Threatened but not conserved: flying-fox roosting and foraging habitat in Australia

Abstract

Conservation relies upon a primary understanding of changes in a species’ population size, distribution, and habitat use. Bats represent about one in five mammal species in the world, but understanding for most species is poor. For flying-foxes, specifically the 66 Pteropus species globally, 31 are classified as threatened (Vulnerable, Endangered, Critically Endangered) on the IUCN Red List. Flying-foxes typically aggregate in colonies of thousands to hundreds of thousands of individuals at their roost sites, dispersing at sunset to forage on floral resources (pollen, nectar, and fruit) in nearby environments. However, understanding of flying-fox roosting habitat preferences is poor, hindering conservation efforts in many countries. In this study, we used a database of 654 known roost sites of the four flying-fox species that occur across mainland Australia to determine the land-use categories and vegetation types in which roost sites were found. In addition, we determined the land-use categories and vegetation types found within the surrounding 25 km radius of each roost, representing primary foraging habitat. Surprisingly, for the four species most roosts occurred in urban areas (42–59%, n = 4 species) followed by agricultural areas (21–31%). Critically, for the two nationally listed species, only 5.2% of grey-headed and 13.9% of spectacled flying-fox roosts occurred in habitat within protected areas. Roosts have previously been reported to predominantly occur in rainforest, mangrove, wetland, and dry sclerophyll vegetation types. However, we found that only 20–35% of roosts for each of the four species occurred in these habitats. This study shows that flying-fox roosts overwhelmingly occurred within human-modified landscapes across eastern Australia, and that conservation reserves inadequately protect essential habitat of roosting and foraging flying-foxes.

Full text

Threatened but not conserved: flying-fox roosting and
foraging habitat in Australia
Libby A. Timmiss
A
, John M. Martin
A,B,F
, Nicholas J. Murray
A,C
, Justin A. Welbergen
D
,
David Westcott
E
, Adam McKeown
E
and Richard T. Kingsford
A
A
Centre for Ecosystem Science, School of Biological, Earth and Environmental Sciences,
University of New South Wales, Sydney, NSW 2052, Australia.
B
Institute of Science and Learning, Taronga Conservation Society Australia, Bradley’s Head Road,
Mosman, NSW 2088, Australia.
C
College of Science and Engineering, James Cook University, Townsville, Qld 4811, Australia.
D
The Hawkesbury institute for the Environment, Western Sydney University, Richmond, NSW 2753, Australia.
E
Commonwealth Scientific and Industrial Research Organisation, 47 Maunds Street, Atherton,
Qld 4883, Australia.
F
Corresponding author. Email: jmartin@zoo.nsw.gov.au
Abstract. Conservation relies upon a primary understanding of changes in a species’population size, distribution, and
habitat use. Bats represent about one in five mammal species in the world, but understanding for most species is poor.
For flying-foxes, specifically the 66 Pteropus species globally, 31 are classified as threatened (Vulnerable, Endangered,
Critically Endangered) on the IUCN Red List. Flying-foxes typically aggregate in colonies of thousands to hundreds of
thousands of individuals at their roost sites, dispersing at sunset to forage on floral resources (pollen, nectar, and fruit) in
nearby environments. However, understanding of flying-fox roosting habitat preferences is poor, hindering
conservation efforts in many countries. In this study, we used a database of 654 known roost sites of the four flying-fox
species that occur across mainland Australia to determine the land-use categories and vegetation types in which roost
sites were found. In addition, we determined the land-use categories and vegetation types found within the surrounding
25 km radius of each roost, representing primary foraging habitat. Surprisingly, for the four species most roosts
occurred in urban areas (42–59%, n= 4 species) followed by agricultural areas (21–31%). Critically, for the two
nationally listed species, only 5.2% of grey-headed and 13.9% of spectacled flying-fox roosts occurred in habitat within
protected areas. Roosts have previously been reported to predominantly occur in rainforest, mangrove, wetland, and dry
sclerophyll vegetation types. However, we found that only 20–35% of roosts for each of the four species occurred in
these habitats. This study shows that flying-fox roosts overwhelmingly occurred within human-modified landscapes
across eastern Australia, and that conservation reserves inadequately protect essential habitat of roosting and foraging
flying-foxes.
Keywords: bat, fruit-bat, pollinator, conservation, threatened species, Pteropus, vegetation community, mammal.
Received 27 October 2020, accepted 8 February 2021, published online 3 March 2021
Introduction
Globally, more than 8500 vertebrate species are threatened
with extinction (IUCN 2020). Habitat destruction and
degradation, as a result of human land use, are largely
considered the driving threats to biodiversity (Chaudhary and
Mooers 2018;PowersandJetz2019). As such, habitat
protection is frequently prioritised in species conservation
planning (Possingham et al.2002;Wintleet al.2019).
However, habitat protection is not always sufficient to ensure
species persistence, and a multitude of approaches are often
necessary for the successful conservation of threatened species
(Hayward 2011). Understanding species habitat requirements
and use remains crucial for developing effective conservation
action plans.
Flying-foxes (Pteropus spp.) roost colonially, typically in
groups of thousands to hundreds of thousands of individuals,
and often in habitat containing relatively large, emergent trees,
close to floral resources for nocturnal foraging (Granek 2002;
Gulraiz et al.2015; Oleksy et al.2015). Of the 66 Pteropus
species globally, six are extinct and 31 are considered at risk
(Vulnerable, Endangered, or Critically Endangered) on the
IUCN Red List (Todd 2019). Four species of flying-fox are
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Australian Journal of Zoology, 2020, 68, 226–233
https://doi.org/10.1071/ZO20086

native to the Australian mainland: grey-headed (Pteropus
poliocephalus), spectacled (P. conspicillatus), black
(P. alecto), and little red (P. scapulatus)flying-fox. The
grey-headed flying-fox is recognised both nationally and
internationally as Vulnerable to extinction (TSSC 2001;IUCN
2020), and the spectacled flying-fox is nationally Endangered
in Australia (TSSC 2019). Globally, a lack of understanding
regarding flying-fox roosting behaviour and habitat
requirements hinders population assessments and conservation
planning.
Historically, Australian flying-fox roosts have
predominantly been described as associated with natural
habitats including mangroves, wetlands, rainforests and, to a
lesser extent, dry sclerophyll eucalypt (Palmer and Woinarski
1999;Fox2011; McClelland et al.2011). In recent years,
however, colonies have increasingly become associated with
urban landscapes (Williams et al.2006; Plowright et al.2011;
Tait et al.2014). Several urban ‘benefits’have been proposed.
These include night-time lighting improving navigation,
altered climatic suitability of urban areas, and a mixture of
native and exotic plants providing more reliable nectar and
fruit resources year-round (Vardon and Tidemann 1999;
McDonald-Madden et al.2005). However, the exact causes for
an increased use of urban areas by flying-foxes are yet to be
determined, as little is known about the roosting and foraging
habitat preferences of flying-foxes in urban environments.
Flying-fox roosts located close to urban areas are
commonly criticised by the public for being loud and odorous,
and posing a disease risk (Edson et al.2015; Currey et al.
2018). Conflict can lead to ineffective and potentially
damaging management strategies such as roost dispersal
(Roberts et al.2011; Lentini and Welbergen 2019). Conflict
may also occur in agricultural areas, with flying-fox foraging
damaging crops (Divljan et al.2011). These conflicts are
exacerbated by patterns of roost occupancy that appear to be
driven by local foraging resources (Giles et al.2016;
Vanderduys et al.2020). At times, local flowering can lead to
large temporary influxes of flying-foxes, which can lead to or
exacerbate conflict (Lentini and Welbergen 2019). An extreme
example of this has been observed in response to mast
flowering of spotted gum (Corymbia maculata)where
~250 000 grey-headed flying-foxes moved to the Water
Gardens roost located in Bateman’s Bay, New South Wales,
where the community responded with intense calls for
dispersal of this vulnerable species (Welbergen and Eby 2016).
At present, it is unknown on what basis flying-foxes choose
their roost sites, which renders management agencies unable to
design ‘carrot solutions’that help reduce conflict by creating
more attractive roost sites elsewhere. Understanding the local
distribution of roosts, and how they are selected by the
four mainland Australian flying-fox species can therefore be
highly informative for both the management and conservation
of these species and to inform land managers where
human–wildlife conflicts occur.
Flying-foxes provide the ecosystem services of pollination
and seed dispersal to their forage plants (Law 1995; Palmer
et al.2000; Markus and Hall 2004;Parsonset al.2006;Eby
and Law 2008; Hahn et al.2014). Because of the scale of their
movements, flying-foxes are of particular importance in
fragmented landscapes (Welbergen et al.2020). It could be
argued that flying-foxes are ecologically more important in an
anthropogenic landscape, as their foraging behaviour connects
fragmented vegetation (see Westcott et al.2015; Welbergen
et al.2020). Studies assessing flying-foxes’foraging
behaviour report that nightly movements predominantly occur
within a 25 km area surrounding roosts (Roberts 2012;
Welbergen unpub. data) and landscape scale movements of up
to 300 km in a night (Welbergen et al.2020).
For the four mainland Australian flying-fox species, we
described the location and species composition of known
diurnal roosts supporting colonies. We then assessed the land
classification of each roost: protected, urban, or agricultural.
We also assessed the vegetation classification associated with
each roost. Lastly, we assessed the land classification and
vegetation type within the surrounding 25 km of each roost.
Methods
The four mainland Australian flying-fox species are distributed
across tropical regions in the north to the warm-temperate
regions of eastern Australia (Fig. 1)(Parishet al.2012). Grey-
headed flying-foxes have the southernmost distribution of any
flying-fox species, spanning from Queensland around to South
Australia (Westcott et al.2011). The black flying-fox is a
predominantly tropical species, ranging the northern coastline
of Australia, and over the past two decades has spread south
from Queensland along the east coast of New South Wales
(Welbergen et al.2008;Robertset al.2012) with vagrant
records in Victoria. Little red flying-foxes have the most
extensive distribution, spanning from Western Australia across
the north of Australia to Queensland and south to Victoria.
Spectacled flying-foxes have the most restricted distribution of
the four species, being found in the wet tropics and Cape York
in north Queensland in Australia (Garnett et al.1999;Fox
2011).
Flying-fox colonial roost data
The National Flying-fox Monitoring Program (NFFMP)
(Westcott et al.2011) has produced a spatial dataset of the
location of known roosts for the four mainland species of
flying-fox across Australia, with a focus on grey-headed and
spectacled flying-fox colonies. As part of the NFFMP, all
known roosts were surveyed quarterly for flying-foxes
between November 2012 and February 2017 (n= 18 surveys).
Roosts were added during the survey period; these could be
newly occupied by flying-foxes or have previously been
occupied but were unknown. A concerted effort was made to
identify and survey all roost locations, this was aided by
concurrent telemetry studies of all species during the
initial years of the NFFMP (Westcott et al.2015; Welbergen
et al.2020). A total of 654 roosts were surveyed across
Australia during the period covered by this study and all roosts
where flying-foxes were observed are included. NFFMP
coverage of parts of north Queensland, the Northern Territory,
and Western Australia was incomplete due to remoteness and
accessibility and as a consequence there were insufficient data
for these areas.
Flying-foxes are threatened but not conserved Australian Journal of Zoology 227

We initially classified each roost as ‘active’or ‘inactive’
based on the 18 NFFMP surveys recording the presence of at
least one flying-fox species within the sampling period; only
active roosts were included in analyses (n=430)
(Table 1). Surveys were conducted at all locations known to
have had colonial roosting over recent decades, and thus some
roosts were not used by flying-foxes at all within the sampling
period. Data from active roosts were then categorised into
single- and mixed-species colonies across the sampling period.
This resulted in three datasets for each species: (1) all locations
where a species occurred (total active roosts); (2) all locations
where only a single species was recorded (single-species
roosts); and (3) all locations where two or more species were
recorded (mixed-species roosts).
Spatial data
To identify the land use categories that coincided with the
location of active flying-fox roosts across Australia, we
developed a land use map by combining data from Land Use of
Australia 2010–11 and the Collaborative Australian Protected
Areas Database (CAPAD) 2014 (Supplementary Material,
Table S1). Where conflicting land use categories occurred, we
used the land use classification from the more recent
CAPAD. The Land Use of Australia dataset contained 18
categories. We combined these into seven broad categories:
protected areas; minimal use; grazing and native vegetation;
forestry; agriculture; urban; and mining and waste. This
dataset was used to identify the number of active roosts located
within each of these land use categories. We manually
inspected all data points that returned no data or water values at
the roost location (n= 17); using satellite imagery, as well as
proximate data to inform our decisions, we assigned a land use
category to these locations.
Roost land use and vegetation
We used the National Vegetation Information System (NVIS)
data with Present Major Vegetation Groups (DEWR 2007), to
assess the primary vegetation types in which flying-fox roosts
Spectacled flying-fox
Black flying-fox
Little red flying-fox
Grey-headed flying-fox
NT
QLD
N
WA
SA
NSW
ACT
VIC
TA S
0 500 1000 2000 Km
Fig. 1. Distribution of the four mainland Australian flying-fox species. Map by Pia Lentini 2018.
Table 1. Number of active, mixed- and single-species flying-fox roosts
identified during 18 quarterly surveys, 2012–2017
Species Total
active roosts
Mixed-species
roosts
Single-species
roosts
All roosts 430 266 (61.7%) 164 (38.3%)
Grey-headed flying-fox 310 232 (74.8%) 78 (25.2%)
Black flying-fox 291 247 (84.6%) 44 (15.4%)
Little red flying-fox 156 141 (90.4%) 15 (9.6%)
Spectacled flying-fox 36 9 (25%) 27 (75%)
228 Australian Journal of Zoology L. A. Timmiss et al.

were located nationally (Supplementary Material, Table S1).
We used this dataset to determine vegetation type at the roost
location (point), as well as the proportion of vegetation types
within the surrounding 25 km area (buffer; see below). The
NVIS data contained 33 categories; however, only 18
categories were identified in association with roost locations,
and thus other categories were not reported for simplicity. As
flying-fox roosts sometimes occur in aquatic habitat
(e.g. mangroves, wetland) or riparian vegetation, we manually
inspected all data points assigned as ‘water’at the roost
location. Using satellite imagery and proximate data to inform
our decisions, we assigned a vegetation type to these locations,
as well as any location returning ‘no data’(n=28).
Foraging (buffer) land use and vegetation
We assessed the land use category and vegetation composition
within the 25 km area (primary foraging habitat; ‘buffer’)
surrounding roosts, representing flying-foxes’nocturnal
foraging range (Roberts 2012; Welbergen, unpub. data). Of the
33 vegetation types present within the 25 km buffer region
surrounding each roost, three vegetation categories (‘mallee
woodland and shrublands’,‘other open woodlands’,and‘other
grasslands, herblands, shrublands’) were not recorded within
buffers and were therefore excluded from further analyses. All
other categories were recorded within buffers. We added an
oceanic water category to our land use category dataset, using
World Water Bodies data (Supplementary Material, Table S1),
to accurately differentiate between the proportion of buffers
for coastal roosts for which there were no data, and what was
simply ocean. ‘Water’and ‘no data’values were retained for
buffer calculations.
Analysis
Spatial datasets (Supplementary Material, Table S1) were
imported into ArcGIS 10.4, using standard tools to change
projections to Geocentric Datum of Australia 1994 where
necessary. We extracted values of all variables for each active
roost location for the four species at two spatial scales: at the
roost (point) and within a 25 km radius (buffer). A 25 km
radius was chosen to reflect the main foraging zone around a
colony, which corresponds to nocturnal tracking surveys of
these species (Roberts 2012; Welbergen, unpub. data).
To identify how the location of colonies was related to land
use and vegetation type, we intercepted colony location with
land use and NVIS data. We calculated the percentage of the
25 km buffer made up by each land use and vegetation
category for each colony using ‘Tabulate Intersection’tools in
ArcGIS. Descriptive statistics were calculated using standard
tools in R software (R Core Team 2017).
Results
Of the 654 roost sites in our dataset, grey-headed flying-foxes
were recorded at 310 roosts, black flying-foxes at 291 roosts,
little red flying-foxes at 156 roosts, and spectacled flying-foxes
at 36 roosts (Tables 1,2). In total, 430 active roosts were
identified over the 5-year period (2012–2017) through the
NFFMP. Of these, 61.7% were mixed-species roosts
(Table 1). The most common species compositions at mixed-
species roosts were grey-headed and black flying-foxes
(n= 124), followed by grey-headed, black, and little red flying-
foxes (n= 94) (Table 3).
Land use associated with roosts
The more common land use categories associated with all
species of flying-fox roosts were urban (55.1%) and
agricultural (23.5%) land (Table 4). Protected land accounted
for only 6.7% of roost locations. Land use of the remaining
roosts was classified as: ‘minimal use’(6%), ‘mining and
waste’(0.2%), ‘forestry’(1.2%), and ‘grazing, native
vegetation’(7.2%) (Table 4). At the species level, few roosts
were in protected areas: grey-headed (5.2%), black (6.2%),
little red (3.8%) and spectacled flying-fox (13.9%)
(Table 4). For the four species, most roosts were classified as
urban land use: grey-headed (58.7%), black (59.1%), little red
(54.5%), and spectacled flying-fox (41.7%) (Table 4).
The land use classification within the 25 km radius
surrounding flying-fox roosts was diverse, but predominantly
comprised agricultural (24.6%), urban (14.4%), and protected
(14%) land (Table 5). Agricultural land was the most common
land use category within the buffers around grey-headed
(25.2%), black (23.1%), and little red (32.9%) flying-fox
roosts. However, protected land was the most common land
use category within the buffers around spectacled flying-fox
roosts (36%) (Table 5). Urban areas represented a smaller
proportion of buffers for each species: grey-headed (17.5%),
Table 2. Jurisdictions in which flying-fox roosts were identified during
18 quarterly surveys, 2012–2017
Note: no data were available for Western Australia
Species Qld NSW Vic. SA NT ACT
All roosts 256 153 15 1 4 1
Grey-headed flying-fox 152 141 15 1 0 1
Black flying-fox 205 83 0 0 3 0
Little red flying-fox 110 40 3 0 3 0
Spectacled flying-fox 36 0 0 0 0 0
Table 3. Mixed-species composition and number of flying-fox roosts
identified during 18 quarterly surveys, 2012–2017
Species composition No. of roosts
Two species
Grey-headed and black 124
Grey-headed and little red 12
Grey-headed and spectacled 1
Black and little red 27
Black and spectacled 0
Little red and spectacled 6
Three species
Grey-headed, black and little red 94
Grey-headed, little red and spectacled 0
Black, little red and spectacled 1
Four species
Grey-headed, black, little red and spectacled 1
Flying-foxes are threatened but not conserved Australian Journal of Zoology 229

black (16.6%), little red (11.6%), and spectacled flying-fox
(2.9%) (Table 5).
Vegetation associated with roosts
The most common vegetation class associated with flying-fox
roosts was ‘cleared, non-native vegetation, buildings’(59.8%)
(Supplementary Material, Table S2), which we confirmed
largely corresponded to urban and agricultural land. This
vegetation class was the most common for all species: grey-
headed (57.4%), black (64.3%), little red (66.7%), and
spectacled flying-fox (58.3%) (Supplementary Material,
Table S2). Relatively few roosts were in the vegetation
categories typically reported in the literature (Supplementary
Material, Table S2), such as ‘rainforest and vine thickets’
(8.4%), ‘melaleuca forests and woodlands’(5.3%),
‘mangroves’(5.1%), and eucalypt-dominated categories
(17.3%; includes: ‘eucalypt open forest’8.1%, ‘eucalypt
woodlands’6.7%, ‘eucalypt tall open forest’2.1%, ‘eucalypt
low open forest’0.2%, ‘tropical eucalyptus woodlands/
grasslands’0.2%).
The most common vegetation class associated with the
25 km foraging range (buffer) surrounding flying-fox roosts
was ‘cleared, non-native vegetation, buildings’(43.7%)
(Supplementary Material, Table S3). ‘Cleared, non-native
vegetation, buildings’also represented the largest proportion
of the 25 km buffer areas for grey-headed (47.1%), black
(46.5%), and little red (48%) flying-fox roosts. However,
‘rainforests and vine thickets’represented the largest
proportion of buffers for spectacled flying-fox roosts (27.2%)
(Supplementary Material, Table S3). Native vegetation
categories accounted for the next largest proportion of buffer
areas for all roosts: combined ‘eucalypt’dominated categories
(23.8%), ‘rainforest and vine thickets’(5.0%), ‘melaleuca
forest and woodlands’(1.0%), ‘mangroves’(0.8%)
(Supplementary Material, Table S3).
Discussion
This study highlights a serious lack of protection of roosting
and foraging habitat for all four Australian mainland flying-fox
species. Given the major role that roost sites play in the life
of flying-foxes, protecting roosting and foraging habitat is
considered a central component of flying-fox conservation
and management. In contrast, however, only 13.9% of the
roosts of the Endangered spectacled flying-fox and 5.2% of the
Vulnerable grey-headed flying-fox were in protected areas.
This also applied to the two non-listed species, with only 3.8%
of little red and 6.2% of black flying-fox roosts in protected
areas. Likewise, within the 25 km foraging range surrounding
roosts of grey-headed, black, and little red flying-foxes, only
15%oflandusewasclassified as protected areas. However,
Table 4. Land use categories of flying-fox roosts assessed during 18 quarterly surveys, 2012–2017
Note: more than one species can be recorded at a roost (see Table 3)
Land use category All roosts
(n= 430)
Grey-headed
flying-fox
(n= 310)
Black
flying-fox
(n= 291)
Little red
flying-fox
(n= 156)
Spectacled
flying-fox
(n= 36)
Protected 29 (6.7%) 16 (5.2%) 18 (6.2%) 6 (3.8%) 5 (13.9%)
Urban 237 (55.1%) 182 (58.7%) 172 (59.1%) 85 (54.5%) 15 (41.7%)
Agricultural 101 (23.5%) 70 (22.6%) 61 (21%) 43 (27.6%) 11 (30.6%)
Minimal use 26 (6%) 19 (6.1%) 13 (4.5%) 9 (5.8%) 2 (5.5%)
Grazing and native vegetation 31 (7.2%) 18 (5.8%) 24 (8.2%) 13 (8.3% 3 (8.3%)
Forestry 5 (1.2%) 5 (1.6%) 2 (0.7%) 0 0
Mining and waste 1 (0.2%) 0 1 (0.3%) 0 0
Table 5. Land use category within the 25 km foraging habitat (buffer) around flying-fox roosts identified during 18 quarterly surveys, 2012–2017
Land use category All roosts
(n= 430)
Grey-headed
flying-fox
(n= 310)
Black
flying-fox
(n= 291)
Little red
flying-fox
(n= 156)
Spectacled
flying-fox
(n= 36)
Mean ± s.d. Mean ± s.d. Mean ± s.d. Mean ± s.d. Mean ± s.d.
Protected 14.02 ± 11.93 12.66 ± 9.10 11.29 ± 8.31 10.26 ± 9.67 35.96 ± 14.70
Urban 14.43 ± 17.08 17.15 ± 18.28 16.62 ± 17.34 11.60 ± 15.36 2.90 ± 2.47
Agricultural 24.57 ± 22.15 25.19 ± 21.57 23.13 ± 20.18 32.90 ± 26.45 13.34 ± 9.33
Minimal use 6.80 ± 3.80 7.10 ± 3.85 7.31 ± 3.63 6.45 ± 3.85 5.82 ± 3.23
Grazing and native vegetation 13.70 ± 12.15 12.70 ± 8.94 14.56 ± 11.55 17.94 ± 15.07 8.78 ± 11.56
Forestry 4.46 ± 6.94 4.64 ± 7.24 3.88 ± 6.70 4.52 ± 7.54 5.96 ± 4.99
Mining and waste 0.14 ± 0.34 0.16 ± 0.38 0.15 ± 0.32 0.14 ± 0.45 0.01 ± 0.02
Water (inland) 1.02 ± 1.43 1.09 ± 1.55 0.88 ± 1.17 0.88 ± 1.31 0.85 ± 0.78
Water (oceanic) 20.17 ± 20.32 18.65 ± 19.42 21.39 ± 20.90 14.79 ± 19.64 25.74 ± 18.95
No data 0.69 ± 0.79 0.66 ± 0.80 0.80 ± 0.87 0.52 ± 0.74 0.64 ± 0.40
230 Australian Journal of Zoology L. A. Timmiss et al.

protected land was the largest category surrounding spectacled
flying-fox roosts (36%). The lack of habitat protection and
relative importance of anthropogenic landscapes for the four
species highlights the need to consider the human dimensions
of human–wildlife conflict for sound management and
conservation of Australia’sflying-foxes (Kung et al.2015;
Currey et al.2018).
More than half of grey-headed, black, and little red flying-
fox roosts and over a third of spectacled flying-fox roosts were
located in land uses categorised as urban. Since the 1800s
many Australians have viewed flying-foxes as unwelcome in
agricultural areas (Ratcliffe 1938). Over recent decades,
human–wildlife conflict in urban areas has increased, with
some colonies dispersed by human intervention (Ruffell et al.
2009;Robertset al.2011; Currey et al.2018). Such dispersals
have rarely been successful, given our poor understanding
of the factors driving roost use (see Welbergen et al.2020)and
establishment. This study showed that, across eastern
Australia, flying-fox roosts occurred overwhelmingly in
human-modified landscapes and not in protected areas. As a
consequence, a conservation approach that primarily focuses
on protected areas can only poorly protect flying-fox roosts.
Given that our data suggested Australian flying-fox species
predominantly roost in urban areas, and other data that indicate
this may be increasing (Tait et al.2014), conservation
strategies need to be multifaceted, addressing roost habitat
protection outside formally protected areas along with public
perception and education.
Of the 430 roosts assessed in this study, most were in
human-modified vegetation, categorised as ‘cleared, non-
native vegetation, buildings’, and were located across eastern
Australia. This finding dramatically revises our understanding
of the preferred roosting vegetation used by flying-foxes in
Australia. After modified habitats, roosts were predominantly
in rainforests, woodlands, and mangroves, which align more
closely with the established vegetation selected for flying-fox
roosts (Palmer and Woinarski 1999;Fox2011; McClelland
et al.2011). These native vegetation communities were again
prominent within the 25 km buffer surrounding roosts and
contain the plant species most likely to benefit from the
landscape scale ecosystem services (pollination and seed
dispersal) provided by flying-foxes (Eby and Law 2008).
The data presented cover the known distribution for the
grey-headed flying-fox (Parish et al.2012) but inadequately
incorporated distributions of the black and little red flying-fox;
both species also occur across northern and north-western
Australia, which were poorly sampled, and are likely to
support a larger number of roosts in natural areas.
Furthermore, our current understanding fails to consider the
wider distribution of the spectacled flying-fox, into Papua New
Guinea, and the black flying-fox into Papua New Guinea and
Indonesia. Critically, there are also limited data available on
how the location of roosts and flying-fox species assemblages
have changed over recent decades. The distribution of flying-
fox species is highly variable, exemplified by shifts in black
and grey-headed flying-foxes in recent years (Roberts et al.
2012). To improve conservation planning, and community
education, further information on the dynamics of occupancy
of roosts (Meade et al.2019;Welbergenet al.2020)andhow
these are related to changes in the surrounding landscape
(Giles et al.2016) would be informative. In addition, an
evaluation of flying-foxes’ecosystem services (pollination and
seed dispersal), relevant to maintaining healthy forests (see
Fujita and Tuttle 1991), could benefit initatives to enhance
conservation efforts.
Unsurprisingly, given the overlapping distributions of the
flying-fox species, roost locations predominantly supported
multiple species, with relatively few observations of single-
species roosts. The NFFMP focussed on the two listed species
but complementary observations of black and little red flying-
foxes across their distribution were documented; further
research is needed. The NFFMP and telemetry studies
(Westcott et al.2015;Welbergenet al.2020) identified many
previously unknown roosts. Discovering and monitoring
these roosts should improve flying-fox population estimates
(Westcott et al.2011,2015), and further enhance our
understanding of the roost habitat preferences of the species. It
must be noted that the data presented and the effort to identify
roosts was extensive, yet it is inevitable that some roosts
remain unidentified and new roosts form and are not detected
in response to the availability of local food resources. An
increasingly concerning threat to flying-foxes are mass die-
offs associated with extreme temperature events exacerbated
by climate change (Welbergen et al.2008,2014). Combining
land use and vegetation data at known roost locations with
weather forecasts could further improve predictions of the
likelihood and severity of heat stress events on flying-fox
colonies (Ratnayake et al.2019) by accounting for the thermal
buffering properties of land use categories and vegetation
types. Increasing our understanding of the factors driving
flying-fox habitat selection, and how these vary seasonally and
annually, are integral to the recovery and long-term
conservation of flying-foxes in Australia.
Conclusion
We demonstrated that, in eastern Australia, flying-foxes were
predominantly using human-modified landscapes to roost and
forage. This finding demonstrates flying-foxes’adaptability,
and suggests that in Australia this group of species may be
more resilient to habitat change than species that are entirely
dependent upon undisturbed habitat. The reasons for flying-
foxes’adaptation to modified landscapes are poorly
understood, yet it creates key challenges for flying-fox
management and conservation. This highlights the need for
better understanding of the drivers of flying-fox urbanisation
and the consideration of human dimensions in the management
and conservation of these iconic species. Flying-foxes provide
unique landscape-scale pollen and seed dispersal services,
particularly connecting Australia’s increasingly fragmented
forest ecosystems, thus enhanced protection of the ecological
services they provide should be a conservation priority.
Critically, conservation of the two listed species in Australia,
the spectacled and grey-headed flying-foxes, is poorly
represented by protected areas, and roosts and individuals are
exposed to human–wildlife conflict in the human-modified
landscapes where the species increasingly occur (Williams
et al.2006; Plowright et al.2011;Taitet al.2014). Future
Flying-foxes are threatened but not conserved Australian Journal of Zoology 231

research should assess what drives flying-foxes to shift
towards anthropogenic areas, as knowledge of such drivers
will be key for informing policy and practice to better manage
and conserve these species, especially in human-modified
landscapes. Lastly, future research should assess flying-fox
colony size and breeding with respect to land use to inform
roost conservation planning.
Conflicts of interest
Justin Welbergen is a guest Associate Editor. Despite this
relationship, he did not at any stage have editor-level access to
this manuscript while in peer review, as is the standard practice
when handling manuscripts submitted by an editor of this journal.
The authors have no further conflicts of interest to declare.
Acknowledgements
We thank all of the staff and volunteers that contributed to the National
Flying Fox Monitoring Program. Funding for the National Flying Fox
Monitoring Program was granted to CSIRO from the Commonwealth and
State governments. The necessary research permits were managed by
CSIRO and associated government partners.
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