Suomen Luonto
English summaries 6/2003

Wherever there's a redstart there's a cuckoo too
By Lassi Kujala
Pages 4-9

In Finland the redstart is the cuckoo's favourite foster parent. Next in line are the meadow pipit, white wagtail and brambling. Female cuckoos are specialists; those parasitising a redstart, lay eggs that look exactly the same as the ones of its host. She lays only one egg per nest until she reaches a total of around ten.

Baby cuckoos hatch after an extremely short incubation period. Upon hatching, they promptly push any eggs or nestlings belonging to the host out of the nest. The foster parents gaze proudly at their chubby offspring, who is always hungry. In actual fact they do not feed the nestling but the nest bowl. Cuckoo nestling also has a shrill voice equivalent to that of a clutch of six young redstarts all clamouring to be fed. Swiftly the young cuckoo outstrips in size its unwitting parents.

The sound of the cuckoo is without doubt to Finns the most familiar of all bird songs. Many superstitions and tales are connected with it. Few people, though, have actually seen a cuckoo and when one is glimpsed it is usually regarded as a small hawk. Small wonder that, according to an old folk tale, after ceasing to sing the cuckoo changes into a hawk and flies away.

Worst water shortage since the 1940s
By Juha Kauppinen
Pages 16-19

Hydrologist Esko Kuusisto says that in a normal year Finland's soil and bedrock contain 600 cubic kilometres of water on May 1st. On 01.05.2003 there were 21 cubic kilometres less than normal, reports Kuusisto. While this deficit may appear small, in practice it is large. Finland's deepest and third largest lake, Päijänne, contains 17 cubic kilometres of water - thus the groundwater shortfall amounts to a whole Päijänne-lakeful of water.

If surface waters (lakes, pools), the moisture in the soil, and the water in bogs and mires, are all taken into account, the present shortage amounts to 50 cubic kilometres - in other words, the country has three Päijänne-lakefuls less water than it ought to have. Kuusisto says that the situation would improve over the summer months, if it were to rain 180 mm more than during a normal summer. However, this water should be distributed such that it ends up where the lack of water is greatest.

The worst drought since the 1940s has been obvious in wells and at waterworks. Wells have gone dry in the countryside and around towns and cities. Serious problems have been encountered at dairy farms, where the need for water is great. For townsfolk the shortage has meant a reduction in electricity output at hydropower stations and higher energy prices.

If the current situation persists, many more people will feel its effect. Water taps may dry up in cities and settlements, as 60 % of Finland's piped water comes from groundwater or artificial groundwater. Towns and cities drawing their water from lakes are unlikely to experience difficulties - for example, Helsinki and the entire Helsinki Metropolitan Area take their water from Lake Päijänne. Finland's deepest lake will not dry up, even if it stops raining for a long, long time.

The natural environment also suffers when there is excessive dryness. In particular, vegetation growing on bedrock is liable to be harmed if the drought is a prolonged one. Lower water levels in shallow or eutrophicated lakes or bays may prove catastrophic. Low rainfall could also lead to an increase in salinity in the Baltic Sea, which would affect the marine ecology.

Frenzy at the lake, peace on the mire
By Markku Lappalainen
Pages 20-23

Established in 1993 to protect the rich bird waters of Lake Puurijärvi and the extensive mires of Isosuo, with their alternating hummocks and small pools, Puurijärvi and Isosuo National Park is located in south-western Finland. Both areas have a unique flora and fauna and the national park ranks among Finland?s best sites for observing birds, for instance. To make watching the birds easier, observation towers have been erected from which a good view can be obtained over large areas of the park. Duckboards laid across the wetter places make navigating the large mire less of a hassle.

Puurijärvi offers those interested in birds a wealth of things to see. Around 10 pairs of cranes nest along its fringes, in addition to which there is an impressive number of subadult individuals without nests. The lake is occupied in spring by a colony containing 1,200 pairs of black-headed gulls and around 50 pairs of little gulls, black terns, bitterns, red-necked grebes, whooper swans, coots, water rails and spotted crakes.

Several marsh harriers, ospreys, white-tailed eagles and hobbies hunt over or around the lake, and at night eagle owls take to the wing for the same purpose. Puurijärvi also constitutes an important resting place for migrants, especially whooper swans, bean geese and various kinds of ducks. In short, Puurijärvi is Finland's second best inland 'bird paradise', being beaten only by the famous Siikalahti in Parikkala.

Mires are the national park's other element and are of a rather different character. After the prolificness of life on the bird lake, they are far more subdued and quiet. The plaintive whistle of the golden plover, the sharp cries of cranes, a silent great grey shrike atop a pine sapling, the ghostly call of a red-throated diver on a mire pool, the willow grouse's mindless cackle, and the clear song of the rustic bunting all tend to be rare in southern Finland.

Life of the eider
By Pekka Hänninen

In the Porvoo outer archipelago east of Helsinki lies the Söderskär group of islands. A Finnish Game and Fisheries Research Institute research station is located there which has been conducting intensive studies on the eider (common eider) since 1949. Incubating females are ringed at the nest using coloured rings, making it easy to identify them with binoculars or a telescope. Nowadays they are also subjected to DNA analysis. All the nest sites are numbered.

Eiders arrive in the Archipelago as soon as the ice melts from the sea in spring. In mild winters they appear as early as at the beginning of March, but after severe winters they are not seen until the end of April. Pairs distribute themselves over the islands and begin their mating displays. On calm days the ducks' characteristic cries fill the entire Archipelago. Once the females have laid their last egg and begun to incubate, the males seek out each other?s company. Soon they move out to the open sea, and even to the southernmost Baltic, for moulting.

Female eiders sit on the eggs for less than four weeks. They sit motionless, their spotted brown plumage providing excellent camouflage. Often the bird will be out in the open, without any other protection. Yet detecting it as it incubates may be very difficult indeed. The females eat no food at all while hatching out their eggs. They only leave the nest for a short time in the night in order to drink. Each bird may lose as much as 40 % of its body weight during incubation.

Mankind has exploited eiders since the Stone Age. Archaeologists have discovered eider bones in old settlements. The birds provided meat, eggs and eider down. This persecution reached a peak in the late 19th century, when the Archipelago's eider populations took a sharp downward turn. Thanks to official protection, eider populations gradually began to expand, although they were still very low during the 1920s and 1930s. Part of the reason was spring hunting, which continues in Finland and Åland even today, despite having long been prohibited elsewhere.

In the mid 1970s Finland's eider population began to expand rapidly. There may have been several reasons for this. Spring hunting ceased in Sweden, hunting in Finland was reduced, conservation areas were established, eggs were no longer collected, and eutrophication of the Baltic allowed the eider?s chief food, the common mussel, to increase. In the mid 1980s there were 200,000 breeding pairs of eiders in Finland. From then on the population declined, falling by almost one half. Scientists are not sure of the real reason for this, but at least lead, virus infections and a reduction in food could conceivably be responsible.

Erratics and the memory of stone
By Marja Innanen
Pages 42-46

Erratics - large boulders - lie scattered everywhere in Finland. They stand alone in forest or field, or stretch in long chains for quite a distance. Stones have always fascinated people, who have tried to discover the reasons for their being where they are. They have fallen from the sky or some giant has thrown them down, it has been thought. Magical properties have been associated with many erratics. Nowadays the location of a lot of these 'special boulders' is marked in travel guides and on maps.

Finland's largest erratics are 15-20 metres in length and sometimes even higher than this. The largest visible specimen is Kukkarokivi, in Ruissalo, Turku: it is 40 x 30 metres long and 12 metres high, and as much is hidden from view underwater. Elsewhere in the world there are far larger boulders, measuring up to hundreds of square kilometres in area.

Erratics are formed when a glacier creeps across bedrock of a certain type. Such suitable forms of rock include granites, and especially rapakivi granite. Bedrock is shattered by changes in temperature and by alternately freezing and melting water. Even large boulders may be borne along by a glacier, to be dumped several hundred kilometres away. Erratics formed of Finnish rapakivi granite are common in Estonia, but many of them are found as far away as Poland and central Russia.

Teksti: Leigh Plester