Common House Martin

• Its nest is a closed half-sphere of mud pellets with a small entrance at the top, put up by the pair in about ten days over hundreds of trips.
• A study in Scotland found that 15% of the chicks were not the offspring of the male raising them, and that 32% of broods contained at least one chick by another father.
• The chicks of the first brood stay with the family and help feed their siblings from later ones.

Skeleton type

Vertebrate - internal bony skeleton (bird)

Habitat & environment

Towns and cities across temperate Eurasia and North Africa, where it breeds under eaves and bridges. It keeps colonies on natural rock faces up to 2,200 m of altitude. It winters in sub-Saharan Africa and tropical Asia

Gestation / incubation

12-19 days of incubation (usually 14-15), by both parents. The chicks stay in the nest for 24 to 28 days

Litter / clutch size

3-6 eggs, with two clutches a year and sometimes three. The size decreases: an average of 5 eggs in the first, 4 in the second and 3 in the third

Sources consulted: SEO/BirdLife (ficha del avión común occidental); IUCN Red List; Asturnatura; Turner y Rose 1989, Swallows & Martins; Carrascal y Palomino 2008, Las aves comunes reproductoras en España

Best time: From March to September in Spain; the first arrive in February in the south of the peninsula