Welcome back to Islay Seasonwatch which this week is continuing our look at the geese species which can be discovered on Islay. This week we are focusing on the Greenland Barnacle Goose (Branta leucopsis) a winter visitor to Islay.
Population and Distribution: The breeding populations of Barnacle Geese are confined to four areas: coastal north east Greenland, northern Siberia, Svalbard and southern Sweden. The Greenland population winters in western Scotland (primarily Islay) and Ireland. Svalbard birds winter on the Solway Firth. Swedish and Siberian populations winter in the Netherlands and Germany. The Greenland birds leave their breeding grounds from late August to mid September and migrate via Iceland arriving on Islay from late September into October. They return again to Greenland in April stopping off in Iceland again on their northward migration arriving in Greenland in May. The Barnacle Goose is an internationally important Species of Conservation Concern listed as amber. Information on the Barnacle Goose and its conservation and population status is provided by the Wildfowl and Wetlands Trust. Current monitoring of this population is undertaken by the Scottish Natural Heritage (SNH) Greenland Goose Census (Argyll) and the International Greenland Barnacle Goose Census, Spring 2008. 'In March 2008 Barnacle Geese numbers were recorded as 44,961 on Islay.' (SNH) Continue reading.....
Migration and breeding: The Barnacle geese pair for life. In the breeding season the male and females display to maintain their bond by standing alongside each other facing opposite directions pumping their heads up and down whilst wing flicking and barking loudly. Nesting is mainly colonial with nests as close as 2m apart reusing previous yearâ€™s secure nest sites. The male guards his mate and nest. Inaccessible nest sites on cliff ledges or rocky islands shared with other sea birds are chosen to help guard against predators such as arctic fox. There is little material for nest building so the female may add droppings to create a low mound around the scrape she has excavated. The female incubates the eggs for up to 25 days and when hatched the family move to their rearing areas. To get to these areas the goslings can face a drop of 60m from their cliff nest!. Those who nested on islands may have to swim some 2km to reach the mainland rearing grounds. They are very vulnerable to predation by gulls and foxes at this time before they are reunited with their parents. Families group together in flocks at the rearing areas where their young fledge at 45 days. The family group stay together for the winter migration to Scotland and separate at the Greenland breeding grounds the following spring. They start breeding at 2-3 years of age.
Behaviour: Early nesting is essential for the Barnacle Geese allowing time for the goslings to grow quickly feeding on the highly nutritious flush of summer vegetation in the arctic tundra. The summer diet includes the buds of purple saxifrage and willow, horsetail, mosses and liverworts. They feed by rotating around a number of areas to ensure a continuous supply of nutritious shoots. Feeding is mainly by day but in the continuous summer daylight of the arctic the birds can forage throughout the night. Their vegetable diet comprises of leaves and stems of grasses, herbs, stolons, and seeds of saltmarsh and cultivated plants. Their short bill is suited to grazing of short vegetation and is also used for probing and pulling up vegetation and stripping seeds from stalks. After the autumn migration when the birds arrive on Islay natural seeds and stubble grain provide a rich source of energy to restore their condition before the winter sets in. When these are exhausted they switch to stems of white clover, rye grasses, timothy (botany) and stubble of spring grown cereals. During midwinter and early spring they prefer feeding on the more improved grass swards. On moonlight nights they feed at night as there is enough light to be alerted to any potential predators.
Identification: Barnacle geese are distinguished from other black geese such as the Canada Goose and smaller Brent by its creamy white face contrasting boldly with the black hind crown, neck and breast. Both male and female are similar appearance and there is no seasonal change in their plumage. They are highly gregarious, often noisy and quarrelsome, throughout the year with thousands in winter flocks as seen on Islay. Flocks are noisy with a shrill barking call. As they fly overhead you can hear a distinctive creaking sound with their wing beat.
Barnacle Geese on Islay: From late September thousands of Barnacle Geese arriving from Greenland congregate on the tidal mudflats at the head of Loch Gruinart and Loch Indaal which are also their main roosting sites. After a while they disperse across Islay for the winter seeking feed on pastures and stubbles. Good areas to see them in addition to the Loch Grunairt RSPB Reserve are around Loch Gorm, Bridgend and Laggan. Barnacle Geese use a wide range of habitats which Islay provides including natural and semi-natural grassland, agricultural grasslands and arable stubbles, saltmarsh and dune grasslands. They roost on tidal mudflats, offshore uninhabited islands, beaches and occasionally inland. The ultimate geese spectacle on Islay is at dusk when the skeins of geese come into roost at the head of Loch Gruinart and Loch Indaal from their daytime feeding areas across the island.
If you have not yet witnessed this then it certainly justifies a visit to Islay this winter! Enjoy your goose watching,
Teresa Morris, Islay Wildscapes.