Dunnock

• It has one of the most complex mating systems of any European bird: it forms trios of one male with two females or one female with two males, and also pairs and larger groups.
• When a female has two males, both help her raise the brood in proportion to how much they have mated with her, and her clutch can be double the usual size.
• It is one of the common cuckoo's favourite victims, and is parasitised by it regularly.

Skeleton type

Vertebrate - internal bony skeleton (bird)

Habitat and environment

Scrub, hedgerows, heathland and woodland edges with dense vegetation. As a breeder it is limited to the northern third, the Sistema Ibérico and the Sistema Central, with an isolated pocket in Sierra Nevada; in winter it occupies practically the whole peninsula and the Balearics

Birth weight

Altricial: born blind, naked or with sparse down and entirely dependent

Size at birth

The chicks hatch partly covered in black down

Sexual maturity

12 months

Gestation / incubation

12-13 days, by the female alone. The chicks leave the nest at 12 days

Litter / clutch size

3-7 deep blue eggs, though when the female mates with two males she may lay as many as 12. Two or three clutches between April and August

Sources consulted: SEO/BirdLife (ficha y III Atlas de las aves en época de reproducción en España); IUCN Red List; Asturnatura; Taboada Martínez y Justo Álvarez 2022, III Atlas; Ponce y Leal 2013 (SEO/BirdLife); MITECO - Inventario Español de Especies Terrestres; Cramp 1988

Best time: From October to March in most of Spain, when the European wintering birds arrive