I'm lucky enough to have a little colony of house sparrows in my tiny inner London garden, and for the past three or four years they've been nesting in the roof. The entrance is a hole in the mortar next to an overflow pipe, underneath the soffit board. You can frequently see the birds darting in and out during the spring and summer and the young leaving the nest.
A couple of months ago, at the height of the bitter cold weather, I began noticing pieces of white loft insulation material scattered around in the garden, like this one, caught in a garden bench. Some pieces were quite sizeable - around two and a half inches square, or 60x60mm.
I traced the trail back to the bedroom windowsill directly beneath the nest entrance, where I could see a mixture of loft insulation, twigs and grass, and droppings.
Around the same time I began hearing scratching noises overnight coming from the bedroom ceiling just next to the nest entrance. It's not possible to see what's going on inside, since the attic floor is boarded up, but I presume the sparrows have been roosting there during the winter months.
All this is understandable - but what's the explanation for the loft insulation in the garden? Are the sparrows removing it and replacing it with more natural nesting and roosting material? Or are other birds getting in and taking it away to make nest linings of their own? And has anyone come across this behaviour before?
This is a relatively common occurence with house sparrows and starlings at the start of the nesting season. Whilst some of this material will end up in bird nests, the removal of it and dispensing it outside is likely to be the result of the birds doing some house keeping, creating a suitable internal space where they will build their nest. They can be quite thorough which often leaves to large amounts of insulation material being removed, however not enough to make much difference to the total quantity in your loft!
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