Mr. J. Cordeaux on the Migration of Birds

Notwithstanding several other attractions in the town, an audience of about 260 assembled in the Guild Hall on the evening of Wednesday, February 9th, on the occasion of Mr. Cordeaux’s lecture. It is many years since the Scientific Society tried the experiment of getting a well known scientist from outside their membership roll to deliver an address, and the great success of the present venture will encourage them to continue the good work in the future.

The Society is certainly to be congratulated on having obtained the services of one of the best ornithologists of the day, and on hearing him speak on his own particular branch od science, Mr. Cordeaux, in the course of his lecture, referred to the rise of the systematic and scientific study of the phenomenon of bird migration.

The appointment of a Committee of Research, by the British Association for the Advancement of Science, to investigate the subject, resulted in the adoption of the committee’s suggestion of having schedules printed and distributed to the keepers of all the lighthouses on our coasts. The tremendous amount of material, in the form of filled-up schedules that they received in reply fully justified the course taken. The great labour of tabulating the many thousands of schedules was undertaken and successfully carried out by Mr. Eagle Clarke, who was highly delighted at the intelligence displayed by the lighthouse men in filling-up the papers, though, of course, in the majority of cases they used the local names of the birds mentioned. Canvas envelopes were also given to the men of the lighthouse, with instructions to fill them with the wings and feet of any unknown birds that were killed at the lamps, such wings and feet being easily recognised by the skilled ornithologists to whom they where forwarded. An immense amount of invaluable information was thus obtained from the systematic recording from the lighthouses, which may be synopsised as follows: –

There are very few species of birds that are not migratory. There are two great lines of migration –
(1) From north-east to south-west in the autumn, and vice versa in the spring:
(2) East to west, and vice versa.
The first, or north-east to south-west flight, consists of those species that go north to breed in the spring, and return to winter. It is a common belief that in the great migratory journeys the old birds lead the young. This is not the case. The young always return first, some species beginning the voyage as early as July. Different species migrate at different times, and in inconceivable numbers, extending over wide areas, the lighthouse reports sometimes showing that on the same night and almost at the same hour a given species of bird arrives at all stations from the north of Scotland to Spurn Head. The best weather for making observations on the flights at the lighthouses is during storms and on dark nights. At such times great “rushes” occur, when hundreds of birds dash themselves against the lamps. In fair calm weather the birds fly very high and are seldom seen.

“Rushes” frequently occur by day, though most migratory flights take place at night. Such birds as arrive by day probably travelled many hundreds of miles during the past night and are at the end of their journey when they land on our coast. On arrival they are often so exhausted that they will hardly move out of the way and seek rest and shelter wherever they can. The majority of the birds that take part in the north-east and south-west migration are of such species as are generally known to be migrants, many of them only calling at our coast on their way furth south, though others pass the winter with us.

The second great flight direction. That from east to west, was not known until lately. Many of the species taking part in it are our own native species, commonly supposed to remain with us – for instance, the redbreast, the gold crest, the rook, and many others. The observations taken at the lighthouses with regard to this line of migration have established the curious fact that, while birds of certain species are arriving on our coasts from east to west, the very same species are leaving us from west to east. This is emphatically shown in the case on the common staling. This single species has two well marked varieties, those that breed with us have green heads, while those that breed in Eastern Europe and Asia have purple heads. All the starlings that arrive on our coast in the autumn are of the purple-headed Eastern form, and at the same time green-headed starlings are leaving our east coast and flying in a westerly direction.

One cause of migration is not, as is often supposed, the coming cold. Birds migrate south that can comfortably withstand intense cold. Probably the chief cause is, in the spring, to seek secluded breeding places with abundance of food. Nowhere is this found better than in the Tundra of Artic Asia and Europe. There in the brief summer insect food abounds, and as the summer draws to a close the ground is literally covered with berry-bearing under shrubs, laden with food. Before a tithe of this is eaten the birds have started on their southern journey. The snow comes on, the fruit is thickly covered throughout the long winter. On the return of spring the snow melts and the fruits, preserved by it during the winter, furnishes an inexhaustible supply of food for the newly-arrived birds. These Tundra’s, of vast extent, furnish the great breeding places of the majority of migrants.

The direction of the migrating streams is probably influenced by inherited instinct first adopted long ago, when the British Isles formed a part of the Asio-European Continent. Many other matters of interest connected with migration were mentioned, such as the great height at which some birds fly – birds have been seen by astronomers to cross the fields of their telescopes, and the height calculated to be about five miles; the wonderful speed of flight, some species possibly attaining to 200 miles per hour; the occasional arrival of casual wanderers from their proper line of flight, such as American migrants landing on our west coasts, or species whose usual line is from north to south across Asia, wandering as far west as Britain; and the immense distance that some species travel. The Knot winters in South Africa and breeds high in the Artic regions, probably actually passing the Pole and reaching Grinnel’s Land.

A few interesting personal experiences concluded a most instructive lecture.