The common merganser

The common merganser is a rare breeding visitor in Denmark, but along the coasts of the island of Als there are several breeding pairs. Nature guide Jens Jørgensen recommends that you take the binoculars with you on your trip so that you can really see the beautiful bird.

Moving along Sønderborg Municipality's beautiful coastline of approx. 250 km you will in several places, where there is vegetation all the way to the coast, be able to see some large boxes hanging in the trees at a height of 5-8 metres.

There are quite a few in forest Sønderskoven Als, but you can also see these boxes in other forests that grow all the way to the waters edge. These are nest boxes that have been set up to promote the population of Sønderborg Municipality's special bird of responsibility: the common merganser. It is a seaduck that is somewhat larger than the mallard and has a different profile. The male can be recognized by the metallic green head with a long red beak with a distinct hook and the generally light, slightly salmon-coloured plumage. The female is more discreet with a gray upperside and dark brown head.

During the municipal mergers back in 2007, all the country's municipalities were assigned a bird species by the state,  that they had to take special care of and support the progress of.

Sønderborg Municipality ended up getting the responsibility of the common merganser. The choice was made on the basis that the bird is a common winter visitor, but a rare breeding bird in Denmark. It is especially in the southern parts of Denmark that the species breeds and on the coasts around Als the breeding pairs are on the rise.

The common merganser is a cavity nester, i.e. it likes to build its nest in old hollow trees. The past several decades of intensive forestry, where old trees have been cut down, have not been favorable for cavity-nesting birds in general. Fortunately, the trend has reversed and measures are being taken in many places to improve the conditions for flora and fauna. After all, it takes many years to get the old hollow trees back, so to increase the supply of suitable nesting places it can help to hang up nest boxes in the meantime.

The bird has responded well to the offer of housing, and the population has improved in recent years. This is probably due both to access to nest boxes, but also to the fact that the bird has been completely protected in Denmark. In the past, the bird was hunted, as its food consists of fish, and it has a fondness for especially eels and fish of the salmonids species - which we humans also like.

The bird is not particularly shy and quite willing to be observed. In winter, migratory birds are often seen staying close to the coast in larger or smaller flocks. In the summer you can be lucky to see birds with chicks. Immediately after hatching, the chicks fearlessly throw themselves out of the nest box to follow the parent birds into the water, where they look for food. The female takes good care of the chicks and you can sometimes see the young laying on her back if there is danger on the way or they simply need a rest.

The nesting boxes that are not used by the merganser are certainly not redundant. The night owl also likes to occupy a box as a home here and there.

There is always fresh air and great experiences out in nature waiting, so it's just a matter of going on a trip. Perhaps you will see a common merganser along the coast, or perhaps you will meet one of Sønderborg Municipality's nature guides who wears a Logo with, among other things, the common merganser.

Have a nice trip and remember the binoculars!

Jens Jørgensen
Nature guide in Sønderborg Municipality