Residential & Commercial Development

By NABCANABCA, on 09 Feb 2017 03:43

Threat Description

The impacts of industrial (including military bases) and urban development on habitat and associated impacts including: loss of foraging and roosting habitats due to development, water loss and degradation, light, noise, and air pollution and predation by domestic pets.

Perceived Importance of this Threat

The apparent importance of this threat varied among regions from low in the north to high in the south.

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Urbanization

Research on the role of bats in urban ecosystems often comes from two non-overlapping perspectives; community ecology and public health surveillance (O’Shea et al. 2011). Community ecology surveys often find that bats are the most diverse group of mammals in the urban environment (Threlfall et al. 2012), with bat activity being higher in urban areas relative to rural habitats Coleman and Barclay 2012). However, this pattern is biased by the abundance of a few synanthropic species (such as Myotis lucifugus and Eptesicus fuscus in North America and Nyctalus noctula and Pipistrellus nathusii in Europe) that often dominate the bat community (Loeb et al. 2009, Mehr et al. 2011, Coleman and Barclay 2012). This is particularly true when the urbanization is occurring in proximity to agricultural habitat or grasslands (Gehrt and Chelsvig 2003, 2004).

It is generally assumed that synanthropic bat species are well adapted to the urban environment (Coleman and Barclay 2011). Threlfall et al. (2012) separated these urban bat species into ‘adaptors’ (species that adapt to urban habitat but also use natural habitats) and ‘exploiters’ (species that are dependent on human resources), but cautioned that there are also ‘avoiders’, species that are extremely sensitive to development and tend to disappear from the landscape during urbanization. Long-term monitoring programs such as the National Bat Monitoring Program (NBMP) in the United Kingdom (Guest et al. 2002) and the North American Bat Monitoring Program (Loeb et al. 2015) acknowledge the impact of development on bat communities and incorporate urbanization into their survey methodology.

Predation from Cats

Predation from domesticated cats represent one of the biggest wildlife a significant threat to mammals, with one study extrapolating predation of up to 18 billion mammals annually (McRuer et al. 2017). Domestic cats also represent a huge predation risk for bats, accounting for almost 30% of all bats brought into wildlife rescue centers (Ancillotto et al. 2013). This is particularly true in rural areas where cats often stay out overnight (Ancillotto et al. 2013), and in some places multiple cats have been observed hunting a single colony of bats, catching them in the air with swift movements of their paws. Predation by free-roaming cata on an insular population of bats (Rodriguez-Duran et al. 2010).

Mitigation Measures

The most effective mitigation measures involve comprehensive land-use planning that considers conservation values, not only for bats, but for all other wildlife in relation to siting of urban and industrial development.

Given that a development has occurred, or is occurring, there are a few measures that can reduce the negative impacts on bats, including:
- retention of as much natural vegetation as possible, to support insect communities and provide foraging sites for bats
- creation of bat roosting habitats (at least in areas where there is still suitable foraging habitat). This could include bat boxes or, in some cases, bridge expansion joints or other structures in buildings where there is low risk of bat-human conflicts
- encouraging cat owners to keep their cats indoors to reduce predation on bats. Another alternative is the use of pounce protectors such as the CatBib (Calver et al. 2007). The CatBib is a neoprene bib that fits around the collar of a domestic cat that reducing the ability of the cat to capture mammalian prey up to 45% without impacting the cat’s ability to run, jump, or climb.

Urbanisation and Its Effects on Bats—A Global Meta-Analysis

Challenges/Barriers to Addressing this Threat

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