AT OXFORD University’s Natural History Museum, birds of a feather definitely flock together.

Since 1947, the swifts which nest in the tower of the University museum in Parks Road have been unwitting subjects of research.

This makes it one of the longest running studies of any species of bird.

Researcher Dr Sandra Bouwhuis, 31, has dedicated the past two months of her life to the swifts in the tower.

She said: “Swifts are struggling in the UK and studying them for a really long time enables us to find out why they are struggling.

“Numbers have been going down over the past couple of years. Last year there were 50 nests in the tower, but this year there are only 37.”

Possible reasons for the decline in swifts could include falling immigration rates or birds dying before they manage to breed.

David Lack, from the Department of Zoology, began the Oxford Swift Research Project in May 1947 when he noticed the swifts nesting in the tower’s ventilation shafts.

He then found a church in Switzerland where they had put platforms for the swifts to make nests, and brought the idea to Oxford.

The swifts, which have a relatively long life-span of up to six years, return to the tower year after year to nest.

Researchers Roy Overall and George Candelin had run the project, but retired last autumn.

Dr Bouwhuis took over the research at the beginning of this summer. She spends her days weighing the chicks then giving them unique identification rings. She also checks the population levels of the adult birds and monitors which ones regularly return to the tower using a database.

She said: “I spend about seven hours in the tower a day. We only use infrared lights so it is very dark.

“I have no idea why they come to the tower. They have been coming for as long as anyone can remember.”

The museum operates a webcam to see the swifts from April to August, at http://www.oum.ox.ac.uk/ swifts.htm