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VOSLAMBER B, JEUGD H VAN DER & KOFFIJBERG K (2007) Numbers, trends and distribution of breeding goose populations in the Netherlands. LIMOSA 80 (1): 1-17.

In the past two decades, breeding geese have expanded rapidly in The Netherlands. A national survey in 2005 revealed a total number of nearly 40,000 breeding pairs and 155,500 individuals including non-breeders (but not moulting Greylag Geese from abroad; Tab. 1, Fig. 1). The majority are Greylag Geese Anser anser (25,000 pairs, 100,000 individuals). Since its re-introduction in 1961 (after extinction in the early 20th century), the population has shown an annual increase of 20% (Fig. 4). Today, it is distributed over major parts of the country (Fig. 5). Meanwhile, also Feral Geese A. anser f. domestica have started to breed, but in much smaller numbers (3700- 5000 pairs) and with a lower rate of increase, due to generally poor breeding success. Counts in winter suggest an overall population of 15,000 birds. Barnacle Goose Branta leucopsis (6000 pairs) has shown an annual increase of 46% since the first breeding attempt in 1982 (Fig. 12), the highest growth rate observed in any goose population. Core breeding areas are situated in embanked estuaries in the northern part of the Delta area (Fig. 13), where also large flocks gather to moult in summer. At least some small populations originate from escaped or abandoned breeding pairs from parks, but the origin of the large Delta population is not entirely clear. The increase in the Netherlands follows westward expansion of the Russian breeding areas and establishment of a large breeding population in the Baltic. Recoveries of marked individuals have demonstrated exchange of birds between the Russian, Baltic and North Sea populations, and we therefore consider Barnacle Geese a native breeding bird in The Nether - lands. The introduced Greater Canada Goose B. cana densis is expanding rapidly from its core breeding areas in the SW Netherlands (Fig. 8,9). Sightings of ringed birds have revealed movements between the Netherlands and western Germany and northern Belgium, including moult movements (Fig. 11). Hutchins' Canada Goose B. hutchinsii is an introduced species restricted to a few breeding sites. The same applies to Greater-White fronted Geese, assumed to originate mainly from live decoys abandoned in the late 1980s. Numbers are still quite low (Fig. 2) and breeding success seems poor. Introduced Bar-headed Goose increased by 20% annually since 1972 but today, numbers seem to be fairly stable at 100 breeding pairs (350 individuals). Other species listed in Table 1 are considered introduced too, but breeding has not been proven yet or numbers are below 10 pairs. The increase in breeding goose populations in the Netherlands coincides with a general increase in many NW-European countries and a southward expansion of the arctic breeding areas of some species, notably Barnacle Goose. Changes in agricultural practice that have improved feeding conditions, along with a lower hunting pressure, are considered the main driving forces behind the growing goose numbers, both in arctic and temperate breeding areas (Fig. 14). Similar developments have been observed in Nearctic goose populations. Additionally, breeding geese in The Netherlands have benefited from the creation of wetlands and recent embankments. Especially Greylag Goose has expanded rapidly in small wetlands found scattered through the country, even in park-like suburban areas. Often, food is limited in such areas, but due to the proximity to attractive food resources in the surrounding agricultural areas, geese have found a perfect breeding habitat. Breeding of Barnacle Geese in the Delta area, SW-Netherlands, was facilitated by the embankment of the Krammer-Volkerak in 1987 and the grazing of large nature reserves with livestock. Here, islands provide safe breeding places and families and non-breeding flocks feed in the grazed areas.
Population models using demographic parameters and amount of available habitat predict that the increase will continue in the years to come. So far, only some long-established Greylag Goose populations show signs of saturation, but as unoccupied breeding habitat is still available in several parts of the country, the population might increase further to a level of perhaps 60,000- 90,000 pairs, if predation, competition with other species and population control measures are not taken into account. Greater Canada Goose might grow to 40-60,000 pairs, at the expense of Greylag Goose that would be expected to reach at most 38,000 pairs in this scenario, and become the second-abundant breeding goose species. Barnacle Geese might be less successful due to their coloniality and dependence on islands for safe breeding. Many colonies in the Baltic have already suffered high predation rates by Red Fox Vulpes vulpes, a phenomenon which might also constrain further population expansion in The Netherlands, especially when fox numbers in the core breeding areas are allowed to increase.

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limosa 80.1 2007
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