The Natural History of Selborne

As most of the second brood of Hirundines are now out, the young on fine days congregate in considerable numbers on the church & tower: & it is remarkable that tho’ the generality is on the battlements & roof, yet many hang or cling for some time by their claws against the surface of the walls in a manner not practiced at any other time of their remaining with us.  By far the greater number of these amusing birds are house-martins, not swallows, which congregate on trees.  A writer in the Gent. Mag. supposes that the chilly mornings & evenings, at the decline of the year, begin to influence the feelings of the young broods; & that they cluster thus in the hot sunshine to prevent their blood from being benumbed, & themselves from being reduced to a state of untimely torpidity.