This is how the release is done - Svenska Jägareförbundet

This is how the release is done

The Lesser White-fronted Goose Project releases geese each year as a supplementation of the wild Swedish population. The activity started already in 1981, but releases were stopped in 1999. After the moratorium, releases were resumed in 2010, using new stock and new methods.

This film was produced in 2012 and gives a clear picture of the way releases were made.

The purpose of the releases were twofold; to reinforce the Swedish population and to deliberately change the traditional migration route, teaching the birds to fly in a more South-Westerly direction. This flyway was regarded safer compared to the one known to used by birds breeding in Sweden at that time, which was a route through Eastern Europe and included wintering in the South-Eastern corner of Europe or South-Western Asia.

A young Lesser White-fronted Goose ready for release in a temporary enclosure in the Swedish mountainous area. The bird is carrying a colour ring with a sign on the left leg and a metal ring on the right leg to facilitate identification in the field. Photo: Lesser White-fronted Goose project.

To succeed with the change of migration route, Barnacle Geese were used as foster parents to the Lesser White-fronted goslings. The Barnacle Geese which were used were breeding in southern Sweden and it was known that they used to spend the winter in The Netherlands. The foster parents and the young were transported to the breeding area in Northern Sweden, where they were released together. In the autumn, they all took off for The Netherlands as planned and the young geese learned the route. Geese normally return to the place where they learned to fly. For that reason the Lesser White-fronted Geese returned to the North of Sweden, whereas the Barnacle Geese due to their site tenacity stopped in Southern Sweden. This method worked well and slowly but steadily the flyway between the breeding area in the Northern Sweden and The Netherlands was used more frequently. For reasons described in other chapters, the releases were stopped in 1999 by the project.

In 2010 the project tentatively decided to resume the releases of Lesser White-fronted Geese. Different reasons led to this choice. In contrast to previous conditions, new stock of birds bred in captivity was available, and this time the releases were made without using foster parents. In spite of the fact that no releases had been made during1999-2010, a slow increase in population size had been observed. In the near future, different release methods will be tested to establish early bonds between the released birds and wild conspecifics, which have already used the flyway to The Netherlands. It is a great challenge for the people involved to develop and refine this method, which has never been tried before.

To find out if yearlings are most suited to establish links with the older birds prior to the migration and eventually return in the following spring, birds from both categories are released. Early during the breeding season, nest sites are identified and once they have been found, a tentative location for one or more enclosures are selected. But the erection of the enclosure has to wait some time to avoid any disturbances. To release young birds in the proximity of moulting geese is an alternative method also being tested.

The release pen is surrounded by a low electric fence to prevent predators entering. On this occasion a red fox was seen approaching the fence, where, however, it turned back.

The staff returns to the sites where breeding pairs have been observed earlier and try to find a couple with goslings. This is normally a time-consuming task as wild geese with young tend to hide unobtrusively due to their shyness. Close to these sites, the release pens are erected in a carefully selected position. It is important that the birds bred in captivity are offered ample time to get acquainted with new elements like water bodies and natural boreal vegetation. A release pen is simple, has the size of about 50-100 m², is covered by a roof and is easy to dismantle after the release. The roof is needed to prevent raptors from attacking the birds and the surrounding electric fence protects the geese from ground living predators.

Building of the release pen

Topmost to the left you can see how the erection of the release pen begins and to the right the pen is ready. The lower picture shows geese inside the pen (left) and how the birds are released into the wild (right). Photo: Lesser White-fronted Goose project and Emilia Westerberg.

The birds are transported from the breeding complex to Northern Sweden in boxes. Upon arrival they are released inside the pen to adapt to the new environment in the mountainous heathland. The change for a captive-bred bird is dramatic. But everyone involved in the project is surprised at the relaxation shown by the inexperienced birds. After the long journey they normally start preening at once and then rest with other birds in the enclosure. After a short period they start exploring the new environment and it does not take long before they begin feeding on the plants. The geese are left in the pen for at least 24 hours before being released. During this period the birds are carefully inspected at a distance to make sure that neither predators nor other problems occur.

The release

The actual release takes place when the weather is favourable. To see the captive-bred birds in the wild is a great experience for everyone involved. The event, however, is normally short in duration, since the birds usually disappear quickly into the vegetation, where they are difficult to observe.

After the release the staff stay for a few days, hoping to be able to study the behaviour of the birds and to identify possible threats or problems which might be avoided in future releases. All birds are given a metal ring from the Swedish Bird Ringing Centre and a colour ring with an engraved letter or figure to make identification in the wild possible. Through this marking it will be possible to follow the life story of the released birds.

The early great challenge for the birds is to reach the first stop-over site during the autumn migration. The project staff is, every year, waiting in anticipation to find out which birds have been able to make the journey to the coast of Northern Sweden. In the area of Hudiksvall, the birds tend to arrive by late August. Later local voluntaries visit different stop-over sites more to the south to count birds and report on identified rings.

  • Dela med e-mail
  • Skriv ut
2014-02-18 2014-02-25