440 The Bird 
large complement of eggs (eight to twenty) in order to 
bring to maturity enough young to replace the yearly 
mortality, for the ground-built homes and huddling chicks 
encounter a multitude of dangers to which birds in trees, or 
even the small-sized ground-nesters, are not exposed. One 
exception here singularly favours the rule. The Thibetan 
Peacock Pheasant inhabits the heights of the Himalayas, 
where it has to contend with only three or four nest- 
robbers, instead of the countless foes that infest the lower 
jungles; hence its ample breast warms but two eggs. 
“The doves and pigeons lay only two eggs, and a few 
lay but one; but this seems to be due to the fact that 
their extraordinary powers of flight render them, as adults, 
unusual immunity from capture and famine, rather than 
to any special safety pertaining to their method of nidifi- 
cation. 
‘“ Hawks and owls in general have four or five eggs, 
and as this is about the average number of the small 
birds on which they largely prey, it seems evident that 
their chances of life and the difficulty of sustaining it 
are, on the whole, no less than are met with by their 
victims. The owls, however, vary much among them- 
selves in this respect; the Snowy Owls, whose home is in 
the snowy north, where a nest in the tundra moss is acces- 
sible to every marauder, and the Burrowing Owls, whose 
underground homes are constantly robbed, being obliged 
to lay twice as many eggs as the remainder of the family 
in order to overcome the high percentage of casualties 
due to these unfortunate situations. 
‘An odd feature in the nidification of some of the 
