The Davis Strait - DCE - Nationalt Center for Miljø og Energi

Figure 4.7.10. The density of
moulting harlequin ducks recorded
in July 1999 expressed as the
number of birds recorded per km
surveyed coastline (Boertmann &
Mosbech 2002). The moulting
period is July to September.
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Harlequin duck, Histrionicus histrionicus
The harlequin duck breeds at inland rivers. However, they also occur in
marine habitats: non-breeding individuals and post-breeding males assemble
from July at exposed rocky coasts and skerries and in winter all birds are
found in these extreme habitats. A few non-breeding birds may stay at these
coasts also before the moulting period.
The breeding population in Greenland is low, numbering probably only a
few thousand pairs. However, Canadian birds also use the Greenland coasts
for moulting and wintering (Robert et al. 2008) explaining why the number
of birds along the outer coast – estimated at 5,000-10,000 birds – is higher
than the Greenland population can muster (Boertmann 2008a, Robert et al.
2008).
In July 1999 the population of moulting birds was surveyed from aircraft
(Fig. 4.7.10) and the resulting estimate was 5,000-10,000 males (Boertmann &
Mosbech 2002, Boertmann 2003, 2008a). The winter population has not been
surveyed, but is estimated at roughly more than 10,000 birds (Boertmann et
al. 2006).
The moulting and wintering birds are very sensitive to marine oil spills due
to their preference for exposed habitats along the outer coastline (Fig.
4.7.10). The highest concentrations of moulting birds within the assessment
area was in 1999 found just south of Nuuk, while the distribution of the
wintering birds is not known (Boertmann & Mosbech 2002, Boertmann
2003).
Due to the small breeding population, harlequin duck is listed as Near
Threatened (NT) on the Greenland Red List (Boertmann 2007).
Red-breasted merganser, Mergus serrator
This is a breeding bird in fjords and on sheltered coasts. Especially moulting
birds assemble in high concentrations in some fjords, where they are sensitive
to potential oil spills (Boertmann & Mosbech 2001). However, the
known moulting sites are far from the outer coast where it is unlikely that
oil spills from Davis Strait can reach. Winter concentrations may also be
sensitive, but no knowledge on this is at hand.
The red-breasted merganser is listed as Least Concern (LC) on the Greenland
Red List (Boertmann 2007). The population is probably isolated from
neighbouring populations in Iceland and Canada.
Black-legged kittiwake, Rissa tridactyla
This small gull is a numerous breeder in the assessment area, with the breeding
colonies centred in Maniitsoq district (Fig. 4.7.2). The most recent survey
of the breeding population in Greenland lists 35 occupied colonies holding
approximately 34,000 breeding pairs (Labansen et al. 2010) within the assessment
area. The breeding colonies are usually found in the fjords, and the
birds often forage in the open sea, performing daily migrations in and out of
the fjord. Breeding birds arrive to the colonies in the period March to May
and leave again during August when the chicks are fledged.