The breeding population in Sweden - Svenska Jägareförbundet

The breeding population in Sweden

Today, breeding Lesser White-fronted Geese are confined to a very restricted area in Swedish Lapland. In older times, the species was a rather common bird in the country and was found in the main parts of the mountainous area. The captive-bred birds have been released within the area that still holds a breeding population. Probably the species has disappeared from the remaining parts of the country.

Number of breeding Lesser White-fronted Geese in Fennoscandia 1980-2011

The estimated the number of breeding pairs in Fennoscandia around 1980 was about 75. Since then, the number has decreased and during the1990´s, the species probably disappeared from Finland. In Sweden, however, the number of breeding pairs shows a slow increase due to the actions taken.

When release of birds started in 1981, breeding Lesser White-fronted Geese still existed in the same area. It is likely that released birds and birds from the local population mixed and coupled. The population of today is therefore a mixture of birds from the original population and a number of released birds. Consequently it should be regarded as a supplemented population according to IUCN definitions.

The Swedish population of Lesser White-fronted Geese is the only global population which has not been decreasing during the last decade. In spite of the fact that the release of young birds was halted in 1999, a slow increase in numbers has been recorded. When the release of captive-bred birds, this time of Russian origin, was resumed in 2010, the total breeding population was estimated to 120-130 individuals and the breeding number of pairs was thought to be15-20. During 2012 and 2013, however, a significant decrease in population size took place, probably due to heavy predation during breeding and moult.

The breeding success varies significantly from one year to another. The most likely explanation is the fluctuating number of predators and consequently a variation in predation pressure on goslings and eggs. The pattern of great changes in breeding success is typical for ground breeding birds in the mountainous areas such as ptarmigans, ducks and waders. The number of predators found in this region is by large determined by the existence of small rodents like lemmings and field mice. During years when small rodents are abundant, the predators are favoured, but at the same time they exert less pressure on the birds due to ample access to food. Foxes and other predators are simply occupied with eating lemmings and field mice.

Number of fledged young in the Swedish population 1986-2011

The number of young in the wild population varies significantly from one year to another, but the general trend indicates a growing number of fledged young and this increase has accelerated during the 2000´s. The blue arrow in the diagram shows when the release for supplementation was interrupted in 1999.

Lesser White-fronted Geese are difficult to survey during the breeding period as they are very shy and favour habitats without reach of field personnel, such as delta areas covered by willows. Therefore, the estimation of the population size is primarily based on counts made on the staging grounds during migration.

Typical breeding site for Lesser White-fronted Geese in Sweden, showing a delta area and impenetrable willow habitats bordering a lake and with ample opportunities for grazing along the shoreline. In the middle of the picture, standing on a sandbar, a Lesser White-fronted Goose family can be seen. Photo: Lesser White-fronted Goose project 2011.

Breeding sites

Lesser White-fronted Geese in the breeding area are extremely sensitive to human disturbance. Several observations indicate that once the female has been scared from the nest by a humans, the nest may be abandoned. A disturbance may also cause exposure of nest and young to predators. Therefore it is of utmost importance that human disturbance is avoided as much as possible. Activities like sport fishing, which may result in fishermen moving along lakes and rivers used by geese, are particularly serious. Preferably, breeding areas for Lesser White-fronted Geese therefore should be protected from such activities. When the project personnel visit the breeding area, a number of restrictions are applied to minimize disturbance.

Lesser White-fronted Geese normally arrive at their breeding sites by the end of May, depending upon the local snow and ice situation. As soon as the snow has disappeared, the geese start to occupy their territories. A backlash in weather condition may force the geese to leave the high altitudes and temporarily go back to more suitable sites. Probably such sites are of utmost importance during late springs and deterioration of such key sites may have great consequences for the breeding success during such years.

A female Lesser White-fronted Goose with goslings trying to hide in the shoreline vegetation. It is extremely unusual to have such a nice view of a breeding Lesser White-fronted Geese family. This successful breeding took place in 2011.

Moulting sites

During years when the geese desist from breeding or when breeding attempt is interrupted in an early phase, birds tend to gather in flocks. For a while these flocks move around in the breeding area, but then they disappear to moult. The moulting site is very important since the birds are unable to fly and therefore vulnerable to attacks by predators. Probably the choice of moulting site therefore includes a calculation of the risk for being attacked and the chances to hide. Lesser White-fronted Geese are known for making extensive movements to suitable moulting sites.

The Swedish population of Lesser White-fronted Goose is still so small that loss of individuals or poor breeding success may threaten their long-term survival. For that reason the Lesser White-fronted Goose project will continue to release bird as supplementation and to address the issue of high mortality in the breeding and moulting areas. By reducing human disturbances and by red fox hunting in the breeding area, the risk for eggs and young being taken will be lowered.

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2014-02-17 2014-02-25