LONDONERS are being asked to keep a watch out for one of the capital’s most iconic birds.

The small fast-moving swift can been seen circling overhead in the evenings, usually in pairs or small groups, between May and early September.

But their numbers have halved between 1994 and 2007, and one of the problems is the lack of nesting sites.

Now the RSPB has teamed up with London Mayor Boris Johnson to find out where London’s swifts are and to provide extra nesting places.

Already the Met Police is installing 20 swift nest boxes on its buildings and Mr Johnson is looking to find more places.

Meanwhile the RSPB is asking people to fill in a survey if they see swifts in their area, at