XATURAL HISTORY XOTES 
71 
responsible for the derivation of “ Knot ” from “ Canute,” and he gives quite a 
different reason. His words are: '‘Knotts, id est, Canuti aves, ut opinor, e 
Dania enim advolare creduntur" (Britannia, Lincolnshire). Knotts means, he 
thinks, Canute’s birds, for they are believed to fly here from Denmark. There 
is apparently nothing to support Camden’s conjecture. His etymology, however, 
suggested to Liunaus a specific name for the bird, which is, and probably always 
will be, known as Tringa canutiis. J. L. Otter. 
610. A Bird’s Education. — There is no doubt, I think, that young birds 
do learn from their parents how to fly, feed, sing, and indirectly, perhaps, how to 
build nests, but that they also learn the gentle art of migration by direct tuition 
is, I am sure, unlikely, especially as a much more simple explanation meets the 
case. Birds migrate because of a scarcity of food, and the trigger, so to speak, 
which sets them off is a cold northerly or north-easterly wind in the autumn 
migration, and a hot southerly one in the spring. Hot weather in the tropics 
causes scarcity of insect food, exactly as cold weather does here. The inherited 
experience called “instinct ’’sends them off in the right direction, and young birds 
go before their parents because the latter are still rearing a brood which often 
[leiishes if it be very late, and severe weather sets in. The cuckoo is an exception, 
for obvious reasons. C. Nicholson. 
611. With reference to the much-controverted question of bird-migration, 
attention may be called to a suggestive address by Professor E. A. Schafer, F.R.S., 
on “The Incidence of Daylight as a determining Factor in Bird Migration,” 
delivered to the Scottish Natural History Society on November 7, 1907, and 
printed in Nature for December 19. The eminent author suggests that most 
birds find their food by sight, and therefore require light so to do. They are 
feeding for many hours in every twenty-four, and therefore migrate from north to 
south when the days in the north shorten (i.e., for the winter), and from south to 
north when the northern days lengthen (i.e., for summer). 
Editor, Nature Notes. 
612. I notice the statement in the article entitled “ A Bird’s Education,” that 
“ some American birds (so Heinrich Gatke, author of “ Heligoland ” tells us) make 
the journey to Ireland, a distance of “ four thousand eight hundred miles, in nine 
hours." As this seemed to be rather fast travelling even for birds, I pointed it 
out to a friend of mine, who also is inclined to discredit the statement as either 
misquoted or misprinted. I looked up the question of “ Flight of Birds” in a 
book I have, “Science for All,” and in an article by A. Leith Adams, F.R.S., 
he says; “ It has been computed that the greatest speed of the Common Black 
Swift of Europe is about 276 miles an hour,” which I believe it is known to main- 
tain for about six hours. But this pace, as you see, is not anything like that 
mentioned in your article. I might add, in conclusion, that I lived for over two 
years in Sligo, N.W. coast of Ireland, and neither saw nor heard of any bird from 
America that attained anything like that speed. I shall be glad to see any 
remarks from your other readers on this most interesting subject. 
31, Graham Street, S. IV. W. G. Nightingale. 
613. Birds and Mountains. — A friend of mine when touring round 
Snowdon last summer, was told by the residents there that no birds were ever 
seen in the Valley of Gwynant,- between Beddgelert and Pen y gwryd, nor in the 
Valley of Llyn Idwal ; the tradition as regards the latter place being that a young 
Prince called Idwal was said to have been drowned in the lake by his foster-father, 
since which no birds would fly over it. I am anxious to know if any of your 
correspondents can corroborate this absence of birds in these walled-in valleys. 
If so, it corroborates an observation which I made and w'rote about twenty years 
ago, that most birds avoided mountains, and could with difficulty be induced to 
cross them. I was living then at Mpwapwa, on the western edge of the great 
mountain chain that extends in a practically unbroken range from Lower Egypt 
along the East Coast of Africa to Cape Colony. I noticed that the ordinary 
English swallows which arrived early in December and left in February, though 
they had come several thousands of miles to get there, never penetrated even one 
mile into the range, which was fifty miles wide at this spot, in the latitude of 
