About Apus pallidus (Shelley, 1870)
Size and Similarity to Common Swift
This 16–17 cm (6.3–6.7 in) long species is very similar to the common swift, and the two can only be distinguished with good clear views.
Tail and Wing Structure
Like its relative, it has a short forked tail and very long swept-back wings that resemble a crescent or a boomerang.
Throat Coloration
It is entirely dark except for a large white throat patch which is frequently visible from a distance.
Plumage Contrast with Common Swift
It is chunkier and browner than the common swift, and its slightly paler flight feathers, underparts and rump create more contrast than seen in the common swift.
Belly Texture and Flight Action
It also has a scalier-looking belly and a subtly different flight action.
Vocalization
Its call is a loud dry scream similar to that of its relative, though possibly more disyllabic.
Breeding Range and Reproduction
Pallid swifts breed on cliffs and eaves around the Mediterranean, and on the Canary Islands and Madeira, laying two eggs.
Rarity Outside Breeding Areas
They are rare north of their breeding areas, although they are likely to be under-recorded due to identification challenges.
Migration Timing Compared to Common Swift
Because of its more southerly range, the pallid swift arrives earlier and leaves later than the closely related common swift, so particularly early or late swifts north of the normal range should be carefully observed.