M.J.J.E. Loonen1, C. Zöckler2, B. Ebbinge3
1University of Groningen, Arctic Centre
Since the 1970's, many goose populations have gone through an impressive increase in size. In the last decade, the global goose population almost doubled from 12.5 million birds (Madsen et al. 1996) to a current total of 21.4 million (Wetlands International, 2006). Most of these population increases have coincided with large range extensions within the Arctic, but also into temperate regions. Changing agricultural practices have resulted in new, abundant and high quality food sources for wintering geese (Van Eerden et al. 1996, Fox et al. 2005). This has occurred while hunting pressure has decreased through improved legislative protection, a decline in the ratio of hunters per 1000 geese and the establishment of refuge areas.
Goose populations are intensively monitored. Population estimates are based on simultaneous counts in wintering areas, often supplemented with data on nesting densities, ring recoveries and sightings of colour-marked individuals. Wetlands International (www.wetlands.org) is the organization which compiles all population data with help of its Goose Specialist Group (www.geese.nl/gsg).
Geese are common in many parts of the Arctic. All Arctic populations are migratory and their annual migration routes and stop over places involve a large proportion of the Northern Hemisphere, including almost all countries in North America, Europe and North, Central and East Asia. Goose populations have a direct and significant influence on Arctic ecosystems as exemplified by recent impacts on tundra vegetation due to expanding populations and via the role played by goslings and eggs as a food source for predators in the Arctic.
The most recent review of water bird populations (Wetlands International, 2006) considers several Arctic goose populations as declining. The declines are widely distributed across all flyways indicating a possible link to phenomena acting on a circumpolar scale. Figure E1 depicts the overall distribution of trends within Arctic goose populations. For nine percent of the population, there is no or insufficient information on trends. Thirty-six percent of the populations are still increasing, thirty-two percent are stable, but twenty-three percent are declining – a proportion slightly higher than compared with ten years ago (Madsen et al. 1996).
Fox, A.D., Madsen, J., Boyd, H., Kuijken, E., Norris, D.W., Tombre, I.M., and Stroud, D.A. (2005) Effects of agricultural change on abundance, fitness components and distribution of two arctic-nesting goose populations. Glob. Change Biol., 11: 881–893.
Madsen, J., Reed, A., and Andre, A.(1996) Status and trends of geese (Branta and Anser sp.) in the world: Review, updating and evaluation. Gibier Faune Sauvage, Game Wildlife., 13: 337–353.
Van Eerden, M.R., Zijlstra, M., and Van Roomen, M. (1996) The response of Anatidae to changes in agricultural practice: long term shifts in the carrying capacity for wintering waterfowl. Gibier Faune Sauvage, Game Wildlife, 13: 681–706.
Wetlands International (2006) Waterbirds Population Estimates - Fourth edition.
Fox, A.D., Stroud, D.A., Walsh, A.J., Wilson, H.J., Norris, D.W., and Francis, I.S. (2006) The rise and fall of the Greenland White-fronted Goose: a case study in international conservation. Brit. Birds, 99: 242–261.
Kerbes, R.H., Kotanen, P.M., and Jefferies, R.L. (1990) Destruction of wetlands habitats by Lesser Snow Geese: a keystone species on the west coast of Hudson Bay. J. Appl. Ecol., 27: 242–258.
O'Connell, M.J., Huiskes, A.H.L., Loonen, M.J.J.E., Madsen, J., Klaassen, M., and Rounsevell, M. (2006) Developing an integrated approach to understanding the effects of climate change and other environmental alterations at a flyway level. Waterbirds around the World. Eds. G.C. Boere, C.A. Galbraith & D.A. Stroud. The Stationary Office, Edinburgh, UK. pp. 385–397.