22 THE BIOLOGY OF BIRDS 



parent more comfortable. The eider-duck in leaving her 

 nest for a meal draws the quilt of down over the eggs. 

 MacGillivray counted 2379 feathers in the " feather-poke " 

 nest of the long-tailed-tit. They belong to other birds. 



(6) A number of peculiar uses may be grouped together. 

 We have already mentioned the belief of some ornithologists, 

 that the peculiar powder produced by the disintegration 

 of the powder downs in herons, bitterns, parrots, and 

 other birds is useful in keeping the plumage in good 

 order and checking the multiplication of ectoparasites. It 

 is seen as a bloom on the beak and face of the African parrot 

 and on the beak and face of cockatoos. 



Other feathers form the eyelashes and others project 

 near the base of the beak, both probably akin to filoplumes. 



It is probable that conspicuous white patches, as on the 

 wheatear's rump, may help to distract the eye of the bird of 

 prey from the more vulnerable head. It may also be that 

 conspicuous markings help in the recognition of kin by kin. 



Succession of Plumages. — Many a young bird, like the 

 pigeon squab, is practically naked when newly hatched ; 

 its skin shows numerous feather tracts or pterylae — rows of 

 pits or follicles — which form a characteristic pattern. The 

 succession of different sets of feathers is not altogether 

 clear ; we shall begin with an outline of the usual version 

 of the story. 



There is in most cases a preliminary nestling suit of 

 down-like feathers, which are technically called " neos- 

 soptiles " (Greek, neossos, a chick), in contrast to the sub- 

 sequent adult feathers or " teleoptiles " (Greek, teleos, 

 mature), whether these be contour feathers or downs. In 

 typical cases some of the nestling down feathers (called pre- 

 pennae) are immediately succeeded by contour feathers of 

 the adult type, while others (called preplumulae) are 

 succeeded by adult down feathers. In some cases, e.g. 

 nestling Owls, only prepennae are developed ; in other 

 cases, e.g. nestling Cormorants, there are only preplumulae. 

 In a few cases the bird has no feathers before the teleoptiles. 



The down-like nestling feathers or neossoptiles are 



