Foraging resource use by grey-headed flying-foxes in urban and non-urban Australia

Urbanisation is a major threat to ecosystems globally, resulting in habitat loss and habitat fragmentation, reduced biodiversity, and/or species extinction. However, urban habitats also create opportunities for exploitation by adaptable species, and this often leads to unbalanced management actions that have little regard for species conservation. Better understanding of the underlying drivers of wildlife species urbanisation will assist wildlife managers in developing effective and balanced conservation-management strategies. The grey-headed flying-fox (Pteropus poliocephalus), is a large, highly mobile species, that is becoming increasingly dependent on urban areas. Flying-fox urbanisation has been hypothesised to be a result of loss of natural foraging habitat, an attraction to increased spatiotemporal stability of food resources in urban areas, and/or both. Yet, little is known about how P. poliocephalus utilise urban areas for foraging. This study aims to investigate foraging resource availability as a driver of the documented P. poliocephalus urbanisation. Foraging habitat use was assessed using a large satellite tracking dataset from 98 individuals between 2012-2017. These data were combined with vegetation type data, and published indices of P. poliocephalus habitat quality to assess foraging habitat preferences. Tracked individuals were overwhelmingly dependent on human-modified landscapes for foraging, particularly where they roosted in major-urban areas. To identify the specific food plant species that support P. poliocephalus in urban areas, paired GPS and accelerometer data were used to identify trees visited by foraging individuals roosting in Adelaide. Tracked individuals preferentially visited residential areas and road-side habitats. Individuals visited a relatively high diversity of food plant species in these habitats, and flowering/fruiting phenology records indicated collective year-round availability of food resources for P. poliocephalus. This study suggests that P. poliocephalus urbanisation is, at least in part, driven by spatiotemporal availability and stability of food resources

Human-modified landscapes provide key foraging areas for a threatened flying mammal : the grey-headed flying-fox

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 nonurban 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 nonurban 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

Variety is the spice of life : flying-foxes exploit a variety of native and exotic food plants in an urban landscape mosaic

Generally, urbanization is a major threat to biodiversity; however, urban areas also provide habitats that some species can exploit. Flying-foxes (Pteropus spp.) are becoming increasingly urbanized; which is thought to be a result of increased availability and temporal stability of urban food resources, diminished natural food resources, or both. Previous research has shown that urban-roosting grey-headed flying-foxes (Pteropus poliocephalus) preferentially forage in human-modified landscapes. However, which land-use areas and food plants support its presence in urban areas is unknown. We tracked nine P. poliocephalus roosting in Adelaide, South Australia, between December 2019 and May 2020, using global positioning systems (GPS), to investigate how individuals used the urban landscape mosaic for feeding. The most frequently visited land-use category was “residential” (40% of fixes) followed by “road-side,” “reserves” and “primary production” (13–14% each). However, “reserves” were visited four times more frequently than expected from their areal availability, followed by the “residential” and “road-side” categories that were visited approximately twice more than expected each; in contrast, the “primary production” category was visited approximately five times less than expected. These results suggest that while residential areas provide most foraging resources supporting Adelaide’s flying-fox population, reserves contain foraging resources that are particularly attractive to P. poliocephalus. Primary production land was relatively less utilized, presumably because it contains few food resources. Throughout, flying-foxes visited an eclectic mixture of diet plants (49 unique species), with a majority of feeding fixes (63%) to locally indigenous Australian native species; however, in residential areas 53% of feeding visits were to non-locally indigenous species, vs only 13% in reserves. Flowering and fruiting phenology records of the food plants visited further indicated that non-locally indigenous species increase the temporal availability of foraging resources for P. poliocephalus in urban Adelaide. Our findings demonstrate the importance of residential areas for urban-roosting P. poliocephalus, and suggest that the anthropogenic mixture of food resources available in the urban landscape mosaic supports the species’ year-round presence in urban areas. Our results further highlight the importance of conserving natural habitats within the urban landscape mosaic, and stress the need for accounting for wildlife responses to urban greening initiatives