DOI: 10.5061/dryad.3tx95x6gx
title: Human-modified landscapes provide key foraging areas for a threatened flying mammal: the grey-headed flying-fox

description: Urban expansion is a major threat to natural ecosystems but also creates
 novel opportunities that adaptable species can exploit. The grey-headed
 flying-fox (Pteropus poliocephalus) is a threatened, highly mobile species
 of bat that is increasingly found in human-dominated landscapes, leading
 to many management and conservation challenges. Flying-fox urbanisation is
 thought to be a result of diminishing natural foraging habitat or
 increasing urban food resources, or both. However, little is known about
 landscape utilisation of flying-foxes in human-modified areas, and how
 this may differ in natural areas. Here we examine positional data from 98
 satellite-tracked P. poliocephalus for up to 5 years in urban and
 non-urban environments, in relation to vegetation data and published
 indices of foraging habitat quality. Our findings indicate that
 human-modified foraging landscapes sustain a large proportion of the P.
 poliocephalus population year-round. When individuals roosted in non-urban
 and minor-urban areas, they relied primarily on wet and dry sclerophyll
 forest, forested wetlands, and rainforest for foraging, and preferentially
 visited foraging habitat designated as high-quality. However, our results
 highlight the importance of human-modified foraging habitats throughout
 the species’ range, and particularly for individuals that roosted in
 major-urban environments. The exact plant species that exist in
 human-modified habitats are largely undocumented; however, where this
 information was available, foraging by P. poliocephalus was associated
 with different dominant plant species depending on whether individuals
 roosted in ‘urban’ or ‘non-urban’ areas. Overall, our results demonstrate
 clear differences in urban- and non-urban landscape utilisation by
 foraging P. poliocephalus. However, further research is needed to
 understand the exact foraging resources used, particularly in
 human-modified habitats, and hence what attracts flying-foxes to urban
 areas. Such information could be used to modify the urban foraging
 landscape, to assist long-term habitat management programs aimed at
 minimising human-wildlife conflict and maximising resource availability
 within and outside of urban environments.
description: This study analysed
 <em>P. poliocephalus </em>satellite tracking data collected
 between 9th May 2012 - 27th April 2017 in NSW. Data were subsetted such
 that of 100,463 data points, all 51,585 high quality ARGOS location data
 classes 2 and 3 were initially retained. Positional fixes of these classes
 are estimated to be accurate to within 250 m and 500 m of the true
 location, respectively [55]. To investigate foraging locations, following
 Meade et al. (2021), we selected all positional fixes collected during the
 10 h ‘on’ periods for which both daytime and night-time location data were
 available. The daytime fix allowed the roosting colony to be identified,
 and the night-time fix furthest from the roost site was selected as the
 assumed foraging location. This resulted in 5,118 paired roosting and
 foraging locations. Next, we excluded all paired locations (n = 52) where
 their distance was greater than 50 km, as 99% of foraging takes place
 within 50 km from a roost [54, 56, 57] so that greater distances likely
 represent movements between roosts. Recent research suggests that
 <em>P. poliocephalus</em> individuals travel directly to a
 foraging site early in the night and then undertake smaller movements
 between foraging sites before returning to the roost [28]. Thus, while we
 cannot be certain that these locations are ‘foraging locations’ it is
 likely that the location furthest from the roost site in a night is in an
 area that an individual was foraging. Finally, we subsetted the data to
 those animals foraging in NSW to allow for comparison with available data
 layers (below), resulting in 4,198 paired roosting and foraging locations
 for 98 of the 99 tracked individuals in this study area. Land-use categories were extracted
 for each of the foraging locations in NSW (n = 4,198). For this we used a
 shapefile of Urban Centre and Locality data obtained from the Australian
 Bureau of Statistics [58], to classify NSW into three land-use categories.
 Land was defined as ‘of
 urban character’ based on dwelling density and population density
 [59]. ‘Major-urban’ areas
 were defined as urban centers with a population of &gt; 100,000 [59].
 ‘Other-urban’ areas were urban centers with a population of between 1,000
 and 99,999 [59]. All other areas were defined as ‘non-urban’. For ease of
 interpretation, we refer to the ‘other-urban’ land-use category as
 ‘minor-urban’ throughout. Vegetation types were extracted for
 each of the foraging locations in NSW (n = 4,198). For this we used the
 Vegetation Formations and Classes of NSW (version 3.03 - 200 m Raster) to
 classify vegetation type in NSW to 16 core classes [60]. The raster was
 created and published in 2012 and is thus concurrent with our tracking
 data. In the Vegetation Formations and Classes of NSW, ‘cleared land’ is
 defined as land that is not structurally intact native vegetation [61].
 Thus, cleared land comprises human-modified land including agriculture,
 parks, gardens, and tree-lined streets. Cleared land may also include
 small remnant patches of native vegetation up to 2 hectares. For clarity,
 we refer to ‘cleared land’ as ‘human-modified land’ henceforth.
 Flying-fox foraging habitat
 quality ranks from Eby and Law (2008) were available for
 3,757 of the n = 4,198 foraging locations in NSW. These habitat quality
 ranks are based on a complex algorithm incorporating the spatial
 availability of known <em>P. poliocephalus</em> blossom food
 plant species and indices of productivity and nectar flow, as well as
 species richness scores of fruit food plant species [62]. Here, habitat
 quality was ranked from 1 (high quality) to 4 (poor quality), and areas
 were ranked as 0 if neither the dominant nor subdominant species were
 known <em>P. poliocephalus</em> food plant species. We
 extracted likely food plant species from vegetation shapefiles from Eby
 and Law (2008). These vegetation shapefiles only contained food plant
 species in the blossom diet of <em>P. poliocephalus</em>, as
 insufficient data were available on the productivity and reliability of
 food plant species in the fruit diet [62]. Eby and Law’s diet plant list
 comprised 59 species in the blossom diet including species from the
 Myrtaceae, Proteaceae, Arecaceae, Fabaceae, and Pittosporacea families.
 Only dominant and sub-dominant species [63] were considered resulting in a
 list of 55 species (see Table 4.1 in [62]). Habitat quality rank data were
 split into bi-months to account for seasonal variations in flowering
 phenology of the food plant species (Eby & Law 2008);
 December-January, February-March, April-May, June-July, August-September,
 October-November. Where more than one dominant or sub-dominant food plant
 species was available in the bi-month that a foraging fix was recorded,
 the species that flowered most often and that was most abundant was
 selected as the most likely food plant species [62]. We used a shapefile
 of <em>P. poliocephalus’</em> range [40] and of NSW [64] to
 clip all data layers.
description: Definition of habitat rank values: Habitat
 ranks are a representation of the 'quality' of habitats for
 <em>P. poliocephalus </em>foraging. Habitat quality ranks were
 extracted from Eby and Law [62], and are based on a complex algorithm
 incorporating the spatial availability of known <em>P.
 poliocephalus</em> blossom food plant species and indices of
 productivity and nectar flow, as well as species richness scores of fruit
 food plant species [62]. Here, habitat quality was ranked from 1 (high
 quality) to 4 (poor quality), and areas were ranked as 0 if neither the
 dominant nor subdominant species were known <em>P.
 poliocephalus</em> food plant species. Flying-fox foraging habitat
 quality ranks from Eby and Law [62] were available for 3,757 of the n =
 4,198 foraging locations in NSW.   [62] Eby P, Law B.
 Ranking the feeding habitat of grey-headed flying foxes for conservation
 management. Department of Environment, Heritage, Water and the Arts,
 Canberra. 2008.