248 BACKBONED ANIMALS. 
Island they form nests in the guano-beds, and at Fernando 
do Norhona the nests are built on the edge of high preci- 
Pices and contain a single egg. The Z. minor, at Raine 
Fic. 284.—Red-headed pochard (Fudiguda), showing position in 
alighting. 
Island, northeast Australia, builds as a nest a platform of 
twigs about eight inches in diameter, raised in the bushes. 
Fic. 285.—Swan swimming, showing 
the web expanded and closed. 
The American spe- 
cies has a strong, musky 
odor. They follow gulls 
on the Florida reef, forc- 
ing them to disgorge fish. 
Their oil is sometimes 
used in medicine. 
Order V. Ducks 
and Geese (Lamelliros- 
tres). Ducks (Anatide). 
—About fifty-nine spe- 
cies of ducks (Fig. 284) 
are known in North 
America, They are 
swimming birds, and have a wide geographical range, all 
then up. They faced the wind, which tended to blow them up and 
away, but by pitching down slightly they seemed to ride on the gale— 
like a kite—gravity acting as the string. They would retain this posi- 
tion for hours, and it was never attempted except when the wind was 
blowing a gale. 
