THE BIRDS OF PREY. 



255 



HEAD AND BILL OF SEA EAGLE. (After Keulemans.) 

 (a) bony eye-sbelf ; (6) cere. 



ou t is how to tell an Owl from a Hawk. At one time it was supposed that all Owls came out by 

 night and all Hawks by day, and so they were separated into two great divisions, which were called 

 diurnal birds of prey* and nocturnal birds of prey.f Now, 

 however, that the habits of birds are getting better ob- 

 served, these divisions have to be abandoned as not being 

 entirely true, for there are Owls which are quite at home 

 in the daylight, when they hunt for their food like any 

 other bird of prey, and at least one kind of Hawk is 

 known, whose habit it is to feed on Bats in the evening. 

 This is Andersson's Pern, J a kind of Kite, allied to 

 the Honey-kite of England. It is found only in the 

 Damara Country, in South - western Africa, and in 

 Madagascar. A far better way to distinguish Hawks 

 from Owls is seen in the foot, as the latter have the outer toe reversible that is to say, they 

 can turn their outer toe backwards or forwards as they please. This is easily observed in the living; 

 birds; and any one examining a caged Owl in the Zoological Gardens will see that it sits with its toes 

 in pairs two in front and two behind. A Hawk cannot do this, all his toes being arranged as in a 

 little perching bird, such as a Sparrow or a Canary, three in front and one behind. Then, again, Owls 

 have no " after-shaft " to the feathers, a structure which most Hawks possess. The " after-shaft " is. 

 the small accessory plume, which springs from the under-side of the main feather. In some birds it 

 is very large, in others small. It occurs on the body feathers only, and is never found in the 

 quills or tail feathers (see p.. 238). Lastly, in addition to the reversible outer toe, and the 

 absence of an accessory plume or after-shaft, Owls may be distinguished from all other birds of prey, 

 save one, by the proportions of their leg-bones. In the skeleton figured on p. 241 the three principal 

 leg-bones are pointed out ; and it is the length which the tarsus bears in proportion to the tibia, 

 that is here insisted on. In the Owls the tarsus is only about half the length of the tibia ; this 

 is never the case in a Hawk, in which these two bones bear different proportions the one to the 

 other, according to the sub-family. Thus in Sparrow-Hawks and Harriers the tibia and the tarsus 

 are equal in length. In Eagles and Buzzards, Kites and true Falcons, the tibia is always much 

 longer than the tarsus, but is never double its length, as it is in the Owls. The term " Hawk," which 

 has been employed throughout the foregoing sentences, is intended to apply to every bird of prey 

 excepting the Owls, with the sole exception of the Osprey. The habits of the Osprey are noticed 

 later on, but they may be briefly stated to be similar to those of a Sea-Eagle, its prey consisting- 

 entirely of fish, while its plumage and general appearance are also those of an Eagle, so that in many 

 places it is popularly known as the " Fish Hawk," or "Fishing Eagle;" but here the resemblance of 

 the Osprey to the Eagle ends, and in its other characters it is very like an Owl. The tibia is more 

 than double the length of the tarsus, as in the Owls ; the feathers of the body have no after-shaft, as 

 in the Owls, and the outer toe is reversible, as in the Owls. Possessing, therefore, as it does, some of 

 the most prominent features of the Eagles, as well as some of the most striking peculiarities of the 

 Owls, the Osprey holds an intermediate position between these two sub-orders of birds. 

 The birds of prey, then, may be separated into three sub-orders : 



(). Outer toe not reversible ; tibia varying in lengtb in proportion to the tarsus, sometimes equal to it, but never 

 double the length of the latter ; body feathers with an after-shaft or accessory plume. (American Vultures 

 excepted.) 



I. Hawks (Falcones}.\\ 



(b). Outer toe reversible ; tibia double the length of tarsus ; body feathers without an after-shaft or accessory plume; 

 plumage compact, as in an Eagle ; no facial disk. 



II. Ospreys (Pandiones),^ 



(c). Outer toe reversible; tibia double the length of tarsus; body feathers without an after-shaft ; plumage soft and 

 fluffy ; a facial disk. 



III. Striges;** Owls. 



Accoutres diurni of authors. 

 || Falco, a Falcon. 



f Accip'tres nocturni of authors. J Machcerhampkus Anderssoni. Accipitrince 

 ^[ flav&uav, a Greek mythological name. ** o-rpt'-yf, an Owl. 



