Questions & Answersback

Talk a little bit about the blackbird – is it really possible that the same pair of blackbirds has resided in my garden for the past two years?

Answer: The blackbird (Turdus merula) is Denmark’s commonest bird. It measures 23.5–29 cm and the male is jet black with a small orange ring around its black eye.
The female is brown in colour. The female also has a black neck with silver grey stripes.
The eggs are grey-green or grey-blue and covered in fine brown speckles.

The blackbird has two different cries; one to attract females. If it is a male it sounds like this: Sree-sreee-sreee. The other cry is known as a warning cry and sounds like this: Tchink-tchink-tchakk. Famed for its song, the blackbird can imitate bits of tunes and mobile ringtones.

The blackbird is found throughout most of Europe and in the southern part of Central Asia, India and further east as far as Southern China. The blackbird has also been introduced into Australia and New Zealand.
In Denmark the blackbird is both a migratory and a non-migratory bird. The large numbers of blackbirds that winter in Denmark (about 80%) survive on a diet which includes fallen fruit etc. - a fact that helps to explain their preference for urban gardens with fruit trees and bushes.

It is quite remarkable that the fifth of blackbirds that migrate to the slightly warmer climates in Western Europe mainly comprises females and young, whereas the black males remain to defend their territory.
Previously the blackbird mainly lived in forest areas, but from the turn of the 19th century it began a process of immigration to city areas so that today it is chiefly found in suburban and residential areas.

The blackbird is Denmark’s commonest bird with a population numbering two million breeding pairs. The blackbird’s average lifetime is 2.4 years but some have lived as long as 20. It keeps to the ground, where it moves by hopping about. It eats insects, snails and earthworms. In autumn it eats berries and fruit lying on the ground. Its enemies include the domestic cat and the magpie.

The breeding season is from April to August. It builds its nest in bushes, hedges, trees, cavities, under eaves or in similar places and the male and female jointly build the nest from twigs, dried grass, withered leaves and soil.
The female normally lays 3-5 eggs (yellow-green with brown specks), which are mainly hatched by the her alone.
The eggs take about 12-15 days to hatch and both parents take turns in feeding the young, which are ready to leave the nest about two weeks later. A blackbird couple can raise anywhere between 2 and 4 broods in a single summer. The overall population varies from about 1-1½ million in winter to around 4½ million birds in spring, when the females and young have returned from their winter migration in the south-western parts of Europe. In late summer, after the last brood of chicks has hatched but before the females and young head south, the total population numbers more than ten million birds. After the effects of winter when many wintering blackbirds starve or freeze to death and the effects of the winter migration south, the spring population is relatively stable at around 4½ million birds. And yes, it is quite likely that the same blackbird couple has lived in your garden for the past few years.