STAFF and visitors at the Wildfowl and Wetlands Trust in Slimbridge are confident the 300 Bewick's swans that spend their winters at the reserve are on their way.

Contrary to some reports, the late arrival of the swans is not unusual.

Although the first birds fly in on or near October 21, arrivals in previous years have been as late as the second week in November.

Julia Newth, a research officer at the trust, said: "There's still time for them to break the record for late arrival, but we are certainly not in a position where Bewick's swans are no longer coming to Slimbridge.

"I have heard of around 450 Bewick's in north-west Holland, so this is a clear signal that the mass migration is well under way."

She said wind direction and temperature were the primary factors influencing the timing of migration. The past few weeks have seen mild weather and predominantly westerly winds, which seem to be the reason for the delay.

Bewick's swans need a north-easterly wind to migrate, so the forecast of easterly winds and low temperatures will encourage the birds to continue their journey to the UK.

Slimbridge staff hope to see the first Bewick's arriving within days, when they will become a major attraction to the many visitors.

Dr Baz Hughes, the trust's head of species conservation, said: "Clearly climate change is an issue, as short-stopping due to warmer winters and a decline in total population size has affected Bewick's swan numbers and distribution in recent years. But numbers wintering at Slimbridge have remained stable over the past five years."