NATURAL HISTORY NOTES 
93 
south coast, work their way up country slowly and do not appear in Scotland till 
some weeks later. There is no doubt that when the birds cross over large 
expanses of sea they have to go in one long uninterrupted flight till they reach 
the next land, and in all probability they migrate at a great height, for astrono- 
mers have seen them through their telescopes, and have calculated the height to 
be several miles. There is, of course, no reason why, for instance, a flock of 
birds which is travelling over England on migration, not intending to stop there, 
should fly right over, high in the air, without descending low. In fact it is im- 
possible to set down a hard and fast rule, since birds on migration differ so widely 
according to the different species. 
Then, as to the supposed high speed of certain birds, Mr. Daubeny’s instance 
of Herr Giitke’s appears to me to be far too hypothetical, lie .'ays : He knows 
where it starts and where it goes.” This .seems to be ratber stretching a point, 
for surely it is impossible to tell accurately where birds are bound for. Thus, for 
instance, starting from Heligoland they might fly to England, but they might not 
rest as soon as they got to shore, but might go right on to Ireland ; and what is 
more, birds over land follow a rather circuitous route, at least it appears so from 
certain authentic maps which I have seen, so that I do not see how it is possible 
to determine the speed even approximately. Then, as to the statement “that 
no migratory bird which sets out in the evening and flies all night continues its 
flight more than fifteen or sixteen hours at a stretch.” I do not see, again, how 
this can be proved. It may vary so with different birds. In the days of the 
glaciers the migration of birds southwards before the ice took place slowly, for 
the glaciers, I suppose, did not move with any great speed. Hence it is surely 
improbable that the relic of this movement .should take place at most abnormal 
speeds. 
In conclusion, I should like to say, that although I have taken Mr. Dixon’s 
theories in most cases and tried to corroborate them, still, I do not agree with 
that author in all his arguments on the migration of birds. For instance, I do 
not agree with his theory on the cause of migration and other minor details. 
Hut the general trend of his arguments are to “ reduce the avine season-flight to 
law,” and to show that it is a perfectly natural phenomenon, and that it is 
accomplished in a perfectly natural way, with no extraordinary and wonderful 
characteristics. 
Pen Moet, Chepstow. M. P. Price. 
102. Migration and Speed of Birds.— Respecting the various notes 
from Mr. E. T. Daubeny and others which have appeared herein, I should like 
to mention that whereas it is generally supposed that birds when migrating fly- 
very swiftly and at a very high altitude (Mr. Daubeny mentions that the 
Virginian Plover when on its migratory flight “ ascends to regions probably far 
higher than the Condor.” This latter species, he states, searches for food 40,000 
feet above sea-level), Mr. W. Eagle Clarke, in the ]bis (vol. iv.. No. 13, p. 132), 
practically disproves this. Mr. Clarke, in the course of his most valuable 
observations, carried out at the Kentish Knock Lightship, the Eddystone Light- 
house, and elsewhere, states from actual observation as utider ; “ That some birds 
do fly at great heights, and that under certain conditions (which are at present 
unknown to us) it may- be an advantage to them to do so, I will not for a moment 
deny, but I am convmced that it is not a necessity as a means of finding their 
way.” Mr. Clarke further states that “ duiing all these movements, great and 
small, the migrants of every species Jlew close to the stirface of the water under all 
conditions of weather. On certain occasions, notably on October ll, the state of 
the atmosphere was such that it must have been quite impossible for them to see 
more than one, or at most two hundred, yards ahead ; and yet under these con- 
ditions, when it might possibly have been an advantage to fly high, they sped 
onwards just skimming the crest of the waves, and never departing from a true 
east to west course. On fine clear days, with a light wind, these flights were 
performed in a precisely similar manner.” 
Mr. Clarke further touches upon the speed at which birds fly when on 
migration, and states that, “ speaking generally, the migrants pursued their way at 
the steady rate characteristic of their respective species. Thei-e -was no hurry, 
but at the same time there was a business-like manner about them, which was in 
