210 FALCONIDZ, DIURNAL BIRDS OF PREY.—GEN. 151. 
The genera Astur and <Accipiter are perfect illustrations of this group; the several 
other genera usually adopted are not very different. There appear to be about 
seventy-five species, of most parts of the world. 
9. Lastly, the true falcons are prominently distinguished by the presence of a 
tooth behind a notch of the upper mandible, in the foregoing birds the tomia being 
simply lobed or festooned, or merely arched. The falcons are birds of medium and 
small size (one of them is not larger than some sparrows), but extremely compact 
and powerful organization, and bold ruthless disposition ; they prey by sudden and 
violent assault, and exhibit the raptorial nature in its perfection. The wings are 
strong, long and pointed, the tip formed by the 2d and 3d quills supported nearly 
to the end by the 1st and 4th; the tail is generally short and stiff. The typical and 
principal genus is Falco, of which there are, however, several subdivisions corres- 
ponding to minor modifications. The Australian Jeracidea, the East Indian Jeraa, 
and the Brazilian Harpagus, which is doubly-toothed, are the principal other forms. 
There are upwards of fifty species of true falcons. 
With many exceptions, in this family the sexes are alike in color, but the female 
is almost invariably larger than the male. The changes of plumage with age are 
great, and render the determination of the species perplexing—the more so since 
purely individual, and somewhat climatic, color-variations, and such special condi- _ 
tions as melanism, are very frequent. ‘The modes of nesting are various; the 
eggs as a rule are blotched, and not so nearly spherical as those of owls. The 
food is exclusively of an animal nature, though endlessly varied; the refuse of 
digestion is ejected in a ball by the mouth. The voice is loud and harsh. As a 
rule, the birds of prey are not strictly migratory, though many of them change 
their abode with much regularity. Their mode of life necessarily renders them 
non-gregarious. 
In the following sequence of our genera, the student will observe an attempt to 
indicate affinities not only in the family itself, but with allied families, by the 
central position of the typical Malco, the series beginning with the most owl- 
like form, and ending with the vulturine buzzards. But it is hoped that he will 
detect the imperfection of the arrangement, and that his studies will soon convince 
him of the impossibility of expressing natural relationships in any linear series. 
With this hint, the inviting problem is left open to stimulate investigation. 
151. Genus CIRCUS Lacepede. 
Marsh Harrier. Adult g@ pale bluish-ash, nearly unvaried, whitening 
below and on upper tail coverts; quills blackish toward the end; 16-18; - 
wing 14-15; tail 8-9; @ larger, above dark 
brown streaked with reddish-brown, below the 
reverse of this; tail banded with these colors ; 
the immature ¢ is like the 9, though redder, 
but in any plumage the bird is known by its 
white upper tail coverts, and generic charac- 
ters: face with ruffs ; wings, tail and tarsi very 
Fig. 139. Marsh Marrier. long, the latter scutellate before and behind, 
and twice as long as the middle toe ; nostrils oval, ete. North America, abund- 
ant. Nests on the ground. WILsS., vi, 67, pl. 51, f. 2; Nurr.,i, 109; Aup,, 
i, 105, pl. 26; Cass. in Bp, 38; Coor., 489. . cCYANEUS var. HUDSONIUS. 
