The Greenland White-fronted Goose Anser albifrons flavirostris

4 Spring staging in Iceland and the flight to Greenland
4.1 Introduction
Until the 1980s, little was known about the status
of staging Greenland White-fronted Geese in Iceland.
It was known that large numbers passed
through Iceland in autumn, but now it is known
that the population also stops there in spring en
route to the breeding grounds (MS4). It is clearly
important to establish whether, where and for
how long birds stage on spring migration since
feeding at staging sites enables individuals to recoup
depleted energy and nutrient stores and
hence potentially affect subsequent breeding success
(see review by Thomas 1983). Weather conditions
in Iceland in spring had been shown to
correlate with subsequent breeding success of the
Pink-footed Geese Anser brachyrhynchus which
nest there (Fox et al. 1989). Hence, it was reasonable
to assume that weather conditions and the
availability of forage were likely to affect the condition
of migrating Greenland White-fronted
Geese departing for the breeding grounds from
Iceland in spring. During the late 1980s and
throughout the 1990s, a series of studies were carried
out examining the spring staging of different
goose species in Iceland, to assess the importance
of feeding ecology of pre-nesting staging
in that country. An important aim was to establish
the importance of specific staging areas and
to assess the distribution and abundance of the
different goose populations there, examining the
use of different habitats and the way in which
the geese exploit these (e.g. Boyd & Fox 1992,
1995, Fox et al. 1991, 1992, 1994a, 1994b, 1999). In
very recent years, these studies have involved a
Ph.D study (Kristiansen 2001) and Masters student
study (Nyegaard 2001), but from which selected
results are presented here.
In conservation terms, the most important elements
in the study of spring staging relate to the
identification of staging areas, the habitats and
food plants used by the geese, the level of energetic
gain that can be achieved by geese utilising
different habitat types and how they may derive
the maximum nutritional benefit from them. In
this way, it is possible to establish some basis for
ranking the importance of sites and habitats in
terms of the number of birds using different sites
for site safeguard and nature conservation management
purposes. Finally, studies have also con-
sidered how much nutrient gain can be derived
from the staging period in Iceland during the prelude
to migration over the Greenland Ice Cap to
the breeding grounds on the west coast.
4.2Distribution of spring staging
Greenland White-fronted Geese in
Iceland
Observations from many years confirm that a
large proportion (if not all) Greenland Whitefronted
Geese stage in Iceland from c. 10 April to
c.12 May in most seasons (MS4, MS19). At this
time, they use two main areas, namely the southern
lowlands (Árnessýsla, Rangárvallassýsla and
Vestur-Skaftafellssýsla) and the western lowlands
(Kjósarsýsla, Borgarfjarðarsýsla, Mýrarsýsla and
Snæfellsness- og Hnappadalssýsla). Spring migration
phenology appears to differ between areas,
with earlier arrivals but a slower build-up to
maximum numbers in the southern lowlands.
Here, numbers peaked during 24-26 April in 1990-
1992, but dispersed earlier compared to the rapid
build up in western staging areas to peak numbers
during 18-22 April in 1997-1999, where substantial
numbers of birds remained well into May
each year (MS19). These differences most likely
relate to the timing of migration in the years concerned,
but could also reflect different migration
strategies of birds using the two areas (records of
individuals using both staging areas are rare,
MS27). The southern lowlands, especially along
the coast, experience a slightly milder climate and
hence earlier thaw than the west, which may initiate
plant growth a little earlier in the spring. In
addition, there are substantial areas of tillage in
the southern lowlands that do not occur in the
west (see below).
At the most important staging site in the western
lowlands, Hvanneyri, up to a maximum of 1,600
birds have been counted (MS19). Based on observations
of individually marked birds at Hvanneyri,
more than half of the geese remained for less
than a week, mostly early on in migration, whilst
more than a third stayed for almost the entire staging
period (c. 24 days).
From observations of individually marked Greenland
White-fronted Geese, at least 90% of goslings
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