The Barnacle Goose is a particularly social bird, calling almost constantly, perhaps to reinforce its highly gregarious nature, regardless of the time of year. The huge flocks into which they gather on the wintering grounds provide one of the great true wildlife spectacles that can be seen in the UK.
On the Solway they are present from mid-September until late May, with some birds beginning their northward migration in mid-April. They are generally monogomous and pair for life. An annual divorce rate of 2% was found in Solway birds due perhaps to partners losing contact with one another during migration.
Appearance
The Barnacle Goose is a medium sized goose with a fairly long neck and short, small bill. Larger than the Brent Goose and smaller than the Greater Canada Goose, its white or creamy-coloured face and forehead and crisp black and white appearance immediately distinguishes it from these other species of black Branta geese.
Population
The population has gone from strength to strength since the 1940's when only 300 birds were present on the Solway. This is due to the implementation of hunting bans throughout the flyway and the introduction of reserves (such as WWT Caerlaverock in 1970) or management schemes in 90% of the areas used by the geese for feeding or breeding. Roost sites have also received protection through SPA designation.
WWT has monitored the population closely since the 1960s and in collaboration with the Norwegians has ringed over 10,000 individuals. The ecology of these geese is therefore well known, although there are still some major questions to be answered. The population currently appears to be stable at present at just over 25,000 individuals.
Whilst breeding so far north in the Arctic may reduce competition for nesting areas and food, it also has the associated risk of being difficult to reach, and the often adverse and unpredictable weather conditions.
Threats
Upon arrival at breeding sites in early June, low temperatures and prolonged snow cover can delay egg-laying. In some years, poor grass growth and predation can result in less than 5% young being produced by the population. In most years only a small percentage will attempt to breed and many birds often remain unpaired for many years. In "good years" though up to 25% of the autumn population may be comprised of juveniles (young birds hatched in the summer).
The Arctic Fox, alongside Glaucous Gulls and Skuas, is one of the main predators, and its numbers fluctuating between years. They will often scavenge the young which injure themselves during the jump from the cliff nesting sites or swim to the islands to eat the eggs and young. Changes in sea ice conditions - unpredictable under global warming - can also mean that Polar Bears will feast on the colonies if seals are unavailable.
Habitat
In autumn and winter the habitats used are mainly the open saltmarsh and intensive pastures found along the Inner Solway coast. At WWT Caerlaverock the swards on the fields are cut, grazed and reseeded to maintain optimal conditions for the geese, with the saltmarsh grazed to remove rank growth. They rest and roost on the mud and sandbanks of the estuary.
During the two week migration through Norway they feed on grazed meadows and improved pastures as well as the saltmarsh fringing the many thousands of islands. On the breeding grounds, Barnacle Geese feed on a variety of wetland vegetation such as the grass, horsetail and moss found on the wet meadows fringing the many pools. The broods of birds breeding on islands will often have to swim a couple of kilometers to find suitable areas of food. In the Arctic they also feed on the drier swards typical of the tundra, taking mosses and liverworts. Here, their droppings can provide a source of food for Reindeer.
Satellite tracking
Click here to follow the geese on their migration
http://www.wwt.org.uk/our-work/wetland-wildlife/barnacle-geese