54 BULLETIN 126, UNITED STATES NATIONAL MUSEUM. 



yellow." The measurements of 82 eggs in various collections average 

 59.4 by 43. 2 millimeters; the eggs showing the four extremes measure 

 64 by 43, 01.2 by 44.8, 55 by 42.5 and 58.5 by 41 millimeters. 



Young. — Incubation lasts for 20 or 28 days and is performed by 

 the female alone. The males usually desert the females as soon as 

 the eggs are laid and flock by themselves, leaving their mates to hatch 

 the eggs and care for the young. In this the duck proves to be a 

 faithful and devoted mother: she sits close upon the eggs, particularly 

 as the hatching time approaches. The process of hatching is 

 described by Mr. Charles S. Allen (1893) in the following interesting 

 detail : 



The exact method adopted by the bird in freeing itself from tlie sliell proved inter- 

 esting. I will describe tlie procedure as it occuiTed in an egg that I took from the 

 nest before tlie first crack had appeared. While examining it there was evidence of 

 a strong muscular effort on the part of the bird inside, and a small disk of shell was 

 chipped out and raised above the surface at about one-third of the distance from the 

 end; then came a second or two of rest, followed by wliat felt like a scramble inside; 

 then a second oi quiet and tlie horny little knob on the end of the bill was driven 

 through the shell one-eighth of an inch to tlie right oi the first puncture. This rou- 

 tine v,'as repeated over and oven- until some 25 or ?.0 punctures had been made, com- 

 pletely encircling one end of the egg, each being about one-eiglith of an inch to the 

 right of the preceding one. The efforts seemed stronger as it started around the 

 same circle again, and the cap of the shell would be lifted a little each time, showing 

 that it was attached by little more than the tough membrane beneath the shell. 

 Before the second circle was half completed, it tore the cap loose so that it could be 

 raised like the lid of a box, with 1 inch of the membrane acting as a hinge. In free- 

 ing itself from the shell tlie neck was stretched out and the little one breathed for 

 the first time. Then tlie shoulders were pushed out into my hand, free of the shell, 

 one wing after the other being freed, while the bird lay gasping and gaping widely 

 with its bill. In half a minute more it was entirely free from the shell and lay weak 

 and helpless in the sun, its wet, slimy skin absolutely bare, save here and there 

 small dark hairs widely separated. As it began to dry it gained in strength and made 

 feeble efforts to stand, resting on the Avhole length of the tarsus. In drying, the 

 hairs no longer adhered to the skin. Soon each little pointed hair began to crack 

 and split open, and from this protective casing there came a light fiuff of down nearly 

 as large as the end of one's finger. It was more surprising than the bursting of a grain 

 of pop corn, though far less rapid. It took comparatively few of these yellow and 

 brown fluffs to convert tlie naked weakling into a beautiful downy duckling that 

 stood up boldly in my hand and began to notice what was going on about it, especi- 

 ally the calls of the parent bird close by. Each went through the same procedure, 

 invariably breaking the shell from left to right. They showed no fear and would 

 cuddle imder one's hand very confidingly. 



The young remain in the nest for a few hours after hatching some- 

 times not over an hour, until they have gained a little strength, become 

 dry and freed the Huffy dov.-n from its wet sheaths. Then the careful 

 mother leads them forth to introduce them to the world and its many 

 dangers, teaching them how to escape from their various enemies, how 

 to hide in the thickest grass, under the leaves or any other object 

 that will cover them, how to crowd and ''freeze" in any little pro- 



