Data from: Functional responses of insectivorous bats to increasing housing density support 'land-sparing' rather than ‘land-sharing’ urban growth strategies

Debates about ‘land-sparing’ and ‘land-sharing’ strategies for conserving
biodiversity in cities provide an overly simplistic characterization of
alternate planning options. Increased urbanization manifests in a number
of ways and sophisticated analyses of how species respond to urban
environments are required before generalizations about the relative merits
of either planning strategy should be made. We investigated how
insectivorous bats respond to housing density (a measure of urbanization
intensity) and a range of habitat variables by modelling the occupancy and
activity of 12 species in Melbourne, Australia. In addition to
species-level analyses, species were grouped into guilds (‘matrix’,
‘patch’ or ‘edge’ species) depending on their ecomorphology and level of
patch-dependency. Housing density (dwellings per hectare: dph) was the
dominant explanatory variable of occupancy and activity of most species
studied. Site occupancy probabilities of patch and edge species were
reduced by half at housing densities of just 1·1–4·5 dph depending on
species, while their activity was halved at housing densities of 2·6–10·3
dph. The activity of two matrix species also declined, but at higher
housing densities (reducing by half at 4·5–7·9 dph). Patch and edge
species responded nonlinearly to tree cover at low housing densities, with
peaks in occupancy and activity at 20–60%. This response broke down at
medium housing densities, however, as most species were no longer present.
Synthesis and applications. Occupancy probability and activity of almost
all bat species studied were substantially reduced even at very low
housing densities. Increasing tree cover had no positive effect on the
occupancy and activity of patch and edge species once medium housing
densities were reached. In order for land-sharing strategies to provide
good habitat for patch and edge bat species housing densities would need
to be so low as to be impractical in most urban planning contexts. By
contrast, land-sparing with forested habitat remaining in 20% or more of
the landscape could provide positive conservation outcomes for the species
modelled here. We discuss the relevance of our findings in planning for
conservation of bats and their habitats in other recently established and
expanding cities.