80 BIRD GALLERY. 



in plumage. Other forms represented are the Madagascar Kestrel 

 (Dissodedes zoniventris) (961), the Australian Quail-Hawk (Hieracidea 

 berigara) (963)^ and the Bush-Hawk [Harpa australis) (964). 



Family III. Pandionid^. Ospreys. 



'C 63 1 '^^^ ^^^^ family includes the Ospreys and Fishing-Eagles, which occupy 

 a somewhat intermediate position between the Hawks and Owls. They 

 resemble the latter in possessing a reversible outer toe, which can be 

 turned backwards or forwards at will, and the soles of the feet are pro- 

 vided with spicules to enable them to hold the fish on which they 

 prey. The Osprey or Fish-Hawk {Pandion haliaetus) (966) is a cosmo- 

 politan species and, though now a very rare bird in Great Britain, 

 bred till within a few years ago in one or two places in the North of 

 Scotland. The other allied genus, Polioa'etus, includes three species 

 of Fishing-Eagles inhabiting the Indo-Malayan region. The Grey- 

 headed form (P. ichthy actus) (966) haunts rivers and its food consists 

 almost entirely of fish. 



Order XXIII. STRIGIFORMES. Owls. 



[Case 54.1 The Owls form a well-marked group of Birds of Prey and are mostly 

 nocturnal in their habits. They are easily distinguished from all the 

 Hawks, except the Harriers, by the facial disc surrounded by a ring of 

 short crisp feathers and by the absence of the cere or naked wax-like 

 skin at the base of the bill seen in almost all the true Accipitres. ' The 

 large eyes are directed obliquely forwards and the upper eyelid shuts 

 over the eye, and not the lower as in birds generally. The external 

 opening of the ear is large and often extremely complicated in structure, 

 while in some genera the right and left openings are asymmetrical. The 

 outer and fourth toe is reversible at will, enabling the Owls to perch 

 with either one or two toes behind. The eggs are oval in shape and 

 white in colour, and vary in number from two to ten, the larger species 

 as a rule laying fewer eggs than the smaller forms. The nesting-site is 

 very varied ; some breeding in holes in trees or in deserted birds^ nests, 

 while others prefer the ground, and Speotyio, the American Burrowing- 

 Owl, uses the burrows of prairie-marmots and other small mammals. 

 Many species are dimorphic, that is to say have two phases of coloration, 

 a grey and a rufous. Two families are recognised, distinguished bv 

 various anatomical differences. 



