The Eurasian Wren (Troglodytes troglodytes) is one of Sweden's smallest birds, yet pound for pound it carries one of the most powerful voices in the country's bird fauna. It measures just 9-10 cm in length, has a wingspan of roughly 13-17 cm, and weighs a mere 8-12 grams. Its compact, almost spherical body and short, often jauntily cocked tail make it easy to recognise as it creeps mouse-like through brushwood piles, root plates and stone walls at the forest floor. The plumage is rusty brown and densely barred across the wings, tail and flanks, with a pale eyebrow stripe standing out against an otherwise dark face and a thin, pointed bill.
Despite its tiny size, the wren's song is an explosive, trilling burst of rapid trills and clear whistles lasting around five seconds and audible several hundred metres away; it is sung from January to June but peaks in March-April, best heard at dawn along forest edges with brushwood and root plates. Its alarm call is a hard, clicking "tek-tek-tek", like two sticks being struck together. Found throughout Sweden but most numerous in the south and central regions, the national population runs into several hundred thousand to around a million pairs; southern birds are largely resident while northern populations move short distances south for winter. The male builds several round, domed nests of moss and leaves, from which the female chooses one to line and lay 5-8 eggs, incubated for about two weeks; successful males may mate with more than one female. Feeding almost exclusively on small insects and spiders gleaned from low vegetation, the wren is vulnerable to hard, snowy winters, when insect scarcity can sharply reduce numbers, though the population usually rebounds quickly in good years that follow.
Read about this species in Swedish →