Arctic geese : Herbivore-vegetation interaction, predators and human pressures - A symposium synthesis

A symposium on the Svalbard geese was hosted by the Norwegian Polar Institute in Oslo, Norway, 23-26 September 1997, to collaborate new information on the three goose populations that breed in Svalbard: the barnacle goose Branta leucopsis, the light-bellied brent goose Branta bernicla hrota and the pink-footed goose Anser brachyrhynchus. This paper attempts to synthesise information gained in recent years on these goose populations. Also echoed here are management problems related to these goose populations and priorities for future research. Looking back over several decades of intensive effort devoted to the goose species breeding in Svalbard, four research themes are touched upon. We argue that (A) unravelling the mechanisms of response of the individual to increasing population density is both technically feasible and theoretically rewarding. A cooperative effort here deserves unflagging priority if we are to achieve population models useful for management purposes. Although individual responses at the various sites utilised through the annual cycle fit the paradigm of density dependence, this does not imply overall population control. The weakest link in the causal chain is (B) understanding the interaction between geese and their food plants, and we contend that this topic should head the new research agenda. This work can profitably be linked with (C) new technologies which allow the tracking of individuals in relation to potential food supplies that can in turn be quantified by means of remote sensing techniques. Under ideal conditions the birds can subsequently be recaptured and profiles of past energetic expenditure reconstructed from indwelling heart-rate loggers. Finally, the geese are not alone, and (D) various predators (notably arctic foxes, polar bears and man) have major impacts on habitat use and influence goose numbers both directly and indirectly, often in an interaction with weather conditions (ice and snow cover). Recently there have been major changes in numbers and distribution of these key predators and at least locally they may now be acting to limit goose populations.