Bats like city living

We’re used to sharing our cities with pigeons, ants, and the occasional skunk. In part of Australia, though, urban areas are increasingly overrun by thousands of bats — and a new study suggests that the animals’ inclination for city life is only growing.

Urban development can splinter habitat and force out wildlife, but it also can provide an enticing refuge for some species. After all, cities aren’t entirely hostile to animals: they may have fewer predators, plentiful food, and shelters from natural disasters. Unfortunately, some urban species prove to be difficult cohabitants. These animals can carry diseases, harm pets, cause car crashes, and generally add to the chaos.

Take the flying fox, a type of bat that has infiltrated cities in Australia. Tens of thousands of bats can live in a single “camp,” and — as researchers delicately put it in PLOS ONE — these sites are “potent point sources of noise, odour and faeces.” Flying foxes also can transmit viruses such as Hendra virus and Australian bat lyssavirus. Not everyone wants the animals gone, since they help spread pollen and seeds, and some species (such as the spectacled flying fox) are considered threatened. But knowing where the bats tend to roost could help people figure out how to manage the problem.

The team studied spectacled flying fox camps in a roughly 9,000-square-kilometer patch of Queensland, Australia. From 1998 to 2012, surveyors tried to estimate the number of bats in 30 to 50 camps per year by counting the animals in flight or while roosting in trees. The researchers categorized each camp as urban, next to urban areas, or non-urban.

The number of occupied camps in urban areas rose over the course of the study, the team found. And the fraction of spectacled flying foxes found in or near cities also increased. For example, during the November surveys from 1998 to 2002, about 60 to 80 percent of the bats lived in or close to urban areas. But later, that number rose to nearly 100 percent.

The changes didn’t come about because cities expanded into the bats’ habitat, the authors say. Instead, it appears that flying foxes simply like the perks of urban areas. Managers will need to explore strategies “that facilitate the co-existence of humans and flying-foxes,” the team writes. In other words, we’ll have to learn to live together. Roberta Kwok | 16 October 2014

Source: Tait, J. et al. 2014. Are flying-foxes coming to town? Urbanisation of the spectacled flying-fox (Pteropus conspicillatus) in Australia. PLOS ONE doi: 10.1371/journal.pone.0109810.

Image © CSIRO | Wikimedia Commons