You hear it on the radio, you hear it on the TV. We must see that we don't lose too much heat in our houses, we must renovate and close all gaps. The trend to built houses are without a gutter.
But what about the animals that live in those holes and gutters, where must they go? I don't speak here only of swifts, there are bats and what more living with us in our houses.
The RSPB made a survey of this problem, you can read about it here.