DUCKS, GEESE, AND SWANS: MALLARD 
109 
broken, perhaps “for self-protection as well as rivalry, the apparent dis¬ 
continuity of outline rendering the bird invisible as he sits motionless 
on the shore or amongst the grass and sticks” (Eaton). Both sexes 
usually have a bright iridescent mirror, speculum, or beauty spot and 
elaborate color patterns on the wing used in courtship display, as various 
handsome wing markings are in other species. Nearly all the con¬ 
spicuously marked drakes have a post-nuptial molt into a dull “eclipse” 
plumage as obscure as that of the brown, mottled females. The eclipse 
plumage elaborately figured by the English naturalist and artist J. C. 
Millais in his British Surface-feeding Ducks is generally little known and 
offers an interesting subject for observation. It serves for protection 
during the period when, unable to fly because of the simultaneous loss 
of all their wing quills, the drakes leave their mates and withdraw to 
some protected reedy ground within reach of water wide enough for 
them to escape their enemies without flight, in which safe harbor they 
can complete their molt. In this environment, where as Mr. Thayer 
says they skulk among the reeds, a mottled grass and reed-like pattern 
harmonizes better with their surroundings, than the “pied, water- 
pattern” of the full plumage. In the fall, by a second partial molt, 
the drakes resume their former handsome plumage, which they keep 
until after the next breeding season, so appearing in both spring and 
fall migrations in their full coloration. 
The Surface-feeding Ducks eat so many mosquito larvae and pupae 
that they have been used by the Pennsylvania Health Commission to 
keep down the mosquitoes in swamps expensive to drain. They also 
feed upon other insects and their larvae, mollusks, crustaceans, and the 
seeds and roots of aquatic plants. “The 1 gutters’ on the sides of the 
bill act as strainers, and after probing the bottom, the mere act of 
closing the bill forces out the mud and water taken in with the food. 
They do not gather in such large flocks as the sea ducks, and in our 
waters are generally found in groups of less than fifty” (Chapman’s 
Handbook). 
References.—Millais, J. G., The Natural History of Surface-feeding Ducks, 
1902.— Roberts, T. S., Biennial Rept. State Fish and Game Comm. Minn., 62-64, 
1919. 
MALLARD: Anas platyrhjrnchos platyrhynchos Linnaeus 
Description. — Length: About 20-25 inches, wing 10.2-12, bill 2-2.4, tarsus 
1.5-1. 8 . Adult male in winter and breeding plumage: Head and most of neck 
iridescent green , with narrow white collar above rich chestnut breast ; upper back with 
brown medium streak bordered by gray; rump and tail coverts (upper and under) 
black, four middle tail feathers black, recurved, outer ones largely white; speculum 
purple enclosed by black and white bars; axillars and wing linings white; belly gray 
marked with fine wavy lines; iris brown, bill greenish yellow, legs and feet orange- 
red. Adult male in post-nuptial eclipse: Bill greenish but head without green, 
neck without white collar, underparts without chestnut or gray vermiculations and 
