The Greenland White-fronted Goose Anser albifrons flavirostris

Madsen 1997, Madsen 1998), demonstrating impacts
at the population level have proved more
difficult (Madsen 1995). If it is possible to establish
such links, it becomes more possible to address
the causal factors, identify the points in the
life cycle at which these factors operate and implement
management to mitigate such factors.
Does poor feeding opportunities and/or disturbance
directly affect survival or breeding success,
and what are the proximate causes? It is well demonstrated
that disruption to feeding patterns on
spring staging areas prior to migration to breeding
areas affects the reproductive potential of
geese (Madsen 1995), but what of disturbance at
other times of year?
Given the relative slow build up in body stores
throughout the winter in this population, it may
seem less likely that disturbance in mid-winter
could affect departure condition than during the
spring pre-departure phase. In comparing between
individuals, Figure 9.1 shows graphically
how reduced rates of mass accumulation could
result in longer term fitness consequences, but
such a model could equally apply between sites.
Where nutrient and energy acquisition is reduced
relative to best feeding opportunities, the potential
to attain store thresholds at staging areas later
in the annual cycle is diminished. Birds departing
from poor quality or highly disturbed wintering
areas may not be able to compensate in Iceland
and Greenland, and hence may suffer reduced
fitness as a consequence. Indeed, if the numbers
of geese wintering on high quality habitats increases,
and these birds depart in good condition,
birds departing in poor condition from wintering
areas are likely to face even greater competition in
spring if food resources in Iceland and Greenland
are limited. Hence, a mechanism of intra-specific
competition operating away from the wintering
areas may actually be influencing the relative
changes in abundance of Greenland White-fronted
Geese at different wintering resorts.
Climate change may play a role at several stages
in the life cycle of the geese. There is a trend
amongst Greenland White-fronted Geese for the
most southern wintering flocks to show the most
dramatic declines (MS14). The recent declines at
Wexford are attributable to falling fecundity at
that site at least, but does this hold for other wintering
flocks in the south of Ireland showing similar
trends? Is this reduction in breeding because
of global climate change affecting their breeding
conditions in the north of their west Greenland
80
range? Or could it be that the same climate change
is affecting the phenology of growth of food plants
exploited in spring on the wintering areas and
staging grounds in Iceland? Could the spring
flush of grass production in southern Ireland (the
so-called “spring bite”) be occurring earlier and
earlier as a result of climate change, that it occurs
too soon for geese to effectively exploit? A full
exploration of the weather archive needs to be
undertaken before we can answer such questions.
Furthermore, the patterns of change in goose
numbers at different wintering resorts need to be
investigated in terms of their demography and
distribution, before it is possible to identify what
environmental factors are likely to shape these
processes.
In many areas of the summering grounds, Whitefronted
Geese follow the phenology of thaw in
the west Greenland landscape. This involves the
exploitation of plants in the early stages of growth
as they are released from dormancy by the thaw,
but before the onset of rapid growth. On a macro
scale, this involves a movement up-hill following
the general amelioration of temperature as the
spring and summer progress. Later in the season,
at high altitudes, this pattern reflects aspect and
topography, with the geese essentially following
the disappearance of late lying snow patches,
which offer the last burst of plant production in
the landscape. The geese especially exploit this
phenology of plant growth during the moult,
when their ability to switch between habitats is
severely limited by their association with water
bodies to which they resort when threatened by
predators. The proximity of late snow patches in
association with open water therefore limits available
moult habitat in many areas and the timing
of melt of these areas may be critical to the
regrowth of flight feathers at this time. Changes
to patterns of melt and hence the phenology of
plant growth at different altitudes could therefore
have consequences for the feeding efficiency
of geese throughout the summer.
And what of the effects of competition from Canada
Geese on the summering areas? Accumulating
evidence suggests exclusion of White-fronted
Geese from formerly occupied moult sites. If
maintained, this represents net Whitefront habitat
loss. If available moulting habitat is in any way
limited, this will ultimately have some effect on
the population as a whole, as long as the numbers
of Canada Geese continue to increase. This
represents yet another dimension to population