Thursday, 14 June 2012

A box of eggs

There are three nest boxes on the side of the house, near the front door. They are sheltered by shrubs and have House Sparrow sized entrance holes. In the five or so years that they've been there one has been used by a Sparrow on one occasion and one by a Great Tit at least once.

This year a handsome Cock Sparrow has been
"singing" on the roof of Rose Cottage, the sits just below us, and I think they are nesting in the cottage roof somewhere. I did notice some noisy Great Tits a couple of weeks ago in the bushes near the boxes and last week I had a quick look in. The first two were empty, but the far one had a nest with three scattered eggs in it. I left it there for a week to see if there was any activity but the nest looked much the same today. I think that the eggs are indeed Great Tit eggs, and although there are no signs of the nest being occupied, it is possible that some young did fledge from this box.

The eggs weren't neatly in the centre, in fact one was almost hidden in the nest fabric. I've never been an egg collector, not even as a small boy, when it was a popular occupation, but I have to admit that the eggs are fascinating things. It is hard to imagine a female Great Tit being able to produce clutches of up to 18 eggs. The average is probably around eight. Each egg weighs around 1.75 gms, and a hen Great Tit about 17.5 gms. Without using a calculator I reckon that means if a clutch of 10 is produced she's laid her own weight in eggs. As eggs are laid, normally at one a day, she has to be eating well and one would think expending a great deal of energy in this activity. This, season with such awful weather, must have been very hard, and apart or a brief encounter, as described above, I haven't seen any young families of Blue or Great Tits in the garden this year. As neither normally has second clutches (Blue Tits only as replacements if the first clutch is lost early on) it might well signal that we are in for a population crash next year.

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