Nature in Cities: should we care?

When most people think of ‘natural spaces’ they envision the wide-open countryside, elephants roaming around Africa, or maybe somewhere deep in the heart of the Amazon. But what about the nature right under our noses? Most people in the UK live in urban areas leaving a growing estrangement between society and the natural world (Dye, 2008). Yet if you look hard enough, biodiversity can be found all around cities.

Figure 1. Green spaces in cities provide a haven for wildlife and benefit society.

Gardens for example provide a much-needed refuge for species that have come to thrive in developed areas (Gaston et al., 2003). They also enable great opportunites for people to interact with nature on a daily basis (Dallimer et al., 2012). City parks and even green verges also house a variety of wildlife. However, with an area over twice the size of Hyde Park being lost every year from London’s green spaces alone, the question is – should we care?

Benefits to Biodiversity

Many of the World’s declining species thrive in urban areas. For example, the common frog has seen large declines in rural areas within the UK, yet they have thrived in our towns and cities (Carrier and Beebee). The same can be said for our bees (Goulson et al., 2002). Its not just in the UK we see these patterns, urban parks in the USA support a higher number of bees than parks in rural areas (McFrederick and LeBurn, 2006). The availability of green spaces also goes some way in reducing the impacts of habitat loss and disturbance (McKinney, 2008).

Figure 2. The common toad population declines, yet thrives in urban areas.

Figure 2. The common frog population declines, yet thrives in urban areas.

Benefits to Society

Besides the enjoyment people feel from being around nature, natural spaces in cities provide a variety of benefits to society, including improved mental and physical health, flood defence and temperature regulation. Bolund and Hunhammer (1999) outlined these benefits and categorised them into broad functions; air filtration, noise reduction, sewage treatment, reducing surface water run off and climate regulation. Greener environments have also been linked to benefits like quicker recovery times in hospitals, reducing population obesity levels and attracting a higher qualified work force. Although many of these systems can be replaced by technology, the cost for these would have to be paid for by residents.

Increasing the Value

There are many actions that can be taken to improve the value of urban areas to preserve and increase the outlined benefits. Wildlife gardening for example has the potential for mass participation and can provide numerous benefits for wildlife and people. Novel ideas like green roofs and walls are also a great way to attract biodiversity. Plans for ‘future green cities’ are also being drafted with unique ideas to incorporate nature into modern lives.

Figure 3. Predictions of future cities that incorporate biodiversity.

Finally, simply appreciating and preserving those spaces we already have is vitally important. Various organisations now put great emphasis on schemes to promote urban nature, including the RSPB (http://homes.rspb.org.uk/),

Wildlife Trusts (http://www.wildlifetrusts.org/living-landscape/schemes/exeter-wild-city) and local councils.

Figure 4. Impression of what the future for cities could hold.

Useful Links

http://www.thenatureofcities.com/

https://www.sheffield.gov.uk/out–about/parks-woodlands–countryside/parks/urban-nature-project.html

http://topdocumentaryfilms.com/nature-cities/

http://www.bbc.com/future/story/20130530-bringing-nature-back-into-cities

http://www.innovcity.com/2011/07/19/cities-of-the-future-will-be-dense-green-and-interconnected/

References

Bolund, P and Hunhammar, S (1999). Ecosystem services in urban areas. Ecological Economics. 29, 293-301.

Goulson, D, Huges W.O.H, Derwent L and Sout J.C. Bombus terrestris, in improved and conventional agricultural and suburban habitats. Oecologia130, 267-273.

Carrier, J-A. and Beebee, T.J.C. (2003) Recent, substantial, and unexplained declines of the common toad Bufo bufo in lowland England. Biol. Conserv.111, 395-399.

Dallimer, M. et al. (2012) Biodiversity and the feel-good factor: Understanding associations between self reported human wellbeing and species richness. BioScience. 62, 47-55.

Dye, C (2008) Health and urban living. Science. 310, 766-769.

Gaston, K. et al. (2005) Urban domestic gardens (IV): the extent of the resource and its associated features. Biod. Conserv. 14, 3327-2249.

Goulson, D.et al. (2002) Colony growth of the bumblebee,

McFrederick, Q.S. and LeBuhn, G. (2006) Are urban parks refuges for bumble bees Bombus spp. (Hymenoptera: Apidae)? Biol. Conserv. 129, 372-382.

McKinney, M. (2008) Effects of urbanization on species richness: A review of plants and animals. Urban Ecosyst.11, 161-176.

Feral cats… they’re so un-Australian

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By Tom Evans @thomgevans

Following my recent blog regarding the control of invasive alien species, I want to take a look at one particular animal that’s been receiving a great deal of media attention of late – the feral cat. According to the Australian Wildlife Conservancy (AWC), there are somewhere in the region of 20 million feral cats in Australia… and they kill about 75 million native Australian animals every night.

A feral cat and prey. Source: The State of Victoria

Extinction crisis

Australia has the worst rate of mammal extinctions on the planet, with 29 since European settlement. That’s about 10% of Australia’s original mammal fauna, including mice, bandicoots, potoroos, bettongs, rats, a wallaby and one of Australia’s only two bilby species – and marauding moggies are the principal culprits.

It is estimated that an individual feral cat kills an average of five animals every night – with some killing many more. Journalists in Australia recently published a controversial photograph showing a culled cat alongside the contents of its stomach (a vast array of dead animals). It’s a graphic image, but they argue that given the dire state of Australia’s wildlife, publishing the photo was justified. I’m inclined to agree – the image conveys an important message. You can access the article (and the photo) here (warning: graphic image).

The Action Plan for Australian Mammals, published earlier this year, represents the first comprehensive assessment of the conservation status of mammals across Australia – it identifies feral cats as the most significant threat to their survival. Furthermore, predation by feral cats is now listed as a key threatening process under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act), which specifically identifies 35 bird species, 36 mammals, seven reptiles and three amphibians to which feral cats represent a specific threat. Evidence also suggests that feral cats are on the verge of causing a second wave of extinctions in Australia’s north – the nation’s sole remaining landscape reflecting Australian biodiversity prior to the arrival of Europeans.

You get the picture – one of only two continents in the world with no native cat species is now the world’s largest cattery.

Time is running out, but for whom?

It seems shameful that 20 million feral cats are still able to run riot in a relatively stable and wealthy country, which without doubt has the capacity to deal with the issue. So what’s being done about it?

Last Wednesday, the Federal Environment Minster, Greg Hunt, set out a plan to halt the loss of Australian mammals in Australia by 2020. At the centre of this plan is a pledge to eradicate all significant feral cat populations. Presumably this is because the Australian Government recognises that if it is going to make any progress towards meeting its 2020 biodiversity targets, signed up to under the Convention on Biological Diversity (CBD), then feral cats have to go. All hail the power of the multilateral agreement.

John Gould print image of the Pig-footed Bandicoot – a species extinction largely attributed to feral cat predation. Source: Museum of Victoria

This pledge has been met with a mixed response. Some describe Hunt as a hero, others question the Australian Government’s motivations, the likelihood of achieving the task, and in particular, the current proposals to use a poison bait called Curiosity. Hunt believes this approach “has the potential to make a real difference to the protection and recovery of our native species”. The bait contains a toxin that restricts the flow of oxygen in the bloodstream. Placed within a small piece of food, it is ‘less likely’ to be eaten by wild animals because unlike cats, they tend to nibble their food, resulting in rejection of the bait. However, tests have yet to demonstrate that this approach won’t harm other animals. It is curious then, that the success of the Australian Government’s strategy to eradicate feral cats relies quite heavily on the use of an unapproved poison bait.

Landscape management

In truth, there may be sites where a program of targeted baiting could be successful in reducing feral cat populations. However, it is unlikely to work in isolation. Australia is an enormous continent – baiting simply isn’t feasible. What’s needed is a range of techniques to deal with feral cats, including the broader management of Australia’s landscapes. The Victorian Government is currently progressing with plans to introduce the Tasmanian Devil into Wilsons Promontory National Park. The proposition here is that this top predator will compete with feral cats (and foxes) for food and nesting space, and may also take their young, reducing feral cat populations. Interestingly, Hunt recently acknowledged that he had not heard about the Victorian Government’s proposals, which perhaps suggests that Australia has yet to develop a coordinated national approach to deal with feral cats.

The cat-proof fence

Another approach that has proved successful in recent years is the establishment of a network of cat-proof enclosures. The AWC manages 23 properties, covering three million hectares of cat free land, with successful results for native species. One out of every five wild greater bilbys, and one of every three numbats now live within these enclosures. The AWC is currently constructing a 43 km fence to create the largest cat (and fox) free area on mainland Australia, with the aim being to reintroduce nine of Australia’s most endangered mammal species. The message here is that when feral cats are removed, wildlife bounces back.

I leave you with a final quote from the Chief Executive of the AWC, Atticus Flemming:

“…if we remove feral cats from the landscape, we will see massive increases in the numbers of native animals… You wander at night through those areas where we’ve eradicated feral cats, and it’s like stepping back 200 years. The bush is alive. There are bilbys everywhere, bettongs everywhere, bridled nailtail wallabies. The ground is moving with little animals. That is what the bush must have been like before there were foxes and cats.”

Sounds purrfect to me.

Tom Evans
PhD Candidate – The London NERC DTP
University College London
Twitter: @thomgevans
Research Gate: https://www.researchgate.net/profile/Thomas_Evans6

Invasive alien species

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By Tom Evans @thomgevans

The aliens have landed. They’ve taken up residence in our waterways, our cities, our farmland and forests. Their negative impacts to both the environment and the economy are enormous, and they aren’t going home any time soon. So what are ‘alien species’? In short, they are animals, plants or other organisms that we have introduced to areas outside of their natural range. They are considered to be ‘invasive’ when they become established, disperse and have negative impacts on people and/or wildlife.

Free oyster cards

Pretty much every habitat across the globe has been invaded by alien species – and the inalienable fact is, we put them there. The world is getting smaller – with improvements to transport by air, land and sea, international travel and trade have increased dramatically. As a result, species that wouldn’t otherwise have the opportunity to travel (mussels don’t have feet – well actually they have a foot, but it’s not made for walking long distances) are hitching a ride across the globe.

Alien species have been introduced to new surroundings both intentionally and unwittingly. The unrelenting frogmarch of the cane toad along the eastern seaboard of Australia, much to the detriment of large predator populations (think quolls, snakes, lizards and goannas) is an example of a deliberate introduction with significant environmental consequences. The Shine Lab at Sydney University has been working to contain the toad invasion for many years.

A death adder killed by a cane toad. Source: canetoadsinoz.com.

The zebra mussel’s grip on the Great Lakes, where it clogs water supply infrastructure and outcompetes native species, reducing the food supply for important commercial fish species, is an example of an accidental introduction with disastrous environmental, recreational and economic impacts. In this case, the tenacious mollusc was transported to North America in the ballast water of ships embarking from ports in Western Europe. The Centre for Invasive Species Research (CISR) at the University of California, Riverside (UCR), recently estimated that costs to control zebra and quagga mussels in the Great Lakes amount to $500 million/year.

Zebra mussels smothering a current meter (Lake Michigan). Source: National Oceanic and Atmospheric Administration (NOAA).

Ponto-Caspian catastrophe?

The UK has not escaped the impacts of invasive alien species. Earlier this month, the quagga mussel was found in the UK for the first time. Prior to this unwelcome discovery, the quagga mussel was identified by scientists at the Centre for Ecology and Hydrology (CEH) as the single greatest threat to British wildlife of all alien species. Equally alarming is this month’s revelation that the threat of invasion by the quagga mussel, along with several other species from the Ponto-Caspian region (that’s Southeast Europe to you and me) is now so real that parts of Great Britain face the grim prospect of invasional meltdown¹.

Evicting toad from Toad Hall

Last month, in recognition of the ever growing threat posed by potential invasions such as the quagga mussel, along with the lack of a coherent EU wide strategy to address invasive alien species, and the mounting costs associated with their containment and management (recently estimated to be €12 billion/year in Europe) (http://www.eea.europa.eu/highlights/invasive-alien-species-a-growing), the EU adopted a new regulation on invasive alien species (http://ec.europa.eu/environment/nature/invasivealien/index_en.htm). This legislation requires Member States to develop a list of species of Union concern, informed by risk assessments for individual species. It therefore encourages a cross-border approach to a cross-border problem – something that has been lacking to date. The regulation will be published in the Official Journal of the European Union in the coming weeks.

Instructions to boaters at Lake Mead, Nevada to prevent quagga mussel transportation. Source: JN Stuart. (CC BY-NC-ND 2.0).

A number of recent research initiatives within the field of invasion biology aim to compliment and inform the above process. A protocol for scoring the impacts of invasive species has recently been developed² and refined³, enabling the severity of a suite of environmental, economic and social impacts associated with a species to be calculated, informing risk assessments for potential invasions. Studies have shown that this methodology can be effectively applied to different taxonomic groups⁴ (see also Kumschick et al. In press⁵), and can also be used to inform studies that aim to predict the impacts of a species prior to invasion⁶.

This scoring methodology is also integral to a proposal to develop a global list of alien species classified by their environmental impacts⁷ that aligns with the existing IUCN Red List of Threatened Species (which is celebrating its 50^th birthday in 2014, having become a global reference tool for biodiversity). The development of a standardised approach to quantify and compare the impacts of alien species will help us to predict whether potential invaders are likely to have negative impacts in their new range. This is important, as it allows for early intervention to prevent the establishment of alien species, and enables us to efficiently allocate money and resources where they are most needed to prevent or contain an emerging invasion.

Tom Evans
PhD Candidate – The London NERC DTP
University College London
Twitter: @thomgevans
Research Gate: https://www.researchgate.net/profile/Thomas_Evans6