88 PETRELS, 
TUBE-NOSED SWIMMERS. (ORDER TUBINARES.) 
PETRELS. (FAMILY PROCELLARIIDZ.) 
Petrels, or “ Mother Carey’s Chickens,” are true chil- 
dren of the sea. Their home is the ocean, and they come 
to land only when nesting. To the 
landsman, therefore, they are strangers, 
but to most people who have been to 
sea they are known as the little, white-rumped swallow- 
like birds who on tireless wing follow in the wake of the 
ship day after day, patiently waiting for the food which 
experience tells them will be thrown overboard. 
Petrels, 
Plate LV. 
Two species of Petrels are found off our coasts, Wil- 
son’s and Leach’s. The former has a yellow area in the 
webs of the toes and a square tail, while Leach’s Petrel has 
the webs of the toes wholly black and a slightly forked 
tail. These differences, however, would not be appre- 
ciabie at a distance. Wilson’s Petrel nests in certain 
islands of the southern hemisphere in February, and 
later migrates northward, reaching our latitude in May 
and spending the summer, or what in fact is its winter, 
in the North Atlantic. It is, therefore, probably the 
Petrel most frequently seen by transatlantic voyagers at 
this season. 
Leach’s Petrel nests on our coasts from Maine north- 
ward, arriving from the South in May. The nest is 
smade in a burrow in the ground or beneath a rock, and 
a single white egg is laid. Generally one of the birds 
spends the day on the nest while its mate is at sea, but 
_ at night the incubating bird leaves the nest, its place being 
taken probably by the one who has been feeding during 
the day. 
