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Urban Biodiversity in Australia

January 20, 2016
Grey-headed flying fox, (c) Mike Lehmann, via Wikimedia Commons

Grey-headed flying fox, (c) Mike Lehmann, via Wikimedia Commons

A new paper (Ives et al., 2016; see citation below) discusses the important role urban areas can play in Australian biodiversity conservation. The authors compared the distributions of Australia’s threatened plants and animals to the area covered by 99 cities in Australia. They also created “dummy” cities in the same areas to make sure that their results weren’t skewed if cities were found in particularly diverse bioregions.

The authors claim that this is the first study to show (at least at the “continental scale”) that urban areas can not only be biodiverse, but that they can contain more threatened species per hectare than rural areas. This has huge implications for biodiversity conservation planning in general, which historically has omitted or at least given short shrift to urban areas (although this is changing quickly and for the better).

All of the cities they included (covering only 0.23% of the continent) either had or were likely to contain threatened species — and in fact a full 30% of Australia’s threatened species were found or likely to be found in these cities (the authors did control for other factors that might cause a high level of biodiversity).

Some species were restricted to urban areas. Perhaps not-surprisingly, this was more true for plants (who are not as able to move away as human disturbances increase) than animals. In fact, some endangered plant species’ ranges were exclusively in urban areas, demonstrating that cities might be tremendously important when it comes to plant conservation.

Species made use of different types of land in urban areas. Some relied on remnants of relatively untouched (and it’s all relative, to be sure) areas – again, many plant species fell into this category. Other species made use of modified landscapes. For example, the authors point out that the Carnaby’s black cockatoo uses human-created pine plantations in Perth. In general, they found that “nomadic and migrant” species (they cite in particular the grey-headed flying fox (Pteropus poliocephalus) and swift parrot (Lathamus discolor)) often relied on these human-modified resources as stable sources for food, given that humans tend to plant a variety of things and often supplement natural conditions by watering and otherwise tending to them.

There were a few caveats to their study. As many urban areas in Australia are relatively young, these cities may be carrying a so-called “extinction debt,” which might help account for their high biodiversity (the same might be true for US cities). In addition, they acknowledged that there is no agreed-upon definition of urban areas, so what some researchers might consider urban others might not. This needs to be remedied as urban-focused biodiversity conservation research grows.

But, no matter what sort of habitat and resources these species use, this study provides important evidence that cities need to be considered in conservation planning in general. Plus, it further demonstrates that Australia has some kick-ass urban wildlife!

Swift Parrot, (c) Frank Wouters via Wikimedia Commons

Swift Parrot, (c) Frank Wouters via Wikimedia Commons

Ives, Christopher D., Lentini, Pia E., Threlfall, Caragh G., Ikin, Karen, Shanahan, Danielle F., Garrard, Georgia E., Bekessy, Sarah A., Fuller, Richard A., Mumaw, Laura, Raynor, Laura, Rowe, Ross, Valentine, Leonie, and Kendal, Dave. 2016. Cities are hotspots for threatened species. Global Ecology and Biogeography25: 117-126.



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