As we approach Christmas and the shortest days of the year, snuggled down in front of warm fire, it is easy to think that nature is hunkered down too. Hibernating species like hedgehogs, and all cold-blooded animals like frogs and insects, are. But now the nights are long, birds have the challenge of finding enough food to lay down sufficient fat to see them through until morning. Tiny birds like wrens, for example, can burn up half their bodyweight just staying alive while they sleep. Meanwhile, flocks of loudly ‘chack-chacking’ fieldfares, winter visitors from Scandinavia gorging on rotten orchard apples, remind us that many millions of birds just deal with the winter by migrating somewhere warmer. Or, in the case of those that come here, to somewhere less cold!
Partridges in pear trees notwithstanding, our imaginations might just wander to think about our summer birds – blackcaps, cuckoos and East Farleigh church’s very own swift. If not hibernating or hunkering, where are they? Actually, swifts can hibernate after a fashion – but that’s for another Lifeline.
'Our' East Farleigh Church swfit - here's hoping s/he's safe and warm.
The blackcap, with its loud, robin-like song, is an interesting example of the effect of our warming climate. For eons, birds that have spent summer in northern Europe have simply flown south to Spain and northern Africa to spend winter in Mediterranean comfort. Now, some blackcaps that spend summer in Germany migrate instead to the UK, where our winters are becoming milder. If they survive our winter (many have learnt to use our plentiful garden feeders) they then have a shorter flight back to their breeding grounds than other blackcaps that made the journey to the Mediterranean. This means they can nab the best territories and raise more young – which are then genetically programmed to spend winter in a UK heated by a warming Atlantic Ocean. Evolution in action.
We know from satellite tracking that our cuckoos migrate down to sub-Saharan Africa, where they arrive in November, often in exactly the same area they went to in previous winters. From Equatorial Guinea or Gabon they move just south of the equator to spend Christmas in the tropical Congo Forest, before starting their long migration north again around February. So just four months of their year are spent here, around The Farleighs – yet we think of them as typically British birds: our birds, in fact. Recent studies, though, have shown the UK to be the most nature-depleted country in Europe. I wonder how long it will take our continuing onslaught on the countryside in general, and insects in particular, before cuckoos no longer grace our shores.
And what of the swift – just thirty-five grams of feathered life that graced our church twice this summer? Again, modern technology has helped us discover that they too spend their winters aloft circling tropical Africa, and flying in a wide arc over the adjacent Atlantic. We know now that it’s not just ‘our’ swifts either that do this; studies on Chinese swifts fitted with tiny tracking devices in Beijing show them wintering in the same area as ours. Same species, different populations from opposite sides of the world, happily sharing that most basic resource, food. Is there a lesson here for us?
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