The structure of a micro-bat community in relation to gradients of environmental variation in a tropical urban area

Abstract

We investigated patterns of community structure (species composition, foraging activity, and nightly foraging patterns) of bats in relation to gradients of environmental variation in a tropical urban area. A total of 32 sites spread equally across eight habitat types were sampled in the city of Townsville, North Queensland, Australia. Each site was sampled on 3 non-consecutive occasions using automated AnaBat systems. Eleven species were confidently identified while a possible four more were identified only to the genus level. Ordination of environmental variables measured at these sites identified two distinct environmental gradients reflecting the degree of urbanisation and foliage density. With increasing urbanisation there was a decline in species richness and total foraging activity. We used regression trees to characterise foraging preferences of each species. This analysis suggested that only one species of Mormopterus was able to exploit the resources provided by urbanisation. This species foraged in areas with higher numbers of white streetlights. The remaining species of bats preferred to forage within close proximity to natural vegetation and with low numbers of streetlights. The density of vegetation in long-established suburbs did not substantially reverse the trend for urban areas to have fewer bat species than original habitats.

Relationship between urbanization and bat community structure in national parks of the southeastern U.S.

“…While some studies have found a reduction in bat species richness in urban areas compared to surrounding rural areas (Avila-Flores and Fenton 2005), others have found that bat species richness is not affected by urbanization (Kurta and Teramino 1992;Sparks et al 1998;Ulrey et al 2005). However, within cities, bat species richness often declines with the amount of urbanization (Gaisler et al 1998;Hourigan et al 2006). Thus, parks within urban areas may serve as important refuges for bats and may explain why species richness was preserved in the urban parks we studied.…”

“…Several studies have examined the use of urban areas by bats and have found that bats prefer wooded or riparian areas within cities and avoid high density residential and commercial-industrial areas (Gaisler et al 1998;Gehrt and Chelsvig 2003;Duchamp et al 2004;Sparks et al 2005;Hourigan et al 2006;Walters et al 2007). However, only a few studies have examined the effects of urbanization on bat populations or community composition.…”

Bats (Mammalia: Chiroptera) in urban fragments of Maringá, Paraná, Brazil

“…However, some species of bats have been shown to resist anthropogenic effects and sometimes even benefit from them, either by inhabiting urban forest fragments or settling directly in urbanized areas (Bredt and Uieda 1996;Fenton 1997;Esberárd 2003;Reis et al 2003;Barros et al 2006). Considering that a better understanding of the influence of urban areas in communities of tropical bats is required (Hourigan 2006), we present here a list of bat species recorded in forest fragments in the municipality of Maringá, state of Paraná, Brazil.…”

Biomass and biodiversity of nocturnal aerial insects in an Adelaide City park and implications for bats (Microchiroptera)

“…Insectivorous bats (Microchiroptera) are among the native mammalian taxa that persist in Australia's urban environments, but only a small number of studies has examined the ecology of Australia's urban bat populations (Kirsten and Klomp 1998;Hourigan et al 2006;. Little is known about what bat species occur in cities, what food resources are available, and whether populations are viable given the decline of urban insectivorous bat populations overseas (noted by Kurta and Teramino 1992;Arlettaz et al 2000;Guest et al 2002;Duchamp et al 2004).…”