Ben Gurion University of the Negev
Blaustein Institutes for Desert Research
Background: Molecular techniques are increasingly employed to recognize the presence of cryptic species, even among commonly observed taxa. Previous studies have demonstrated that bats using high-duty cycle echolocation may be more likely... more
Background: Molecular techniques are increasingly employed to recognize the presence of cryptic species, even among commonly observed taxa. Previous studies have demonstrated that bats using high-duty cycle echolocation may be more likely to speciate quickly. Pteronotus parnellii is a widespread Neotropical bat and the only New World species to use high-duty cycle echolocation, a trait otherwise restricted to Old World taxa. Here we analyze morphological and acoustic variation and genetic divergence at the mitochondrial COI gene, the 7 th intron region of the y-linked Dby gene and the nuclear recombination-activating gene 2, and provide extensive evidence that P. parnellii is actually a cryptic species complex. Results: Central American populations form a single species while three additional species exist in northern South America: one in Venezuela, Trinidad and western Guyana and two occupying sympatric ranges in Guyana and Suriname. Reproductive isolation appears nearly complete (only one potential hybrid individual found). The complex likely arose within the last~6 million years with all taxa diverging quickly within the last~1-2 million years, following a pattern consistent with the geological history of Central and northern South America. Significant variation in cranial measures and forearm length exists between three of the four groups, although no individual morphological character can discriminate these in the field. Acoustic analysis reveals small differences (5-10 kHz) in echolocation calls between allopatric cryptic taxa that are unlikely to provide access to different prey resources but are consistent with divergence by drift in allopatric species or through selection for social recognition. Conclusions: This unique approach, considering morphological, acoustic and multi-locus genetic information inherited maternally, paternally and bi-parentally, provides strong support to conclusions about the cessation of gene flow and degree of reproductive isolation of these cryptic species.
- by Amanda Adams and +1
- •
The probability of detecting the echolocation calls of bats is affected by the strength of the signal as well as the directionality and frequency response of the acoustic detectors. Regardless of the research question, it is important to... more
The probability of detecting the echolocation calls of bats is affected by the strength of the signal as well as the directionality and frequency response of the acoustic detectors. Regardless of the research question, it is important to quantify variation in recording system performance and its impacts on bat detection results. The purpose of this study was to compare the detection of echolocation calls among five commonly used bat detectors: AnaBat SD2 (Titley Scientific), Avisoft UltraSoundGate 116 CM16/CMPA (Avisoft Bioacoustics), Batcorder 2·0 (ecoObs), Batlogger (Elekon AG) and Song Meter SM2BAT (Wildlife Acoustics).We used playback of synthetic calls to optimize detection settings for each system. We then played synthetic signals at four frequencies (25, 55, 85 and 115 kHz) at 5-m intervals (5–40 m) and three angles (0°, 45°, 90°) from the detectors. Finally, we recorded free-flying bats (Lasiurus cinereus), comparing the number of calls detected by each detector. Detection was most affected by the frequency dominating the signal and the distance from the source. The effect of angle was less apparent. In the synthetic signal experiment, Avisoft and Batlogger outperformed other detectors, while Batcorder and Song Meter performed similarly. Batlogger performed better than the other detectors at angles off-centre (45° and 90°). AnaBat detected the fewest signals and none at 85 kHz or 115 kHz. Avisoft detected the most signals. In the free-flying bat experiment, Batlogger recorded 93% of calls relative to Avisoft, while AnaBat, Batcorder and Song Meter recorded 40–50% of the calls detected by Avisoft. Numerous factors contribute to variation in data sets from acoustic monitoring; our results demonstrate that choice of detector plays a role in this variation. Differences among detectors make it difficult to compare data sets obtained with different systems. Therefore, the choice of detector should be taken into account in designing studies and considering bat activity levels among studies using different detectors.
- by Amanda Adams and +1
- •
1. Omnivory enables animals to fill more than one trophic niche, providing access to a wider variety of food resources with potentially higher nutrient value, particularly when resources become scarce. Animals can achieve omnivory using... more
1. Omnivory enables animals to fill more than one trophic niche, providing access to a wider variety of food resources with potentially higher nutrient value, particularly when resources become scarce. Animals can achieve omnivory using different strategies, for example opportunistic foraging, or switching between multiple trophic niches.
2. The Neotropical bat Glossophaga soricina (Pallas, 1766) is a common and widespread species known for nectar-feeding, but it also eats fruit and insects. Approaching stationary objects (flowers and fruits) or moving objects (insects) pose different sensory tasks and should require different echolocation behaviours. Here we tested the contrasting hypothesis that G. soricina can approach both stationary and moving objects using the same echolocation behaviour, thus feeding at different trophic levels by a single sensory mechanism.
3. Using DNA barcoding, we demonstrate that G. soricina eats beetles (Coleoptera), flies (Diptera), and noctuid moths with bat-detecting ears. Lab observations show that G. soricina actively hunts for prey so insect consumption does not appear to be opportunistic. After capture, individuals consumed prey while perched and manipulated them with jaw, thumb, wrist and wing movements, but food handling was longer and chewing rate slower than in obligate insectivores.
4. In contrast to most insectivorous bats, the echolocation calls of G. soricina are of high frequency and low intensity, and G. soricina did not produce feeding buzzes when approaching insects. An acoustic model of detection distances shows that its low intensity calls fail to trigger the auditory neurons of eared moths, allowing G. soricina to overcome auditory prey defences.
5. Individuals achieved niche flexibility using a unique but generalist behavioural approach rather than employing two different specialist methods. Our findings provide a novel insight into the functional mechanisms of insect capture in G. soricina and highlight the importance of considering niche flexibility in classifying trophic links in ecological communities.
2. The Neotropical bat Glossophaga soricina (Pallas, 1766) is a common and widespread species known for nectar-feeding, but it also eats fruit and insects. Approaching stationary objects (flowers and fruits) or moving objects (insects) pose different sensory tasks and should require different echolocation behaviours. Here we tested the contrasting hypothesis that G. soricina can approach both stationary and moving objects using the same echolocation behaviour, thus feeding at different trophic levels by a single sensory mechanism.
3. Using DNA barcoding, we demonstrate that G. soricina eats beetles (Coleoptera), flies (Diptera), and noctuid moths with bat-detecting ears. Lab observations show that G. soricina actively hunts for prey so insect consumption does not appear to be opportunistic. After capture, individuals consumed prey while perched and manipulated them with jaw, thumb, wrist and wing movements, but food handling was longer and chewing rate slower than in obligate insectivores.
4. In contrast to most insectivorous bats, the echolocation calls of G. soricina are of high frequency and low intensity, and G. soricina did not produce feeding buzzes when approaching insects. An acoustic model of detection distances shows that its low intensity calls fail to trigger the auditory neurons of eared moths, allowing G. soricina to overcome auditory prey defences.
5. Individuals achieved niche flexibility using a unique but generalist behavioural approach rather than employing two different specialist methods. Our findings provide a novel insight into the functional mechanisms of insect capture in G. soricina and highlight the importance of considering niche flexibility in classifying trophic links in ecological communities.
- by Holger R. Goerlitz and +2
- •
In southern Ontario, Canada, the range and distribution of bats is well known, but their activity in the northeastern part of the province (north of 47°N, east of 85°W) is poorly documented. Using acoustic sampling, we documented the... more
In southern Ontario, Canada, the range and distribution of bats is well known, but their activity in the northeastern part of the province (north of 47°N, east of 85°W) is poorly documented. Using acoustic sampling, we documented the occurrence of six species of bats in the boreal forest of northeastern Ontario: Eptesicus fuscus (Big Brown Bat), Lasiurus borealis (Eastern Red Bat), L. cinereus (Hoary Bat), Myotis lucifugus (Little Brown Bat), M. septentrionalis (Northern Long-eared Bat), and Lasionycteris noctivagans (Silver-haired Bat). Hoary Bats were recorded more frequently than all other species. Little Brown Bats were second-most frequently recorded, and the remaining four species were encountered (mean number passes/hour) significantly less often. Our records are the most northerly for Big Brown Bats in this part of Ontario. Although the other species were expected in this area, this is the first study to identify and confirm the bats present in the boreal forest of northeastern Ontario. This new information will contribute to efforts to conserve biodiversity in the province and may inform future studies or monitoring programs associated with the spread of white-nose syndrome in Ontario.
- by Amanda Adams and +1
- •
1. Omnivory enables animals to fill more than one trophic niche, providing access to a wider variety of food resources with potentially higher nutrient value, particularly when resources become scarce. Animals can achieve omnivory using... more
1. Omnivory enables animals to fill more than one trophic niche, providing access to a wider variety of food resources with potentially higher nutrient value, particularly when resources become scarce. Animals can achieve omnivory using different strategies, for example opportunistic foraging, or switching between multiple trophic niches. 2. The Neotropical bat Glossophaga soricina (Pallas, 1766) is a common and widespread species known for nectar feeding, but it also eats fruit and insects. Approaching stationary objects (flowers and fruits) or moving objects (insects) poses different sensory tasks and should require different echolocation behaviours. Here we tested the contrasting hypothesis that G. soricina can approach both stationary and moving objects using the same echolocation behaviour, thus feeding at different trophic levels by a single sensory mechanism. 3. Using DNA barcoding, we demonstrate that G. soricina eats beetles (Coleoptera), flies (Diptera) and noctuid moths with bat-detecting ears. Laboratory observations show that G. soricina actively hunts for prey so insect consumption does not appear to be opportunistic. After capture, individuals consumed prey while perched and manipulated them with jaw, thumb, wrist and wing movements, but food handling was longer and chewing rate slower than in obligate insectivores. 4. In contrast to most insectivorous bats, the echolocation calls of G. soricina are of high frequency and low intensity, and G. soricina did not produce feeding buzzes when approaching insects. An acoustic model of detection distances shows that its low-intensity calls fail to trigger the auditory neurons of eared moths, allowing G. soricina to overcome auditory prey defences. 5. Individuals achieved niche flexibility using a unique but generalist behavioural approach rather than employing two different specialist methods. Our findings provide a novel insight into the functional mechanisms of insect capture in G. soricina and highlight the importance of considering niche flexibility in classifying trophic links in ecological communities.
1. The probability of detecting the echolocation calls of bats is affected by the strength of the signal as well as the directionality and frequency response of the acoustic detectors. Regardless of the research question, it is important... more
1. The probability of detecting the echolocation calls of bats is affected by the strength of the signal as well as the directionality and frequency response of the acoustic detectors. Regardless of the research question, it is important to quantify variation in recording system performance and its impacts on bat detection results. The purpose of this study was to compare the detection of echolocation calls among five commonly used bat detectors: Ana-Bat SD2 (Titley Scientific), Avisoft UltraSoundGate 116 CM16/CMPA (Avisoft Bioacoustics), Batcorder 2Á0 (ecoObs), Batlogger (Elekon AG) and Song Meter SM2BAT (Wildlife Acoustics). 2. We used playback of synthetic calls to optimize detection settings for each system. We then played synthetic signals at four frequencies (25, 55, 85 and 115 kHz) at 5-m intervals (5-40 m) and three angles (0°, 45°, 90°) from the detectors. Finally, we recorded free-flying bats (Lasiurus cinereus), comparing the number of calls detected by each detector. 3. Detection was most affected by the frequency dominating the signal and the distance from the source. The effect of angle was less apparent. In the synthetic signal experiment, Avisoft and Batlogger outperformed other detectors, while Batcorder and Song Meter performed similarly. Batlogger performed better than the other detectors at angles off-centre (45°and 90°). AnaBat detected the fewest signals and none at 85 kHz or 115 kHz. Avisoft detected the most signals. In the free-flying bat experiment, Batlogger recorded 93% of calls relative to Avisoft, while AnaBat, Batcorder and Song Meter recorded 40-50% of the calls detected by Avisoft. 4. Numerous factors contribute to variation in data sets from acoustic monitoring; our results demonstrate that choice of detector plays a role in this variation. Differences among detectors make it difficult to compare data sets obtained with different systems. Therefore, the choice of detector should be taken into account in designing studies and considering bat activity levels among studies using different detectors.
Many animals reside in burrows that may serve as refuges from predators and adverse environmental conditions. Burrow design varies widely among and within taxa, and these structures are adaptive, fulfilling physiological (and other)... more
Many animals reside in burrows that may serve as refuges from predators and adverse environmental conditions. Burrow design varies widely among and within taxa, and these structures are adaptive, fulfilling physiological (and other) functions. We examined the burrow architecture of three scorpion species of the family Scorpionidae: Scorpio palmatus from the Negev desert, Israel; Opistophthalmus setifrons, from the Central Highlands, Namibia; and Opistophthalmus wahlbergii from the Kalahari desert, Namibia. We hypothesized that burrow structure maintains temperature and soil moisture conditions optimal for the behavior and physiology of the scorpion. Casts of burrows, poured in situ with molten aluminum, were scanned in 3D to quantify burrow structure. Three architectural features were common to the burrows of all species: (1) a horizontal platform near the ground surface, long enough to accommodate the scorpion, located just below the entrance, 2-5 cm under the surface, which may pr...
Echolocating bats face the challenge of actively sensing their environment through their own emissions, while also hearing calls and echoes of nearby conspecifics. How bats mitigate interference is a long-standing question that has both... more
Echolocating bats face the challenge of actively sensing their environment through their own emissions, while also hearing calls and echoes of nearby conspecifics. How bats mitigate interference is a long-standing question that has both ecological and technological implications, as biosonar systems continue to outperform man-made sonar systems in noisy, cluttered environments. We recently showed that perched bats decreased calling rates in groups, displaying a behavioral strategy resembling the back-off algorithms used in artificial communication networks to optimize information throughput at the group level. We tested whether free-tailed bats (Tadarida brasiliensis) would employ such a coordinated strategy while performing challenging flight maneuvers, and report here that bats navigating obstacles lowered emission rates when hearing artificial playback of another bat’s calls. We measured the impact of acoustic interference on navigation performance and show that the calculated red...
Context Identifying key spatio–temporal periods of an organism’s activity is an important focus of many ecological studies. Bat activity, as assessed by passive acoustic monitoring, can be extremely variable and currently there exists no... more
Context Identifying key spatio–temporal periods of an organism’s activity is an important focus of many ecological studies. Bat activity, as assessed by passive acoustic monitoring, can be extremely variable and currently there exists no agreed-upon method for identifying periods of high activity. Aims We proposed a new application for the space–time scan statistic (SaTScan) as an objective technique for identifying peak periods of bat activity. We aimed to test the validity of SaTScan as a method for identifying peaks in bat activity and demonstrate its use for assessing species-specific temporal patterns of activity. Methods To evaluate the effectiveness of SaTScan for detecting peaks in activity, we compared SaTScan to peaks identified with percentile thresholds. We evaluated peaks in activity across three scales: within nights; among nights at a site; and among sites. We applied SaTScan to demonstrate analysis of species-specific activity as further use of this technique. Key re...
As molecular tools for assessing trophic interactions become common, research is increasingly focused on the construction of interaction networks. Here we demonstrate three key methods for incorporating DNA data into network ecology and... more
As molecular tools for assessing trophic interactions become common, research is increasingly focused on the construction of interaction networks. Here we demonstrate three key methods for incorporating DNA data into network ecology and discuss analytical considerations using a model consisting of plants, insects, bats and their parasites from the Costa Rican dry forest. The simplest method involves the use of Sanger sequencing to acquire long sequences to validate or refine field identifications, for example of bats and their parasites, where one specimen yields one sequence and one identification. This method can be fully quantified and resolved and these data resemble traditional ecological networks. For more complex taxonomic identifications, we target multiple DNA loci e.g. from a seed or fruit pulp sample in faeces. These networks are also well resolved but gene targets vary in resolution and quantification is difficult. Finally for mixed templates such as faecal contents of insectivorous bats we use DNA metabarcoding targeting two sequence lengths (157bp, 407bp) of one gene region and a MOTU, BLAST and BIN association approach to resolve nodes. This network type is complex to generate and analyse and we discuss the implications of this type of resolution on network analysis. Using these data we construct the first molecular-based network of networks containing 3304 interactions between 762 nodes of 8 trophic functions and involving parasitic, mutualistic, and predatory interactions. We provide a comparison of the relative strengths and weaknesses of these data types in network ecology.
A new simulation model, QUICK II, is presented and numerous verification case studies performed on naturally ventilated buildings are discussed. Four new case studies performed on two buildings located in the Negev desert in Israel are... more
A new simulation model, QUICK II, is presented and numerous verification case studies performed on naturally ventilated buildings are discussed. Four new case studies performed on two buildings located in the Negev desert in Israel are discussed in detail. All the measurements pertaining to these new case studies were taken independently by the Desert Architecture Unit of the Jacob Blaustein Institute for Desert Research. These measurements are provided, along with a description of the buildings. The verification results show a good correlation between the measured and simulated parameters. The simulated temperatures were found to be within 1oC of the measured temperatures for 73% of the time, and within 2oC for 95% of the time.
The majority of the population of the planet (6.6 billion) now live in urban areas, which have distinct impacts upon climate at scales from the local to the global. This urban effect is due to the physical form of the city (its... more
The majority of the population of the planet (6.6 billion) now live in urban areas, which have distinct impacts upon climate at scales from the local to the global. This urban effect is due to the physical form of the city (its three-dimensional geometry and material composition) and its functions (the day-to-day activity patterns that generate emissions of waste heat and materials into the overlying air). While a substantial body of knowledge on the science of urban climates has been developed over the past fifty years, there is little evidence that this knowledge is incorporated into urban planning and design practice. This paper focuses on this gap by examining the nature of urban climate expertise and the needs of those that make decisions about urban areas. In conclusion it makes recommendations to maintain and enhance urban observations and data; to improve understanding of local, regional and global climate linkages; to develop tools for practical planning; and to disseminate urban climate knowledge and its relevance to urban planning to both practicing meteorologists and urban decision makers.
CAT (Canyon Air Temperature) is a parametric model that predicts site-specific air temperature in an urban street canyon for extended periods on the basis of data from a reference station in the region. A method is described for... more
CAT (Canyon Air Temperature) is a parametric model that predicts site-specific air temperature in an urban street canyon for extended periods on the basis of data from a reference station in the region. A method is described for incorporating spatial and temporal variations in ...
- by Evyatar Erell and +1
- •
CAT (Canyon Air Temperature) is a parametric model that predicts site-specific air temperature in an urban street canyon for extended periods on the basis of data from a reference station in the region. A method is described for... more
CAT (Canyon Air Temperature) is a parametric model that predicts site-specific air temperature in an urban street canyon for extended periods on the basis of data from a reference station in the region. A method is described for incorporating spatial and temporal variations in ...
- by Evyatar Erell and +1
- •