Roost Disturbance Research Articles

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.

Secrets of the night: roost sites and sleep disturbance factors during the autumn migration of first‐year white storkCiconia ciconia

The migration phase of birds is divided into two main states: stopovers and actual migratory flights. For soaring birds, such as storks, nighttime is especially important to conserve energy and to start the next day in favourable weather conditions. Although there is a large number of recent studies on white storkCiconia ciconia, for example using advanced technologies such as GPS technology, the nocturnal behaviour of the species is still an enigma. Thus, we GSM–GPS‐tagged 90 immature storks and checked their nocturnal behaviour, especially roost disturbance, during their first autumn migration from breeding grounds in southern Poland to wintering places in Africa. Storks roosted on three types of site: on buildings, on the ground or in trees. Birds that roosted on the ground had a higher probability of nighttime disturbance than those that used trees or buildings. The probability of disturbance at night was also related to longitude and latitude; the most easterly birds and those at the start of the migration route were disturbed more often during the night. Furthermore, and interestingly, environmental conditions at roosts were also significantly related to the probability of disturbance; birds roosting at tree sites with higher NDVI (greener) and with higher levels of artificial light both had a lower probability of disturbance. A possible explanation of this could be related to lower potential predatory pressure at night. We found that after long flights birds were disturbed more often at night, and that disturbed birds migrated further the next day. For a better understanding of the nocturnal behaviour of storks, as well as of other migratory birds, the use of modern technological tools with greater precision is recommended.

Alopecia in Bats

Reports of hair loss in bats in the wild are scarce and have not been summarized. We performed a literature review to summarize the affected species, prevalence, clinic diagnostics, and factors that cause alopecia in bats. We found only 28 studies that reported alopecia in 26 species of bats, within five families. Together, these studies examined 10,186 bats, of which 10.8% had alopecia, with a sex bias to females (3:1). Most studies did not identify a specific ethologic agent responsible for the hair loss. However, alopecia was attributed to five non-exclusive causes: endocrine factors related to reproduction and lactation, ectoparasites, the ingestion of toxins, and environmental stress. In the latter, anthropogenic stressors are of increasing concern — the incidence of alopecia in urban areas reflects reproductive stress, limited food availability, roost disturbance, and pollution in these poor-quality environments. Better reporting of alopecia in bats would help us better understand this pathology and to precisely measure environmental stress in these animals.

Assessing roost disturbance of straw-coloured fruit bats (Eidolon helvum) through tri-axial acceleration.

The disturbance of wildlife by humans is a worldwide phenomenon that contributes to the loss of biodiversity. It can impact animals' behaviour and physiology, and this can lead to changes in species distribution and richness. Wildlife disturbance has mostly been assessed through direct observation. However, advances in bio-logging provide a new range of sensors that may allow measuring disturbance of animals with high precision and remotely, and reducing the effects of human observers. We used tri-axial accelerometers to identify daytime flights of roosting straw-coloured fruit bats (Eidolon helvum), which were used as a proxy for roost disturbance. This bat species roosts on trees in large numbers (often reaching hundreds of thousands of animals), making them highly vulnerable to disturbance. We captured and tagged 46 straw-coloured fruit bats with dataloggers, containing a global positioning system (GPS) and an accelerometer, in five roosts in Ghana, Burkina Faso and Zambia. Daytime roost flights were identified from accelerometer signatures and modelled against our activity in the roosts during the days of trapping, as a predictor of roost disturbance, and natural stressors (solar irradiance, precipitation and wind speed). We found that daytime roost flight probability increased during days of trapping and with increasing solar irradiance (which may reflect the search for shade to prevent overheating). Our results validate the use of accelerometers to measure roost disturbance of straw-coloured fruit bats and suggest that these devices may be very useful in conservation monitoring programs for large fruit bat species.

A habitat suitability analysis at multi-spatial scale of two sympatric flying fox species reveals the urgent need for conservation action

In this study we used a multi-spatial scale approach to investigate habitat suitability, roosting characteristics, and ecological niche in two flying fox species on the Comoros Islands—Pteropus livingstonii and Pteropus seychellensis comorensis. At a broad scale, we assessed the ecological niche and habitat suitability for both species using the Species Distribution Modeling method based on the recent ensembles of small models (ESM) approach. At a fine scale, Ecological Niche Factor Analysis (ENFA) was applied to assess habitat selection by each species. Direct observation was used at each roost to estimate the total number of individuals and to identify the roost characteristics. At both broad and fine scales, the analyses highlighted clear niche partitioning by the two species. We found that P. livingstonii has a very limited distribution, restricted to steep, high-elevation slopes of the islands’ remaining natural forests, and the patterns were the same for roosting, foraging sites and the entire habitat. By contrast, P. s. comorensis has a relatively large geographic range that extends over low-elevation farmlands and villages and it was negatively correlated to natural forest across the entire area and all roosting sites, but its foraging areas were positively correlated to natural forest and high elevation areas. Both species selected large, tall trees for roosting. The total number of individuals in the studied area was estimated to be 1243 P. livingstonii and 11,898 P. s. comorensis. The results of our study demonstrated that these two species use different habitat types and ensure different ecosystem services in pollination and seed dispersion and thus are both critical for maintaining overall ecosystem dynamics. However, the currently high level of hunting pressure and roost disturbance makes them vulnerable to extinction. To ensure the viability of both species, conservation measures need to be taken by the Comoros government.

The Diet of the Cave Nectar Bat (Eonycteris spelaea Dobson) Suggests it Pollinates Economically and Ecologically Significant Plants in Southern Cambodia.

Hoem Thavry, Julien Cappelle, Sara Bumrungsri, Lim Thona, and Neil M. Furey (2017) The importance of the cave nectar bat Eonycteris spelaea as a pollinator of economically significant crops and ecologically important plant species is increasingly documented, although information on the plants visited by this widely distributed bat species is currently confined to Thailand and Peninsular Malaysia. We undertook a dietary study on E. spelaea by sampling faecal rain produced by a colony in Kampot, southern Cambodia each month for one year and identifying plant taxa visited by the bats by their pollen. Our results indicate the diet of E. spelaea in Cambodia includes at least 13 plant taxa, eight of which were identi ed to genus or species. Pollen of Sonneratia spp. and Musa spp. had the highest mean monthly frequency at 30.9% and 16.9% respectively, followed by Oroxylum indicum (11.3%), Bombax anceps (11.2%), Parkia spp. (9.8%), Durio zibethinus (6.3%), Ceiba pentandra (6.0%) and Eucalyptus spp. (0.3%). With one exception, all of the plant taxa recorded at our study site are also visited by the bat species in Peninsular Malaysia and Thailand, although their relative dietary contributions differ. This variation likely reflects local differences in the availability, proximity and flowering phenology of chiropterophilous plants between regions, but also suggests a reliance of Cambodian bats on species that ower continuously, coupled with periodic shifts to species that ower profusely for short periods. Only three signi cant colonies (> 1,000 bats) of cave-roosting pteropodids are currently known in Cambodia, all of which are in Kampot and threatened by bushmeat hunting and roost disturbance. We recommend public education and law enforcement e orts to conserve these colonies, not least because Kampot is the premier region for Cambodian durian and this crop depends on nectarivorous bats for fruit set. Protection of mangroves would also bene t durian farmers because these are an important resource for nectarivorous bat populations.

Grey Crowned Crane threat assessment around the wetlands of eastern Uganda

The Grey Crowned Crane Balearica regulorum was uplisted to globally Endangered in 2012. There is urgent need to determine the threats they face at local levels for their conservation. I conducted formal point-count surveys around the wetlands of eastern Uganda and observed no cranes. Groups of cranes were encountered when following directions from local inhabitants. Results from a questionnaire survey suggested that cranes make use of most of the wetlands in the region, and that the birds occur in small flocks averaging 6–8 individuals. Wetland loss through farming was reported to be the main threat, but I also documented poisoning, roost disturbance, and the collection of eggs and chicks. Rigorous conservation and education programs are needed to ensure the long-term survival of cranes and storks in this region.

Flying-Fox Roost Disturbance and Hendra Virus Spillover Risk

Bats of the genus Pteropus (flying-foxes) are the natural host of Hendra virus (HeV) which periodically causes fatal disease in horses and humans in Australia. The increased urban presence of flying-foxes often provokes negative community sentiments because of reduced social amenity and concerns of HeV exposure risk, and has resulted in calls for the dispersal of urban flying-fox roosts. However, it has been hypothesised that disturbance of urban roosts may result in a stress-mediated increase in HeV infection in flying-foxes, and an increased spillover risk. We sought to examine the impact of roost modification and dispersal on HeV infection dynamics and cortisol concentration dynamics in flying-foxes. The data were analysed in generalised linear mixed models using restricted maximum likelihood (REML). The difference in mean HeV prevalence in samples collected before (4.9%), during (4.7%) and after (3.4%) roost disturbance was small and non-significant (P = 0.440). Similarly, the difference in mean urine specific gravity-corrected urinary cortisol concentrations was small and non-significant (before = 22.71 ng/mL, during = 27.17, after = 18.39) (P= 0.550). We did find an underlying association between cortisol concentration and season, and cortisol concentration and region, suggesting that other (plausibly biological or environmental) variables play a role in cortisol concentration dynamics. The effect of roost disturbance on cortisol concentration approached statistical significance for region, suggesting that the relationship is not fixed, and plausibly reflecting the nature and timing of disturbance. We also found a small positive statistical association between HeV excretion status and urinary cortisol concentration. Finally, we found that the level of flying-fox distress associated with roost disturbance reflected the nature and timing of the activity, highlighting the need for a ‘best practice’ approach to dispersal or roost modification activities. The findings usefully inform public discussion and policy development in relation to Hendra virus and flying-fox management.

Diversity, distribution and status of bats on the Andaman and Nicobar Islands, India

AbstractInformation on the bat fauna of the Andaman and Nicobar Islands was limited previously to the results of sporadic surveys, with no specific focus on the habitats or distribution of the species. We carried out the first extensive survey of the Andaman and Nicobar Islands during 2003–2006, covering 40 islands. Our objective was to map the bat species, their habitats and distribution. This resulted in identification of 25 bat species representing 13 genera, location of > 300 roosts and validation of previously recorded species. Notable findings included the rediscovery of the endemic Nicobar flying foxPteropus faunulusafter a century and its extinction from the type locality on Car Nicobar Island, the sighting of an albinoHipposideros diadema nicobarensisfrom Katchal Island, and the first records ofRhinolophus yunanensis, Murina cyclotisandHipposideros larvatusfrom the Andaman Islands, andTaphozous melanopogon, Murina cyclotis, Pipistrellusspp.,Myotis horsfieldii dryasandCynopterus brachyotisfrom the Nicobar Islands. Threats to the bat fauna appear to be primarily roost disturbance and hunting for sport. Anthropogenic pressure on species ofPteropusis high as hunting occurs throughout the year. Secondary sources and our field observations confirmed the decline ofPteropusin several islands as a result of hunting and alteration to habitats. We introduced a community initiative to monitor and protect roosts and foraging sites close to settlements in the Nicobar Islands. Priorities identified for conservation of the bat fauna of the archipelagos are mitigation of threats to flying foxes and cave dwelling bats, initiation of research on endemic bat species such asP. faunulus, and a voluntary ban by local communities on hunting in specific areas and seasons.

Bat conservation in China: should protection of subterranean habitats be a priority?

AbstractSubterranean environments are essential for the survival of many bat species and other cave fauna but these places are subject to increasing human disturbance. To examine the significance of subterranean habitats for the conservation of bats in China we surveyed bat species in 225 underground sites during 2003–2011. Our results show that 77% of bat species in China, including 30 nationally Endangered or Vulnerable species and nine endemic species, roost in caves and other subterranean habitats. The number of species in occupied roosts was 1–15. Almost 90% of the roosts surveyed contained signs of human disturbance, most of which was from recreational activities. One hundred and twenty-one roosts merit special concern because they harbour ≥ 6 species or > 1,000 individuals, or species of special concern (threatened or endemic species). Generally, larger roosts support more species and a greater abundance of bats than smaller roosts but there is no direct correlation between the presence of species of special concern and roost size. Disused tourist caves have significantly more bat species than other types of roosts. Our data demonstrate that roost disturbance by recreational activities has pronounced detrimental effects on the number of bat species and the presence of species of special concern. We discuss the social, economic and political issues that could adversely affect bat conservation in caves in China, and we recommend that protection of subterranean habitats should be a high priority for bat conservation.

Recovery of the Vulnerable Pemba flying foxPteropus voeltzkowi: population and conservation status

AbstractFlying foxes of the genusPteropusare predominantly island taxa, with high levels of endemism, and face high risks of extinction. Their ecological and economic importance in island ecosystems has been widely recognized. Here we investigate the population size and conservation status of the VulnerablePteropus voeltzkowi, endemic to the western Indian Ocean island of Pemba, Tanzania. Direct counts and patch counts were used to determine abundance of flying foxes at roost sites, supplemented with evening dispersal counts, which were conducted to test accuracy of counting techniques under varying conditions of visibility. We estimate that the population size is now a minimum of 18,200–22,100, thus validating reports of annual increases by in-country monitoring teams since the last documented population survey of 4,600–5,500 bats in 1995. Taking into account differences in the counting methodologies for roosting bats we estimate that the population size could be as high as 35,600 individuals. We identified 44 occupied roosting sites, with just four of these supporting up to 87% of the population. Roost disturbance represents a continuing threat to this species and was found to influence roost occupancy and colony size. The implications of the population increase for the local human community are discussed and recommendations provided for continued monitoring and future management of this species on Pemba Island.

Population size, distribution, threats and conservation status of two endangered bat species Craseonycteris thonglongyai and Hipposideros turpis

The population size, distribution, threats and conservation status of 2 bat species included as 'endangered' in the IUCN Red List were assessed in Thailand and Myanmar. Craseonyc- teris thonglongyai Hill, 1974 and Hipposideros turpis Bangs, 1901 are both rare and poorly known cave-dwelling species, which have restricted distributions and small population sizes. Surveys of the 2 species were conducted in a large number of locations including previously reported sites and potential new locations. Colony size was counted at currently known localities, and population size was estimated. The known distribution and population are larger than in previous estimates, but both species still remain threatened by roost disturbance and the destruction of foraging habitat. Clarifi- cation of the taxonomic status of allopatric populations within each species is urgently required.

Roost availability may constrain shorebird distribution: Exploring the energetic costs of roosting and disturbance around a tropical bay

High tides force shorebirds from their intertidal feeding areas to refuges known as roosts. This paper explores the energetic costs of roost disturbance of great knot ( Calidris tenuirostris) and red knot ( C. canutus) at Roebuck Bay, North-western Australia, assessing disturbance levels at different roost sites through direct observation and automatic radio-telemetry, and applying physiological equations and predictive roost choice models to estimate energetic costs of disturbance through a complete tidal cycle. The study area had a variety of roosts, but use of each was constrained by conditions of tide and time. The roost most suitable for shorebirds on daytime high tides of intermediate height experienced high levels of disturbance from both natural sources (birds of prey) and humans. Flight costs caused by disturbance at this site exceeded the costs of flying to and roosting at the nearest alternative roost, 25 km away. However, shorebirds did not roost at the alternate site, possibly because of the risk of heat stress in a prolonged flight in tropical conditions. Increases in disturbance levels at just one of the roost sites of Roebuck Bay would increase energetic costs substantially, and could easily reach the point at which feeding areas accessed from this roost cannot be used without incurring a net energy deficit. Roost availability can therefore limit access to feeding areas and hence limit population size. Adequate provision and management of roost sites is accordingly an important consideration in conservation of sites used by coastal shorebirds.

Another Seychelles endemic close to extinction: the emballonurid bat Coleura seychellensis

The only microchiropteran endemic to the granitic Seychelles, the sheath-tailed bat Coleura seychellensis, is categorized as Critically Endangered on the IUCN Red List. Using bat detectors, the islands of Mahé, Praslin and La Digue were surveyed to establish the current distribution of this species. Although two new roosts were discovered on Mahé, no bats were observed on Praslin and La Digue, and the range of C. seychellensis appears to have further contracted in the last 2 decades. A total of 19 C. seychellensis were counted emerging from or entering three roosts in boulder caves on Mahé during 18 evenings of observations. The bats foraged in open coastal habitat, some of it anthropogenic, and their echolocation calls were also characteristic of bats feeding in open habitat. This study provides no evidence that C. seychellensis is dependent on forest or wetland for foraging. Dietary analysis indicated that C. seychellensis feeds on Coleoptera, Lepidoptera and Diptera. A public education programme to highlight the conservation status of the bat and the consequences of roost disturbance is recommended, together with the urgent need for legal protection of the bats and their roosts.

Modelling the efficacy of proposed mitigation areas for shorebirds: a case study on the Seine estuary, France

A behaviour-based model was used to explore the effect of an extension of the port at Le Havre (Port 2000), and the effect of proposed mitigation measures, on the mortality and body condition of the three main shorebird species that overwinter in the estuary of the river Seine, France. In the model, a 20% reduction in the area of mudflats on the north side of the estuary had little effect on curlew Numenius arquata mortality and body condition but significantly increased mortality and decreased body condition in dunlin Calidris alpina and oystercatchers Haematopus ostralegus. Disturbance of feeding birds both day and night had a significant effect on the mortality and body condition of all three shorebird species, as did disturbance of roosting birds. Disturbance of feeding birds in the daytime only had a significant effect on dunlin mortality and body condition, but not that of curlew and oystercatchers. In the model, the creation of a buffer zone to reduce disturbance of feeding birds restored shorebird mortality and body condition to pre-disturbance levels. A new mudflat area was also effective in mitigating the effect of habitat loss on all three shorebirds and in mitigating the effect of roost disturbance on dunlin and curlew. However, a new mudflat area was not effective in mitigating the effect of roost disturbance on oystercatcher mortality and body condition. The effectiveness of the mitigating mudflat depended as much on its size as its quality. We believe that this is the first time that anyone has been able to forecast the efficacy of proposed mitigation measures.

Habitat use, diet and roost selection by the Big Brown Bat (Eptesicus fuscus) in North America: a case for conserving an abundant species

ABSTRACTInsectivorous bats are integral components of terrestrial ecosystems. Despite this, a growing number of factors causing world‐wide declines in bat populations have been identified. Relatively abundant species are important for bat conservation because of their role in ecosystems and the research opportunities they offer. In addition, species that have been well‐studied present unique opportunities to synthesize information and highlight important areas of focus for conservation and research. This paper focuses on a well‐studied abundant bat, Eptesicus fuscus. I review the relevant literature on habitat use, diet and roost selection by E. fuscus in North America, and highlight important areas of conservation and research for this species, including the effects of roost disturbance, control of economically important insect pests, exposure to pesticides, long‐term monitoring of populations, and the potential consequences of expanding populations. These issues have broad implications for other species and can be used to focus future research and conservation efforts.