Brown Booby

The booby's head and upper body (back) is covered in dark brown to black plumage, with the remainder (belly) being a contrasting white. The bare part colours vary geographically, but not seasonally. The species also displays sexual dimorphism of the bare part colours, the males having a blue orbital ring, as opposed to the yellow orbital ring of the female. In addition the male of subspecies S. l. brewsteri is distinctly plumaged in having the forehead, forecrown and chin white, merging to a greyish brown neck and breast. The female booby reaches about 80 centimetres (31 in) in length, her wingspan measures up to 150 cm (4.9 ft), and she can weigh up to 1,300 g (2.9 lb). The male booby reaches about 75 centimetres (30 in) in length, his wingspan measures up to 140 cm (4.6 ft), and he can weigh up to 1,000 g (2.2 lb). Unlike other species of sulid the juvenile plumage already resembles that of the adult. They are gray-brown with darkening on the head, upper surfaces of the wings and tail, while the lower breast and underpart plumages are heavily flecked brown on white. Juveniles of subspecies S. l. brewsteri are once again distinct in having the underpart plumage more evenly mouse brown. Their beaks are quite sharp and contain many jagged edges. They have fairly short wings resulting in a fast flap rate, but long, tapered tails. While these birds are typically silent, bird watchers have reported occasional sounds similar to grunting or quacking.