Intensification of agriculture since the 1950s has enhanced the availability, competitive ability, crude protein content, digestibility and extended growing seasons of forage grasses. Spilled cereal grain also provides a rich food source in autumn and in winter. Long-distance migratory herbivorous geese have rapidly exploited these feeding opportunities and most species have shown expansions in range and population size in the last 50 years. Results of long-term studies are presented from two Arctic-breeding populations, the Svalbard pink-footed goose and the Greenland white-fronted goose (GWFG). GWFGs have shown major habitat shifts since the 1950s from winter use of plant storage organs in natural wetlands to feeding on intensively managed farmland. Declines in local density on, and abandonment of, unmodified traditional wintering habitat and increased reproductive success among those birds wintering on farmland suggest that density-dependent processes were not the cause of the shift in this wintersite-faithful population. Based on enhanced nutrient and energy intake rates, we argue that observed shifts in both species from traditionally used natural habitats to intensively managed farmland on spring staging and wintering areas have not necessarily been the result of habitat destruction. Increased food intake rates and potential demographic benefits resulting from shifts to highly profitable foraging opportunities on increasingly intensively managed farmland, more likely explain increases in goose numbers in these populations. The geographically exploratory behaviour of subdominant individuals enables the discovery and exploitation of new winter feeding opportunities and hence range expansion. Recent destruction of traditional habitats and declines in farming at northern latitudes present fresh challenges to the well being of both populations. More urgently, Canada geese colonizing breeding and moulting habitats of white-fronted geese in Greenland are further affecting their reproductive output.

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Although periodic breeding failures of Arctic-nesting birds on a regional scale are common, a breeding failure encompassing almost the entire Arctic in the same year is exceptional. In the spring and summer of 1992, however, the aerosol cloud resulting from the 1991 eruption of Mount Pinatubo (Philippines) had reached the high northern latitudes and caused significant cooling in most of the Arctic, with widespread negative consequences for Arctic-breeding birds. At the same time, low abundance of small rodents and high abundance of predators presented additional problems for breeding birds in parts of the Palearctic. We compiled data on breeding biology of Arctic waterfowl and waders from more than 30 field studies to illuminate in what ways the circumpolar bad weather and predation influenced the breeding season of Arctic birds in 1992. Most projects reported a higher proportion of nonbreeders and a delayed onset of nest initiation compared to other years. Hatching and fledging success of the low number of late breeders was reduced. In addition, some projects reported lower clutch sizes and increased adult mortality. Detailed data from field studies are complemented by data on overall reproductive success of waterfowl and wader populations collected from staging and wintering grounds. In total, there was an almost complete reproductive failure for waders and waterfowl throughout the Arctic in 1992, suggesting a short-term effect on global waterbird populations. This is an example of climatic fluctuations influencing reproductive biology of a group of species on a circumpolar scale.

The effects of simulated goose grazing on Phleum pratense plants were tested in an Iceland hayfield during the spring goose staging period (19 April-11 May 1997). Plants in an area exclosed from the influence of grazing and the nutrient effects of goose faeces were subject to the removal of the youngest lamina once, three and four times during this period. Clipping three and four times resulted in 25-41% increases in cumulative elongation of youngest laminae compared with unclipped plants. Total cumulative lamina growth of entire plants showed no significant difference between unclipped plants and those clipped three and four times, hence no overcompensation occurred. Sequential clipping elevated the protein content of the youngest laminae from 20% to 27-33%, whereas there was no change amongst shoots clipped only once. Because geese only consume the youngest lamina of each Phleum plant, measurements from this experiment showed that regular physical removal of growing biomass doubled the biomass of preferred tissue available to geese and increased the potential protein intake 3.5 times at experimental clipping frequencies similar to levels of sequential harvesting observed amongst staging geese compared to less frequent harvesting. These increases were achieved without any fertilising effects of goose faeces implicated in such effects in previous studies.

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SUMMARY A review of published data on the mortality and fertility of 23 species of wading birds (Charadrii) breeding in or visiting western Europe. Recoveries of ringed birds are the main source of estimates of mortality. In some cases recaptures of marked birds can also be employed. Apparent mortality in the first year after fledging is usually higher than in later years, though most estimates are probably biased by the preponderance of recoveries due to shooting. Adult mortality‐rates in stable populations vary from about 15·7% (Oystercatcher) to 51·9% (Common Snipe) with most in the range 30–45%. Closely related species tend to have similar mortality‐rates. There is a strong inverse correlation between death‐rate and body‐size, using wing‐length and weight as indices of size. Studies of fertility are scarce and meagre, though. clutch‐sizes are adequately known. Few waders are double‐brooded, though many re‐nest if their first nest is destroyed. In most thriving breeding colonies, 66–96% of the eggs laid hatch. Survival of chicks from hatching to fledging, which is hard to measure, typically averages 40–80%, though success often varies widely from year to year. Intensive long‐term studies of breeding groups make the most effective contribution to knowledge of population dynamics. For the many species for which breeding studies are likely to remain impracticable, studies of population composition in winter or on passage may provide useful substitutes, but only if techniques of sampling and of age‐ and sex‐classification can be improved.

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. Wiley and Nordic Society Oikos are collaborating with JSTOR to digitize, preserve and extend access to Ornis Scandinavica.Weights of 900 Brent Geese captured at 30 sites while flightless are examined. The geese included representatives of two breeding stocks and some moult-immigrants. The population to which an individual belonged seemed to have less effect on its weight than did its age, sex, recent breeding effort or the site where it was moulting. The mean weights, in kg, of adult males were 1.37 ? 0.35, of adult females 1.23 + 0.40, of yearling males 1.22 ? 0.26, and of yearling females 1.16 ? 0.28. Females that had laid tended to weigh less than non-breeders taken in the same place. Though the weather in the spring and summer of 1974 was exceptionally poor, so that no geese nested and there was little plant growth, moulting geese weighed as much in late July 1974 as in the other years. The geese at a few sites weighed well above the general average. The mean weights of these moulters are only 5-7% less than the annual means of a collection of published weights of other Brent Geese. Capture caused appreciable temporary loss of weight, averaging 80 g after 5 d. Measurements of the growth of the longest primary feather indicated a mean daily increment of about 6 mm d-l; the geese being able to fly again before the wings are fully grown, the flightless period was no more than 22-25 d. Individuals with well grown new primaries weighed less than those caught at the same time and not yet showing new primaries, the difference being more marked in males.