Arrival of the Chiffchaffs

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?