Birds: Housemartin/Andorinha-dos-Beirais

RSPB wrote:The house martin is a small bird with glossy blue-black upper parts and pure white under parts. It has a distinctive white rump with a forked tail and, on close inspection, white feathers covering its legs and toes. It spends much of its time on the wing collecting insect prey. The bird's mud nest is usually sited below the eaves of buildings. They are summer migrants and spend their winters in Africa.

Aves de Portugal wrote:Conhecida de todos, a andorinha-dos-beirais é uma presença
bastante frequente nos binóculos dos observadores no nosso
território. A sua cauda ligeiramente bifurcada, as partes
superiores escuras contrastantes com o uropígio branco e largo,
e as partes inferiores brancas, aliadas ao bico fino e bastante  
curto, tornam esta silhueta de fácil identificação, permitindo a
separação da andorinha-das-barreiras, à qual se assemelha
nas dimensões.