gay and conspicuous, the female dull and obscure, the nest is open and the sitting bird exposed to view*. I will now proceed to indicate the chief facts that support this statement, and will afterwards explain the manner in which I conceive the relation has been brought about.
We will first consider those groups of birds in which the female is gaily or at least conspicuously coloured, and is in most cases exactly like the male.
- Kingfishers (Alcedinidæ). In some of the most brilliant species of this family the female exactly resembles the male; in others there is a sexual difference, but it rarely tends to make the female less conspicuous. In some, the female has a band across the breast, which is wanting in the male, as in the beautiful Halcyon diops of Ternate. In others the band is rufous in the female, as in several of the American species; while in Dacelo gaudichaudii, and others of the same genus, the tail of the female is rufous, while that of the male is blue. In most kingfishers the nest is in a deep hole in the ground; in Tanysiptera it is said to be in a hole in the nests of termites, or sometimes in crevices under overhanging rocks.
- Motmots (Momotidæ). In these showy birds the sexes are exactly alike, and the nest in a hole under ground.
- Puff-birds (Bucconidæ). These birds are often gaily coloured; some have coral-red bills; the sexes are exactly alike, and the nest is in a hole in sloping ground.
- Trogons (Trogonidæ). In these magnificent birds the females are generally less brightly coloured than the males, but are yet often gay and conspicuous. The nest is in a hole of a tree.
- Hoopoes (Upupidæ). The barred plumage and long crests of these birds render them conspicuous. The sexes are exactly alike, and the nest is in a hollow tree.