The news, today, has been featuring footage of the crushing winter of 1962/63. I can just remember it. My Dad and I rescued half a dozen moribund redwings from under the garden hedge and took them inside to warm up. Looking at those huddled bundles of feathers standing on the kitchen table is one of my earliest bird memories.
That winter occurred at the dawn of organised monitoring of common birds and the data showed the massive population crashes of birds like wrens and goldcrests followed by recovery in subsequent years. One bird that was almost wiped out by that brutal winter was the Dartford warbler (pictured in warmer times) – this tiny resident bird was reduced to just six pairs in the following spring. They clung on at Arne in Dorset, a special place that was later to become an RSPB reserve.
The modern history of this little bird has been one of success against the odds. Always vulnerable to cold weather, they are one species that has benefited from warmer winters in recent decades. Their distribution is also limited to lowland heathland. Dartford warblers really need special places to live – and that’s where the RSPB and partners have been able to help them directly. In Dorset and elsewhere we have been re-creating heathland and this has helped them to spread out and means, quite literally, that their eggs aren’t all in one basket. Alongside recreating heathland and caring for it on some of our nature reserve we have also regularly stepped in to object to development proposals that threaten to damage or destroy vital heathland sites - our most recent success was at Crowthorne in Berkshire.
The cold weather of February 2009 reminded us of just how vulnerable they still are as the healthy population on the Thames Basin and Wealden Heaths Special Protection Area (SPA) crashed by 88% from just over 1000 pairs to just 117 (it was part of this site that we fought for at Crowthorne). Ecologists call these stochastic events (ecologists like their Greek – it just means random) – but if a population of birds is stuck in a small area and it’s hit by a random event it can be in real trouble. This latest freeze is a second random event hard on the heels of last February. This time, the freeze is over a greater area but enough Dartford warblers should survive the winter to kick-start their recovery in the spring – provided, of course in the long term there’s enough heathland in good condition to support them.
Looked at just through British eyes, Dartford warblers appear to have benefited from climate change. Milder conditions have helped to drive their spectacular population increase. But on continental Europe the picture is not so rosy – the climate suitable for these little specialists is predicted to move northwards, indeed the centre of their population is set to move towards southern England. The UK will become evermore important for Darties, yet even as the climate changes we aren’t immune from a blast of old fashioned winter. You can find out more about our work to help predict changes to the climate suitable for Europe's breeding birds here.
For the birds that visit our gardens there are practical things we can do, they are the generalists and our feeding and watering can really help them. For the specialists it’s a harder job – and you might like to consider helping us to restore 50 square meters of heathland.
It’s not just Dartford warblers that are confined to their special places. Bitterns need to be able to find food in their wetland homes – it will be tough going for days yet and I expect to bring you news of how bitterns are faring. Many wetland birds have the option to move and the cold, easterly weather system will be driving waders and waterfowl westwards in search of easier conditions. For our wildlife to cope with the pressures of a changing climate or to get through some very old fashioned winter weather they need enough space, enough special places to enable them to survive.
It’s certainly a good year to be a migrant.