Figure 6A. Migrationof Pa- 
cific golden plover (6B) from 
a summer range in Siberia 
and northwest Alaska to a 
winter range inthe southwest 
Pacific. Records ofthis spe- 
cies sighted from ships in the northwest portion of the Pacific are in- 
dicated by the symbol©, showing that several birds were not flying a 
direct course. 
Pacific golden plover: 
deviating sometimes by 30 to 40 degrees (Schuz, 1949). Still another 
experiment involved capturing adult hoodedcrows as they passed through 
an area on the coast of the Baltic Sea, and transporting them west to 
Flensburg where they were released to continue their spring migrations 
(Riippell, 1944). All but one of these recoveries lay tothe north andeast 
of Flensburg, in an area roughly the size of the normal summer range, 
but displaced westward. It appears that the crows continued in the nor- 
mal directionof their spring migration but flew into Denmark instead of 
into the Baltic States and Finland. 
These three experiments and the one involving the gannets suggest 
a conceptof migration which is different from that ordinarily presented. 
Clearly, there must be some factor, not yet understood, which guides 
migrating birds in the right general direction. But it seems that this 
guidance may not be as precise as we have often believed. The three 
experiments. with young migrants, for example, showed a tendency for 
the routes to be scattered over an angle from 30 to 90 degrees. If it 
were true that bird migrations were guided only with this degree of 
accuracy then at least it would not be necessary to explain a pin-point 
type of navigation. It has often been argued that, because birds fre- 
quently return hundreds of miles to breed in the same small area or 
even at the same nesting site, they must be able to set a very precise 
course from their winter range. But if the birds have well developed 
visual memories and can use,exploration at the end of the flight to de- 
termine where they will stop, there would be no need for such precision. 
We know, in fact, of no case where a bird steers a straight course for a 
distant goal across trackless areas. 
Spectacular cases where precise navigation has seemed necessary 
are the annual flights of many birds to small islands. The Pacific golden 
plover (Figure 6, A and B), for instance, migrates from the arctic tundra 
where it nests, through the Alaskan Peninsula and the Aleutian Islands 
to a winter range which includes almost all the islands of the Pacific 
Ocean. In the case of those birds which fly to the Hawaiian Islands, it 
has been argued that they. must use precise navigation to cross 2000 
‘miles of open sea and yet strike an island which is only a few miles 
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