Signs of pre-migratory behaviour
As the days become noticeably longer, the swans at Slimbridge are showing strong signs that they are about to embark on their spring migration back to arctic Russia.
Their days are now spent stretching their wings during ‘practice flights’ around the reserve in large flocks of up to 80 birds. In between flying sessions, they are feeding and loafing around. Like many long-distance migrants breeding at high latitudes, day length is the main trigger for migration with precise dates of departure also heavily influenced by weather conditions. Clear skies and a south-westerly breeze are their favoured conditions for spring migration.
We grasped one of our last chances to catch some swans this week with the aim of marking newly caught birds with coded leg-rings to enable us to track them throughout the year, and to X-ray swans to assess levels of illegal shooting. Sadly, our research has shown that despite international protection, Bewick’s are still being illegally shot at, with 23% of live birds caught between 2000 and 2008 found to carry embedded shotgun pellets in their bodies. We are currently working with hunting groups across Europe to address this problem. Unfortunately our hopes of catching more swans to ring and X-ray were dashed as the latest bout of mild weather had seemingly made them uninterested in the food in the swan-pipe trap so we will have to try again another time!
A total of 195 birds were recorded on the reserve today and they will certainly not be here for much longer...........
