{ Case 53. | 
[Case 54.] 
80 BIRD GALLERY. 
in plumage. Other forms represented are the Madagascar Kestrel 
(Dissodectes zoniventris) (961), the Australian Quail-Hawk (Hieracidea 
berigora) (963), and the Bush-Hawk (Harpa australis) (964). 
Family III. Panpionip#. Ospreys. 
The last 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 haliaétus) (965) 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, Polivaétus, includes three species 
of Fishing-Eagles inhabiting the Indo-Malayan region. The Grey- 
headed form (P. ichthyaétus) (966) haunts rivers and its food consists 
almost entirely of fish. 
Order XXIII. STRIGIFORMES. Owss. 
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 Speotyto, 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 by 
yarious anatomical differences, 
