From Birding-Aus

I am very sorry for earlier sending this piece in an inappropriate way; I had lost the internet at home, and clearly improvised in the wrong way. I hope this now arrives safely.

Wim



Winter birds in Tromsø, N. Norway


I recently wrote about the common birds in Tromsø in summer. Some people asked: But what is the situation in winter, so far north (almost 70*N)?


Our town has ‘mørketid’ (‘the dark period’), when the sun never rises above the horizon in two months (21 November- 1 January) and with quite short days also the rest of the winter half year. Winter is maybe not particularly severe—we are on an island, close to a coast heavily influenced by the Gulf Stream, and temperatures here very rarely sink below -17*C (The inland may have -40*)–, but is is quite long. There is usually snow on the ground from October till far into May, and all freshwater is ice-covered at least as long. But the sea, and most of the fjords and sounds, never freezes over, although there may be some ice in the intertidal. It is therefore no wonder, that most land birds migrate away from northern Norway in the autumn, while many sea birds are here year round.


Cold in itself is usually not really a big problem for birds. The species that live here, are usually well adapted and tolerate low temperatures quite well: dense feather covering, suitable behaviour and well chosen roosting areas at night. But birds live at high speed: they have a much higher heart-beat frequency than most mammals and therefore also a faster metabolism. They are also not able to store extra food in the form of an extra layer of flesh, as mammals do in the cold areas; a flying bird cannot weigh too much! This means that small birds need to feed very often; most birds that die in winter die primarily from lack of food and not directly from freezing. Sufficient and regular food is extremely important for our winter birds. The birds we have in Tromsø in winter are therefore not a random selection among the species that are here in summer.

Freshwater birds have little to expect here, if they cannot flee to the coast, as part of the Mallards of Prestvannet do; we find them on the shore—fewer since the municipal sewers were cleaned–, and they winter well there. Also our Grey Herons move to the shore in winter; I always find it amazing that they apparently can catch their fish also in the dark.


Birds that get their food from the ground in open terrain cannot winter in Tromsø either, because everything is snow-covered all winter. The same goes for most insect feeders; no mosquito problems in winter! There are a few insect and spiders in the trees for sharp eyes, but not many, and as we shall see, many insect eaters switch to vegetable food in winter. There are therefore only certain categories of birds that can winter here. I have divided them in 8 groups, but please remember that every such categorization has its weaknesses.


1. Seabirds. In winter there are clearly more birds in the fjords than there are on land. The sea never freezes, and one could therefore think that we have the same bird species here year round. But there is another factor playing here: mørketiden, the absence of daylight. For birds like terns, that find their food by flying around and diving for the fish they see, there is clearly not enough light here in winter; in addition , many small fish and crustaceans migrate to somewhat deeper water in winter. So the terns migrate, our Arctic Terns all the way to the Antarctic, the longest migration route of any bird. Also the Baltic Gull, in many ways rather tern-like in its foraging behaviour, migrates far, in its case to E. Africa. Auks and cormorants also dive, but for them the absence of daylight somehow does not seem to be a problem. Cormorants are in fact much more common in Tromsø in winter than in summer, when for some reason they go elsewhere to nest, either north or south of here. The fish-eating Red-breasted Merganser, also a species that is here year round, maybe also belongs here, rather than with the other sea-ducks. Auks are not common close to Tromsø in winter; they mostly keep to the outer coast or the open sea.


Our nesting loon species, the Red-throated and Black-throated Loons, migrate south to the North Sea area, but we still have loons here in winter: the Yellow-billed Loon (White-billed Diver, if you prefer: the bills are neither quite yellow or quite white), that nests in the tundra of Northern Russia, winters in some numbers in our area. All our grebes migrate.


The most common seabirds in our fjords in winter are nevertheless ducks, diving seaducks, that get their food from the sea bottom and mainly use other senses than sight in foraging. By far the most common is the Common Eider, foraging in large flocks many places, and present year round. In winter we have also some King Eiders, another arctic bird for which Tromsø is the deep south. Other diving seaducks here in winter are Long-tailed Duck, and Black and Velvet Scoters. But somehow the numbers seem to decrease around town here and nowadays I but rarely hear the joyful yodeling of the long-tailed ducks in the dark, when I walk along the sound in mid winter, and I don’t think this is because I am increasingly hard of hearing.


Virtually every flock of ducks is attended by a few large gulls, Herring Gulls or Great Black-backed Gulls, which try to rob the ducks as soon as they come up from a dive with prey; in this way the gulls get hold of prey animals they themselves cannot catch. Often it looks as if these gulls defend ‘their flock’ against newcomers, and they stay with their flock also when the ducks, as is their wont, now and then take a pause from foraging. 


2. Shorebirds. Of those we have relatively few in winter. This has two main reasons: ice often forms in the intertidal zone, and many of the shore invertebrates retract to somewhat deeper water in winter. So almost all the common shorebirds of summer, the Oystercatchers, Redshanks, Turnstones and Ringed Plovers  ‘come to their senses and fly south’ (as a well-known song here has it); also our by far most common gull in summer, the aptly named Common Gull, leaves N. Norway for the North Sea area in winter. Only a few Curlews have tried to winter locally in recent years. 


There is one exception to this rule, however. The Purple Sandpiper, a roly poly little shorebird with the colour of the shore rocks, and therefore quite inconspicuous even when as usually in a small flock, winters in some numbers in the area. They are very little shy, so one can easily watch them and see that they mostly seem to feed on periwinkles, one of the shore species that stays in the intertidal year round. As they mostly forage on exposed shores, beach ice is rarely a problem for them. Purple Sandpipers nest in the hills around Tromsø, but those migrate south, and our winter birds are breeders from the Arctic. As mentioned before, also the Grey Heron becomes a shore bird in winter. 


3. Crows and Gulls. Otherwise our shores in winter are mainly the domain of the large gulls, as well as the Hooded Crows, much more a shore feeder here than the crows further south in Europe. Crows and gulls are largely omnivorous and find their food also on refuse dumps, in town and near the fishing boats. In town the Hooded Crows and the Magpies know exactly what is in the refuse bins, and I have seen the crows lift the lid on some to get at the contents. They also compete with our large flock of feral pigeons for food, and some magpies have become adept in taking sun flower seeds from the hanging feeding cylinders, that are in many gardens. A few Ravens can now and them also been found in town in winter. They are often in pairs, and always seem to indulge in a cozy conversation. 

The large gulls are most common on the shore and at the refuse dumps, the fishing boats and the quays. These large gulls are not the same birds (although the same species) as the ones that nest here. Ours migrate south, and these come from further north. Often one can find a few Glaucous Gulls and more rarely even an Iceland Gull among them in winter, but these become much more regular on the Finnmark coast. As I said, our Common Gulls all disappear in winter, as do the Kittiwakes, that in the last years have started nesting on buildings in town.


4. ‘Commensals’. With this term I mean the bird species which are almost or wholly dependent on humans, either through direct feeding, or because ‘they take the crumbs from the rich man’s table.’ The best example is no doubt the feral pigeons in town, that survive the winter through regular feeding, and the House Sparrows, that survive because the pigeons get fed. We have had a few pairs of Collared Doves since 1969 (as so many things here, the northernmost in the world), that live a very inconspicuous and little noticed life near a tree-rich cemetery and that most probably owe their survival to an old lady that feeds them in winter. Also the Great Tit probably belongs here; this is a tit species that does not hoard food, and it was absent until winter feeding became commonplace.


5. ‘Bulk food vegetarians‘. With this term I want to characterize birds, that eat large amounts of one type of food, that is easy to get, even in the dark. Here grouse typically belong. Willow Grouse and Ptarmigan feed mainly on willow buds and shoots, Black Grouse on birch shoots, and Capercaillie on pine needles. All this is easy to find, even when the ground is snow-covered, and the birds eat large amounts of this not all that nutritive food.

The Bullfinch also feed on buds in winter and spring, but this beautiful calm large finch (That takes over for the European Robin on our Christmas cards) has long since found out, that many feeders in town contain sun flower seeds. They have under these circumstances also become quite tame, contrary to what most bird books still maintain. A relative newcomer in Tromsø is the Greenfinch, often roaming in small flocks of largely immature birds in winter. These are not very green at all, but still can be easily identified by their yellow wing stripes. Greenfinches are very frequent guests at bird feeders; their bills are, contrary to those of Chaffinches and Bramblings (who migrate), strong enough to crack sunflower seeds. They have increased enormously in the 45 years that I have lived in Tromsø; in 1973 they did not occur at all–‘too far north’–, but now they are among the most common songbirds all the way to the Russian border. 


6. Other tree-foraging birds. This is a quite variable group; they have in common that their numbers in winter vary a lot from year to year, depending on what the trees have to offer. Rowans (Mountain Ash, Sorbus aucuparia) have some years when they are laden with berries, with lean years in between. In these rich years our thrushes (mainly Fieldfare and Redwing), usually migrating south in October, delay their departure and feast on the berries till they have eaten almost all of them , by which time it may be January, or even February. In such years we have extra large flocks of Bohemian Waxwings arriving in late autumn, and also small numbers of the beautiful tame Pine Grosbeaks. In the same way rich seeding years for the birches will yield flocks of wintering Common and Arctic Redpolls, and good cone years on the pines may bring Pine Crosbills to our area.


In this group we can maybe also place those bird species which are insectivorous in summer, but that switch to vegetal food in winter. Here belong our woodpeckers. There are no woodpeckers on Tromsøya in summer (Apart from the occasional Lesser Spotted Woodpecker), but in many autumns we have small invasions of Great Spotted Woodpeckers from further east, and these often stay all winter and also visit gardens. These switch from their summer diet of insects to mainly feeding on pine seeds in winter; these they obtain by wrenching loose the cones, then wedging them in some crack and hammering out the seeds. And they love sunflower seeds Also our common winter tits, Great Tit and Willow Tit (and since a few years also Blue Tit) shift to vegetable fare in winter They are very fond of the sunflower seeds, which people put in their feeders; they take out one seed, fly off with it, fix it under one foot and hammer it to pieces. The Willow Tits (and the Coal Tits and Siberian Tits of the inland, rare winter visitors here on the coast) have a further trick to help them through the winter scarcity of insects: they hoard insects and seeds all through the autumn, and hide those in nooks and crannies in the trees, to find them again in winter. (Our Treecreepers often rob these hoards and profit in this way also from this habit of our winter tits)


7. Insectivores. As I mentioned earlier conditions here are very little advantageous for insectivores in winter, and almost all migrate south. But strangely enough the smallest of them all, the Goldcrest, is odd man out, and bases itself on insects all through the year. This is a very risky strategy and in some winters, when the tree-branches are during longer periods covered by a thin layer of ice, it is fatal and there is large mortality among the Goldcrests. The numbers in our area vary therefore enormously from year to year. A similar story probably lies behind the large oscillations in numbers of the cozy Long-tailed Tits.


8. Predators. Part of our birds of prey, maybe especially those that are dependent on ground -living rodents, such as the Rough-legged Buzzard, migrate south, and the same applies to most of the falcons, for whom the lack of daylight maybe is a sizeable problem (Merlin, Kestrel, Peregrine). But some, and maybe especially those that hunt on birds, and those that feed also on carrion, stay put. In town we regularly see Sparrowhawks hunting small songbirds (even among the feeders in the gardens) and Goshawks that hunt the crows and pigeons. Also the Gyrfalcon, a specialist grouse-hunter, now and then comes to town and looks for pigeons. And the majestic and here quite common White-tailed Sea Eagle circles round and hunts both birds and fish, and also takes a lot of carrion. Owls are well represented in our area; at least 8 species nest in Troms province. But we almost never see one in winter here near the coast; probably all too much snow. 


The winter lasts long in Tromsø and there is snow on the ground until mid May most years. But there are signs of springs also before that, also beyond the steadily longer hours of daylight. The eider drakes start displaying, and their somewhat dove-like crooning can be heard everywhere. And the magpies fly with branches and start to repair their most conspicuous round nests. Already in April the first spring migrants return. Among the first are usually Starlings, Oystercatcher and Common Gull, but the best signs of spring are the swarms of Snow Buntings, suddenly present everywhere in town and on the shore. These winter in Russia somewhere, stay a few weeks in our area to fatten up and charge their batteries, and then embark on the long and perilous flight across the Atlantic to their nesting areas in Greenland and Arctic Canada. When the ‘titinger’ are here and thousands of the yellow stars of Coltsfoot (Tussilago) twinkle among the rests of snow cover, we know that spring is really on its way. 

Wim Vader, Tromsø, Norway 

PS. Let me know if this was written in the right way, or whether I e.g. should have added the scientific names of the birds. Maybe it was also more than you ever wanted to know about Tromsø winter birds.



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