An increase in the number of swans arriving at a nature reserve in Gloucestershire could be a sign that the county will have a white Christmas.
More than 150 Bewick's swans have flown from Russia to the Wildfowl and Wetlands Trust (WWT) in Slimbridge.
Julia Newth, from the WWT, said: "We saw a similar pattern in 2004 when we did have a white Christmas. This year we have even more birds arriving."
More swans are expected, with freezing temperatures predicted next week.
Ms Newth continued: "Maybe it's just an old wives' tale, but it certainly seemed an accurate prediction when the last white Christmas occurred in 2004.
"The weather really does play a part in the timing of migration, so perhaps the Bewick's sense the colder weather ahead?"
In 2004, 53 Bewick's swans arrived at Slimbridge during the first 17 days of December. This year the number has increased, with 74 flying in over the past week.