MALLARD 
33 
6000 feet in the Caucasus (Radde, 1884), and 9000 feet in the western Himalayas 
(Hume and Marshall, 1879). Of course only isolated pairs are met with at the most 
extreme elevations. 
There is nothing characteristic about the nest of the Mallard. It is loosely con- 
structed of grass, reeds and rushes, with a considerable depression, which, toward 
the end of the laying period, becomes thickly lined with down. Some nests, close to 
the water, are said to have little or no down. The male assists his mate in the nest- 
hunt, but when incubation commences he becomes more and more independent, 
until toward the middle of the period he deserts the female entirely. It seems that 
very rarely, the male will stay with the female until after the young are hatehed. 
Such is said to be the case occasionally in Iceland (Hantzsch, 1905), and Wetmore 
(1921) has noted it in rare cases at Bear River, Utah. 
The eggs are from five to fourteen in a clutch, averaging about ten. Clutches of 
from fourteen to eighteen have been commonly reported, probably the work of two 
birds. Young birds are said to lay smaller clutches than the older ones. The color of 
the eggs is very variable. Although the typical egg is pale greenish blue, many are 
yellowish cream or almost white. They measure from 52.3 to 64.7 mm. by 38.0 to 
45.7 mm. The usual period of incubation is twenty-six days, but so many authori- 
ties have given longer periods that one must conclude that the variation is greater 
than is generally thought. Much of the supposed variation is due, no doubt, to 
freshness or staleness of eggs; perfectly fresh ones always hatch sooner. Eggs placed 
under a hen will hatch, according to some writers, about two days sooner than when 
incubated by the parent; but I have no data to confirm or disprove this. 
The female sits very closely, especially when the eggs are far advanced. During 
the last few days she will not move unless almost stepped on, and she may often be 
removed by hand. Not only is the nest usually well concealed from above, but the 
sitting bird draws leaves and grasses around and over her, so there is little except 
her eyes to attract attention. She leaves the nest once or twice a day (never at 
night) and when the eggs are well incubated probably not more than once a day. 
When leaving voluntarily, she covers the eggs with down, but no harm seems to 
result, even when the nest is left uncovered for a considerable period, since the down 
serves rather for concealment than warmth. During the last few days of incubation 
she probably does not leave the nest at all. 
There is some diversity of opinion as to the relation between the sexes during 
incubation. At times the females on coming from the nest seem to be persecuted 
not only by their own mates, but by other males. Some writers have even said that 
the female is compelled to conceal her nest from her mate lest he disturb her by his 
attentions. As usually observed, however, the male remains at no great distance 
from the nest, and joins the female during her brief feeding period (Wetmore, 1920; 
et ah). When Mallards are artificially crowded on small breeding ponds the males 
