By Richard Bradbury, RSPB Centre for Conservation Science
Protecting the best places for wildlife from damage is a huge priority for us at the RSPB. These special places are well known to readers of this blog; Sites of Special Scientific Interest, Special Protection Areas and Special Areas of Conservation are the designations that are the starting point for effective protection and can help conditions to be managed for vulnerable wildlife and provide the basis for protection from damaging development proposals, disturbance and other pressures. For the Dartford warblers that I blogged about recently, their ability to respond to climate change in Britain would have been considerably less without the decades of good work to protect populations in their crucial southern English strongholds.
But how important will these protected sites be in a future influenced by climate change? I’ve previously blogged (here and here) about collaborative science projects that have shown already that they have been very important in the face of this challenge, by providing essential new homes for species that, to survive, must shift their range in response to climate change. This is true both for a whole range of animal species which are expanding their range North in Britain and specifically for those wetland bird species which have naturally colonised Britain from Europe.
Mediterranean gull in black-headed gull colony – a species expanding it’s range inBritain having arrived under its own steam. By Ron Knight (Flickr: Mediterranean gull) [CC-BY-2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons.
In a new paper in the journal Diversity and Distributions, led by PhD student Jonathan Hiley from the University of York, we again look at the role of protected areas in helping species to expand their range. This time, however, we compared how Britain’s special places for nature have been exploited by species which have colonised Britain naturally from Europe, such as the little egret and the Mediterranean gull, and by non-native, introduced wetland birds such as the Black Swan.
Seven non-native, introduced wetland birds are now established in Britain. These species initially bred away from reserves and protected areas before showing an increasing association with them as their populations grew. In contrast, reserves and protected areas provided important new homes for natural colonists to Britain, which then spread out as their populations grew.
So, protected areas have been vital to the expansions of natural colonists, without acting (at least initially) as the prime sites through which introduced species can gain a toe-hold. There is a worry that they are then at increasing risk of colonisation by these species with potential problems ahead.
A real difficulty is that many introduced species like the black swan and Egyptian goose were introduced simply because they are attractive and engaging creatures and without thought of the negative consequences. ‘Invasions’ of non-native species are becoming increasingly common across the World, and in some cases threaten the survival of native species.
Egyptian goose, one of the non-native species expanding it’s range in Britain. By Andreas Trepte (Own work) [CC-BY-SA-2.5 (http://creativecommons.org/licenses/by-sa/2.5)], via Wikimedia Commons.
The challenge is to identify which of the non-native species might cause future problems. For instance, the introduced North American ruddy duck disproportionately colonised protected areas and is a potential threat to the native European white-headed duck. In contrast, the Mandarin duck is less frequently associated with reserves, and would seem unlikely to cause ecological damage even when it does colonise them. But our goldeneye population has been very dependent on reserves, and like the Mandarin nests in holes (and nest boxes!), so even this is something to keep an eye on.