262 MICHIGAN BIRD LIFE. 
134. Marsh Hawk. Circus hudsonius (Linn.). (331) 
Synonyms: Frog Hawk, Bog-trotter, Harrier, Marsh Harrier, Mouse Hawk, White- 
rumped Hawk.—Falco hudsonius, Linn., 1766.—Circus hudsonius, Vieill., 1807.—Circus 
AD) 
eyaneus var. hudsonius, Ridgw., 1872. 
Figure 69. 
Recognizable in any plumage by the pure white upper tail-coverts which 
form a conspicuous mark in females and young birds, but not so noticeable 
in the adult male, which is largely bluish white. 
Distribution.—North America in general; south to Panama and Cuba. 
Breeds throughout its North American range. 
The Marsh Hawk is one of our commonest and best known birds, arriving 
from the south usually in March, often before the uplands are free from 
Fig. 69. Nest and Iggs of Marsh Hawk. 
From photograph by Thomas L. Hankinson. 
snow and before the ice is gone from the marshes. It is commonly seen 
hunting back and forth over the low grounds, keeping generally within 
a few yards of the surface and rising above the trees only in passing from 
one marsh or field to another. 
Its food is varied, consisting of meadow-mice, ground squirrels, frogs, 
snakes, insects, and occasionally small birds, mainly blackbirds and the 
smaller ground-nesting species. According to Dr. Fisher “It is unquestion- 
ably one of the most beneficial of our hawks and its presence and increase 
should be encouraged in every possible way, not only by protecting it by 
law but by disseminating a knowledge of the benefits it confers. It is 
probably the most active and determined foe of meadow-mice and ground 
squirrels, destroying greater numbers of these pests than any other species, 
and this fact alone should entitle it to protection even if it destroyed no 
other injurious animals.’? Out of 124 stomachs reported on by Dr. Fisher, 
