking bat Eptesicus bottae (Vespertilionidae). Bats flew close to their predicted minimum power speed. Source level increased with call duration; the loudest call of E. bottae was at 133 dB peSPL. The calculated maximum detection distance for large flying objects (e.g. large prey, conspecifics) was up to 21 m. The corresponding maximum echo delay is almost exactly the duration of one wing beat in E. bottae and this also is its preferred pulse interval. These results, obtained by using videogrammetry to track bats in the field, corroborate earlier findings from other species from acoustic tracking methods. [ABSTRACT FROM AUTHOR]

In this paper we discuss how yeast, fungi ubiquitously present in sugar-rich fruit, can influence the interaction between frugivores and fleshy-fruited plants via ethanol. We suggest that plants, the seeds of which are mostly dispersed by vertebrates, exploit the ethanol from alcoholic fermentation by yeast in their seed dispersal strategy. Moderate consumption of ethanol, i.e., at concentrations close to those in naturally ripening fruit, by frugivores may have beneficial short- and long-term effects for these potential dispersers, whereas consumption of larger quantities may have negative short- and long-term effects. Ethanol vapor emanating from palatable fruit may act as an odor cue, guiding bats and other frugivores to the fruit, and aiding them to assess its quality. In addition, we suggest that ingested ethanol may be an appetitive stimulant. We also evaluate the possibility that ethanol within fruit may he used as a source of energy by frugivorous vertebrates. Our preliminary data indicate that Egyptian fruit bats (Rousettus aegyptiacus) can use the odor of ethanol to assess food suitability, but also that it may not serve as an attractant over short distances (i.e., <1 m). Instead, ethanol is avoided at concentrations greater than 1%, a value which might typically characterize overripe and otherwise unpalatable fruit. Our initial results further indicate that Egyptian fruit bats significantly decrease their food consumption if it contains 1 or 2% ethanol. Overall, ethanol may play diverse roles in the nutritional ecology and behavior of fruit-eating bats, and in the interaction between frugivores and plants, in general. [ABSTRACT FROM AUTHOR]

This article focuses on measuring fat mass in small birds by dual-energy x ray absorptiometry. In numerous studies, body condition of animals trapped in the wild has been expressed either as a function of body mass or as a ratio of body mass to some linear body measurement, such as snout-vent length in animals, or simply by visual assessment of stored fat. Different direct and nondestructive methods have been used to measure body condition. These methods include the ratio of total body water to body mass total body electrical conductivity, or bioelectrical impedance analysis.

This study explored how a flying frugivorous mammal, the Egyptian fruit bat (Rousettus aegyptiacus), meets the increased energy requirements of reproduction. This bat feeds on low-protein fruit, and females have bimodal polyestrous cycles that are relatively long for a small mammal. We measured the energy and water balance of captive nonreproductive, pregnant, and lactating females, and of free-ranging lactating females. Our results indicate that females use more than one strategy to cope with the high energy demands of reproduction. These strategies may change according to the availability of food and reproductive status. The primary strategy near the end of pregnancy and at peak lactation was increased food consumption. In the laboratory, mean metabolizable energy intake (Mel) of pregnant and lactating females (271 and 360 kJ/d, respectively) increased by 35% and 80%, respectively, compared to that of nonreproductive females (200 kJ/d). At peak lactation, energy intake measured by doubly labeled water averaged 350 kJ/d. During late pregnancy, water turnover rate (WTO) increased by 15-23% compared to that of nonreproductive females. In the field, WTO at peak lactation was 44% higher than in captive lactating females, and milk production was estimated to be 22 mL/d. Absolute resting metabolic rate (RMR) in late pregnancy was significantly lower than the RMR of nonreproductive females, suggesting that a metabolic depression was used as a compensatory mechanism. Fat deposition was evident during the second pregnancy, when food availability was high, presumably in preparation for a second lactation period. Fetal tissue represented ∼ 1.3% of the total energy assimilated during pregnancy, and the gross efficiency of lactation averaged 24%. Both values are lower than the values reported for other eutherian mammals, but similar to estimates for other bat species, and probably reflect the high energy costs associated with flight. [ABSTRACT FROM AUTHOR]

In past studies, several rodent species of the murid subfamilies Gerbillinae and Cricetomyinae from the Namib Desert, when deprived of water, excreted allantoin precipitate in their urine. Shifting nitrogen excretion from urea to allantoin allows them to save much water. This phenomenon has not been reported in other rodents, and whether it is a trait that is common among desert rodents, but undocumented, or is unique to these Namib Desert species, is not known. We found no allantoin precipitate in the urine of any of five additional species of water-deprived murid rodents of two subfamilies from the Negev Desert. There was no discernible precipitate in the urine of Gerbillus andersoni allenbyi (Gerbillinae), Gerbillus pyramidum (Gerbillinae), or Acomys cahirinus (Murinae). Sodium oxalate was found in both the precipitate and the liquid urine of Psammomys obesus (Gerbillinae), and the as yet unidentified precipitate in the urine of Gerbillus dasyurus (Gerbillinae) was not allantoin. This preliminary study suggests that not all gerbilline rodents have the capacity to switch from urea to allantoin excretion. The Namib Desert gerbilline and cricetomyine rodents may be examples of closely related mammalian taxa that have evolved a new metabolic pathway to produce a nitrogenous product that results in sizable water savings, i.e., by switching from urea to allantoin. [ABSTRACT FROM AUTHOR]

Uricotely (uric acid > 50% of urinary nitrogen) in birds was once considered ubiquitous. However, Anna's hummingbirds (Calypte anna) have been shown to be an exception to this rule; under conditions of low ambient temperature (Ta ) and on a nitrogen-free diet, they increased their water intake and often became ammonotelic (ammonia > 50% of urinary nitro-gen). Our aim was to identify the effects of nitrogen intake, water intake, and Ta on the ammonia excretion of yellow-vented bulbuls (Pycnonotus xanthopygos). We chose this predominantly frugivorous species because many of the characteristics of nec-tarivores that were used to explain increased ammonia excre-tion by C. anna are also characteristics of frugivorous birds. We assayed ureteral urine composition in eight yellow-vented bulbuls (P. xanthopygos), each randomly allocated a diet of 20% (0.6 M) sucrose solution supplemented by either 1.03 g/L or 7.23 g/L soy protein and held at a Ta of either 28 ° C or 10 ° C. Food, and therefore water, intake rates varied with nitrogen intake but not with Ta . Food intake increased significantly with decreased nitrogen intake, while concentrations of all the ex-cretory compounds in the urine ( ) decreased; yet their P =0.05 proportions in the urine did not change significantly. The lower Ta had no significant effect on food intake or on the concen-tration of uric acid. However, at 10° C, the ammonia and urea concentrations increased ( ), and this led to a significant P=0.05 increase in the proportion of ammonia in the urine. Our results demonstrate that, when bulbuls are exposed to low Ta , they are able to save energy by increasing the proportion of the am-monia in their urine. [ABSTRACT FROM AUTHOR]

We describe fruiting characteristics for 12 species in a community of strangler figs (Moraceae: Urostigma) studied in Panama. We quantify diurnal and nocturnal removal rates and proportions of fruits removed, and relate them to the activities of the main dispersers of the figs: bats and birds. These results combined with previous studies show that there are clear differences between fig species with fruit that ripen red and those with fruit that remain green(ish). In the red-fruited species, the fruit are small, ripen asynchronously over relatively long periods, produce little scent, and are mainly taken during the day by birds. In contrast, in the green(ish)-fruited species, the fruits are larger, span a range of sizes, ripen relatively synchronously, produce very distinctive aromas, and are mainly taken at night by bats. This dichotomy in fruiting characteristics suggests coadaptive links between groups of dispersers and different species within the genus Ficus. All fig species produce a range of fruit crop sizes (10–155 fuits/m2 canopy area) of which a high proportion were removed by seed dispersers (>80%). Removal rates (fruit removed per day) were positively correlated with crop size, suggesting that trees with large crop size attract more frugivores. Removal rates of green-fruited figs were significantly lower and persistence and abortion of ripe fruit were significant higher around full moon, apparently due to the reduced activity of bats. We further estimate the number of bats that are sustained by a tree fruit crop and account for the observed fruit removal. We then discuss the evidence for coadaptation between different groups of figs and their seed dispersers, Finally, we consider the conservation implications for figs as keystone resources in tropical forests. [ABSTRACT FROM AUTHOR]

Studies the changes in milk composition of the free-ranging Egyptian fruit-bat during lactation period. Materials and methods used; Milking procedure; Milk analysis; Results and discussion.

Central-place (CP) foraging theory predicts a positive correlation between the time a breeding CP forager spends in a patch and the distance of the patch to the CP. We found that nursing female Hemprich’s long-eared bats (Otonycteris hemprichii Peters, 1859; Vespertilionidae) that forage around a lake in the Negev roost in only two areas: one 0.5-2 km (near) and one 9 km (far) from the foraging area. If these bats are CP foragers, then the strategies of the two groups should differ. We predicted that females roosting farther away would have longer but fewer foraging bouts. Using radiotelemetry, we measured the activity of six females from the near site and three from the far site. Without exception, females from the far site made a single, prolonged foraging bout each night, while females roosting nearby made several shorter bouts. Among the females from the near site, daily foraging time, mean daily foraging bout length, and first daily foraging bout length were all significantly and positively correlated with distance between the roost and the foraging site. Our data support the prediction that female O. hemprichii are CP foragers. We suggest that the females trade off using a safe roost site, distant from a choice foraging area, and lower nursing frequency against using a risky roost site close to the foraging area and greater nursing frequency. La théorie de la quête alimentaire depuis un point central (CP) prédit qu’il y aura une corrélation positive entre le temps qu’un organisme reproducteur qui s’alimente depuis un CP passe dans une parcelle et la distance de cette parcelle du CP. Nous avons observé que des femelles allaitantes de l’oreillard d’Hemprich (Otonycteris hemprichii Peters, 1859; Vespertilionidae) qui s’alimentent autour d’un lac dans le Néguev se perchent seulement dans deux sites, l’un (proche) à 0,5-2 km et l’autre (éloigné) à 9 km de la région d’alimentation. Si ces chauves-souris s’alimentent depuis un CP, il devrait alors y avoir des différences de stratégie entre les deux groupes. Nous avons prédit que les femelles qui se perchent à une distance plus grande devraient avoir des épisodes alimentaires plus longs, mais moins nombreux. Nous avons mesuré par radiotélémétrie l’activité de six femelles du site rapproché et de trois du site éloigné. Sans exception, les femelles du site éloigné entreprennent une seule sortie alimentaire prolongée chaque nuit, alors que les femelles qui nichent tout près font plusieurs sorties plus courtes. Chez les femelles du site rapproché, la durée journalière de la quête alimentaire, la durée journalière moyenne des sorties alimentaires et la durée de la première sortie chaque jour sont toutes en corrélation significative et positive avec la distance entre le site de perchage et le site d’alimentation. Nos données appuient la prédiction que les femelles d’O. hemprichii s’alimentent depuis un CP. Nous croyons que les femelles font un compromis entre un site sécuritaire de perchage loin du site d’alimentation et une fréquence réduite d’allaitement, d’une part, et un site plus hasardeux près du site d’alimentation et une fréquence d’allaitement plus grande, d’autre part. [ABSTRACT FROM AUTHOR]

Bat abundance and activity in deserts is affected by the distribution of water sources. Kuhl’s pipistrelle (Pipistrellus kuhlii) is one of several bat species that penetrated the Negev desert from Mediterranean habitats following anthropogenic development, and potentially competes with desert dwelling bats of the same guild. Pipistrellus kuhlii is an obligate drinker requiring a clear ‘swoop zone’ to drink. Thus, to reduce the competitive load that P. kuhlii has on desert dwelling species, we tested the effectiveness of obstructions above water surfaces, which we hypothesised would reduce the drinking ability of P. kuhlii, thus providing desert species a competitive edge. We obstructed the water surface of a swimming pool and successfully prevented P. kuhlii from drinking. Next, we manipulated natural water sources used by bats for foraging. This was done on two spatial and temporal scales: on 11 adjacent ephemeral water pools in Nahal Zin where each treatment was applied for several nights and on eight isolated natural pools in the Negev where treatments were alternated every 20 min. Manipulation of adjacent pools had no effect on activity levels of bats, but in isolated pools, the obstruction reduced the proportion of P. kuhlii activity by up to 15%. Although this tool cannot be used for management without further examination of its long-term effects on other bats and wildlife, this study does demonstrate its feasibility. Conservation schemes aiming to mitigate effects of undesirable species can be designed by identifying ecological differences between competing species, and manipulating the environment accordingly. [ABSTRACT FROM AUTHOR]