and fifty miles; the number of miles dividing the westernmost point of Norway from the easternmost point on the Scotch coast is roughly two hundred and seventy-five miles.

The speed at which birds travel while migrating, weather conditions being not unfavourable to their flight, largely transcends the speed they exercise on other occasions. This statement is quite ex parte, of course. We do not yet know all that we ought to know about bird migration by a very long way, and there exists a large mass of widely varying opinions on the

matter.

The speed of the woodcock-one of the very swiftest and most strongly flying birds-when migrating under favourable conditions is no doubt enormous, but as 'cock, under such conditions, invariably reach our shores during the hours of darkness it will always be impossible to make observations which would decide the question of the birds' speed. We can only draw inferences from the speed of birds whose habit it is to make their oversea passage by day. A bird that lends itself better than any other to observation in this connection is the hooded crow.

On various occasions the migration of hooded crows between Heligoland and the Humber has been accurately timed, Gatke, an eminent ornithologist and

observer, having been mainly responsible for the necessary arrangements. Gatke lived in Heligoland for many years. The strict accuracy of his records has been doubted, but to the minds of the ornithological world at large the results arrived at are quite conclusive.

Hooded crows were timed by Gatke and his coadjutors to pass over Heligoland at a certain time, taking a line which would carry them direct to the Humber, and to reach the Humber in three hours. If this had been noticed only once or twice there would be no real evidence, for the birds which were seen to arrive on this part of the English coast might have started from the coast of the Continent further north or further south than Heligoland, and might have started much earlier in the day and therefore made a much slower journey. But continuous observation yielded the same results every time: over and over again the birds were seen passing Heligoland at about eight o'clock in the morning, the stream continuing till about two o'clock in the afternoon, and in all cases, the weather being normal, the in-coming stream at the Humber began about eleven o'clock in the morning and ended about five o'clock in the afternoon. The distance between the Humber and Heligoland being about three hundred and twenty miles, we find the

migration speed of the hooded crow-the bird we know as such a heavy, slow-flying bird while resident with us -to be over a hundred miles an hour. No one with an open mind can doubt that the birds which pass Heligoland are the same birds which reach the Humber only three hours later. From the one point to the other stretches their beaten track, if one may use such a term. Year after year they take the same course, as no doubt they have taken it for ages; fixed instinct gathers them together at a certain time of the year on a certain part of the Schleswig-Holstein shore and impels them in a certain line; and following this line they land season after season on the same certain part of the coast of England. Organised observation would almost assuredly disclose other lines followed by hooded crows when migrating from the coast of the Continent to our own.

The longest flight over unbroken sea known to be made by migrating birds is that of the Virginian plover, which nests in Labrador and spends its winter in Brazil. The distance between the North Brazilian coast and the coast of Labrador is about three thousand two hundred miles.

If the migration speed of so clumsy and slowflying a bird as the hooded crow is over a hundred miles an hour, what must be the migration speed of so

dashing and swift a bird as the woodcock? Perhaps a hundred and fifty miles an hour, a speed which would enable it to cross from the south of Norway to the north of Scotland in less than two hours. A hundred and fifty miles an hour falls far short of the velocity with which birds pass through the air under certain circumstances. Their speed, when descending from a great height to a distant point, vastly exceeds the speed suggested as that of the woodcock on its migration journey; but, when descending, a bird has the same augmentation of speed from gravitation that a cyclist receives when going down hill. Four miles to the east of Heligoland are certain oyster-beds on which, at low tide, birds congregate in enormous numbers at the time of the spring and autumn migration. Duck, curlew, plover, and other birds, when descending from a considerable elevation, have been repeatedly timed to cover these four miles in one minute, that is at the prodigious speed of two hundred and forty miles an hour for the base line only.

Critics have often denied that migrating birds can travel at the velocity claimed for them by observers, because the swiftest of birds seen flying near the earth at non-migration periods of the year—birds living their ordinary life, that is never attain a speed of anything approaching a hundred miles an hour. This

is quite true; doubt or denial is not to be wondered at when one's notice is directed to, for instance, the hooded crow, and one is then told that this bird, so sluggishly flapping about the shore, can cover three hundred miles or so on end at a speed of something like double that of an express train. In the present state of our knowledge, the explanation of the great speed of migrating birds compared with their normal. speed is impossible.

There are, however, two contributing factors-perhaps the only ones-which seem practically certain. First, at the time of the spring and autumn migration Nature braces up the system of a bird to a point at which it can exercise energy to a degree quite impossible to it during other periods of the year, and at the same time brings into play a powerful sub-instinct to the migratory instinct proper -namely, to steel itself up to and plunge into a far more sustained physical effort than ever it feels called upon to make at other times. The only real effort of flight made by the bird at these other times is that short, sudden rush to escape from real or imaginary danger. When fairly on the wing, and not considering itself any longer in peril, I do not think it ever makes a call upon its fullest powers of flight.

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