The Greenland White-fronted Goose Anser albifrons flavirostris

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Arrival mass in West Greenland confirmed that geese lost more mass flying from Iceland to Greenland than during the same flight distance from Iceland to Ireland. The difference was consistent with the predicted extra costs required to cross over the Greenland Ice Cap. After arrival, breeding geese fed intensively for a period of 10- 14 days during which mass accumulation for investment in reproduction occurred at the same rapid rate as in Iceland. Female geese protected by attendant ganders were able to exploit a rich food supply (storage organs of plants) during uninterrupted periods of foraging. Nest densities were low and nest habitat apparently unlimited, so it seems unlikely that breeding habitat per se limits breeding numbers. More likely, the extent and availability of pre-nesting feeding habitats in the central part of breeding range could limit pre-nesting accumulation of stores. This would potentially limit the numbers of individual females attaining adequate body stores to achieve successful reproduction. Hence, increasing goose densities exploiting a finite pre-nesting food resource may increasingly limit the numbers of geese attaining a level of body condition sufficient to enable successful reproduction. Birds breeding in the north of the summer range stage further south in Greenland (where they compete for resources with locally nesting birds) before moving north. Global climate change models predict that the northern breeding element of the population will face continuing reductions in summer temperature. In addition, northern breeding birds will encounter greater goose densities in southern spring areas with which they must compete for spring food resources. Despite the recent increase in total population size under protection, the absolute numbers of successfully breeding pairs returning with young to the two most important wintering areas have been more or less constant. This suggests that some finite resource limitation may now operate (most likely on the breeding grounds), restricting recruitment. Amongst known age marked individuals, the probability of survival to successful breeding had fallen from 15% amongst goslings hatched in 1983 to 3% amongst those from 1992 and the mean age of first breeding increased from c.3 years prior to 1988 to c.5 years of age in subsequent cohorts. The proportion of potentially breeding adults returning with young to the wintering areas is falling at both the wintering sites at Wexford and Islay, but the faster rate of decline at Wexford has had a greater effect and is now 6 causing a decline in wintering numbers there. It may be that the cooling of the climate in North West Greenland and increasing densities further south are already affecting the Wexford wintering birds. At the same time, the Islay wintering birds that tend to nest further south, benefit from improvements in spring climate conditions in central west Greenland. Greenland White-fronted Geese moult flight feathers at amongst the lowest levels of body mass and showed no change with moult stage, suggesting they meet energetic and nutrient demands from exogenous sources. However, confinement of the flightless geese to the proximity of water to escape predation constrains total available habitat. Newly colonising Canada Geese have increasingly exploited the same moult sites and are behaviourally dominant over Whitefronts. Dramatic increases in the numbers of Canada Geese (which winter in North America) suggest the potential for increasing conflict on the breeding areas between the two species in future. The increase in numbers since protection from winter hunting at Wexford is consistent with a constant apparent annual adult survival since the 1960s but the relative stable numbers before 1982 seem to have been maintained by the balance between hunting kill and breeding success. Immediately following protection (i.e. in the absence of apparently additive hunting mortality), numbers increased at rates regulated by the potential of reproduction to replace lost individuals. Since the early 1990s, Wexford numbers have declined due to falling fecundity and to a catastrophic loss of first-year birds and their parent adults in one single year. Hence, reductions in reproductive output now seem to be limiting Wexford numbers. Since fecundity has also declined on Islay and some other winter resorts, this appears to be a general phenomenon in the population as a whole at this time. On Islay, reductions in the reproduction rate have yet to halt the linear increase in numbers since protection. It would therefore appear that the population was limited prior to the 1980s by hunting mortality. Under protective legislation, the population expanded to reach a new equilibrium level set by limits to reproduction. Given the predicted effects global climate change, the increases in goose density and the colonisation of the breeding areas by Canada Geese, the future conditions affecting
Greenland White-fronted Geese are unlikely to remain as they are now. The results of many years monitoring are reviewed in the light of the con- servation issues facing this population in the future and recommendations are made for future research. 7
Page 1 and 2: National Environmental Research Ins
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Page 5 and 6: Contents Summary ..................
Page 7: Summary The Greenland White-fronted
Page 11 and 12: Dansk resumé Den grønlandske blis
Page 13 and 14: 1 Introduction 1.1 Why Greenland Wh
Page 15 and 16: The Greenland White-fronted Goose i
Page 17 and 18: more direct measures of 'body condi
Page 19 and 20: 2Limits to population size in recen
Page 21 and 22: Despite the morphological similarit
Page 23 and 24: Scotland, the wettest peat soils we
Page 25 and 26: of this goose population. At the sa
Page 27 and 28: Spring count 16000 12000 8000 4000
Page 29 and 30: 3 Accumulation of body stores and t
Page 31 and 32: Body mass (g) 3500 3000 2500 adult
Page 33 and 34: h -1 and none showed any sign of re
Page 35 and 36: labelled water), the precise extent
Page 37 and 38: 4 Spring staging in Iceland and the
Page 39 and 40: Body mass (g) Body mass (g) 4000 35
Page 41 and 42: Goose droppings/m 2 6 5 4 3 2 1 0 P
Page 43 and 44: er 3KJ was a behaviourally dominant
Page 45 and 46: 5 Pre-nesting feeding 5.1 Introduct
Page 47 and 48: imagery and searches in helicopters
Page 49 and 50: 6 Reproduction 6.1 Breeding distrib
Page 51 and 52: predicted that at the end of this p
Page 53 and 54: Percentage of juveniles Figure 6.1.
Page 55 and 56: Mean age of first breeding 8 7 6 5
Page 57 and 58: periods in each winter as the exten
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Geese, it might be expected that in
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7 Moult of flight feathers 7.1 Intr
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mass at different stages of regrowt
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of available fresh green growth of
Page 67 and 68:
8 Survival 8.1 Introduction Almost
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the hunting mortality rate K t for
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during the period when the populati
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lands. This process was certainly u
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9 Synthesis 9.1 Anticipatory acquis
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Mass based on API scores 3600 3200
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social system has traditionally reg
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ers (J. Madsen unpubl. data). In th
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limitation which operates during an
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NUTRIENT & ENERGY ACCUMULATION RATE
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eeding geographical locations respe
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10 Acknowledgements A thesis is sup
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mark and to Ebbe Bøgebjerg for the
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L. Kramer, J.N. Kristiansen, T. Lai
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Marked Individuals in the Study of
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mussels, Mytilus edulis. Journal of
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Nichols, J.D. (1991) Extensive moni
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Thompson, S.C. & Raveling, D.G. (19
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12Appended manuscripts 1: Fox, A.D.
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National Environmental Research Ins
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The Greenland White-fronted Goose Anser albifrons flavirostris

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