The Gamblers are back!
Dropping temperatures and south-easterly winds have seen a continuous trickle of new swans reaching our reserves in recent days, culminating in 40 birds at the Slimbridge feed this morning.
We were thrilled by the arrival of firm favourites, Croupier and Dealer at the end of last week. Both are members of the long-standing Gambling Dynasty, established in 1969 when Croupier’s grandparents, Nijinsky and Caroline, were first recorded at Slimbridge by the Scott family.
Croupier’s mother, Casino, was the longest-lived wild Bewick’s swan on record for many years, reaching a grand old 27 years in 1998. Her record has since been surpassed by Brimstone (29 years) and Winterling (28 years). During her long reign, Casino and mate Punter brought 34 cygnets back to Slimbridge from arctic Russia, making them a highly productive family.
These fertile genes have obviously been passed to Croupier, who with Dealer has produced 26 cygnets over 17 years. Although they are without cygnets this winter, our studies have found that breeding success usually increases with the number of years that a pair has been together.
During their years together, they’re likely to have learned where the best breeding sites are on the tundra, and their co-operation in defending that territory and their off-spring is likely to have increased. They are in fact a very dominant pair and throughout winter are often seen taking the best spot for food in front of the Peng Observatory at the 4pm feed! We have found that dominance rank may also increase with the length of partnership. Though this suggests that cooperation between the pairs during aggressive encounters may improve over time, the influence of this on breeding success remains unclear. In fact, a pair’s increase in dominance rank may be a direct result of their improved breeding success, as families are usually dominant over pairs without cygnets and single birds during the winter.
Croupier is here for his 24th winter, which illustrates the remarkable loyalties Bewick’s swans have to their wintering sites. This cocktail of reproductive success and site fidelity has meant that there are many Gamblers returning each winter from different generations. Croupier’s offspring from 2009, Wager, has also flown in with mate Zonk for another winter at Slimbridge. It is likely that members of the Gambling Dynasty will be here for many years to come....
