A last fruit from my stay in the Weddell Sea, triggered by the Arctic terns
I saw fly around there. Part II was never written, and it may be some time
before I get around to that.
Wim Vader
MIGRATORY BIRDS IN TROMSØ, N.NORWAY (69*50'N)
I.BIRDS WINTERING IN TROMSØ
I write this piece at 65*S, as far away from Tromsø as I have ever been
probably, on a ship in the open Weddell Sea in the Antarctic. Our ship, the
Polarstern, lies on station near a large table iceberg, floating over a sea
just here 4780m deep (I know, as we are sampling the bottom fauna ), and
around the iceberg fly a couple of terns, Arctic Terns, possibly on their
way to Tromsø to nest there. This is about the longest migration route of
any bird known (although some southern shearwaters fly comparable distances
from their southern nesting areas to winter in the northern Pacific, and
South Polar Skuas have also been observed quite regularly in both the
northern Atlantic and Pacific). Still, all the other birds seen here never
make it even as far north as the equator, so the Arctic tern is definitely
a special case.
It made me think, though, about the great variation in migration patterns
among the birds that are common in Tromsø, and as I have time on my hands
here---deep-sea collecting is often a slow business--- I thought it might
be of some interest to give an impression of this variation, even though I
can not check up all the details down here.
Not all birds in Tromsø migrate, in fact, in spite of our far northern
locality and our very long, although not overly severe, winter. Our crows,
ravens and magpies are sedentary, and so are the various grouse: Willow
Grouse, Ptarmigan, Black Grouse and Capercaillie. Among the small birds,
the House Sparrows stay put, and so do most of the tits, the Creeper, and
the Goldcrest, as well as the Bullfinch and latterly also the Greenfinches
of our feeders. Also a few raptors spend the winter in the far north; local
examples are the White-tailed Sea Eagle, the Sparrow Hawk and the
Gyrfalcon, as well as some forest owls. On the coast the local Common
Eiders stay year round, and so does the newcomer Grey Heron, while the
Mallards of the island content themselves with moving from their nesting
lake on top of the island of Tromsøya to the coasts of the sounds around
the island, where the water never freezes over. Also our Red-breasted
Mergansers are with us summer and winter.
For some other species the situation is more complicated than it seems at
first sight; we do have them on our island both summer and winter, but
these may well not be the same individuals. Good examples of this are
Herring and Great Black-backed Gulls; they are common year round in Tromsø,
but ringing results seem to indicate that the majority of our nesting
birds migrate to the countries around the North Sea, while they are
replaced in Tromsø in winter by birds that nest further north and east,
e.g. in North Russia. Also our eider flocks are augmented in winter by
northern birds, i.a. those that nest on Spitsbergen, easily recognized by a
somewhat different bill colour. Similarly, the Kittiwakes on the coast in
winter, and the Guillemots (Murres) in the outer fjords may well be
primarily far northern birds, and not our own nesters; in fact we also have
had returns from immature British guillemots from winter Tromsø
.
We know that for sure for a few other species that have been better
studied: Purple Sandpipers nest in the hills around Tromsø, although
sparingly, and they are, as the only shorebirds left in that season, also
common in winter on our stony shores. But these are exclusively birds from
northern Russia and the Arctic areas, and our own Purple Sandpipers spend
the winter further south in Europe.
(Similarly, Snow Buntings are common nesting birds of stony slopes in the
surrounding hills, where their cheerful presence and song greatly enliven
that often a bit depressing landscape. They are also well-loved in town as
harbingers of spring, and in April-early May may occur in large numbers in
town and on partly snowfree areas along the coast; they also come to
feeders in the gardens at that time. But these are not our nesters; these
hordes all belong to the E. Greenland population of Snow Buntings! These
have a complicated migration pattern, and apparently winter somewhere in
Russia --- they then move to the coasts of N.Norway where they stay for a
while a fatten up before the long and arduous oceanic crossing to
Greenland. Meanwhile our local Snow Buntings sneak in more or less
unnoticed on their nesting territories, and we see them rarely in town.).
As far north as Tromsø may seem to be for most of you, we still have a
number of wintering birds that consider our winter climate an improvement
to that of their nesting areas, and who winter regularly in the Tromsø
area.These are almost exclusively coastal or sea birds, at least in
winter. These hail mostly either from the Arctic islands: the Svalbard
archipelago, Frans Josef Land and Novaya Zemlya, or from the bleak northern
coastal areas of Russia. A few, like the two scoters and the Long-tailed
Ducks, all common winter birds on the fjords, come partly from closer by,
the now frozen freshwater lakes of N.Scandinavia. But the King Eiders from
Svalbard and the White-billed Divers from N.Russia (Yellow-billed Loons, if
you prefer; it is still the same bird, with a bill neither truly yellow or
white), the most famous of our wintering birds, do not nest in Norway at
all, and the same goes for the Glaucous and Iceland Gulls that also are
regular, though never very common winter visitors here---they are much more
common on the Finnmark coasts, where also Steller=s Eiders winter in large
numbers.
There are also more local movements which result in wintering birds in
Tromsø. For some reason Cormorants Phalacrocorax c.carbo do not nest in the
immediate area around Tromsø, although they have colonies both north and
south of us. But in winter they migrate to Tromsø harbour in considerable
numbers, and some old wrecks and derelict piers are literally festooned
with them in the winter half year. Auks of several sorts (mainly Razorbills
and Little Auks (Dovekies, who nest on Svalbard) stay in winter normally
mostly on the open coast, but come near town under certain circumstances
(large shoals of pelagic fish for the Razorbills and occasionally Puffins,
mostly adverse weather for the Little Auks). As reported before, we can get
wrecks of Little Auks when strong winds blow the birds ashore and often far
inland.
As inland Troms is so much colder than the coastal areas where we live,
there may be also be movements coastwards in winter. These are not regular,
however, but have more the character of infrequent influxes. Underlying
causes are often as much scarcity of the right food as directly the cold
itself. In years of very rich crops of Rowanberry (Mountain Ash, Sorbus
aucuparia) not only our nesting thrushes (Fieldfares and Redwings) stay
much longer in autumn, but we may also have invasions of Bohemian Waxwings
and, less often, Pine Grosbeaks from the taiga forest of inland
northeastern Scandinavia, Finland and N.Russia. From the same regions in
many winters come influxes of Great Spotted Woodpeckers, Crossbills and
forest owls, chiefly Hawk Owls; more rarely we have had Siberian Goshawks
and ditto Nuthatches, while the invasions of Siberian Nutcrackers usually
go further south into S.Scandinavia and W.Europe.
Some winters we also have large numbers of birds that are normally uncommon
in the area, such as Long-tailed Tits, Coal Tits, Goldcrests, and Redpolls,
but such top years concern the entire area, and seem more to be a temporary
large increase in numbers than a migration. The normal resident birds of
the inland usually stay put, although a few Tree Creepers may turn up on
the island in winter; Siberian Tits, for example, I see not more often on
Tromsøya than maybe once every five years, and the Siberian Jays and
Three-toed Woodpeckers of inland Troms I have never met here on the island
at all.
These are the birds that make up the wintering population at 69*50*N. In
the next piece (whenever that may come) we shall talk about the wintering
areas of our Tromsø nesting bird population.
Weddell Sea, 10-14 March 2002
Wim Vader, Tromsø Museum
9037 Tromsø, Norway
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