Tolong jelaskan mengenai Gray-throated martin, Riparia chinensis dari Daftar burung Taiwan

Pale sand martin, Riparia diluta (A)

Common house-martin, Delichon urbicum (A)

Bulbuls are medium-sized songbirds. Some are colourful with yellow, red or orange vents, cheeks, throats or supercilia, but most are drab, with uniform olive-brown to black plumage. Some species have distinct crests.