Bats Face Research Articles

Application of the MENTOR model to advance One Health by promoting bat conservation and reducing zoonotic spillover risk

For few taxonomic groups do conservation efforts have such a disproportionate impact on biodiversity and human well-being as they do with bats. Bats face significant conservation challenges that affect their long-term viability, inhibit their ecosystem functions and services, and increase zoonotic spillover risks. Protecting bat populations and their habitats ultimately reduces these conservation threats, helps prevent pandemics, and supports essential ecosystem services. MENTOR-Bat is a fellowship program focused on strengthening technical research, and leadership capacity in the Global South to promote healthy environments where bats and humans can coexist with reduced risks of pathogen transmission. Co-designed by the United States Fish and Wildlife Service (USFWS) and Bat Conservation International (BCI), MENTOR-Bat mirrors the One Health framework by featuring a transdisciplinary team of three mentors and nine fellows from Cameroon, Colombia, and Indonesia. Fellows and mentors receive academic and field-based training on bat ecology and conservation, One Health, human dimensions of conservation, behavior change, strategic communications, international policy, adaptive management, project planning, conservation leadership, and public health. Fellows will then design and implement team pilot projects to advance One Health and bat conservation in their respective countries. Program evaluation of MENTOR-Bat is based on Kirkpatrick’s Hierarchy and focuses on measuring the development of established One Health core competences. By incorporating One Health and conservation within its activities, MENTOR-Bat can become a valuable programmatic template for transdisciplinary programming advancing evidence-based strategies for improving the well-being of bats, humans, and the environment.

Light-averse behaviour of attic-dwelling bats when commuting through urban areas

Light pollution is spreading around the world, causing a variety of problems, particularly for nocturnal animals such as bats. As urban areas expand, attic-dwelling bats face the problem of being exposed to more and more artificial light as they move to their dark foraging areas. Avoiding street lights could force bats to make energetically costly detours, which could eventually lead to the collapse of urban colonies. We therefore investigated the response of attic-dwelling bats to street lighting, using the brown long-eared bat (Plecotus auritus) as an example. Using radio-tracking, we followed 17 bats during their commutes through two urban areas: a small town and a village in rural Germany. After a conservative filtering process to ensure a high spatial accuracy of the tracking data, we analysed the data of nine bats in detail, using a use-versus-availability approach for the small town and a descriptive approach for the smaller dataset obtained from the village. The best-fitting model confirmed that the bats responded to artificial light at night. Close to the roost (∼10 m), bats preferred areas with low light intensities, but seemed to tolerate some light levels. We speculate that this pattern was caused by bats being forced to leave the roost into an illuminated area. At medium distances from roosts (∼400 m), most bats avoided street lights. In fact, all bats avoided being in close proximity to street lights, even when the lanterns produced only low levels of light. We conclude that brown long-eared bats avoid street lights when moving through urban areas. We recommend the establishment of dark corridors in urban areas to support high bat diversity, including all species along the continuum of light-opportunistic and light-sensitive species.

Feeding efficiency of two coexisting nectarivorous bat species (Phyllostomidae: Glossophaginae) at flowers of two key-resource plants.

Animals should maximize their energy uptake while reducing the costs for foraging. For flower-visitors these costs and benefits are rather straight forward as the energy uptake equals the caloric content of the consumed nectar while the costs equal the handling time at the flower. Due to their energetically demanding lifestyle, flower-visiting bats face particularly harsh energetic conditions and thus need to optimize their foraging behavior at the flowers of the different plant species they encounter within their habitat. In flight cage experiments we examined the nectar-drinking behavior (i.e. hovering duration, nectar uptake, and the resulting feeding efficiency) of the specialized nectar-feeding bat Hylonycteris underwoodi and the more generalistic Glossophaga commissarisi at flowers of two plant species that constitute important nectar resources in the Caribbean lowland rainforests of Costa Rica and compared nectar-drinking behavior between both bat species and at both plant species. We hypothesized that the 1) specialized bat should outperform the more generalistic species and that 2) bats should generally perform better at flowers of the nectar-rich flowers of the bromeliad Werauhia gladioliflora than at the relatively nectar-poor flowers of the Solanaceae Merinthopodium neuranthum that has an extremely long flowering phase and therefore is an extremely reliable nectar resource, particularly for the specialized Hylonycteris. While we did not find substantial differences in the feeding efficiency of the generalist G. commissarisi, we observed an increased feeding efficiency of the specialized H. underwoodi at flowers of the nectar-poor M. neuranthum. This suggests that familiarity and ecological importance are more important determinants of the interaction than just morphological traits. Our results demonstrate that in addition to morphology, behavioral adaptations are also important drivers that determine the fitness of nectar-feeding bats. Both familiarity with and the ecological importance of a resource seem to contribute to shaping the interactions between pollinating bats and their plants.

Roost characteristics of Indian flying fox along urban noise gradient: A case study in Sallaghari Forest, Kathmandu Valley, Nepal

The Indian flying fox, Pteropus medius is a fruit bat that contributes significantly to seed dispersal and pollination services. These bats face serious threats from the loss of roosting trees due to urbanization and deforestation. This study aimed to assess the roost characteristics of Indian flying foxes and the effects of anthropogenic noise on roost tier selection in an urban forest patch. We carried out population surveys of Indian flying foxes in the Sallaghari Forest in Kathmandu Valley, Nepal by direct roost count method from July to November 2023. Further, we quantified the intensities of anthropogenic noise at every five-meter interval along the transects from the forest edge towards the main forest and recorded the minimum roosting heights at each point. Indian flying foxes were found to be roosting on trees belonging to six species. Eucalyptus sp. was the most abundant roost tree (50%) in the forest whereas the highest relative abundance of roosting Indian flying foxes was on Populus ciliata (40.1%). The regression analysis revealed that tree DBH and height and the combined interaction of height and canopy cover significantly increase the abundance of Indian flying foxes. The noise intensity at ground level and roosting height of Indian flying foxes showed a significant strong positive relationship indicating their roosting at higher tier under intense noise. We recommend measures for reducing anthropogenic noises and conserving large and tall trees to ensure the roosting habitat of Indian flying foxes in urban setups.

Oceanic Island Bats as Flower visitors and pollinators

Oceanic islands are relatively poor in insects compared to mainland areas. Therefore, insect-eating island birds and lizards may include other food sources into their diet, e.g. nectar and pollen. Here, we explore if insect-eating island bats face a similar problem and accordingly join the birds and lizards and incorporate plant resources into their diet. Thus, a priory, we assume flower visitation by bats to be more common on oceanic islands than elsewhere. To test this, we reviewed the literature to obtain information on the geographic distribution and diet of all 1,399 species of bats in the world and found that 49%, 21%, and 31% of species have a mainland, mixed mainland-island, and island distribution, respectively. Diets are known for only 65% (905 species) of the bats in the world, and 70%, 22%, and 8% of these, respectively, rely on insects, fruit, and floral resources as their major diet component. Twenty-seven species are even obligate flower visitors. This study confirms that flower-visiting bats, especially Pteropodidae, are significantly more frequent on oceanic islands, while insect eaters are more frequent on mainland and continental islands. Consequently, we argue that flower visitation and pollination by insect-eating island bats require more attention in future island ecology studies. For a start, we list known examples in the literature and report a case study from the Canary Islands. In the latter, we examined the foreheads of 34 museum specimens of the seven Canarian bat species. Half of them carried pollen from ≥ 9 taxa, but only three bat species had larger amounts. Pollen was not identified, but many Canarian and exotic plant species are candidates. Thus, flower visitation by bats may be an oceanic island phenomenon, but requires more focused research, especially night-time flower observations and examination of bats for pollen.

Batting around a new idea: attracting insect buffets for endangered bats

During the autumn months, many bat species face challenges to find sufficient food and generate the large fat stores they require to survive winter. However, North American bats face an additional challenge: a fungal disease called white-nose syndrome. The disease causes bats to arouse too frequently during hibernation, eventually starving to death before spring. Twelve bat species are currently affected, and some are listed as Endangered in either the USA or Canada. Winifred Frick, from Bat Conservation International and the University of California, Santa Cruz, USA, with a team of collaborators from various US and Canadian institutions, set out to test a new conservation approach that could protect bats by increasing the number of flying insects in an area, allowing the animals to gorge before and after hibernation.To test their approach, the team chose caves in the Upper Peninsula of Michigan, USA, which were known to have ∼100 remaining hibernating little brown bats (Myotis lucifugus) after declines from white-nose syndrome. They then monitored five caves in the autumn of 2019 (1 September–4 October), when the bats were fattening for hibernation, and four caves in the spring of 2021 (19 April–25 May), when bats that survived white-nose syndrome were emerging from hibernation. To attract flying insects, Frick and colleagues placed a single UV light 250 m from each cave entrance, 3 m above the ground. In the autumn, the team alternated nights when the UV lights were on, to assess changes in the number of insects they attracted. However, in the spring, to determine whether the bats could learn to respond to changes in the numbers of insects available to dine on, some of the caves were provided with a UV light on each night, while others had no UV lights on.The team also measured insect abundance every night during the autumn but only once a week during the spring, using a funnel and bucket to trap insects that were then brought back to the lab to be weighted and identified. To monitor bat foraging activity at the caves, the researchers used bat detectors placed at the sites to record the bats’ ultrasonic calls while flying from sunset to sunrise each night during the autumn and spring. Back in the lab, the recordings were reviewed to identify and count the number of ‘feeding buzzes’ – the echolocation calls that bats make when successfully catching insects – to determine the bats’ foraging success rates.The researchers found that when the UV lights were on during the autumn fattening period, the bats successfully captured and ate three times more insects than on nights when the UV lights were off. Additionally, the team collected a far greater mass of insects (16.7 times more) on the UV illuminated nights. Additionally, in the spring, the hunting bats were 8.5 times more successful in capturing prey, and the mass of insects collected by the team was 26.1 times greater at the locations where the UV lights were on than at the locations where the UV lights were off. These results show that UV lights in the autumn and spring increase the insect abundance for bats to eat, and that bats learn to forage more when there is increased food availability.Overall, Frick and colleagues have successively shown a novel approach for artificially attracting greater numbers of insects for bats to feast on during the critical spring and autumn periods. The results from the study could aid in the recovery of bat populations from white-nose syndrome and inspire wider conservation approaches for critically endangered hibernating bats in North America.

Negative Perception of Bats, Exacerbated by the SARS-CoV-2 Pandemic, May Hinder Bat Conservation in Northern Uganda

Bats face diverse challenges that cause global bat population declines, including habitat loss and roost disturbance. Additionally, negative perceptions of bats and their potential role in several zoonotic diseases have led to actions against bats. We documented existing knowledge and perception of bats through interviews with 151 participants of fifteen tribes in Northern Uganda in 2020 and conducted a sensitization campaign that prevented planned actions against bats. The interviews revealed distinct firm beliefs, negative perceptions, limited knowledge on bats, and the influence of media in shaping actions against bats. In addition, modified landscapes and habitat loss increased encounters and subsequent deterioration of relations between humans and bats. Targeted threats towards bats were exacerbated by public misinformation during the SARS-CoV-2 pandemic. No deliberate conservation efforts exist, and negative perception largely hampers the implementation of bat conservation in Northern Uganda. Importantly, the study also demonstrates that sensitization campaigns can be effective tools to protect bats in the short term. Regular sensitizations and education are recommended for sustainable changes in attitudes to and coexistence with bats.

Testis and brown adipose tissue xenografts from yellowish myotis (Myotis levis).

Yellowish myotis present a seasonal reproduction, influenced by rainfall distribution, in which the testis mass, germ cell composition, and brown adipose tissue mass change along the reproductive stages. In the present study, tissue xenografts were performed in immunodeficient mice to investigate spermatogenesis development in a stable endocrine milieu and the possible androgenic role of brown adipose tissue. Forty-one adult male bats were captured in the Santuário do Caraça, Minas Gerais, Brazil. The gonads and brown adipose tissue were collected, weighed, and grafted under the mice's back skin. Mice biometric and hormonal data were evaluated after grafting, and the testis grafts and mice gonads were fixed for histological and immunohistochemical analyses. As a result, testis grafts from adult bats presented a continuous germ cell development in all reproductive phases, showing round spermatids in all testis tissues. Furthermore, testis fragments in the Rest stage presented elongating spermatids as the most advanced germ cell type in the seminiferous epithelium after seven months of grafting. These data indicated that yellowish myotis spermatogenesis could be continued (presenting a constant spermatogonial differentiation) in a stable endocrine milieu, as found in mice. In addition, the best spermatogenic development was achieved when testis fragments were transplanted at their lowest activity (Rest stage). Regarding the brown adipose tissue grafts, the adipose tissue consumption by mice increased seminal vesicle mass and testosterone serum levels. This data proved that the brown adipose tissue is related to testosterone synthesis, which may be critical in stimulating the differentiation of spermatogonia in yellowish myotis.

How aerial insectivore bats of different sizes respond to nightly temperature shifts.

Small, volant and nocturnal, bats face strong challenges to avoid heat loss. Among aerial insectivores, body mass varies by two orders of magnitude between the smallest and the largest species. At low temperatures, physiological constraints should be harsher for smaller bats, as they lose more heat through their body surface than larger species. So, temperature variations should lead to distinct behavioural responses by bats of different body masses. Also, because they feed on arthropods, dependent on ambient temperature, aerial insectivores should halt feeding at low temperatures. Using ultrasound detectors and temperature and humidity sensors, we investigated how aerial insectivores of the coldest region in austral Brazil respond to nightly temperature variations and compared those responses between guilds of distinct body masses. We predict that smaller bats reduce their activity faster than larger bats, but that foraging should reduce simultaneously in the two guilds, as they depend on ectothermic prey. Bat activity reduced significantly below 12°C. Larger bats maintained their activity at temperatures where the activity of smaller bats had already halted. However, larger bats foraged mostly during the first half of the night, at higher temperatures than those chosen by smaller bats to forage. We associate these differential responses to the thermal convection process, which may increase prey availability at higher altitudes, where larger molossids are known to forage. Smaller species, mostly edge-space hunters, probably take advantage of less variable prey availability during the night, resulting in a more regular behavioural pattern of navigation and foraging.

Urinary creatinine varies with microenvironment and sex in hibernating Greater Horseshoe bats (Rhinolophus ferrumequinum) in Korea

BackgroundIn temperate regions many small mammals including bats hibernate during winter. During hibernation these small mammals occasionally wake up (arouse) to restore electrolyte and water balance. However, field data on water stress and concentration of bodily fluids during hibernation is scarce. Urinary creatinine concentration has long been used to calibrate urinary hormone concentration due to its close correlation with urine concentration. Therefore, by investigating urinary creatinine concentration, we can estimate bodily fluid concentration. In this study, we investigated changes in urinary creatinine from greater horseshoe bats (Rhinolophus ferrumequinum) hibernating in abandoned mineshafts in two regions in South Korea.ResultsWe collected 74 urine samples from hibernating greater horseshoe bats from 2018 to 2019. We found that urinary creatinine concentration was higher in February and March and then declined in April. There were also indications of a sex difference in the pattern of change in creatinine concentration over the three months. Bats in the warmer and less humid mineshaft had higher urinary creatinine concentrations than bats in the colder and more humid mineshaft.ConclusionsThese results indicate that hibernating bats face water stress as urinary concentration increases during winter and that water stress may vary depending on the microenvironment. Sex differences in behaviour during hibernation may influence arousal frequency and result in sex differences in changes in urinary creatinine concentration as hibernation progresses. Although further behavioural and endocrinal investigations are needed, our study suggests that urinary creatinine concentration can be used as a proxy to estimate the hydration status of bats and the effect of sex and environmental factors on arousal patterns during hibernation.

Disease recovery in bats affected by white-nose syndrome.

Processes associated with recovery of survivors are understudied components of wildlife infectious diseases. White-nose syndrome (WNS) in bats provides an opportunity to study recovery of disease survivors, understand implications of recovery for individual energetics, and assess the role of survivors in pathogen transmission. We documented temporal patterns of recovery from WNS in little brown bats (Myotis lucifugus) following hibernation to test the hypotheses that: (1) recovery of wing structure from WNS matches a rapid time scale (i.e. approximately 30 days) suggested by data from free-ranging bats; (2) torpor expression plays a role in recovery; (3) wing physiological function returns to normal alongside structural recovery; and (4) pathogen loads decline quickly during recovery. We collected naturally infected bats at the end of hibernation, brought them into captivity, and quantified recovery over 40 days by monitoring body mass, wing damage, thermoregulation, histopathology of wing biopsies, skin surface lipids and fungal load. Most metrics returned to normal within 30 days, although wing damage was still detectable at the end of the study. Torpor expression declined overall throughout the study, but bats expressed relatively shallow torpor bouts - with a plateau in minimum skin temperature - during intensive healing between approximately days 8 and 15. Pathogen loads were nearly undetectable after the first week of the study, but some bats were still detectably infected at day 40. Our results suggest that healing bats face a severe energetic imbalance during early recovery from direct costs of healing and reduced foraging efficiency. Management of WNS should not rely solely on actions during winter, but should also aim to support energy balance of recovering bats during spring and summer.

Evidence for spring stopover refuelling in migrating silver-haired bats (Lasionycteris noctivagans)

Migrating animals must acquire sufficient fuel to sustain migratory movement, but how time is allocated to achieve this can vary greatly. The fuel strategies used by migrating bats are not well understood and have not been investigated during the spring when insectivorous bats face low food abundance. Migrating silver-haired bats (Lasionycteris noctivagans (Le Conte, 1831)) were captured at a stopover site in Long Point, Ontario, Canada, in April and May of 2012–2014. We followed the movements of 40 bats outfitted with radio transmitters using an automated telemetry array and examined the effects of ambient temperature, fat stores, and sex on stopover duration. As seen previously in autumn, most bats departed the evening following capture, but one-third of bats used multiday stopovers. Extended stopover was associated with lower ambient temperature. There was no effect of sex or fat at capture on stopover departure probability. Bats captured closer to dawn had greater fat mass and lean mass than those captured early in the night, a trend indicative of fuel deposition at this site. This is the first study to provide evidence that bats use stopover habitat for refuelling.

Male long-distance migrant turned sedentary; The West European pond bat (Myotis dasycneme) alters their migration and hibernation behaviour.

During autumn in the temperate zone, insectivorous male bats face a profound energetic challenge, as in the same period they have to make energy choices related to hibernation, mating and migration. To investigate these energetic trade-offs, we compared the body mass of male and female pond bats (Myotis dasycneme) through the summer season, characterized the known hibernacula in terms of male or female bias, and subsequently compared their population trend during two study periods, between 1930–1980 and 1980–2015. Towards the end of summer, males began losing weight whilst females were simultaneously accumulating fat, suggesting that males were pre-occupied with mating. We also found evidence for a recent adaptation to this energetic trade-off, males have colonised winter roosts in formerly unoccupied areas, which has consequently led to a change in the migration patterns for the male population of this species. As male bats do not assist in raising offspring, males have ample time to restore their energy balance after hibernation. Our results suggest that choosing a hibernacula closer to the summer range not only decreases energy cost needed for migration, it also lengthens the mating season of the individual male. Our findings have important conservation implications, as male and female biased hibernation assemblages may differ critically in terms of microclimate preferences.

A review of the major threats and challenges to global bat conservation.

Bats are an ecologically and taxonomically diverse group accounting for roughly a fifth of mammalian diversity worldwide. Many of the threats bats face (e.g., habitat loss, bushmeat hunting, and climate change) reflect the conservation challenges of our era. However, compared to other mammals and birds, we know significantly less about the population status of most bat species, which makes prioritizing and planning conservation actions challenging. Over a third of bat species assessed by the International Union for Conservation of Nature (IUCN) are considered threatened or data deficient, and well over half of the species have unknown or decreasing population trends. That equals 988 species, or 80% of bats assessed by IUCN, needing conservation or research attention. Delivering conservation to bat species will require sustained efforts to assess population status and trends and address data deficiencies. Successful bat conservation must integrate research and conservation to identify stressors and their solutions and to test the efficacy of actions to stabilize or increase populations. Global and regional networks that connect researchers, conservation practitioners, and local stakeholders to share knowledge, build capacity, and prioritize and coordinate research and conservation efforts, are vital to ensuring sustainable bat populations worldwide.

Relationships between technique and bat speed, post-impact ball speed, and carry distance during a range hitting task in cricket

The ability of a batsman to clear the boundary is a major contributor to success in modern cricket. The aim of this study was to identify technique parameters characterising those batsmen able to generate greater bat speeds, ball launch speeds, and carry distances during a range hitting task in cricket. Kinematic data were collected for 20 batsmen ranging from international to club standard, and a series of ball launch, bat-ball impact, and technique parameters were calculated for each trial. A stepwise multiple linear regression analysis found impact location on the bat face in the medio-lateral and longitudinal directions and bat speed at impact to explain 68% of the observed variation in instantaneous post-impact ball speed. A further regression analysis found the X-factor (separation between the pelvis and thorax segments in the transverse plane) at the commencement of the downswing, lead elbow extension, and wrist uncocking during the downswing to explain 78% of the observed variation in maximum bat speed during the downswing. These findings indicate that players and coaches should focus on generating central impacts with the highest possible bat speed. Training and conditioning programmes should be developed to improve the important kinematic parameters shown to generate greater bat speeds, particularly focussing on increased pelvis to upper thorax separation in the transverse plane.

Conservation Strategies for Bats Flying at High Altitudes

Numerous bats use the troposphere for hunting, commuting, or migrating. High-altitude flying bats face various direct and indirect threats, including collision with tall anthropogenic structures and aerial vehicles, aerial fragmentation, reduced insect biomass, and the altered ambient conditions associated with climate change. Furthermore, dust and chemical pollutants in the troposphere might impair the health and survival of bats. Such indirect threats are diffuse regarding their origin and effect on bats, whereas direct threats are site and context specific. Overall, troposphere habitat conservation is hampered by the “Tragedy of the Commons” because its stewardship is in the hands of many. We conclude that high-altitude flying bats are likely to become more threatened in the near future because of the increased use of the troposphere by humans. Therefore, we should target the protection of the troposphere for organisms, such as high-altitude flying bats, that strongly depend on intact skies.

The relationships between impact location and post-impact ball speed, bat torsion, and ball direction in cricket batting

ABSTRACTThree-dimensional kinematic data of bat and ball were recorded for 239 individual shots performed by twenty batsmen ranging from club to international standard. The impact location of the ball on the bat face was determined and assessed against the resultant instantaneous post-impact ball speed and measures of post-impact bat torsion and ball direction. Significant negative linear relationships were found between post-impact ball speed and the absolute distance of impact from the midline medio-laterally and sweetspot longitudinally. Significant cubic relationships were found between the distance of impact from the midline of the bat medio-laterally and both a measure of bat torsion and the post-impact ball direction. A “sweet region” on the bat face was identified whereby impacts within 2 cm of the sweetspot in the medio-lateral direction, and 4.5 cm in the longitudinal direction, caused reductions in ball speed of less than 6% from the optimal value, and deviations in ball direction of less than 10° from the intended target. This study provides a greater understanding of the margin for error afforded to batsmen, allowing researchers to assess shot success in more detail, and highlights the importance of players generating consistently central impact locations when hitting for optimal performance.

A curve fitting methodology to determine impact location, timing, and instantaneous post-impact ball velocity in cricket batting

This study aimed to develop a methodology for accurate determination of the impact location of a cricket ball on the bat face, as well as the identification of bat–ball contact timing and post-impact instantaneous ball velocity in a whole-body kinematic data collection environment. Three-dimensional kinematic data of bat and ball were recorded during 14 batting strokes: 8 hitting a static ball and 6 against a bowling machine. Curves were fitted separately to the pre- and post-impact phases of the ball position data against time in three axes according to logarithmic equations determined from mechanical principles. Separate Fourier series models were similarly fitted to the four corners of the bat face against time during the downswing prior to ball impact. Time of impact for the dynamic ball trials was determined based on the intersection of pre- and post-impact curves, with impact location calculated from ball and bat face curves at this time. R2 values for the goodness of fit of the ball and bat curves averaged 0.99 ± 0.04 and 1.00 ± 0.00 with root mean square errors of 7.5 ± 2.6 and 0.8 ± 0.2 mm, respectively. Calculated impact locations were assessed against measured impact locations derived from the impression imparted to a fine powder coating on the bat face, finding absolute differences of 6.4 ± 4.2 and 7.1 ± 4.4 mm in the transverse and longitudinal axes of the bat, respectively. Thus, an automated curve fitting methodology enables the accurate determination of cricket bat–ball impact characteristics for use in experimental investigations.

Suppression of emission rates improves sonar performance by flying bats

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 reductions in interference rates are sufficient to reduce interference and improve obstacle avoidance. When bats flew in pairs, each bat responded to the presence of the other as an obstacle by increasing emissions, but hearing the sonar emissions of the nearby bat partially suppressed this response. This behavior supports social cohesion by providing a key mechanism for minimizing mutual interference.

A Multidisciplinary Investigation of the Effects of Competitive State Anxiety on Serve Kinematics in Table Tennis.

Displays of anxiety in table tennis were assessed through subjective (a self-report questionnaire), physiological (heart-rate variability) and kinematic variables. Using a within-group crossover design, 9 university-level table tennis players completed a series of serves under low- and high-anxiety conditions. Anxiety manipulation was achieved through the introduction of a national standard table tennis player, known to the participants, to receive serves in the high-anxiety condition, whilst serves were received by no opponent in the low-anxiety condition. Automated motion capture systems consisting of high-speed 3D motion cameras and analytical software (QUALISYS) determined the subject’s movement kinematics: bat face angle (degrees) and serve routine duration (s). Self-reported state anxiety (MRF-Likert) and heart rate measurements were collected to examine changes between conditions. Contrary to the hypothesis, bat face angles did not change significantly between anxiety conditions (F (1.8) = 2.791, p = 0.133) and movement times were faster in the high-anxiety condition. In light of these findings, research into other facets of movement behaviour must be analysed to gain further understanding of the effects of anxiety on performance, which remain unclear.