158 



AVES. 



the accessory plume is large, but of soft and downy texture : others have it reduced to 

 a small tuft of down ; while in many it is absent altogether. In some Birds, the 

 vanes of the feathers are to a variable extent united, or soldered into an uniform mass , 

 and there are various additional modifications, too numerous to admit of detail]. The 

 touch must be feeble in all parts that are covered with them ; and, as the beak is 

 almost always corneous and but little sensitive, and the toes are invested with scales 

 above and a callous skin underneath, this sense can be of little efficacy in the class of 

 Birds. [In the Snipes and LmnelUrostres , however, the sense of touch in the bill must 

 be delicate, as testified by their manner of feeding, as well as by the many nervous 

 papillae distributed over its surface. The enormous bill of the Toucans, also, is 

 very sensitive ; and even the hardest bills are traversed by ramifications of the fifth 

 pair of nerves, which terminate in scattered papillae.] 



The feathers are cast twice in the year [in some instances, but by far the greater 

 number of Birds renew their plumage in autumn only ; and in no instance are the 

 wing-primaries shed excepting in autumn, or at that moult which corresponds to the 

 autumnal moult. Many, as the Hawks, larger Gulls, &c., retain their entire nesthng 

 "•arb till the second autumn; while others, as the Crows, Starlings, &c., renew every 

 feather previous to the first winter ; and there are some groups, as that of the 

 Thrushes, together with various double-moulting Birds, as the Pipits and Wagtails, 

 which change their first clothing plumage soon after quitting the nest, but retain their 

 nestling primaries until the second autumn — (that is, until the third renovation of the 

 body feathers). In the Cormorants, Grebes, &c., some additional ornamental plumes are 

 developed towards the commencement of the breeding season ; at which time various 

 other Birds undergo a change of colour, unaccompanied by any moult * ; while others, 

 again, cast the terminal portion (commonly of a dingy hue) of the greater number of 

 their feathers, which during winter had concealed the brighter tints of summer : two 

 or more of these various modes, by which a seasonal alteration of appearance is effected, 

 being frequently simultaneously observable in the same individual.] In certain species, 

 the winter plumage differs in its colours from that of summer ; and in the greater 

 number, the female differs from the male by colours less vivid, and the young of both 

 sexes then resemble the female. When the adult male and female are of the same 

 colour, the young have a peculiar livery. [As thus expressed, however, these rules 

 require to be qualified by numerous exceptions : the true enunciation of them being, 

 that, when the plumage of the young differs from that of the adult male, or of the 

 female in those few cases where (as in the common Gallinule) this sex is the brighter, 

 that of the other sex may be similar to either of those extremes, or is in various 

 degrees intermediate: the male and female of the common British Redstart, for 

 instance, are dissimilar, and the young do not resemble the adult female ; but the 

 "•arb of the latter is intermediate to those of the adult male and young.f] 



* When this takes place, as in certain Gambets {^Totanus), the 

 colouring' matter is often entirely absorbed previously to the autumnal 

 change of feather ; and in some double-moulting species, as the Golden 

 Plover, it conunoiiiy happens in spring that the colouring secretion 

 tinges the old feathers that are loose, and ready to drop off , — tlius 

 proving that a circulation obtains in the pores of feathers, even up to 

 the period of their being naturally cast.— Ed. 



t There is a typical state of plumage in most groups of Birds,which, 

 in certain species, as tlie Tree Sparrow, is common to old and young 

 of both sexes ; but which is very usually obtained only by the adult 

 male, as is observable in the common House Sparrow : in the Robin, 

 Goldfinch, &c., to select other familiar examples, it is acquired by the 



jf both sexes ; and, in the Common Gallinule, only by the 

 female. There are also many Birds in which neither sex 

 assumes this comparatively advanced livery: the larger Bitterns, for 

 example, both sexes of which permanently retain the markings and 

 style of colouring characteristic of only the first or immature dress of 

 the Uwarf-bitterns (subgenus Ardeola); the adult male common 

 Bunting {Emberiza miliaria), also, thus exhibits correspond- 

 ing livery to that proper to the females and young of the rest of its 

 group, never advancing, like the males of the other species of Bunting, 

 beyond its primitive nestling colours and markings. We are led to 

 recognize, therefore, two extreme conditions of plumage as riganla 

 the colouring, — one generally, but not always, characteristic of m.itu- 



