Today, Dr Richard Bradbury, the RSPB's Head of Environmental Research, explains how climate change is already forcing wildlife to move. You can read much more about this in our new report on the impacts of climate change on wildlife, that we published just this week.
Things aren’t like they used to be....
When I was a kid, looking at my first field guides, I got used to the idea that species lived in particular habitats and in particular places, marked in a bright colour on a range map. For instance, I got used to the idea that there was a set of native British breeding birds, some of which were common and widespread, some less so. Some, like the Dartford warbler, were specialists of the lowland heaths of southern England, while others, like the dotterel and ptarmigan, were specialists of the montane plateaus of northern Scotland. And of course there was that exciting list of rare visitors, like little egret, that I might just see one day – if I was very lucky.
As I’ve grown older, this fixed view of the world has changed a lot. Species that were common when I was young, from the turtle dove to the tree sparrow to the garden tiger moth, are now much less abundant. Various factors, including changes in agriculture, have driven these declines. Other species, like red kite and marsh harrier, have increased in numbers thanks to conservation efforts.
But now, climate change is also having a dramatic effect on the suite of species which are familiar in any given part of the British Isles. From the south coast, since the 1970s, Dartford warblers have charged north to mid Wales, the English midlands and East Anglia. Having lived about as far north as north Wales prior to 1982, the comma butterfly has now spread as far as Aberdeen. From grasshoppers to spiders to fish – these northwards shifts are being shown right across our wildlife. We’re very confident these northwards advances are in response to the warming British climate. On the other hand, our dotterel population has halved and shrunk in range in the last few decades – maybe this is signs of a climate-driven retreat? And some less mobile warmth-loving southern species, like sand lizard, haven’t moved north as the climate has ameliorated for them – because their habitat is too fragmented.
Northwards shifts in range are exactly what we’d expect under climate change. We’d also expect species to move uphill. And we see this too. Mountain ringlets, perhaps our only truly montane species of butterfly, appear to be losing their lowest altitude colonies. Dartford warblers (that lowland heathland specialist) are now breeding over 400m up the hill on Exmoor.
Even more spectacularly, a host of species are expanding their ranges north and colonising the British Isles for the first time. From small red-eyed damselflies to tree bumblebees to wetland birds. That rarity of my childhood, the little egret, is now a common sight in the southern half of Britain.
So what does this all mean? Well, at a personal level, I find it both thrilling and sobering. I’m wondering when great white egrets will first breed on my local reserve! But, at the same time, I wonder how long I’ll be able to go up to the Scottish highlands to see dotterel. At a professional level, the evidence is clear that climate change is not some far-off threat to our wildlife – it’s here now, and we need to start adapting – to help less mobile southern species move north, and to try to help northern species to hang on. And that will have to include some thinking about when we consider a species to be ‘native’ – with the protection that can lead to. This isn’t an easy thing to decide when species are moving themselves in response to climate change and also being moved around the globe by us, sometimes causing problems when they arrive.
Matt Williams, Assistant Warden, RSPB Snape.