click photo to enlarge
Today I was looking at the bird box in my willow tree. I placed it there two years ago in the hope that a blue tit (Parus caeruleus) would nest in it. Unfortunately it has been spurned each season; as was the other one I put in the cherry tree. So I've decided that I'll enlarge the hole to make it suitable for the slightly larger great tit (Parus major): I've had better luck with that species in the past.
Those thoughts prompted a short reflection on the way in which birds have adapted to man. Our obsessive tidiness has reduced the number of naturally occurring holes that the blue and great tits formerly used, and nest boxes now provide a significant number of the sites favoured by these species. House martins (Delichon urbica), as their name suggests, have also found man to be a useful provider of nesting places. They get their name from the habit of building their cup-shaped mud nests under the eaves of houses. Before man built houses with eaves these birds built their nests under overhangs on cliffs. I'm only aware of one location in England where that still happens - Malham Cove in Yorkshire; everywhere else man-made structures are preferred. So too with swallows (Hirundo rustica), a bird that I've never seen construct its nest anywhere other than in a building. In the UK one of the key bird habitats is the man-made suburban garden, those that naturally frequent woodland edges finding it particularly to their liking. The food that friendly households put out for them is also a big incentive to hang around dwellings, especially in the leaner winter months.
Of course birds aren't infinitely adaptable to the activities of man, and many species - particularly those of open farmland - are in steep decline. However, today I saw a scene that must have been replayed every year since a farmer first ploughed a field: black-headed gulls (Larus ridibundus) (and rooks) following the tractor, picking up the morsels revealed in the turned soil: a symbiotic relationship if ever I saw one. It being February a few birds were showing their breeding plumage of a full head cap of chocolate-brown feathers, though none would be ready for nest building for another three months. I took a couple of shots of the tractor and plough working the Fenland field, one as it headed towards me, and this one that shows the birds to better effect after it had turned away and started its next set of furrows.
photograph & text (c) T. Boughen
Camera: Olympus E510
Mode: Aperture Priority
Focal Length: 150mm (300mm/35mm equiv.)
F No: f7.1
Shutter Speed: 1/250
Exposure Compensation: 0 EV
Image Stabilisation: On