Pale swifts are summer visitors to Portugal. In Berlengas, they nest in rock cavities of Estelas Islet, being that little is known about this population. Pallid swift differs from Common swift Apus apus for its more brownish colour,, lighter throat and wings with more rounded tips. However, juveniles are very difficult to distinguish. Pale swifts arrive earlier to their breeding grounds, in the beginning of March, lay two clutches during the breeding season, and return to their wintering latitudes in Africa in late September. A study conducted in the Arrábida Nature Park found that these swifts are very loyal to their breeding colonies and can live at least 14 years!