Posted by: georginaferry | June 14, 2010

Into the dark tower

On Friday  I was granted the greatest privilege of my residency so far. Roy Overall, who has been documenting the swifts that breed in the Museum tower since the 1960s, took me up with him. Normally he counts eggs and young on a Saturday when the Museum is quiet, but this week the wildlife cameraman Dr Manuel Hinge has been filming some of the first hatchlings, so he was making an extra visit.

He unlocked a door from the gallery and we climbed more than 50 steps up a spiral stone staircase, to find ourselves in a large, light room with a window looking out onto the casts of dinosaur footprints in the Museum lawn far below. (I recognised the view from an episode of Inspector Morse in which one of the characters had threatened to jump.) Here we paused to catch our breath while Roy began to tell me more about the amazing birds that live in the tower.

I knew that they wintered in Africa. What I did not realise is that once they leave Oxford at the end of August, they will not land again until they come back next April or May. They  do everything – feeding, sleeping, mating – on the wing. That makes them very hard to study. Roy rings all the young that are born in the Museum tower, but few of the ringed birds return, and we can only speculate about the fate of those that don’t.

We then climbed a second spiral staircase into the roof space itself. ‘Give me your hand’, said Roy as I emerged blinded from the brightly lit tower room to the gloom above. ‘The swifts don’t like light’, explained Roy. With the help of a few dim red lamps my eyes soon adjusted. Each of the ventilation holes in the roof has been fitted with a double nest box, with a removable glass wall on the inside covered by a small fabric curtain.

Roy lifted the curtain aside, and there was a swift on her nest. She seemed much smaller than I expected with her wings folded behind her. She had large, dark eyes and a beak so tiny it seemed barely useful. Indeed, swifts don’t need their beaks to catch prey as they scoop insects into their wide gape as they fly. But they do use them to build their perfunctory little nests, made of any material they can collect on the wing – feathers or the husks of tree seeds for example – stuck together with saliva. And they preen their partners while in the nest box together – though Roy tells me one of the many mysteries about swifts is how they maintain their feathers for the nine months of the year they spend on the wing.

In a couple of the boxes the eggs had already hatched. The parent birds take turns to brood the blind, featherless young while the other goes off to fill the pouch under its chin with food and bring it back to feed them. Manuel had his cameras focused on two of these boxes, documenting the behaviour of the parents and young. The Oxford swifts have not been filmed in such detail since 1976, when Derek Bromhall made his film Devil Birds. A high-quality infrared camera makes it possible to film the birds on the nest without disturbing them.

By Roy’s count for this weekend, there are 51 nests occupied, 25 young hatched and 19 eggs visible. This time last year there were 68 nests. Numbers go up and down from year to year, but the survival of swifts in Britain is a cause for anxiety: they are on the RSPB’s amber list. The main problem is the scarcity of suitable nesting sites as old buildings are insulated and new ones built without any of the inviting holes under the eaves that attract prospecting swifts.

By 2002 when he and Andrew Lack wrote their booklet The Museum Swifts, Roy calculated that he had climbed the tower over 1000 times – and he has done it weekly during the breeding season every year since. Thanks to his dedication – all his work with the swifts is voluntary –  the Museum’s swifts have been documented for longer than any other colony in the world, ever since the ornithologist David Lack began his studies in 1947.

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