54 SEXUAL SELECTION : BIRDS. Part IL 



the sake of charming the female, is not at all incom- 

 patible ; and, indeed, might have been expected to go 

 together, like decoration and pugnacity. Some authors, 

 however, argue that the song of the male cannot serve 

 to charm the female, because the females of some few 

 species, such as the canary, robin, lark, and bullfinch, 

 especially, as Bechstein remarks, when in a state of 

 widowhood, pour forth fairly melodious strains. In 

 some of these cases the habit of singing may be in part 

 attributed to the females having been highly fed and 

 confined,^^ for this disturbs all the usual functions con- 

 nected with the re]3roduction of the species. Many in- 

 stances have already been given of the partial trans- 

 ference of secondarv masculine characters to the female, 

 so that it is not at all surprising that the females of some 

 species should possess the power of song. It has also 

 been argued, that the song of the male cannot serve as 

 a charm, because the males of certain species, for in- 

 stance, of the robin, sing during the autumn.^ But 

 nothing is more common than for animals to take plea- 

 sure in practising whatever instinct they follow at otlier 

 times for some real good. How often do we see birds 

 which fly easily, gliding and sailing througli the air 

 obviously for pleasure. The cat plays with the cap- 

 tured mouse, and the cormorant with the captured fish. 

 The weaver-bird (Ploceus), when confined in a cage, 

 amuses itself by neatly weaving blades of grass between 

 the wdres of its cage. Birds which habitually fight 

 during the breeding-season are generally ready to fight 

 at all times ; and the males of the capercailzie some- 

 times hold their hahe7is or leJcs at the usual place of 



32 D. Barriiigton, ' Phil. Transact.' 1773, p. 262. Bechstein, ' Stu- 

 benvogel,' 1840, s. 4. 



^^ This is likewise the case witli the water-ouzel, see Mr. Hepburn 

 in the 'Zoologist,' 1845-1816, p. 1068. 



