Epilogue

Although the papers presented here do not have the pretension of exhaustively reviewing the adaptations enabling survival through the polar winter, the range of organisms covered nevertheless allows one to discern recurring themes. For the endotherms it is tempting to set the current views against the background of the generalizations arrived at by Scholander and his co-workers ... in their key papers cited repeatedly during the Life of the Polar Winter conference. ... We can ask why the paradigm of Newtonian cooling advanced at that time has been such a successful approach to the problem of cold adaptation and to what extent the conclusions based on the wide-ranging survey undertaken then are still valid today. ... The basic tenet of the Scholander view was that adaptation to arctic life primarily entailed the acquisition (or perfection) of effective insulation, thus allowing cold exposure without excessive costs. ... The vivid accounts of ongoing research presented during the symposium and in this issue underline the shifting emphasis away from relatively short-term incursions to the arctic environment to capture specimens for subsequent study towards long-term work by teams of investigators following individual animals over long periods (maintaining contact by an impressive array of telemetric devices). The challenge of the years ahead will be to trace the web of adaptation through the food chain by close collaboration among specialists. In the case of herbivory, cooperation between botanists and zoologists alluded to by Sonesson has already revealed the intimate links connecting animal numbers with their food supply and especially with the persistence of the preferred vegetation .... The close fit between the overall standing crop of vegetation and peak reindeer biomass across a range of arctic sites, even extrapolating to an accurate prediction of the carrying capacity of the sub-Antarctic island South Georgia, argues for the pervasive influence of food supply as against the traditional interpretation of populations kept in check by predators .... It is against this background that the exploitation patterns of man must be viewed. From the recent physiological work undertaken on the members of the Finnish polar expedition, it is reassuring to note that urban man has not lost the ability to acclimatize to the dramatic extent envisaged by Hammel (1964), and more surprises may be in store for us

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.</p

Fueling Incubation: Differential Use of Body Stores in Arctic and Temperate-breeding Barnacle Geese (Branta leucopsis)

We compared the use of body stores in breeding Barnacle Geese (Branta leucopsis) in traditional Arctic colonies in the Barents Sea with that in recently established temperate-zone breeding colonies in the Baltic Sea and North Sea by studying female body-mass loss and use of fat and protein stores during incubation. Average daily body-mass loss was almost identical in the 2 temperate-breeding populations (17.0 g and 16.5 g in Baltic Sea and North Sea, respectively), whereas Arctic-breeding females lost significantly less (10.6 g day-1). Temperate-breeding females initiated incubation with body mass 125 g higher than that of Arctic breeders, but at the end of incubation, body mass was similar among the 3 populations, averaging 1,458 g. Body-mass loss during incubation amounted to 23% (North Sea), 22% (Baltic Sea), and 15% (Barents Sea). Fat mass, as measured by isotope dilution in a subsample of females, was consistently higher in North Sea than in Barents Sea birds, but both populations showed similar rates of fat-mass loss (9.4 g day-1, on average). By contrast, loss of fat-free mass (assumed to represent wet protein) amounted to 9.3 g day-1 in North Sea birds but only 1.5 g day-1 in Barents Sea birds. Energy content of 1 g utilized body mass was 21.1 kJ (North Sea) and 34.9 kJ (Barents Sea), which equates to 376 kJ day-1 and 415 kJ day-1 drawn from stored energy, respectively. We suggest that differences in nest-attendance and post-incubation demands are responsible for the differential use of body stores in temperate- and Arctic-breeding Barnacle Geese.