DON'T be surprised if you see groups of people racing around the island with telescopes and binoculars next weekend.

They will be taking part in the 2007 Singapore Bird Race organised by the Nature Society's Bird Group.

The race is into its 24th year and is a fixture in the society's calendar of activities.

Birdwatchers will make their way from forests to coastal sites to parks in a bid to spot as many different species as possible.

'We even go to cemeteries at night because they are the best place to spot owls,' says Mr Ashley Ng, 38, a property agent who will be taking part in the race for the third time.

The race kicks off on Saturday at 4.30pm at Dairy Farm Adventure Centre, an outdoor activities camp.

About 64 participants are expected to compete in two categories: Those in the Advanced category have 24 hours for their bird-sighting while those in the Novice group have 20.

Each group, which comprises either three or four members, records its sightings on a log sheet. Members note the common name of the bird, where it is sighted and the time of the sighting.

All members must have seen the bird before it can be recorded as a sighting. The log sheets are later checked by two arbitrators who are experienced in birdwatching.

Mr Morten Strange, 55, an arbitrator in this year's race and co-owner of nature bookstore Nature's Niche at the Botanic Gardens, says the race attracts all sorts.

'The old-timers take the race more seriously while novices tend to take things easy and treat it as a day to visit parks. That's fine. It's important that they have fun at the end of the day,' he says.

The Danish author of four books about birds has been involved with the society since 1986 and is now a permanent resident.

Engineer Lim Kim Seng, 47, who has written two books about birds and has won at least six races, describes the hunt as 'a marathon'.

'It's important to plan your route. You don't want to go around Singapore three times. You have to plan it such that you get to see the maximum number of species with the least amount of travelling,' he says.

The difference between first and second place often boils down to just one species. The top three teams in each category get trophies. A Century Shield is awarded to the team that manages to record 100 species of birds first.

Winning teams in the Advanced category usually spot between 130 and 145 bird species.

The time limit adds to the excitement with most teams getting by on just an hour or two of sleep during the race.

One year, a team was accidentally locked in a sewage treatment plant in Serangoon. 'They had to call the contractor to let them out but they lost a lot of time in the process,' says Mr Lim.

But some participants have more than birds on their mind.

'Some teams go around thinking of places to eat rather than places to look for birds,' says Mr Ng.

'It's a race where people have fun together. It isn't so much about winning. It's about sharing the fun of birdwatching.'