Chætura dubia McGregor, Bur. Govt. Lab. Manila (1905), 34, 15,
pl. 12; McGregor and Worcester, Hand-List (1906), 59.
Mindoro (McGregor).
Adult.--General color blackish brown; back and rump noticeably
lighter, being light seal-brown, each feather with a subterminal,
more or less concealed area or band of bluish violet; head and body
shot with bluish violet gloss, strongest on chin, throat, breast,
and sides of head and neck; a large white patch on each side between
nostril and lores; crissum white, each feather blackish brown at its
base, the long tail-coverts with edges also blackish brown except
near tip; extending diagonally upward and forward on each flank,
a wide white stripe connected with the white crissum behind as in
Chætura gigantea; exposed edges of wing-feathers black, inner webs
of primaries largely light brown; inner webs of alula, primary- and
secondary-coverts shot with greenish blue gloss; tertiaries greenish
blue; lining of wing brown, each feather bordered with dirty white
which has its greatest extent on innermost feather; axillars dark
brown, shot with bluish violet gloss, exposed portion of tail blackish,
the concealed basal portion glossed with green and blue. Bill black;
iris brown; legs and feet reddish flesh; nails light brown.
Male: Length, 229; wing, 220; tail, 64; bill from frontal feathers,
10; bill from anterior margin of nostril, 7; tarsus, 18. Female:
Length, 234; wing, 218; tail, 64; bill from frontal feathers, 10;
bill from anterior margin of nostril, 7; tarsus, 18.
This fine species is known from the type specimens, a pair taken
on the Baco River, Mindoro. It requires comparison with Chætura
celebensis. The following notes probably refer to Chætura dubia:
"We think it probable that C. gigantea will eventually be found in
Mindoro. We repeatedly saw a very large swift in that island, but
it always kept well out of range. We thought it to be C. gigantea
but could not, of course, be at all sure. On our first trip we found
C. gigantea flying low over the mangrove swamps in Palawan and had
no special difficulty in securing specimens. On our second trip,
however, we were less fortunate, as the few individuals that we saw
kept out of range." (Bourns and Worcester MS.)