The movements of birds as they change their quarters still puzzle the
naturalists.
It is marvellous how they seem to like travelling, and no one can
understand why they take certain paths through the air when they are
doing it.
For instance, the black pool warbler, in America, spends its summer in
Alaska, and goes down to South America for the winter. It takes the
straightest course it can from Alaska to Brazil, flying over land and
sea--and a wide sea, too, is the Gulf of Mexico. But the cliff
swallow, which also spends the winter in Brazil and the summer in
North Canada, takes quite a different route, and goes an extra 2000
miles in order to avoid going over the sea, and follows the land all
round by Panama, Nicaragua, Honduras, Guatemala, Mexico, and so
through the United States.
The distances which birds cover when "migrating" are enormous. Some
American plovers are known to travel for 8000 miles, one part of the
journey being 2500 miles without resting as they pass over the sea.
The arctic tern goes even farther, it nests near the North Pole, and
then makes its way down to near the South Pole, a journey of 11,000
miles.
Perhaps you wonder how we know that the birds travel these long
distances. Well, a good many naturalists and stalkers catch birds when
young or tired and mark them by putting a small ring round their leg
with a number on it. Then other naturalists keep a look out in other
parts of the world, and when they kill or find a bird with such a
number on it they report it.
Aberdeen University marked a large number of birds in this way--with a
tiny aluminium ring round the bird's leg, with the words "Aberdeen
University" and a number on it.
A wild duck which they had marked in Scotland was caught in a net the
same year in Holland.
Of five lapwings marked in Aberdeenshire, four were shot in Ireland
the same year, and one in Portugal, 1250 miles away. A song-thrush was
also shot in Portugal, which had been marked in Scotland the same
year.
A young guillemot was taken from its nest in Aberdeenshire and marked,
and less than five months afterwards it was shot in Sweden.
So, you see, it is interesting to watch in this way what the birds do
in the travelling line.
Scouts can help in keeping a look out, and if ever they capture or
hear of a bird marked with a ring, they should report it to Professor
A. Thomson, The University, Aberdeen. They should state the number on
the ring, the kind of bird, where found, and the date on which it was
found.
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