International Census of Greenland Barnacle Geese
In the 1950s, it appeared that the Barnacle Goose Branta leucopsis had decreased as a wintering bird in Scotland (Boyd 1968). This led to a successful attempt to have the species excluded from the list of birds that could be shot under the Protection of Birds Act, 1954, and the exclusion became affective as of 1 January 1955. In November 1955, an Order was issued that allowed geese to be shot in December and January on islands in the counties of ‘…Argyll, Inverness and Ross & Cromarty, and which lie off the mainland of said counties and to the west of longitude 5 degrees west…’. This decision led to the urgent need to obtain detailed information about numbers of Barnacle Geese in different parts of Scotland and follow the change in the population over the years.
Because the Barnacle Geese were widely dispersed and occurred in many areas that were difficult to access or were uninhabited and too remote for visiting on the ground, it was realised that the best way to survey these sites was from the air. Following some exercises in aerial observation techniques in 1956 the first survey of the Hebrides was made in 1957. A second aerial survey covering sites in Ireland as well as the rest of Scotland was carried out in 1959 as part of an international assessment of the entire population (Boyd 1968). Further surveys were undertaken in 1961, 1962, 1965 and 1968.
The census has taken place approximately every five years; however, there is a likelihood that the frequency will change to every three years, with the latest censuses taking place in 2018, followed by 2020.
Aim and method
The aim of the census is to assess the population size of the Greenland Barnacle Goose and identify important wintering sites.
The census takes place in late March and covers sites in northern and western Scotland, and along the north and western coast of Ireland. It involves a combination of aerial and ground counts: the aerial surveys cover the remote areas whilst the ground counts cover several key sites.
Aerial surveys are made using a high-winged aircraft flying 150-200m above the sea. Counts are made as the geese are flushed by the approaching plane. One observer makes a visual count whilst a second attempts to take a photograph. If the photographs are of good enough quality they are used to derive a count. The visual count is used if the photograph quality was not good enough or a photo of the entire flock was not possible.
Ground counts are undertaken at key sites where access is possible and are used to derive census totals for these sites as this method provides the most accurate assessment of large flocks.
The International Census of Greenland Barnacle Geese take place every five years.
Results from the International Census of Greenland Barnacle Geese can be downloaded from our ‘Reports and newsletter‘ page. Summary results are also presented on the species account page for the Greenland Barnacle Goose.
The next census is not due to take place until either 2023 or 2025 (depending on monitoring requirements).
Due to the remoteness of wintering areas for this population, and the methods employed to count them, there are few opportunities for helping with this census. However, monitoring of abundance and productivity in years between international censuses is also very valuable, and we would welcome interest from anyone able to help with this.
For more information, please contact WWT’s GSMP Team.
The census in Scotland is currently funded by NatureScot, and in Ireland by the National Parks and Wildlife Service.
Boyd, H. 1968. Barnacle Geese in the west of Scotland, 1957-67. Wildfowl 19: 96-107.