ArticlePDF AvailableLiterature Review

Abstract and Figures

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. This paper provides an overview of the global status of bat conservation by reviewing the major anthropogenic threats to bats and special challenges to bat conservation. The authors also discuss two habitats with particular significance for bat conservation, namely islands and subterranean features, and the value of bats to ecosystems. The article concludes with suggestions toward meeting the enduring challenges for global bat conservation.
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Ann. N.Y. Acad. Sci. ISSN 0077-8923
ANNALS OF THE NEW YORK ACADEMY OF SCIENCES
Special Issue: The Year in Ecology and Conservation Biology
REVIEW
A review of the major threats and challenges to global
bat conservation
Winifred F. Frick, 1,2 Tigga Kingston, 3and Jon Flanders 1,4
1Bat Conservation International, Austin, Texas. 2Department of Ecology and Evolutionary Biology, University of California
Santa Cruz, Santa Cruz, California. 3Department of Biological Science, Texas Tech University, Lubbock, Texas. 4School of
Biological Sciences, University of Bristol, Bristol, United Kingdom
Address for correspondence: Winifred F. Frick, Bat Conservation International, 500 North Capital of Texas Hwy Building 1,
Austin, TX 78746. wfrick@batcon.org
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.
Keywords: bats; biodiversity; conservation; Chiroptera; threats; mammals
Introduction
Loss of biodiversity is a global crisis caused by
pervasive threats from anthropogenic activities,1
particularly land-use change,2overexploitation of
species,3introduction of invasive species,4and
climate change.5One fifth of vertebrate species
around the world are considered by the Interna-
tional Union for Conservation of Nature (IUCN) to
be threatened,6a patterned mirrored by the world’s
mammalian species.7,8 Bats are the most widely dis-
tributed terrestrial mammals on Earth and consti-
tute nearly a fifth of mammalian biodiversity, with
almost 1400 species now recognized.9,10 However,
the nocturnal, elusive habits of bats, and a paucity
of bat research in the regions of the world with
the greatest bat diversity, challenge our ability to
prioritize and effect conservation where it is most
needed.11
Identifying the main anthropogenic stressors on
natural populations is key to proposing actions that
can decrease the risk of local or global extinctions
and mitigate the drivers of species declines.12 Exam-
ining threats within taxonomic groups sheds light
on global patterns, identifies common conservation
problems, and guides conservation action. When
Mickleburgh et al.13 reviewed the global conserva-
tion status of bats over 15 years ago, habitat loss or
modification, roost site loss or disturbance, human
health issues, persecution, lack of information, and
overexploitation for food were identified as the
major threats to bats globally. Many of these issues
remain major threats, but in the intervening years,
new threats have also emerged, including mass die-
offs of pteropodid bats in Australia and South Asia
from heat waves,14 high rates of mortality at wind
energy turbine installations,15 and the emergence
doi: 10.1111/nyas.14045
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Ann. N.Y. Acad. Sci. 1469 (2020) 5–25 C2019 New York Academy of Sciences.
Major threats and challenges to bat conservation Frick et al.
of an infectious fungal disease of bats, white-nose
syndrome (WNS), in North America.16,17 The open-
access book Bats in the Anthropocene: Conservation
of Bats in a Changing World offers a recent and thor-
ough review of the major conservation issues for
bats, revealing the breadth and depth of anthro-
pogenic stressors on bat populations globally.11
Here, we provide an overview of the global status
of bat conservation by reviewing the major anthro-
pogenic threats to bats and special challenges to
bat conservation. Using data from the IUCN Red
List, we visualize hotspots of threatened and data-
deficient bat species around the globe and compare
the proportions of threatened and data-deficient
bats to other homeothermic vertebrates (i.e., other
mammals and birds). We rank threats to bats using
the IUCN threat classification schema and review
the literature on the major threats identified by the
IUCN Red List18 to highlight what we currently
know and still need to know. Although the IUCN
Red List provides the most comprehensive global
database on the status and conservation needs of
species, the Red List is based on available infor-
mation and expert opinion and as such is chron-
ically incomplete and out of date. We discuss two
habitats with particular significance for bat conser-
vation, namely islands and subterranean features,
and the value of bats to ecosystems. We conclude
with some of the enduring challenges to global bat
conservation and suggest next steps toward meeting
those challenges.
Global status of bat populations
Global patterns of bat diversity are similar to
biodiversity patterns for mammals, with diver-
sity peaking in equatorial regions of the world
(www.biodiversitymapping.org).1,8 Using range
maps from IUCN, we show areas with the high-
est density of species richness of known threatened
and data-deficient bats and show that global pat-
terns for threatened and data-deficient bats differ
(Fig. 1). Range maps from IUCN are based on cur-
rent taxonomy, available locality records, and expert
opinion and should be viewed as hypotheses of the
extent of occurrence of species. The density of listed
threatened species peaks in Southeast Asia, whereas
the density of data-deficient species is highest in
the Amazon basin in South America. The differ-
ence in the distribution of data-deficient species
may in part reflect a lag in species discovery in
equatorial Africa and Southeast Asia compared to
the neotropics, as newly described species are com-
monly data deficient. Island archipelagos across the
globe, including the Caribbean, African islands, and
islands throughout Asia and the south Pacific, are
hotspots of threatened bats. To some extent, these
patterns reflect the geographic biases in knowledge
and inclusion of species on the IUCN Red List, but it
is clear that islands and equatorial regions of Africa,
Southeast Asia, and the neotropics are priority areas
for research and conservation attention.
We investigated whether the global status of bats
differed from similar taxa by comparing the pro-
portion of bats considered threatened or data defi-
cient by the IUCN Red List to other mammals and
birds. Notably, while 15% of bats are considered to
be threatened by the IUCN (assessed as Critically
Endangered, Endangered, or Vulnerable on the Red
List),19 18% of bat species are Data Deficient, a far
greater proportion than reported for either other
mammals (13%) or birds (1%) (Table 1; Fig. 2).
Critically, over half of bat species assessed by IUCN
(57%) have unknown population trends compared
to 39% of other mammals and just 8% of all birds
(Fig. 3A). The disparity in knowledge about pop-
ulation trends was also significant when just com-
pared among species ranked as Least Concern or
Near Threatened. Thirty-five percent of bat species
classified as Least Concern have unknown popula-
tion trends (Fig. 3B), showing a remarkable gap in
knowing the status of many bat species not currently
considered to be conservation priorities.
There has been rapid growth in the number of
recognized bat species over recent decades10,20 with
over 270 new species described since 2005, when the
last version of the Mammal Species of the World was
published.21 The increase in described bat species
(>25%) over the past 15 years has outpaced that
of other mammals.10 Many of these species are not
yet classified by IUCN, which currently has 1236
species compared to the 1395 species now recog-
nized in the online global bat taxonomy database.9
The pace of species discovery is consistently faster
than that of species assessments by the IUCN. The
Global Bat Taxonomy Database working group was
recently created as part of the IUCN Bat Specialist
Group to centralize and harmonize descriptions of
new species and taxonomic revisions that can sup-
port more rapid assessments of new taxa. Despite
these efforts, the number of data-deficient species
6Ann. N.Y. Acad. Sci. 1469 (2020) 5–25 C2019 New York Academy of Sciences.
Frick et al. Major threats and challenges to bat conservation
Figure 1. Heat maps showing areas of highest species density of threatened (top) and data-deficient (bottom) bat species. Data
based on IUCN range maps and classifications.
on the IUCN Red List remains a minimum estimate.
We recommend that descriptions of new species or
taxonomic revisions suggest the appropriate IUCN
status based on available data and Red List criteria
to aid in rapid inclusion on the IUCN Red List.
Major threats to bats
We review the major threats to bats, organized
by the categories identified by the threat classifi-
cation schema used by the IUCN19 (Fig. 4). We
used the first-level hierarchy of threat category,
except for the category of “Biological resource use,”
which includes “Hunting and collecting animals”
and “Logging and wood harvesting,” two of the most
widespread yet distinct threats to bats that we con-
sider separately. We discuss threats in rank order
based on the proportion of threatened bat species
for which a threat was listed on the Red List.
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Ann. N.Y. Acad. Sci. 1469 (2020) 5–25 C2019 New York Academy of Sciences.
Major threats and challenges to bat conservation Frick et al.
Tab l e 1. Conservation status of bats compared to other mammals and birds
Taxon Species assessed Threatened species (%) Data-deficient species (%)
Bats 1236 180 (18%)a227 (15%)b
Other mammals 4358 1030 (24%) 578 (13%)
Birds 10,961 1469 (13%) 58 (1%)
Note: Conservation status is summarized as species classified as threatened (Critically Endangered, Endangered, and Vulnerable) or
Data Deficient by IUCN Red List (data accessed on July 26, 2018).
aProportion of species in threatened categories was significantly lower (P<0.001) for bats than other mammals, but not significantly
different from birds (P>0.25), based on a generalized linear model with binomial errors.
bProportion of species classified as Data Deficient was significantly higher for bats (P<0.001) than for other mammals and birds,
based on a generalized linear model with binomial errors.
Logging and harvesting plants
Globally, the two most important habitats for bats
are forests and subterranean features (i.e., caves
and mines). Although caves capture our atten-
tion as uniquely important for bats, forests are the
most critical habitats for supporting local abun-
dance and species diversity for bats at a global
scale.22 Forests not only provide essential foraging
habitats, but they also allow many bat species to
roost in plant structures, such as hollows and cav-
ities in standing and fallen trees, under bark, or
in foliage.23 Although subterranean habitats pro-
vide protected refuges for roosting for roughly 40%
of the world’s bat species, many of these species
also depend on forest habitats for foraging.24 The
importance of forests is evidenced by global pat-
terns of bat biodiversity that peak in tropical forest
ecosystems.25
Continuing loss and degradation of tropical
rainforests,26 particularly in the neotropics27 and
Southeast Asia,28 is a severe threat to global bat
diversity.22,29 The impacts of deforestation are obvi-
ously not unique to bats and conservation efforts
focused on the protection of forests, both temperate
and tropical, will benefit a large component of bat
biodiversity.22,30 Research on bat species responses
and impacts of deforestation and land-use change
on bats in Southeast Asia have historically trailed
behind research effort in the neotropics but have
gained more attention and funding in recent years
in large part due to the efforts of the Southeast Asian
Bat Conservation Research Unit (SEABCRU).29,31
Unfortunately, studies on the impacts of deforesta-
tion on bats in Africa remain rare32,33 and need
more attention. In the managed timber-production
forests of Europe, Australia, and North America,
Figure 2. The proportion of species in each category of the IUCN Red List is shown for bats, other mammals, and birds. The
IUCN categories are EX (Extinct), EW (Extinct in the Wild), DD (Data Deficient), CR (Critically Endangered), EN (Endangered),
VU (Vulnerable), NT (Near Threatened), and LC (Least Concern).19
8Ann. N.Y. Acad. Sci. 1469 (2020) 5–25 C2019 New York Academy of Sciences.
Frick et al. Major threats and challenges to bat conservation
Figure 3. Population trend status from IUCN Red List assessments for (A) bats, other mammals, and birds and for (B) the Red
List categories for bats. The proportion of species with unknown population trends was significantly higher for bats than other
mammals (P<0.001) or birds (P<0.001).
historical silvicultural practices, such as removal of
standing dead trees and even-aged management,
have compromised forest value for bat diversity.
Recent shifts to management practices that cre-
ate spatial-temporal heterogeneity in forest age and
structure at landscape scales and retain mature for-
est trees with cavities are likely to benefit bats, but
need to be propagated across regions.34,35
Forest bats can be difficult to study, particularly in
terms of quantifying population status and trends,
given that they often roost in cryptic locations dis-
persed throughout forest habitats and recapture
rates of individuals are usually too low to allow
effective mark-recapture techniques for population
or demographic studies.23,36 Given that 80% of
bats emit ultrasonic echolocation signals, acoustic
Figure 4. Ranking of major threat types for threatened bat species, based on IUCN Red List assessments. A total of 170 species
(94% of assessed threatened species) had at least one threat type listed. For description of threat categories, see: www.iucnredlist.org.
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Ann. N.Y. Acad. Sci. 1469 (2020) 5–25 C2019 New York Academy of Sciences.
Major threats and challenges to bat conservation Frick et al.
monitoring can be used to conduct longitudinal
studies to assess trends over time as well as com-
pare across environmental gradients (e.g., land-use
change) to provide a baseline understanding of
bat habitat use and population trends.37,38 How-
ever, while acoustic monitoring may be effective in
temperate forests that are mostly populated with
species that use high-intensity echolocation calls,
assemblages of the interior of tropical rainforests are
dominated by species that use low-intensity and/or
high-frequency calls. These faint calls limit detec-
tion distances to a few meters. Consequently, acous-
tic approaches cannot characterize and monitor the
diversity of the most vulnerable tropical ensembles.
Rather, monitoring must rely upon standardized
capture protocols that require substantial effort to
detect population trends.31,39,40
Agriculture
Conversion of land for agricultural production
is one of the most significant land-use changes
occurring across the planet, with an estimate of
nearly 40% of terrestrial land cover now in agri-
cultural production.41,42 Agriculture is identified
as a threat in IUCN Red List assessments for over
50% of threatened bat species (Fig. 4). Agriculture
reduces bat populations through direct habitat loss
and modification, as agricultural habitats present
reduced foraging and roosting resources for most
species. For insectivorous species, widespread
use of insecticides and insect-resistant varieties
of crops reduces foraging resources by reducing
insect prey abundance, and can directly poison
bats, particularly in countries lacking regulation
of organochlorines. In regions where bats feed on
fruit crops, direct conflict between bats and farmers
has led to lethal persecution by both individuals
and government programs.43,44 A geographical bias
toward North America and Europe exists for studies
estimating the consequences for bats of agricultural
conversion and intensification, although some stud-
ies in tropical regions have focused on agroforestry,
particularly in the neotropics.41 The current
evidence from these regions is that lower intensity
agriculture, such as organic farming and shaded
agroforestry, supports higher activity and species
richness compared to more intensive methods,
indicating management interventions that focus on
lower intensity agriculture may benefit bats.41,42
Hunting and collecting animals (including
persecution/control)
One hundred and sixty-seven bat species (roughly
13% of species) are hunted for food or medicine,
and bushmeat hunting is increasingly recognized as
a major conservation threat for bats, primarily in
Southeast Asia and West and Central Africa.3,45,46
Hunting disproportionately affects Old World fruit
bats (Pteropodidae), with roughly half of pteropo-
did bat species (92/183) hunted, primarily for food
but in some cases for traditional medicine and sport.
The most intensely hunted species are typically large
(>100 g body mass) and roost in large accessible
aggregations in trees or caves where they can be
predictably encountered.46 Despite increased aware-
ness and concern about bushmeat hunting of bats,
even at noncommercial scales (e.g., subsistence or
local-scale markets), there are few empirical esti-
mates of population impacts from hunting.45 The
few available studies indicate that harvest rates are
alarmingly high and appear unsustainable based
on what is known of local population sizes and
bat population dynamics.47–51 Harvesting bats for
tourist souvenirs, curios, and decoration is also a
growing concern52 particularly as the online mar-
ket is global in extent. Only species of Pteropus
(65 spp.),Acerodon(5 spp.), and Platyrrhinus (1
sp.) are listed on the Convention on International
Trade in Endangered Species of Wild Fauna and
Flora (CITES) appendices that prohibit or control
trade.53
In addition to overexploitation of bats hunted
for food, bats are intentionally killed for a variety
of reasons,54,55 including fear of bats as a source of
zoonotic disease transmission,56,57 cultural beliefs
that bats are evil or “creepy,”55 eradication of
bats living in human structures,58 and illegal and
legal culling intended to reduce damage to fruit
crops.43 The threat of intentional killing of bats
varies geographically,54 depending on cultural con-
text, existence (or lack thereof) of wildlife protection
laws and their enforcement, and the type of bat fauna
present in a region.55 As loss of natural habitat accel-
erates, bat–human conflicts become more common
as bats increasingly depend on human-dominated
habitats.
A recent example of human–wildlife conflict
threatening bats is the culling of an endemic fly-
ing fox, Pteropus niger, on the island of Mauritius
in 2015 and 2016.59–61 Theconictderivesfrom
10 Ann. N.Y. Acad. Sci. 1469 (2020) 5–25 C2019 New York Academy of Sciences.
Frick et al. Major threats and challenges to bat conservation
consumption of fruit crops, primarily lychee, by
bats, but has been exacerbated by misinforma-
tion and misperception about the extent of dam-
age caused by bats compared to other sources of
fruit damage (e.g., non-native birds, fungal infec-
tion, rats, and wind). Political, economic, and capac-
ity barriers currently prevent extensive use of crop
netting, a technique that has successfully mitigated
bat predation of fruit crops in Australia and Thai-
land. Local political motivations to cull bats have
overridden scientific evidence that shows culls fail
to improve crop yield.61 In two mass culling events
ordered by the government, over 38,000 individuals
were reported killed, a loss of more than a third of
the population in just 2 years.59,62 The rapid and
severe population loss from the government cull,
and associated increases in hunting and persecution
by the public, resulted in a change in status on the
IUCN Red List from vulnerable to endangered.44
In November 2018, a third cull with a target of
20% of the remaining 65,000 bats began. Continued
population declines are projected for P. nig e r from
the 2018 and future culls, illegal killing by farmers,
hunting, reductions in natural forest habitat, and
risk of mortality from cyclone events, highlighting
how island bat species face multiple threats that are
interrelated.44,59 For island flying foxes, including
P. ni g e r in Mauritius, loss of natural habitat from
deforestation increases conflicts with local farmers
as bats become dependent on domesticated fruit
treesforfoodintheabsenceofadequateforest
habitat.59,62
In Central and South America, vampire bats
are a vector of rabies transmission to livestock
and are culled in an attempt to control rabies
transmission.54,57,63 Methods of killing have been
largely indiscriminate, with whole caves being
destroyed or gassed, resulting in mortality and loss
of roosts for species that share roosts with vam-
pire bats.63,64 Research on transmission dynamics
has shown that culling does not reduce transmis-
sion and in some cases has the opposite effect.57
Improving methods and reducing illegal and legally
sanctioned culls of vampire bats is an area of active
conservation. Culling animals for attempted control
of other zoonotic diseases, such as Marburg virus,
has also proven ineffective and leads to unnecessary
extermination of local populations without human
health benefit or, worse, can even increase disease
prevalence.65
Resolving bat–human conflicts requires under-
standing of human behaviors and rigorous app-
roaches to developing effective interventions to
promote behavioral change.55,66 Biologists often
lack the training to address questions related to
human behavior. Collaborations with social scien-
tists are needed to extend research beyond the
boundaries of the natural sciences.55,67 As
Kingston55 points out, many bat biologists believe
promoting positive messages about bats and empha-
sizing their ecosystem services will de facto lead to
cultural shifts toward positive views of bats, which
will then translate into protection or conservation
measures. Yet, there is little empirical evidence to
support this belief and we need to test the efficacy
of educational campaigns and ways to resolve bat–
human conflicts.55,64,68
Human intrusions and disturbance
Bats that roost in caves are particularly vulnerable to
disturbance because they form large, concentrated
aggregations.24 Large colonies of cave-roosting bats
are relatively easy to locate—by local communi-
ties and researchers alike—resulting in documented
cases of intentional disturbance (e.g., persecution,
hunting, vandalism, etc.) or roost destruction (e.g.,
mineral extraction and mining).24 The effects of
unintentional disturbance are more difficult to mea-
sure due to the variety and nature of recreational
activities in caves. Cave tourism, which was esti-
mated to attract 20 million people worldwide by
the mid-1990s, continues to increase in popular-
ity, adding stress to species dependent on subter-
ranean habitats.24 Disturbance affects over a third
of threatened bat species (Fig. 4). Installing bat-
friendly gates that permit bats to continue to use
caves or mines while limiting human access can
reduce disturbance to bats and increase use and
colony size of bats for some species and regions.69,70
Some species may be intolerant of gating structures
and installation should be tested and bat use moni-
tored prior to wide-scale implementation to ensure
that gating leads to roost protection rather than
abandonment.71,72 Gating may also require edu-
cation and communication efforts to target audi-
ences, such as recreational users, or the gates may be
destroyed.
The IUCN threat category of “Human intrusions
and disturbance” includes threats posed by war, civil
unrest, and military exercises. Although political
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Ann. N.Y. Acad. Sci. 1469 (2020) 5–25 C2019 New York Academy of Sciences.
Major threats and challenges to bat conservation Frick et al.
unrest is only listed as a direct threat for six bat
species, political instability and conflict often inten-
sify other threats, such as exploitation of bats for
bushmeat when human food resources are scarce,
or encroachment into protected areas. More gener-
ally, war and political instability frequently restrict
or prohibit access to research areas, and greatly con-
strain or preclude research and conservation activi-
ties. At worst, academic institutions, collections, and
researchers may be directly at risk.
Urban development
Urbanization drastically alters habitats and is pre-
dicted to increase in land cover by 1.2 million
km2by 2030, tripling in extent over 30 years,
with disproportionate expansion in biodiverse areas
such as tropical Africa and Asia.73 The impact of
urbanization on bats is generally negative, although
the response can be species specific.74,75 Some bat
species are synanthropic and have adapted to roost-
ing in human-made structures such as buildings
and bridges for either all or some of their annual life
cycle (e.g., maternity or hibernation roost sites).58,75
Although populations of some species may increase
in some urban settings, the effect of urban liv-
ing on the fitness and population dynamics of
synanthropic species is still not well understood,
and urban environments could serve as ecological
traps.75 As urbanization increases in the biodiverse
tropics, especially in regions such as Africa where
there is less regulatory protection of wildlife and
greater concerns regarding the potential for bats to
transmit disease, it also increases bat–human con-
flicts. Bat colonies that depend on human structures
after loss of natural roost sites become vulnerable to
persecution and extirpation.58,75
Energy production and mining (including
renewable energy)
Mining and quarrying activities threaten bats by
destroying subterranean habitats used for roosting
as well as degrading or destroying surface habi-
tats. Of particular concern is the global demand
for limestone extraction, which typically occurs in
karst regions with a high density of natural cave
roosts.24 Bat roosts in natural caves are associated
with high species richness of other cave organisms
and can indicate high priority sites for biodiver-
sity conservation in areas threatened by resource
extraction.76 In addition to roost destruction, some
mining operations produce tailing impoundments
and toxic surface water that may poison or harm
bats that depend on surface water for drinking.54
Inactive mines often provide suitable roosting habi-
tats for bats and may provide critical roosts for
populations.77,78 Some countries, such as the United
States and Australia, have government-sponsored
programs to close abandoned mines due to human
health and safety concerns and have developed
best management practices, such as installing bat-
friendly gates and requiring preclosure bat sur-
veys, prior to mine closures. Destruction of inactive
mines, either from intentional closure or renewed
mining activities, is a major concern for habitat loss
for bats globally.
Only two species are currently listed as threatened
by “renewable energy” in IUCN assessments. How-
ever, fatalities from collisions with wind energy tur-
bines are now one of the leading causes of observed
mortality of bats globally.54 Over 500,000 bats are
estimated to be killed annually across Canada and
the United States79–81 and over 300,000 killed annu-
ally at wind energy facilities in Germany alone.82,83
Current fatality rates from wind turbines are high
enough to cause rapid declines in populations and
increase the risk of extinction for some migra-
tory species.15 Much of the research attention has
occurred in North America and Europe, but there
is growing awareness and efforts to understand the
impact of wind energy facilities on bats in other
regions, especially as the number of wind energy
facilities increases globally.84–86
In North America and Europe, the majority of
bats killed by turbines are migratory species83,87,88
that generally lack regulatory protection.89 Research
showing effective mitigation solutions to reduce
mortalities has been known for nearly a decade.90,91
Limiting wind turbine operation during the high-
risk periods of nights with low wind speeds dur-
ing autumn migration can reduce bat fatalities
by as much as 44–93%, with minimal impact
on power generation.90,91 Other solutions, such as
acoustic deterrents installed on turbines, may also
reduce fatalities, although further research is needed
on efficacy in different settings before broad-scale
implementation.92
Although scientific research has shown how
to reduce fatalities and demonstrated the need
to reduce fatalities to prevent rapid population
declines,15 implementing regulatory management
solutions has proven challenging.93 Furthermore,
12 Ann. N.Y. Acad. Sci. 1469 (2020) 5–25 C2019 New York Academy of Sciences.
Frick et al. Major threats and challenges to bat conservation
strategies to reduce fatalities of bat species in
tropical habitats, on islands, and in other regions
experiencing rapid growth in turbine installment
are necessary. In 2017, four North American
migratory bat species (Lasiurus spp.) were added
to the Convention on Migratory Species, but since
Canada, Mexico, and the United States are not
parties to the treaty, the listing does not impose
transnational regulatory protection.
Climate change
There is mounting evidence that changing cli-
matic conditions, including extreme events such as
drought and flooding, are causing shifts in species
richness and distribution patterns of biodiversity
at an unprecedented rate.94 Climate change is now
recognized as a significant threat to global biodi-
versity and its effects could surpass those of land
use change by 2070.95 Developing frameworks to
identify species at greatest risk from climate change
by predicting species response96–100 is an urgent
need. The high mobility of bats may enable some
species to respond to changing climates with rapid
range shifts,101,102 and the ability to use diverse
habitats or alter behavior may buffer some species
from extinction risk.103 Climate shifts may disrupt
or change migratory behavior,104,105 survival and
reproduction,106,107 foraging behavior,108 and dis-
rupt food availability for pollinating species through
alterations in flowering phenology.109
The negative forces of climate change are most
likely to impact species that are already vulnerable.
An increase in extreme weather events, such as
unusually hot or dry conditions, or an increase
in the frequency of natural disasters caused by
typhoons and hurricanes, can cause rapid popula-
tion declines that further decrease the resiliency of
populations already threatened by small population
sizes due to anthropogenic degradation or loss of
natural habitats.110,111 Bats on tropical islands are
particularly vulnerable to cyclones, and drastic
declines (80–90% of some Pteropus populations)
arising from direct mortality and loss of forest
resources have been observed throughout the Pacific
Islands.112 Extreme heat events on continents are
increasing in intensity and frequency. Sustained
high temperatures (>42 °C) lead to physiological
stress, resulting in the mortality of flying foxes in
South Asia and Australia.14,113 Die-offs from heat
stress of flying foxes that roost colonially in trees
are readily observable, but the impact of extreme
weather events on other bat species may be harder
to observe and quantify.
While climate change is a global problem necessi-
tating a global solution, local interventions can play
a critical role in protecting species from its adverse
effects. Protecting and restoring wetlands and forests
can reduce the levels of carbon released into the
atmosphere and make habitats more resilient to
extreme weather events and provide bat foraging
habitats.114 In semiarid areas, where the combined
effects of drought and increases in human demand
for water are predicted to be a primary driver of bio-
diversity loss,115 strategies that focus on restoration
of water courses and provisioning water to wildlife
may be successful.116,117
Invasive species
Although invasive species are one of the major
threats to biodiversity globally,118,119 there has been
relatively little attention on estimating the effects
of invasive species on bats.120 An exception is the
invasive fungal pathogen that causes WNS in North
America, a disease that has caused severe mortality
among hibernating bats.17 Wel c h a nd L e pp a ne n120
provide a review of the threat of invasive species on
bats and identified 37 invasive species as threats to
40 bat species based on searching the IUCN Red
List and the literature. Although 40 bat species
represent less than 5% of the fauna, over 60%
of bat species threatened by invasives occur on
islands, where impacts from invasives are gener-
ally compounded by other stressors and the risk
of extinction is generally greater.121 Wel ch a n d
Leppanen note that over half of the cases they
identified were speculative or circumstantial, indi-
cating that better documentation and empirical
research are needed to determine the impact of inva-
sive species on bat populations. Online databases,
such as the Threatened Island Biodiversity database
(http://tib.islandconservation.org/) maintained by
Island Conservation, a conservation organization
focused on eradicating invasive species, provides a
starting point to identify where island bats are most
vulnerable to invasive species.
WNS is an infectious disease of hibernating
bats caused by the fungal pathogen Pseudogym-
noascus destructans that has spread widely across
North America in the past decade.122–124 The dis-
ease emerged in New York State in 2006 and
13
Ann. N.Y. Acad. Sci. 1469 (2020) 5–25 C2019 New York Academy of Sciences.
Major threats and challenges to bat conservation Frick et al.
quickly drew attention as a major conservation cri-
sis in North America when mass die-offs that led
to rapid and dramatic population declines were
observed for hibernating bats, raising alarms about
regional or global extinction of species previously
considered stable or increasing.125–127 The fun-
gus infects hibernating bats and in some species
causes a lethal cutaneous skin infection by dis-
rupting physiology.124,128–130 Although WNS cur-
rently impacts a small percentage of the global bat
fauna, the dramatic nature of the die-offs elevated
public and scientific interest in bat conservation
beyond the species under immediate threat from the
disease.
Pollution
Studies on chemical pollutants and bats have
declined over the past few decades despite gen-
eral increases in chemical products and growing
interest in bats and their conservation.89 Most
of what we know about the impacts of pesti-
cides on bats comes from North America and the
impact of organochlorine pesticides,41 and a few
specific studies on direct mortality131 or demo-
graphic impacts.132 In temperate areas, concentra-
tions of organic contaminants found in bat tis-
sues have declined since the 1970s and 1980s,
when use of the persistent organochlorine pesti-
cide dichlorodiphenyltrichloroethane (DDT) was
banned in the United States and Canada, Australia,
and most European countries.133 However, DDT,
as well as pyrethroids, is still widely used in Africa
and parts of Asia, including India, for the control of
malaria and other vector-borne diseases, although
mostly applied indoors.134 We need more research
on ecotoxicology and quantification of acute and
chronic (sublethal) effects of exposure to pesticides
on bats.133,135 Persistent organic compounds con-
centrate in tissues with higher fat content and could
impact physiological processes for bats that depend
on seasonal fat deposition.133 Recent reviews on bats
and pollutants raise the need for standardized mon-
itoring protocols and online data repositories for
better information sharing on ecotoxicology.133,135
Other types of pollution, such as light pollution136
and noise pollution,137 have received recent atten-
tion given their propensity to disrupt the foraging of
bats, but these threats have yet to be explicitly listed
in IUCN assessments for threatened bat species.
Transportation and service corridors
Transportation and service corridors threaten bio-
diversity by serving as mortality sinks and by causing
habitat loss and fragmentation. The scale and sever-
ity of the threat of roads to bats remains poorly
investigated and only within the last decade has
research attention focused on the effect of roads
on bat populations.138–140 Current evidence suggests
that roads serve as a substantial source of mortal-
ity for many bat species and create barrier effects
and fragmented habitats.138,139 For example, a recent
study from Brazil showed that 44 species (25% of the
local fauna) were observed as roadkill, with frugiv-
orousspeciesidentiedasmostvulnerable.
141 Road
corridors degrade and fragment habitats, thus cre-
ating barriers to movement, and they increase levels
of noise, light, and chemical pollution.138,139 These
effects can lead to reduced foraging efficiency, lower
reproductive success, and ultimately lower species
diversity near roads.142,143 In addition, the expan-
sion of road corridors facilitates land conversion in
areas that were previously inaccessible and intact.
Most of the research on bats and roads has occurred
in temperate regions (mostly in Europe) and more
research attention is needed on mortality rates and
barrier effects of roads in tropical areas.139,141
Geologic events
Geologic events, such as volcano eruptions, earth-
quakes, and landslides, are included in the IUCN
threat classification scheme and were mentioned
in Red List assessments for five bat species. These
threats are not addressable by direct conservation
action but demonstrate the vulnerability of small
populations, particularly on islands, to natural dis-
asters.
Two special habitats for bats as
conservation targets
Islands
Islands are key areas for conservation, with a dis-
proportionate number of rare and endemic taxa
compared to mainland habitats.144 Island ecosys-
tems tend to be small, isolated, and vulnerable to a
variety of threats.144 An estimated 75% of recorded
terrestrial vertebrate extinctions occur on islands
and 40% of species threatened with extinction live
only on islands.145 Because bats can disperse across
wide expanses of water, they are often the only
native mammals on islands and are particularly
14 Ann. N.Y. Acad. Sci. 1469 (2020) 5–25 C2019 New York Academy of Sciences.
Frick et al. Major threats and challenges to bat conservation
important to island ecosystems.146 Bats help main-
tain island ecosystems, particularly in forests, by
dispersing seeds over wide distances.147 Roughly, a
quarter of all bat species are island endemics and
50% of these species are threatened.113,148 Notably,
the five species of bats that have gone extinct were
all island endemics.149
Although bats on islands face many of the same
threats as mainland species, the small size and iso-
lation of habitats magnify these threats, resulting in
a higher background rate of extinction.113,148 Nat-
urally occurring threats, such as extreme weather
events (e.g., typhoons, hurricanes, or extended
drought), put island species at higher risk of episodic
catastrophic losses of population. However, anthro-
pogenic pressures, such as habitat loss and inten-
tional killing, that reduce population sizes decrease
resiliency, making insular bat species more vulner-
able to extinction. Furthermore, the frequency and
intensity of catastrophic weather events is increas-
ing with climate change.150 The combined effect
of habitat change, hunting, disturbance, and inva-
sive species4has intensified the risk of extinction.
Indeed, these threats contributed to the decline and
global extinction of the Christmas Island pipistrelle
(Pipistrellus murrayi), which was formally declared
extinct in 2017, and six extinct species of island fly-
ing fox (Pteropus spp.).59,151
Conservation efforts for island bats are hampered
by a lack of information about species’ habitat needs,
drivers of population declines, and effective ways
to implement conservation measures that improve
resilience to stressors.152 Research on threatened bat
species endemic to islands currently lags that on
continental faunas,148 which is likely driven by chal-
lenges of capacity and access on islands. Despite the
challenges facing island bats, there is also opportu-
nity to make meaningful conservation gains. Efforts
to protect species on islands are likely to focus over
smaller geographic areas and involve fewer govern-
ment agencies, facilitating a quicker, more nimble
approach to implementing conservation strategies.
Research findings can be quickly disseminated to a
small group of stakeholders, enabling practical and
achievable conservation action.
Subterranean refuges
Subterranean habitats are a different type of
“island” but share many similarities to islands with
supporting fragile faunas. Although caves account
for a relatively small proportion of the landscape
compared to other habitats, they support a dis-
proportionate number of endemic species.153,154
Subterranean habitats support some of the largest
and most diverse aggregations of bat species in
the world.149 Inturn,batsplayakeyroleincave
ecosystems and surrounding habitats, especially
when they form aggregations in the thousands to
millions. Bats depositing guano in caves provide
some of the only allochthonous nutrient inputs into
cave environments, thus contributing substantially
to cave ecosystem food webs and supporting
cave-specialist organisms.155 In addition, bats
commuting and foraging to and from a centralized
cave roost provide ecosystem services as consumers
of nocturnal insects, pollinators of tropical plants,
and dispersers of tropical seeds.156
With an estimated 40% of all threatened bat
species149 known to use subterranean habitats,
researchers and conservation practitioners need to
place a greater emphasis on implementing effective
measures in these high-risk habitats. While some
caves and cave-dwelling bats receive some legal pro-
tection, the extent and impact of these protections
vary considerably across the world.157 Legal pro-
tection relies on available and accurate information
and may not always be enforceable without local
support. For example, although caves are protected
by law in the Philippines (Republic Act No. 9072)
and there has been significant progress in protect-
ing karst habitats, challenges arise if local commu-
nities and interest groups are not aware of the value
of habitat restoration and protection, demonstrat-
ing the importance of incorporating education and
awareness campaigns as part of strategies to desig-
nate protected areas.158 Increasingly, conservation
practitioners recognize that direct actions to protect
caves (e.g., land purchase and management) must
include efforts to protect and restore the surround-
ing landscape where cave-roosting bats commute
and forage. Additionally, environmental education
programs with local communities are necessary to
ensure local support and enforcement of conserva-
tion measures.
Accordingly, some of the most effective conser-
vation initiatives for cave-roosting bats have come
from multipartner projects that include groups
with the skills and expertise to address multiple
threats. As one example, a bi-national consortium
of researchers, NGOs, landowners, and government
15
Ann. N.Y. Acad. Sci. 1469 (2020) 5–25 C2019 New York Academy of Sciences.
Major threats and challenges to bat conservation Frick et al.
agencies worked on local and range-wide conserva-
tion programs to protect and recover populations
of the lesser long-nosed bat (Leptonycteris yerbabue-
nae), a migratory species that depends on caves and
forms large aggregations (>10,000 bats) across its
migratory range from Mexico into the southwest-
ern United States.159 Conservation measures in both
Mexico and the United States, including roost pro-
tection measures and research efforts to obtain bet-
ter estimates of population size and trends, resulted
in removal of the species from the Mexican endan-
gered species list in 2013 followed by removal from
the Endangered Species Act in the United States in
2018.160–162
In the immediate term, conservation of cave-
dwelling bats requires identifying and protecting key
roost sites of vulnerable populations before local,
regional, or global populations spiral toward extinc-
tion (e.g., UNEP/EUROBATS Conservation of Key
Underground Sites Database).163 At local to regional
scales, correlates of bat diversity, such as land-use
change and cave complexity, can be used to help
identify priority caves.164 Criteria, such as those
developed as part of the IUCN Key Biodiversity Area
initiative,165 could be used to identify target areas
for conservation action. The IUCN’s Key Biodiver-
sity Area criterion D focuses on large demographic
aggregations in a local habitat, which applies readily
tobatspeciesthatformmasscoloniesincaves.
165
Sustainable conservation will also require invest-
ing in research to determine the relative impacts
of different stressors that contribute to popula-
tion declines of cave-dwelling bats166 and moni-
toring the effectiveness of conservation actions to
protect populations. Direct conservation actions,
such as gating sites to control human access, pur-
chasing caves to establish reserves, or mitigating
roost loss by adapting underground sites or cre-
ating artificial roosts, should be conducted as adap-
tive management so that populations are monitored
to determine whether protective measures result
in desired outcomes of stabilizing or increasing
populations. Guidelines that minimize the impact
of some cave activities have been developed (e.g.,
guano harvesting),167 butgreatereffortstoreach
relevant communities are needed. Finally, efforts
to protect cave-dwelling bats will only succeed if
cultural traditions, sensitivities, and cave use are
considered.164
Value of bats to ecosystems
Bats provide ecosystem services of both economic
and ecological value in addition to their intrinsic
value to global biodiversity.156,168 As the primary
consumer of nocturnal insects, bats consume agri-
cultural insect pests, and their annual services to the
agricultural industry in the United States alone have
been estimated in the billions.169,170 Experimental
studieshavedocumentedthatbatsreducecropdam-
age in a number of agricultural settings in both tem-
perate and tropical regions,171,172 showing that bats
provide quantifiable value to agricultural economies
by consuming crop pests.168 Nectar-feeding and
fruit-eating bats perform ecosystem services by
pollinating plants and dispersing seeds.156,168 Diet
specialization for nectar-feeding and fruit-eating
occurs primarily in just two families of bats, the
old-world Pteropodidae and new-world Phyllosto-
midae, but these diverse phytophagous bats polli-
nate or disperse seeds for well over 1000 different
plants worldwide.173–175
Bats are important contributors to forest ecosys-
tem health and provide both ecological and eco-
nomic value to neotropical and paleotropical forest
ecosystems.176 Frugivorousbatshavebeenstudied
as potential agents to facilitate forest restoration and
regeneration efforts in degraded landscapes due to
their potential to naturally disperse seeds,177,178 but
approaches require refinement to demonstrate suc-
cess at facilitating seedling recruitment in highly
degraded areas.179 Flying foxes are often the only
effective seed dispersers on paleotropical islands180
and therefore are critical for maintaining forest
structure and health on oceanic islands in the Pacific
and Indian Oceans.62
Some plants that rely heavily on bats for pollina-
tion or seed dispersal have significant commercial or
ecological value,156,168 including baobabs in Africa
(Adansonia digitata),181 durian (Durio zibethinus)
and petai (Parkia speciosa) in southeast Asia,182–184
and pitaya cactus (Stenocereus spp.) and agave
(Agave spp.) in Mexico.185,186 A recent meta-analysis
showed that bat-pollinated plants are more depen-
dent on their bat pollinators than plants primarily
pollinated by other vertebrate pollinators such as
birds or rodents, suggesting that loss of bat pollina-
tors could have strong impacts on plant reproductive
success, particularly in tropical habitats.187
16 Ann. N.Y. Acad. Sci. 1469 (2020) 5–25 C2019 New York Academy of Sciences.
Frick et al. Major threats and challenges to bat conservation
The ecosystem consequences of declining bat
abundances, local extirpations, and global extinc-
tions need greater research attention, as our cur-
rent understanding is based primarily on inferences
from what we know of the primary ecological roles
of bats (e.g., insect predators, plant pollinators, and
seed dispersers). General theory about ecological
integrity and the impacts to ecological communities
from loss of biodiversity components should apply
to bats.113 In some cases, we may expect ecological
resilience to reductions in population sizes or loss
of species, but in other cases we may expect cascad-
ing and negative impacts resulting from removal or
reduced numbers of key ecological actors.
Challenges and next steps for global bat
conservation
While many of the threats that bats face (e.g., habitat
loss, bushmeat hunting, and climate change) reflect
the broader conservation challenges of our era, there
are aspects of bat ecology that present specific chal-
lenges and opportunities for conservation action.
For example, bat species that aggregate in large
numbers in concentrated habitats, such as caves or
mines, are particularly vulnerable to direct mortal-
ity threats; loss of large colonies can have a dispro-
portionate impact on populations. But conversely,
focal habitats, such as caves, can be tractable targets
for conservation that can have a significant impact
through protecting and safeguarding species from
extinction, if executed effectively.157 Identifying the
stressors and solutions that overlap among taxa or
require taxon-specific efforts improvesthe efficiency
of deploying limited conservation resources.
A particular challenge for bat conservation is the
pervasive lack of data on population status and
trends (Fig. 3). Data deficiency hinders accurate
assessment of conservation status, which impedes
efforts to prioritize conservation attention when
resources are limited. Data-deficient species can be
under immediate threat and require urgent conser-
vation action, as a recent paper highlights for the
gray flying fox (Pteropus griseus), a species classified
as data deficient but rapidly disappearing because
of hunting pressures in Indonesia.188 Lack of data
on populations also inhibits scientific inquiry to
identify stressors or determine whether conserva-
tion actions result in desired outcomes. Unsurpris-
ingly, the problem of data deficiency is not evenly
distributed across the planet and vexingly peaks in
tropical regions, such as Amazonia and equatorial
Africa, where bat species richness is highest but
resources for research and management are more
limited (Fig. 1).
The rapid pace of species discovery of bats
(>25% increase in described species over the past
15 years)10 highlights the importance of systematics
for conservation. Voucher specimens from biodi-
versity surveys in remote or undersampled areas
provide critical documentation of bat diversity in a
changing world, can confirm species identification
of poorly known taxa or those in need of resolution,
and are essential for the description of new species.40
However, lethal sampling for routine collecting or
as part of studies searching for zoonotic viruses can
be excessive or unnecessary, especially as nonlethal
alternatives are available.189,190 Training, guidance,
and protocols for researchers on safe handling and
nonlethal sampling techniques could reduce lethal
sampling practices and minimize collateral damage
from injury and disturbance to sensitive colonies.189
Successfully conserving bats globally will require
creative and collaborative efforts to tackle the urgent
needs of already imperiled species while simul-
taneously working to improve understanding of
the status and needs of a diverse fauna. Monitor-
ing schemes capable of quantifying whether bat
populations are decreasing, stable, or increasing
are still needed. Yet, we must design programs
that are effective and sustainable. Some species or
faunas may be intractable to effective monitoring
with current technologies or capacities. For exam-
ple, bat species that roost inconspicuously in trees
and do not have echolocation signals that are reli-
ably detectable with ultrasonic microphones present
especially formidable challenges for estimating pop-
ulation changes with reasonable effort and accuracy.
In tropical areas, commitments to long-term mon-
itoring (e.g., 20 years) are recommended to provide
sufficient power for estimating population change.39
Passive acoustic monitoring has been used for bat
research for several decades, but recent improve-
ments in sensor technologies,191,192 progress on data
science toolkits to process and interpret large audio
data streams and classify bat sounds,193 as well
as advances in statistical modeling194 now enable
broad-scale monitoring schemes to determine
the status and trends of bat populations.195 With
appropriate study design and implementation,
such monitoring programs could also help identify
17
Ann. N.Y. Acad. Sci. 1469 (2020) 5–25 C2019 New York Academy of Sciences.
Major threats and challenges to bat conservation Frick et al.
potential drivers of population declines and feed
directly into conservation decision making.37,74
National-scale programs, such as the British Bat
Monitoring Program37 and the North American
Bat Monitoring Program,196 are currently operating
and continue to refine ways to use acoustic data
to monitor and inform decision makers about the
status and trends of bat species. These programs
depend on sustained governmental investment,
dedicated coordination and management, as well as
citizen science participation, which may limit their
scalability in developing countries. Implementation
of acoustic monitoring programs in areas where
we know the least about bat populations, including
tropical ecosystems, will require investments in
monitoring infrastructures, including further
development of echolocation call libraries,197
and commitments to long-term systematic data
collection.
Species that are observable while roosting can
be monitored by directly counting roosting bats.
Annual or biennial counts of hibernating bats are
used throughout temperate regions to monitor pop-
ulations of hibernating species and were respon-
sible for the detection of mass mortality events
during the emergence of WNS in the northeast-
ern United States.125,126 Counts of hibernating bats
provide some of the most reliable data on pop-
ulation trends, but researchers should coordinate
and plan efforts to minimize disturbance to sensi-
tive colonies198 and practice field hygiene to reduce
spread of pathogens.199 Internal roost surveys dur-
ing maternity season should generally be avoided
to reduce disturbance; instead, maternity colonies
can be monitored during exit flights.200 Monitoring
efforts at roosts should be designed with consistency
to account for inter- and intraseasonal variation in
colony size and roost use.196,200
Online databases and sharing portals (e.g., AfriB-
ats on iNaturalist.org) offer new opportunities for
recording species observations, coordinating data-
sharing, and potentially facilitating monitoring of
species that are readily observable. For exam-
ple, the Eidolon Monitoring Network was piloted
using trained citizen science volunteers across sub-
Saharan Africa to monitor the migratory African
straw-colored fruit bat (Eidolon helvum)acrossits
range, given concerns about declining colony sizes at
major roosts.201 However, sustained funding to tr ain
and incentivize data collection by citizen groups are
needed for these efforts to provide consistent col-
lection of data usable for monitoring population
trends and informing conservation planning.
Monitoring alone is insufficient for conservation
success. Mitigating threats and protecting popu-
lations from stressors requires direct action and
strategic planning to identify how actions will pro-
tect conservation targets. The open standards of the
practice of conservation offer guidance and tools
developed from the tenets of the theory of change
and adaptive management to aid conservation
practitioners in planning and executing conserva-
tion delivery.202 The open standards can also be
instructive to scientists and academic researchers
interested in how hypothesis-driven research can
be used to directly inform conservation decisions.
Better collaboration and integration between
academic researchers, conservation NGOs, and
local stakeholders is needed to support building a
body of evidence to inform conservation decisions
and conducting conservation in ways that improve
scientific knowledge and ecological integrity.203
The Conservation Evidence initiative compiles
existing evidence for conservation interventions
through an interactive online database and an open-
access journal (www.conservationevidence.com). In
the first edition of the synopsis of evidence for
bat conservation published in 2014,70 there were
78 interventions for bat species identified. In the
soon-to-be-released edition, 188 interventions have
been identified, representing a 141% increase. How-
ever, the majority of interventions are listed with
“no evidence” and the increase in interventions
may simply reflect efforts to petition a broader
set of practitioners. The effort to collate and syn-
thesize available knowledge relevant to direct con-
servation actions is a useful and promising tool.
Researchers are encouraged to submit findings to
the Conservation Evidence online journal or other
journals that provide ready access to information
so that evidence is available to the global conser-
vation community. Similarly, the North American
Bat Conservation Alliance launched a wiki site in
2017 to collate, share, and discuss findings and prac-
tices to address threats facing bats in North Amer-
ica (http://batconservationalliance.wikidot.com/).
These efforts to share knowledge openly can hope-
fully advance efforts and propel us toward adopt-
ing evidence-based solutions for bat conservation
globally.
18 Ann. N.Y. Acad. Sci. 1469 (2020) 5–25 C2019 New York Academy of Sciences.
Frick et al. Major threats and challenges to bat conservation
Bats are taxonomically and ecologically diverse
and face complex, pressing threats. A wide range
of expertise and rapid responses are thus needed
for effective mitigation. Addressing these needs
requires effective collaborative networks of diverse
individuals and groups (e.g., researchers, NGOs,
and conservation practitioners) and a rapid
increase of in-country research capacity in hotspots
of bat diversity. Countries and regions supporting
some of the highest diversity of bats in the world
lack expertise entirely or are reliant on one or
two dedicated researchers to garner knowledge
on dozens of bat species. Training people and
building more academic capacity is fundamental to
accelerating research that identifies targets for con-
servation. To meet these needs, at least 10 regional
bat conservation networks have arisen in recent
years, allowing rapid knowledge development and
sharing, research capacity building, consensus
approaches to priority setting, and coordination of
conservation effort and advocacy.204 We e n d o rs e
Kingston et al.204 and advocate for a global network
for bat conservation that unifies and connects
existing regional networks to share knowledge,
build capacity, prioritize and coordinate research
effort, and provide a voice for advocacy that can
ensure sustainable bat populations worldwide.
With over a third of bats considered either threat-
ened or data deficient and well over half of species
ranked with either unknown or decreasing popula-
tion trends, a total of 988 known species (80% of bats
classified by IUCN) require conservation or research
attention. When so many species need attention,
researchers and conservation practitioners may feel
overwhelmed or even paralyzed when choosing or
prioritizing where to target efforts. Prioritization
of efforts is obviously necessary since resources are
chronically insufficient to match global needs. How-
ever, criteria for prioritization will depend on the
capacity, objectives, and desired outcomes and may
differ even among groups who share similar values
and goals. Ultimately, we must heed Voltaire’s warn-
ing that “The best is the enemy of the good,” roll up
our proverbial sleeves, and get to work.
Acknowledgments
We thank Douglas Braaten, editor-in-chief of Annals
of the New York Academy of Sciences, for his patience,
support, and sustained interest in this review. We
thank Bruce Patterson and one anonymous reviewer
for constructive reviews.
Competing interests
The authors declare no competing interests.
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... Bats are critical to ecosystems because they sustain important ecological functions and provide multiple ecosystem services (ES) such as pollination and consumption of pest insects (Russo et al., 2022). However, they exhibit a high rate of endangerment, with the main conservation threats being forest loss, agricultural expansion, overharvesting, disturbance, and urbanization (Frick et al., 2020). Bats are further threatened by largely erroneous perceptions about their role in emerging infectious diseasesa phenomenon that undermines support for bat conservation, as recently observed in relation to the COVID-19 pandemic (Rocha et al 2021;Shapiro et al., 2021). ...
... This makes bats unlike some other taxa, such as macaques (Macaca fascicularis) and wild boars (Sus scrofa), that have received individual attention because of their propensity to be involved in conflicts (Nparks, 2021d;Nparks, 2021e). However, it must be noted that teaching the public about the importance of bats and the need to address the threats to their conservation does not guarantee a change in attitude or behavior towards bats (see also Frick et al., 2020). Changing negative attitudes and (more importantly) behaviors toward bats necessitates carefully planned and interdisciplinary studies firmly grounded in social science theories (e.g., Theory of Planned Behavior, Cognitive Hierarchy Theory, etc.) and methodologies (see also Kingston, 2016;Straka et al., 2021). ...
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... These results demonstrate that insectivorous bats may play a crucial role in structuring forest ecosystems. If so, forests may be impacted by global bat declines (Frick, Kingston, and Flanders 2020), and thus, this work further emphasizes the need to conserve bat populations. ...
... rubra; Wright, Hall, and Peacock 1989). Furthermore, defoliation by insects makes plants more susceptible to disease, as insects are common vectors of plant pathogens (Eigenbrode, Bosque-Pérez, and Davis 2018), and previous research has demonstrated that bats, by suppressing insect populations, (Frick, Kingston, and Flanders 2020;Rosenberg et al. 2019), it is worth examining how different tree species cope with persistent sub-lethal defoliation, especially given the role insects and pathogens may play in structuring ecosystems (Orwig 2002). Such research could clarify how dynamic populations of insectivorous predators might ultimately influence forest structure and composition. ...
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... But the world's pollinators are in trouble. Land-use change (including deforestation), pesticide use, climate change, and diseases and parasites are affecting pollinators around the world (Mburu et al. 2006;Vanbergen 2013;Potts et al. 2016;Sritongchuay et al. 2019;Frick et al. 2020). Wild pollinators, which include insects and bats, and are important for both crops and wild plants and are in decline (Biesmeijer et al. 2006;Potts et al. 2010;Vanbergen 2013;Martin 2015). ...
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... In the United States, forest-dependent bat species have suffered significant population declines due to habitat loss and fragmentation [44][45][46]. These negative impacts have been amplified by the spread of white-nose syndrome (WNS), a disease caused by the fungal pathogen Pseudogymnoascus destructans (Blehert and Gargas), which has increased winter mortality rates for many hibernating bat species in North America [47,48]. ...
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Throughout the Midwest United States, agricultural and urban development have fragmented natural areas, with a disproportionate effect on forests and wetlands. The resulting habitat loss, compounded with the spread of white-nose syndrome (WNS), has caused precipitous population declines in several forest-obligate bat species. In 2019, we discovered a remnant northern long-eared bat (Myotis septentrionalis Trouessart) maternity colony in a small forest fragment adjacent to a restored wetland in northeastern Indiana, USA. We investigated roost selection in this colony during the summers between 2019 and 2021 by attaching radio transmitters to northern long-eared bats and tracking them to day roosts. We measured tree, plot, and landscape-level characteristics for each roost and for a randomly selected available tree in the same landscape, then compared characteristics using paired t-tests. Over 70 net nights, we captured and tracked 4 individuals (1 juvenile male, 1 post-lactating female, and 2 lactating females) to 12 different roosts. There were, on average, 3.5 times more standing dead trees (snags) in plots around roosts compared to available trees (t = −4.17, p = 0.02). Bats in this maternity colony selected roosts near a stretch of flooded forest (which contained 83% of roosts) dominated by solar-exposed, flood-killed snags. These roosts likely provide warm microclimates that facilitate energy retention, fetal development, and milk production. By describing roosts within this landscape, we provide insight into the resources that enable an endangered bat species to persist in urbanized forest fragments.
... Studies from all over the world show a decline in bat populations (Frick et al. 2019;Mickleburgh et al. 2002). The main causes are a synergy of factors such as habitat loss, establishment of wind power plants, disease, climate change, and pesticide use (Razgour et al. 2021; Voigt and Kinkgston 2016). ...
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... Forests are crucial habitats for many bat species, and their loss is among the principal threats to global bat diversity (Frick et al., 2020). As such, forest retention, restoration, and management have been core components of bat conservation in many regions of the world (Lacki et al., 2007). ...
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An especially interesting question is “How many species of bats can be found simultaneously in the same cave?” This information is surprisingly rare in the literature, mainly in the Neotropics. The aim of this study was to sample bats in Gruta do Limoeiro cave, Municipality of Castelo, State of Espírito Santo, Brazil after a 53-year interval of the first survey, by the naturalist Augusto Ruschi. Four surveys were conducted in 2005 and 2006, capturing bats with mist-nets and actively exploring the cave. We recorded eleven species of three families, Phyllostomidae, Vespertilionidae and Molossidae, making Gruta do Limoeiro cave one of the most diverse caves in the World for bats. Of the 14 species found by Ruschi, seven were still present, and four species were added. The seven species lost from Ruschi’s list are mainly Emballonuridae and some Phyllostomidae, probably due to landscape changes. We recommend the long-term monitoring of the Gruta do Limoeiro cave to understand the loss in diversity, and consequently in ecosystem services.
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El área contiene una muestra representativa de la comunidad de murciélagos del suroeste de Perú y norte de Chile. Incluye 18 de las 20 especies registradas para esta región. IUCN: En Peligro (Tomopeas ravus y Myotis atacamensis), Vulnerable (Amorphochilus schnablii), Casi Amenazada (Platalina genovensium) y Datos Deficientes (Promops davisoni), las cuatro primeras Amenazadas o Casi Amenazadas en Perú. Asimismo, Eumops chiribaya y Lasiurus arequipae cumplirían con IUCN para ser consideradas como amenazadas. Tres de las especies reportadas son endémicas de Perú (T. ravus, E. chiribaya y L. arequipae) y ocho son endémicas del Desierto Pacífico de Perú y norte Chile (las enlistadas anteriormente y Mormopterus kalinowskii). Existen colonias reproductivas de especies amenazadas, refugios permanentes. El área sufre de vandalismo y disminución de la calidad del hábitat.
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El área posee una alta diversidad de murciélagos (cinco especies) en relación a la riqueza de la provincia de San Juan, donde solo se registraron seis especies. Se reportan dos especies migratorias: Tadarida brasiliensis (Molossidae), Lasiurus blossevillii (Vespertilionidae), además de colonias maternales de Myotis dinellii y Tadarida brasiliensis. En el interior del área existen comunidades humanas con intensas actividades productivas como la ganadería, agricultura y turismo. Los murciélagos registrados en el área son insectívoros por lo que ejercen una importante actividad reguladora de las poblaciones de insectos perjudiciales para los bosques nativos, la agricultura y vectores de enfermedades.
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Human-wildlife conflicts (HWC) pose a growing threat to biodiversity worldwide and solutions can be as sound as the understanding of the HWC itself. Conservation biologists therefore must carefully examine their local situations to inform on which approach and strategies may be best. In this context, Mauritius implemented what may be the first mass-culls of an already threatened native species when it culled the flying fox (Pteropus niger) in 2015 and 2016 to try increase fruit producers’ profits. Although the Red List category of the species consequently worsened to ‘Endangered’ and fruit production dropped substantially, a third mass-cull was decided in 2018. A critical analysis is important to draw lessons that may help to prevent recurrences particularly that HWC involving Pteropus spp. are common and set to worsen. We synthesized the best literature available locally and also elsewhere in relevant situations, to critically appraise the setting, nature, timeline of events and outcome of both completed mass-culling campaigns to explore why and how they happened so as to help towards devising better approaches to such conflicts. The idea to cull P. niger originated around 2002 and a small cull was done in 2006. The first mass-cull started immediately after Mauritius’ biodiversity protection law was weakened in 2015 primarily to legalize culls of threatened native species, but still breached the law in place then. The 2016 mass-cull was recommended in line with the law, but was not evidence-based and consequently did not result in improved profits of fruit producers. Appeals supported by best scientific evidence from local and international organizations and conservationists to the effect that culls will not increase fruit production, but instead further endanger the species, were ignored. To forestall recurrences here and elsewhere, it matters to recognize their precursor signs and the conditions that favoured them including why the mass-culls were not stopped. The events provide a rare opportunity to explore the strategy that was used by conservationists and open the way to propose impactful alternatives or additional actions instead. The situation also exemplifies an eroding commitment towards biodiversity conservation, eased by withdrawal from evidence-based policy that suit short term goals of election cycles at the expense of longer term environmental interests.