AS recent instalments of this column have shown, sound can be very important in locating a bird or even realising that there is a bird there at all, before identifying it. On a hot summer day, lazing in the garden, you may be unaware at first that there are birds overhead in the bright blue sky, but gradually their calls penetrate your consciousness: squeals, harder chirps, soft, lilting, liquid notes. Common Swifts, House Martins and Swallows…
Swifts, of course, give their unmistakable shrill screaming notes, but at considerable height or distance this becomes a less strident, more furtive sound. House Martins have a more-or-less dry chirrup or low rippling call, short and simple or run into little, quick sequences such as trrp-r-r-rp, prr-r’t trr’p (OK, best try your own transcriptions!);…