LIFE ON PELICAN ISLAND, WITH SOME SPECULA- 
TIONS ON THE ORIGIN OF BIRD MIGRATION 
HE study of isolated colonies of 
birds, particularly of those situ- 
ated on islands, throws much light 
on several as yet little-understood 
problems of bird migration. 
With mainland birds of general 
distribution—the Robin, for exam- 
ple—the individual is, except when nesting, lost in 
the species, and unless the bird be pecuharly 
marked who can say whether the Robins which 
nest with us one year are the same as those of 
the preceding season—where our summer Robins 
winter, or our winter Robins summer ? and who can 
tell whether the first Robins to come in the spring 
are our summer resident birds, or early migrants 
en route to more northern nesting grounds ? 
In the case of certain island-inhabiting birds, 
however, some of these questions may be answered 
with a fair degree of certainty. Thus Ipswich Spar- 
rows are known to nest only on Sable Island, off the 
Nova Scotia coast, and we are warranted in believ- 
ing that the same birds, fate permitting, return to 
their sandy home year after year. Gannets (Sula 
bassana) nest in the western hemisphere only on 
three islets in the Gulf of St. Lawrence, and it is 
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