Both Phedina martins have grey-brown upperparts and paler, heavily streaked underparts.
Adult Mascarene martins of the nominate subspecies are 15 cm (5.9 in) long with wings averaging 116.6 mm (4.59 in) and weigh 23.9 g (0.84 oz).
The tail is slightly forked and the wings are blackish-brown.
The Madagascan subspecies is overall paler and larger-billed than the nominate form.
It has denser streaking on the breast, but only very fine lines on the lower abdomen and on the white undertail.
It is distinctly smaller than the nominate subspecies, 12–14 cm (4.7–5.5 in) in length with an average weight of 20.6 g (0.73 oz).
The Brazza's martin is 12 cm (4.7 in) long with dark brown wings averaging 100.5 mm (3.96 in).
It has a brownish tint to the breast plumage and a square tail.
Both species have dark brown eyes and a black bill and legs.
Juvenile birds have more diffuse breast streaking, and white tips or buff edges to the feathers of the back and wings.

Both species can be distinguished from most other swallows in their breeding or wintering ranges by the streaking on the underparts.
Although the lesser striped swallow has white underparts with dark streaking, it is larger, has a deeply forked tail and a very different plumage, with dark blue upperparts, a red rump and a chestnut head.

The vocalisations of the two martins are quite different.
Mascarene martin has a warbled siri-liri siri-liri song given in flight or when perched; some calls given by perched birds end in a glissando.
Other vocalisations may be used during mating or displays of aggression.
There is a chip contact call, and the young birds produce a fast twittering sound when begging for food.
Birds wintering in mainland Africa are usually silent.
The song of Brazza's martin consists of a series of short notes increasing in frequency which are followed by a complex buzz and sometimes completed by a number of clicks.
The song becomes increasingly loud, although the final clicks are quite soft.
The song is similar to that of the banded martin, and does not resemble that of the Mascarene martin, suggesting unresolved taxonomic problems.

The flight of both species is heavy, with slow wingbeats interspersed with glides.
Both Phedina martins have grey-brown upperparts and paler, heavily streaked underparts. Adult Mascarene martins of the nominate subspecies are 15 cm (5.9 in) long with wings averaging 116.6 mm (4.59 in) and weigh 23.9 g (0.84 oz). The tail is slightly forked and the wings are blackish-brown. The Madagascan subspecies is overall paler and larger-billed than the nominate form. It has denser streaking on the breast, but only very fine lines on the lower abdomen and on the white undertail. It is distinctly smaller than the nominate subspecies, 12–14 cm (4.7–5.5 in) in length with an average weight of 20.6 g (0.73 oz). The Brazza's martin is 12 cm (4.7 in) long with dark brown wings averaging 100.5 mm (3.96 in). It has a brownish tint to the breast plumage and a square tail. Both species have dark brown eyes and a black bill and legs. Juvenile birds have more diffuse breast streaking, and white tips or buff edges to the feathers of the back and wings.
Both species can be distinguished from most other swallows in their breeding or wintering ranges by the streaking on the underparts. Although the lesser striped swallow has white underparts with dark streaking, it is larger, has a deeply forked tail and a very different plumage, with dark blue upperparts, a red rump and a chestnut head.
The vocalisations of the two martins are quite different. Mascarene martin has a warbled siri-liri siri-liri song given in flight or when perched; some calls given by perched birds end in a glissando. Other vocalisations may be used during mating or displays of aggression. There is a chip contact call, and the young birds produce a fast twittering sound when begging for food. Birds wintering in mainland Africa are usually silent. The song of Brazza's martin consists of a series of short notes increasing in frequency which are followed by a complex buzz and sometimes completed by a number of clicks. The song becomes increasingly loud, although the final clicks are quite soft. The song is similar to that of the banded martin, and does not resemble that of the Mascarene martin, suggesting unresolved taxonomic problems.
The flight of both species is heavy, with slow wingbeats interspersed with glides.
Phedina