Special Issue "Impacts of Pressure on Bat Populations"

A special issue of Diversity (ISSN 1424-2818).

Deadline for manuscript submissions: closed (31 December 2019).

Special Issue Editor

Dr. Christian Kerbiriou
Website
Guest Editor
Centre d'Ecologie et des Sciences de la Conservation (CESCO), Muséum national d'Histoire naturelle, Centre National de la Recherche Scientifique, Sorbonne Université, Station de Biologie Marine de Concarneau, France
Interests: conservation biology; biodiversity monitoring; anthropogenic pressure on biodiversity; citizen-science biodiversity schemes

Special Issue Information

Dear Colleagues,

Although several studies have highlighted their value in terms of providing ecosystem services (e.g., pest control, seed dispersal, and pollination), and although legally protected in many countries through national or supranational laws, bat populations are declining around the globe—largely as a result of human activity. Of the 1296 bat species that have been assessed by the International Union for the Conservation of Nature (IUCN), almost a third are considered either threatened (critically endangered (23), endangered (56), vulnerable (107)) and 82 are considered near-threatened, highlighting the need for more conservation attention to these species. In addition, bats also are among the most under-studied of mammals: 231 bat species are listed by the IUCN lists as Data Deficient, meaning there is not enough information available to determine their conservation status, underlining the need for more surveys and research.

Numerous causes of this situation have been identified, and include:

1) The loss of natural habitat, which remains the most widespread peril worldwide for bats. This is especially critical in the tropical rainforests, which tend to have high species diversity and experience drastic clearance for the settlement of farm crops, mining operations, cattle pastures, or cities.

2) Agricultural intensification, which is particularly an established threat for bats. In some areas, bats are considered as an agricultural pest due to the damage they cause to fruit production and are directly regulated. At least half of the global population of the Mauritian flying fox (Pteropus niger) was destroyed due to the two successive mass culls planned by the Mauritian government. Using the best available evidence, the IUCN moved the Mauritian flying fox to a higher threat category, from Vulnerable to Endangered. However, in addition to this direct destruction of bats, agricultural intensification also involves (i) the replacement of natural and semi-natural habitat with annual crops, (ii) the fragmentation of natural habitats, (iii) the homogenization of the farming landscape over space and time, and (iv) and increased use of fertilizers and pesticides. A major issue is therefore the reconciliation of agricultural production with biodiversity, and the identification of practices that contribute to maintaining viable bats populations.

3) Emerging infectious diseases such as white-nose syndrome have drastically impacted North American bats: 6 million bats have been killed by a cold-loving fungus called Pseudogymnoascus destructans. This disease continues its spread across the continent, causing mortality rates that approach 100% at some sites.

4) Roost destruction and disturbance. In many countries, bats regularly use artificial above-ground structures as breeding colonies or for hibernacula. However, houses, historical monuments, and public buildings can be subject to rehabilitation works, and in addition cohabiting with bats can lead to disagreements, underlining the need of efficient mitigation strategies for bats in buildings.

5) Destruction due to harmful myths. Unfortunately, bats are still casually killed because of misplaced fears. In Latin America, whole colonies are routinely destroyed in the mistaken belief that all bats are vampires, stressing the need of public awareness.

6) Hunting. In regions such as Southeast Asia and the Pacific islands, bats are hunted, both as bush meat for local consumption and commercially for markets and restaurants.

6) Light pollution. This new emerging human pressure is a major threat to biodiversity worldwide, decreasing habitat quality and landscape connectivity for nocturnal species. The impact of artificial light is poorly accounted for, in a large part due to the lack of quantitative information and relevant guidelines to limit its negative effects.

7) Wind farm development. Hundreds of thousands of bats are killed each year in the United States by collisions with the spinning blades of wind turbines or rapid pressure changes at turbines that can result in barotrauma. According to the low growth rate of bat populations, fatalities at wind turbines may threaten population viability. Another research gap in wind turbines is the loss of habitat use resulting from the potential negative impact of wind turbines. The European recommendations (wind turbines at least 200 m from any wooded edge) set to limit mortality events likely strongly underestimate the loss of bat activity. The current situation is particularly worrying, because few turbines comply with recommendations, which themselves are far from sufficient to limit the loss of habitat use.

8) The development of transportation infrastructure, which involve direct mortality and indirect impact though a road-zone effect (up to five kilometers) where a significant negative effect of major roads on bat activity has been detected. No assessment of these two impacts of road on bat population viability and few offsetting actions are carried out during road construction. It seems urgent to consider these road effects with the cumulative effects of other roads by improving habitat connectivity and foraging areas in land use policies.

Dr. Christian Kerbiriou
Guest Editor

Manuscript Submission Information

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Keywords

  • conservation biology
  • biodiversity monitoring
  • anthropogenic pressure on bats
  • conservation status of bats
  • research priorities in conservation of bats
  • conservation action plan for bats
  • bats population trends
  • house bat management
  • bat fatalities
  • bat mortality

Published Papers (6 papers)

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Research

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Open AccessArticle
Switching LPS to LED Streetlight May Dramatically Reduce Activity and Foraging of Bats
Diversity 2020, 12(4), 165; https://doi.org/10.3390/d12040165 - 24 Apr 2020
Cited by 1
Abstract
Artificial light at night is considered a major threat to biodiversity, especially for nocturnal species, as it reduces habitat availability, quality, and functionality. Since the recent evolution in light technologies in improving luminous efficacy, developed countries are experiencing a renewal of their lighting [...] Read more.
Artificial light at night is considered a major threat to biodiversity, especially for nocturnal species, as it reduces habitat availability, quality, and functionality. Since the recent evolution in light technologies in improving luminous efficacy, developed countries are experiencing a renewal of their lighting equipment that reaches its end-of-life, from conventional lighting technologies to light emitting diodes (LEDs). Despite potential cascading impacts of such a shift on nocturnal fauna, few studies have so far dealt with the impact of the renewal of street lighting by new technologies. Specifically, only one study, by Rowse et al.2016, examined the effects of switching from widely used low pressure sodium (LPS) lamps to LEDs, using bats as biological models. This study was based on a before-after-control-impact paired design (BACIP) at 12 pairs in the UK, each including one control and one experimental streetlight. If Rowse et al. 2016 showed no effect of switching to LEDs streetlights on bat activity, the effects of respective changes in light intensity and spectrum were not disentangled when testing switch effects. Here, we conduct a retrospective analysis of their data to include these covariates in statistical models with the aim of disentangling the relative effects of these light characteristics. Our re-analysis clearly indicates that the switches in spectrum and in intensity with replacement of LPS with LED lamps have significant additive and interactive effects, on bat activity. We also show that bat activity and buzz ratio decrease with increasing LED intensity while an opposite effect is observed with LPS lamps. Hence, the loss or the gain in bat activity when lamp types, i.e., spectrum, are switched strongly depends on the initial and new lamp intensities. Our results stress the need to consider simultaneously the effects of changes in the different lights characteristics when street lighting changes. Because switches from LPS to LED lamps can lead to an increase in light intensity, such technological changes may involve a reduction of bat activity in numerous cases, especially at high LED intensities. Since we are currently at an important crossroad in lighting management, we recommend to limit LED intensity and improve its spectral composition toward warmer colors to limit potential deleterious impacts on bat activity. Full article
(This article belongs to the Special Issue Impacts of Pressure on Bat Populations)
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Open AccessArticle
USA Wind Energy-Caused Bat Fatalities Increase with Shorter Fatality Search Intervals
Diversity 2020, 12(3), 98; https://doi.org/10.3390/d12030098 - 12 Mar 2020
Abstract
Wind turbine collision fatalities of bats have likely increased with the rapid expansion of installed wind energy capacity in the USA since the last national-level fatality estimates were generated in 2012. An assumed linear increase of fatalities with installed capacity would expand my [...] Read more.
Wind turbine collision fatalities of bats have likely increased with the rapid expansion of installed wind energy capacity in the USA since the last national-level fatality estimates were generated in 2012. An assumed linear increase of fatalities with installed capacity would expand my estimate of bat fatalities across the USA from 0.89 million in 2012 to 1.11 million in 2014 and to 1.72 million in 2019. However, this assumed linear relationship could have been invalidated by shifts in turbine size, tower height, fatality search interval during monitoring, and regional variation in bat fatalities. I tested for effects of these factors in fatality monitoring reports through 2014. I found no significant relationship between bat fatality rates and wind turbine size. Bat fatality rates increased with increasing tower height, but this increase mirrored the increase in fatality rates with shortened fatality search intervals that accompanied the increase in tower heights. Regional weighting of mean project-level bat fatalities increased the national-level estimate 17% to 1.3 (95% CI: 0.15–3.0) million. After I restricted the estimate’s basis to project-level fatality rates that were estimated from fatality search intervals <10 days, my estimate increased by another 71% to 2.22 (95% CI: 1.77–2.72) million bat fatalities in the USA’s lower 48 states in 2014. Project-level fatality estimates based on search intervals <10 days were, on average, eight times higher than estimates based on longer search intervals. Shorter search intervals detected more small-bodied species, which contributed to a larger all-bat fatality estimate. Full article
(This article belongs to the Special Issue Impacts of Pressure on Bat Populations)
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Open AccessArticle
Urban Sprawl, Food Subsidies and Power Lines: An Ecological Trap for Large Frugivorous Bats in Sri Lanka?
Diversity 2020, 12(3), 94; https://doi.org/10.3390/d12030094 - 06 Mar 2020
Abstract
Electrocution is one of the less known anthropogenic impacts likely affecting the bat population. We surveyed 925 km of overhead distribution power lines that supply energy to spreading urbanized areas in Sri Lanka, recording 300 electrocuted Indian flying foxes (Pteropus giganteus). [...] Read more.
Electrocution is one of the less known anthropogenic impacts likely affecting the bat population. We surveyed 925 km of overhead distribution power lines that supply energy to spreading urbanized areas in Sri Lanka, recording 300 electrocuted Indian flying foxes (Pteropus giganteus). Electrocutions were recorded up to 58 km from the nearest known colony, and all of them were in urbanized areas and very close ( X ¯ = 4.8 m) to the exotic fruiting trees cultivated in gardens. Predictable anthropogenic food subsidies, in the form of cultivated fruits and flowers, seem to attract flying foxes to urban habitats, which in turn become ecological traps given their high electrocution risk. However, electrocution rates greatly varied among the 352 power lines surveyed (0.00–24.6 indiv./km), being highest in power lines with four wires oriented vertically ( X ¯ = 0.92 indiv./km) and almost zero in power lines with wires oriented horizontally. Therefore, the latter design should be applied to projected new power lines and old vertically oriented lines in electrocution hotspots should be substituted. Given that flying foxes are key seed dispersers and pollinators, their foraging habitat selection change toward urban habitats together with high electrocution risk not only may contribute to their population decline but also put their ecosystem services at risk. Full article
(This article belongs to the Special Issue Impacts of Pressure on Bat Populations)
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Open AccessArticle
Relating Bat Passage Rates to Wind Turbine Fatalities
Diversity 2020, 12(2), 84; https://doi.org/10.3390/d12020084 - 22 Feb 2020
Cited by 3
Abstract
Wind energy siting to minimize impacts to bats would benefit from impact predictions following pre-construction surveys, but whether pre- or even post-construction activity patterns can predict fatalities remains unknown. We tested whether bat passage rates through rotor-swept airspace differ between groups of wind [...] Read more.
Wind energy siting to minimize impacts to bats would benefit from impact predictions following pre-construction surveys, but whether pre- or even post-construction activity patterns can predict fatalities remains unknown. We tested whether bat passage rates through rotor-swept airspace differ between groups of wind turbines where bat fatalities were found and not found during next-morning dog searches for fatalities. Passage rates differed significantly and averaged four times higher where freshly killed bats were found in next-morning fatality searches. Rates of near misses and risky flight behaviors also differed significantly between groups of turbines where bats were found and not found, and rate of near misses averaged eight times higher where bat fatalities were found in next-morning searches. Hours of turbine operation averaged significantly higher, winds averaged more westerly, and the moon averaged more visible among turbines where and when bat fatalities were found. Although dogs found only one of four bats seen colliding with turbine blades, they found many more bat fatalities than did human-only searchers at the same wind projects, and our fatality estimates were considerably higher. Our rates of observed bat collisions, adjusted for the rates of unseen collisions, would predict four to seven times the fresh fatalities we found using dogs between two wind projects. Despite markedly improved carcass detection through use of dogs, best estimates of bat fatalities might still be biased low due to crippling bias and search radius bias. Full article
(This article belongs to the Special Issue Impacts of Pressure on Bat Populations)
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Open AccessFeature PaperArticle
Effects of Forest Fragmentation on the Vertical Stratification of Neotropical Bats
Diversity 2020, 12(2), 67; https://doi.org/10.3390/d12020067 - 07 Feb 2020
Cited by 1
Abstract
Vertical stratification is a key component of the biological complexity of rainforests. Understanding community- and species-level responses to disturbance across forest strata is paramount for evidence-based conservation and management. However, even for bats, known to extensively explore multiple layers of the complex three-dimensional [...] Read more.
Vertical stratification is a key component of the biological complexity of rainforests. Understanding community- and species-level responses to disturbance across forest strata is paramount for evidence-based conservation and management. However, even for bats, known to extensively explore multiple layers of the complex three-dimensional forest space, studies are biased towards understory-based surveys and only few assessments of vertical stratification were done in fragmented landscapes. Using both ground and canopy mist-nets, we investigated how the vertical structure of bat assemblages is influenced by forest fragmentation in the experimentally fragmented landscape of the Biological Dynamics of Forest Fragments Project, Central Amazon, Brazil. Over a three year-period, we captured 3077 individuals of 46 species in continuous forest (CF) and in 1, 10 and 100 ha forest fragments. In both CF and forest fragments, the upper forest strata sustained more diverse bat assemblages than the equivalent understory layer, and the midstory layers had significantly higher bat abundance in fragments than in CF. Artibeus lituratus and Rhinophylla pumilio exhibited significant shifts in their vertical stratification patterns between CF and fragments (e.g., R. pumilio was more associated with the upper strata in fragments than in CF). Altogether, our study suggests that fragmentation modulates the vertical stratification of bat assemblages. Full article
(This article belongs to the Special Issue Impacts of Pressure on Bat Populations)
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Review

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Open AccessReview
Systematic Review of the Roost-Site Characteristics of North American Forest Bats: Implications for Conservation
Diversity 2020, 12(2), 76; https://doi.org/10.3390/d12020076 - 18 Feb 2020
Abstract
Continued declines in North American bat populations can be largely attributed to habitat loss, disease, and wind turbines. These declines can be partially mitigated through actions that boost reproductive success; therefore, management aimed at promoting availability of high-quality roosting habitat is an important [...] Read more.
Continued declines in North American bat populations can be largely attributed to habitat loss, disease, and wind turbines. These declines can be partially mitigated through actions that boost reproductive success; therefore, management aimed at promoting availability of high-quality roosting habitat is an important conservation goal. Following the principles of the umbrella species concept, if co-occurring species share similar roost-tree preferences, then management practices targeting one species may confer conservation benefits to another. We conducted a systematic review of roost-site characteristics of thirteen species inhabiting eastern temperate forests to: (1) synthesize existing knowledge across species; (2) assess niche overlap among co-occurring species; and (3) evaluate the potential for currently protected species to serve as conservation umbrellas. We performed multivariate ordination techniques to group species based on the seven most-reported roost-site characteristics, including tree species, diameter at breast height, tree health, roost type, tree height, canopy closure, and roost height. Species sorted into three roosting guilds: (1) southern wetland inhabitants; (2) foliage specialists; and (3) dead tree generalists. Myotis septentrionalis and Perimyotis subflavus had significant roost-niche overlap with five and four other species respectively, and their existing protections make them suitable umbrellas for other bats in the North American eastern temperate forests. Full article
(This article belongs to the Special Issue Impacts of Pressure on Bat Populations)
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