The Umeälven River Delta

The large Umeälven River Delta is built up of vast quantities of sediment from the two mountain rivers, the Umeälven and the Vindelälven. The active delta encompasses an area of about 15 square kilometres in both the large Österfjärden bay north of Obbola and Holmsund and in the smaller Västerfjärden bay - a separate western riverbed. The land uplift and deposition of sediment cause the land areas of the delta to change very quickly, though erosion in the upper portions of the delta also contributes to extremely large quantities of material being transported in the water. Calculations show that the rivers deposit as much as 100,000 tonnes of material in the delta annually. Studies of old maps also show how quickly the currently existing islands in the delta have formed. The island Stora Tuvan did not even have a name on a map from 1822; it is only about one hundred metres large. At almost 1 square kilometre, Stora Tuvan is now one of the biggest islands in the delta and is covered in lush deciduous forest and even some spruce on the oldest parts of the island. The most recent large land areas that formed are a pair of new islands south of Villanäs, which began to rise out of Österfjärden during the 1980s. These two islands are currently excellent for birding.

The Umeälven River Delta also has 200 hectares of deciduous forests, which are extremely valuable for both birds and insects, since they are essentially untouched and produce vast quantities of dead wood.

The delta is probably best known for its wetland birds. It is one of the areas in Sweden covered by the international Convention on Wetlands because of its major significance for migratory wetland birds. Every year vast numbers of geese, ducks and waders rest here, mainly during the spring migration but also during the autumn. The geese and ducks usually follow a daily pattern in which they eat at the Röbäck and Degernäs flatlands just north of the delta during the day, while resting and washing in the water of the delta at night. The number of geese usually peaks in late April and early May, when a few thousand can often be seen resting on the water and out in the fields. Together with large flocks of cranes (Grus grus) and whooper swans (Cygnus cygnus) they make the area into a true eldorado at this time of year.

In addition to the water areas, the deciduous forests also host a wealth of bird life. It was therefore not just chance that this was where the endangered white-backed woodpecker (Dendrocopos leucotos) carried out its only known Västerbotten breeding during the 1990s. Other species of woodpeckers that are content in the deciduous forests are the lesser spotted woodpecker (Dendrocopos minor), the grey-headed woodpecker (Picus canus), the black woodpecker and the three-toed woodpecker (Picoides tridactylus).

This abundance of birds attracts birds of prey. The peregrine falcon (Falco peregrinus) is one of the unusual species that regularly hunts in the delta in spring. The wealth of birds also makes the Umeälven River Delta an area known throughout Sweden among birdwatchers.

Since 2002 there is now a large area with restored shoreline meadows north of Västerfjärden. Cattle graze on these shoreline meadows in summer and the meadows are excellent for birding.

The delta's shoreline meadows and deciduous forests are also home to many insects. A total of 20 species of dragonflies are found in the shoreline meadows and as many as 14 insects associated with dead wood and listed as endangered have been found in the deciduous forests.

In 2002 efforts are underway to protect the Umeälven River Delta as a nature reserve. The county administrative board is responsible for this initiative. Once the area is protected as a nature reserve it will also become more accessible for visitors.