Saturday, November 30, 2013

Predictions and theories? Not from me!

Factors determining timing and success of breeding?

In captivity, Barn Owls breed prolifically, often having several broods throughout the year. That is why, years back, breeders would be forever releasing young owls into the wild, a practice that has dwindled after legal restraints on release of captive-bred birds were imposed.
Could it be that, underlying and determining the breeding behaviour of wild Barn Owls is the same urge to prolific breeding? Thwarted constantly, of course, by such factors as inability to come into breeding condition because of
inclement weather that makes hunting difficult or lack of sufficient prey when the vole population crashes.
In the season just gone, a lot of pairs formed but didn't breed at the usual time, and then, there was a spate of late first clutches, probably because the vole population had increased in the summer (as often happens) and the breeding imperative kicked in again.
The trouble is that the later in the year the hatch, the less likely it is that the young will make it to fledging. Result: lots of failures, or at best just one or two chicks getting off.
It is important, though, not to make bald statements about good years and bad years, as the situation can vary considerably in different parts of the country. The West Country has a bad season, Suffolk, it seems, doesn't do too badly. Central Cambs and other parts ofthe Fens are disappointing, the Peterborough area has a fairly normal breeding season.
And now, as we approach winter, it is tempting to start another round of theorising and predicting: a poor breeding season means fewer birds means less competition for the food during the winter. Well, maybe. A mild winter favours the owls. Well maybe, but does it favour the rodents and inverterbrates? And is the converse true? How do owls fare in a hard winter? And does the timing of cold snaps, wet spells, strong winds play a role?
About the only prediction that's reliable is, to paraphrase a famous saying of a southern Baptist Minister: “things ain't what we want 'em to be, and things ain't what they're gonna be, but they shure ain't what they wuz.” I find that mildly comforting, even though it is deeply meaningless. Anyway, it's as near as you will get to a prediction from me.

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