Bill strong, straight, compressed, pointed ; the culmen flattened, broad at the base, curved at the end but not hooked ; upper mandible with a linear groove on each side near the culmen ; nostrils completely closed in adults, minute and basal in young birds ; inner margins of both mandibles serrated, especially towards the tip. Sides of head to behind the orbit, chin, and part of throat naked, the feathered area ending on the throat, in all Indian species, in a transverse line. Wings long, pointed; tail long, wedge-shaped. Tarsus short; outer and middle toes equal; claw of middle toe broad and pectinated.
About six species are known, including the Gannets, which inhabit temperate regions and have a narrow naked strip running down the middle of the throat, and the Boobies, which are tropical. Three of the latter are said to be found in Indian seas.
Key to the Species.
a. Tail-feathers 14.
a1. Head,neck, and upper parts brown in adults ; feet pale yellow……………………S. leucogaster, p. 346.
b1.Head, neck, body, and tail white in adults ;
feet red……………………S. piscatrix, p. 347.
b. Tail-feathers 16.
c1. Head, neck, and body white in adults ; tail blackish ; feet slaty……………………S. cyanops, p. 347.
The members of this genus are said to be oceanic birds, but they are more commonly found singly or in flocks about reefs and islands, and they breed chiefly on isolated rocks in the sea, some times near continents, laving a single egg, which is externally chalky white, but bluish green when the outer layer is removed. All have a steady, rather powerful flight, generally to be recognized by the bird's habit of alternately making a few rapid beats with the wings and then sailing for some distance with wings extended. They feed upon fish, the tropical species very generally on flying-fish, but remains of cuttlefishes have also been found in their stomachs. The Gannets, or Solan Geese, as they are often called, dash into the sea after their prey from a considerable height and with great force, but Boobies appear less addicted to this style of fishing. The name Booby appears to be derived partly from the stolid appearance of the birds, partly from their frequently settling on vessels and allowing themselves to be easily captured.