The more one knows and loves those beautiful creatures of the wild, the more the desire grows in one to understand the mystery of their migrations, or at any rate to come into closer touch with them than is possible by reading books. Then among the expeditions planned for the next year comes one or more to places where we may be able to witness the great movements actually in progress. As most of the flights are made at night and at high altitudes, they are not easily observed, but people who live on one of the recognised routes, and among them are Londoners, may sometimes, when the air is still, hear the jingling keep-in-touch calls of the flocks as they pass overhead in the darkness. Such an experience gives one a peculiar thrill: it is like watching the passing of ships at night. Much more satisfaction is derived from actual observation of the travellers. This can be accomplished at many parts of the coast where the passage migrants and the winter visitors arrive, or pass on their great journeys to and from summer and winter quarters. With luck you may see the flocks alighting in the morning to rest after their long journey overnight.
It was in the hope of securing some records of these incoming migrants that I made my first visit to Norfolk. I selected Wells as a likely neighbourhood, and on my way thither I called on a friend in Hunstanton. While walking along the front there I noticed several remarkable things, but did not fully understand them until next day. A flock of rooks came from behind the town and a little later they were followed by a flock of lapwings. This happened twice and I thought, "Surely those birds are very restless; something must be disturbing them on their feeding grounds at the back of the town." Then as they came again and again, I began to take more careful note of their movements. Every time they appeared they were flying fast and direct as if about to make for the opposite shore of the Wash, but when they reached the edge of the sea they changed their minds suddenly, turned sharp to the left and made off south-westwards along the line of the shore. This struck me as curious. Presently another flock of rooks came over, and, like the rest, went straight ahead until they were just over the water's edge. Then like their predecessors they checked. This time only a few turned to the left; the rest hesitated or rather several did, with the result that the flock fell into confusion, some apparently wishing to go one way and some the other. At length one bold spirit set out in a determined manner for the Lincoln coast, which could just be seen dimly in the distance. He proceeded for some time alone, then encouraged by his strong will and fearless self-confidence, two followed him, then three or four more, and gradually the rest of the flock trailed off in his wake. It was an interesting lesson in leadership, and as I had never before seen land birds deliberately start on such a long oversea journey, it set me thinking.
Next day at Wells, some twenty miles distant, I went out on the marshes and there I found the explanation. All day long I saw flock after flock of rooks and lapwings, often several in sight at one time, following each other in procession from east to west, that is, in the direction of Hunstanton. Here was what I had come all this way to see. I was witnessing one of the grand things in Nature, bird migration actually in progress on a large scale. The birds had no doubt arrived earlier in the morning at some point farther east or south, and were now spreading themselves west and north over the available feeding grounds. The following day it was just the same. Thus this great movement of these two species lasted for at least three days and it may have started a day or more before I first noticed it. But in the evening of the third day the wind changed, and when I went out once more in the morning the pageant had ended, and the only rooks and lapwings in sight were those that were already in possession of the marshes and the adjacent fields.
My first expedition had been a success, though I had seen only one small part of the great migration. I have since made others, some successful and some unsuccessful, and I hope I may be able to make many more; for, apart from the spell that is cast by those passing multitudes of travellers from foreign lands, like the call of the sea and the romantic going and coming of ocean-crossing ships, I have always a hope that next time something I may see may throw a light on the whole fascinating problem.
One of my successful expeditions was a voyage from London to Dundee at the beginning of October and back again a fortnight later. On the northward trip I saw few signs of migration except the presence, as far south as Scarborough, of the Arctic skua. Terns were still plentiful along the coast, but no doubt were moving gradually southward, and the skuas were reaping a rich harvest as they passed. At the mouth of the Tay I saw, among other winter visitors that were already well established, an enormous flock of eider duck, a sight for which alone it was well worth while travelling all that distance.
On the southward journey we sailed through a broad belt of migration, which was probably another phrase of the great annual immigration of winter visitors that I had first witnessed at Wells and Hunstanton. The birds come from eastern and central Europe and cross the North Sea between Holland and the south-eastern counties of England. Unlike the travellers on the other highways, they perform the ocean voyage by day, and thus this route affords better opportunities for observation than any other. On this occasion it brought me into direct touch with the problem of how birds find their way across the ocean. From 9 a.m. onwards a hen chaffinch was more or less on board the ship. I did not see her first arrival, so it is possible that she had been one of us for an hour or two longer. I presumed that she was a Scandinavian traveller and had been deceived by the ship when within an hour's flight of her destination. Several times during the afternoon she tried to leave us, either when we passed a lightship or when another steamer going northward had passed us and in the distance appeared like a stationary object. But she always returned after a few minutes.
About midday, when we must have been somewhere off the Yorkshire coast, our passengers were increased by the arrival of two starlings. Then at lunch the Captain announced that he "didn't like the look of things; there were far too many land birds about." I pressed him at once for an explanation of this and he said, "When you see land birds on the ship you may be sure the weather is calm and hazy," the implication being that hazy weather might develop into fog.
Throughout the rest of the day I noticed flocks of rooks or other members of the crow family and starlings travelling in a north-westerly direction towards the coast, which was about fifteen miles distant and hidden by the haze. They were flying at no great height above the sea, indeed, very much as they do over land, just high enough to carry them easily over the tree tops, and they showed no signs of hurry or fatigue. If, as seems probable, they had come from the mouth of the Rhine or from the north of Holland, they must have flown a hundred miles or more, and yet they were going steadily forward with that slow, measured wing-beat which is typical of birds on migration and suggests that they have ample reserves of power. They reminded me of a long-distance runner who has settled into his stride and covers lap after lap at one even pace, and of the navvy who works all day with a pickaxe by going easily instead of wearing himself out in an hour by striving to beat the record.
Rooks on Migration
From plate pp265 by C.F. Tunnicliffe
The flocks seemed to be in no way affected by the appearance of ships, and even small parties and pairs passed overhead without showing any sign that they had noticed us. But some pairs and a number of single birds alighted on deck or rigging, and those that did so lost all sense of direction. For example, a couple of starlings flew to us from a lightship which was a mile or two nearer the shore than we were. They remained with us for some time and then went off to try other ships. A single rook alighted on the flagstaff at the stern, sat there for a few minutes and then instead of making for land, set off northward in pursuit of a steamer that had passed us some time before and was already several miles astern. On the other hand, a couple of rooks, which had been on board for half an hour left us to join another pair which passed confidently overhead in the direction of the coast.
In the behaviour of those that alighted, there was no evidence that the birds were exhausted. My impression was that they had first lost confidence and so had sought the nearest resting place, and then having done this, they had become confused. Those that retained their self-confidence continued on their way unbiased by the appearance of ships. This is probably one strong reason for migrating in flocks; the company gives the birds confidence. Yet small groups and couples and many single birds had accomplished the greater part of the journey successfully, and would have reached land in less than an hour if they had flown straight ahead instead of diverging to the doubtful security of the ship. If the haze had developed into a fog, many more of the migrants would have gone astray, and if the weather had been clear, none of them would have been tempted by a ship. It is well known that on foggy and misty nights birds are lured to death by the lanterns of lighthouses and lightships but are not seen near the lights when the air is clear. This shows that to some extent at any rate, birds depend on their eyesight during their oversea flights. My own observations suggest that once they start they can keep on in the same direction so long as the phenomena on which they depend for guidance remain constant, unless they lose confidence in themselves through being deprived of some or all of the benefits of eyesight by haze or fog, and that the moment they abandon their original course they are as completely lost as a ship without a compass. In other words the popular idea that birds have a sixth sense which has been specially provided to enable them to find their way over trackless oceans, is not supported by the available evidence.