Chiffchaffs are the first summer visitors to arrive, around here
at least, and their distinctive song is hard to miss, and one day
near the vernal equinox suddenly there they are. I have
written down the date in my diary most years since 1990. Last night
I went back through the diaries and collated the data. It's hardly
scientific, but notice there is absolutely no sign of a drift
towards earlier arrival: if anything the reverse.
Yet here is whatThe Telegraph says:
The best evidence for climate change, however, is from
phenology, the study of natural phenomena (seewww.naturescalendar.org.uk):
"Spring is coming about two weeks earlier than it would have been
30 to 50 years ago, and autumn about a week later," says Jill
Attenborough of the Woodland Trust.
Somebody forgot to tell the chiffchaffs.
Frankly, where I live there's been no consistent, discernible
change one way or the other in my lifetime. Some years like this
one the daffodils and snowdrops are weeks late. Some years like
last year, the hawthorn buds are weeks early. Depends on the
weather. I suspect what the phenology folk are measuring is the
same oldurban heat island effect: spring flowers
bloom and birds nest earlier in towns than the countryside,
because it is warmer.
Speaking of chiffchaffs, here's a prediction: that this is going
to be a great year for them and for other warblers. Why do I say
that? Because it's been a harsh winter that has killed a lot of robins,
wrens, goldcrests, tree creepers, tits and the like. So there's
less competition from the over-wintering birds for the ones that
have spent the winter in Africa. Bird bores rarely think about
competition, but it's key. Why have resident birds done
so much better than migrants over the past few decades: because of
bird tables. Redstarts, ring ouzels, whinchats, tree pipits
and willow warblers arrive back from Africa to find their
wintering cousins fat and healthy: robins, blackbirds, stone
chats, meadow pipits and blue tits. Why risk a five
thousand mile trip across the Sahara if there are bird tables just
down the road?