n SCOTLAND has to be buzzing before the spotted flycatchers arrive. In a cool wet spring like this, the one thing there hasn't been much of yet is insects and so the flycatchers will be late in from Africa. Spotted flycatchers eat insects almost exclusively, and if they are flying then so much the better.

They sit on regular perches - a side branch under the tree canopy, the apex of a pergola or a steading gutter - and sally out in quick, acrobatic twirls to pick from the air bluebottles and craneflies, butterflies and midges.

They also catch wasps and bees, knocking off their stings by rubbing them vigorously on a twig. The rate at which they hunt and the agility of their technique make fascinating watching in a warm summer glade.

Although they nest in every corner of Scotland to Caithness and Skye, spotted flycatchers are very inconspicuous birds. They are plain brown, shaped like an upright robin, with a large, warm eye but hardly a song or note to pick them out. It is often a surprise to find that a pair have taken up residence in your garden, nesting in a crevice in a creeper or trellis.

It is the nature of their movement which distinguishes them. If you watch carefully you may see the subtle changes in their diet which indicate breeding success: the females stoking up on slaters to lay down calcium to make their eggs; the desperate search of leaves and tree trunks in cool weather which may mean the young starving as the aphids and little flies the birds find there are not rich enough to give them.

Here in the north they don't even have time for a second brood. In September, when the beasties stop dancing under the boughs and over the pounds, the flycatchers are off, back south of the Sahara, where it's buzzing all the time.