Bud burst standby

5th May 2000 at 01:00
BLUE TITS in Guildford were late with their eggs this year. Why? You can check out one family on the web at www.ee.surrey.ac.ukPersonalD.JefferiesbirdnestB.html The female, agitated in her cup-like nest, had not laid an egg by 24 April (Easter Monday), two weeks later than last year.

Blue tits lay 10-12 eggs, which are incubated over 13-16 days. At this time, the female needs 40 per cent more food and may be fed by her mate up to 1,000 times a day. Once hatched, a nestling needs feeding up to 97 times a day, for about a month. Does the adult tit in this picture look a touch driven?

Research by, among others, Dr Martyn Stenning of the University of Sussex, into the blue tit (species Parus caeruleus), a passerine (genus of bird which flies acrobatically), 11cm long and up to 13gm in weight, has reealed that egg-laying can be synchronised - sometimes to the day - with the bud burst of pedunculate oak (Quercus robur). The moth caterpillars which blue tit chicks love to eat live in the pale green of just-unfurled oak leaves. See epunix.biols.sussex.ac.ukHomeMartyn_Stenning Dr Jefferies, whose video diary has made the Surrey website a hot hit this spring, speculates that late laying may correlate with late oak bud burst: is that agitated female trying to delay her brood until she knows food is secured?

If global warming changes the date of bud burst too much, bird breeding success may wane. It seems unlikely that blue tits' well-publicised success at dunking into foil-capped milk will be able to offset huge ecological change. More on blue tits on www.home.istar.caamonbluetitsintro.htm

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