Captain Blakiston noticed the first arrival of the Passenger Pigeons at Fort Carlton, on the 23d of May. By the middle of June numerous flocks were moving northward. These could, at a long distance, be readily distinguished from flocks of water-fowl or waders, by their flight being in no particular order. On the Mackenzie, Mr. Ross observed these birds as far north as Fort Norman in latitude 65°, while on the coast of Hudson’s Bay they are only found as far as 58°, even in warm summers.
The Wild Pigeon appears to be almost entirely influenced in its migrations by the abundance of its food, excepting in those parts of the country in which it has not been known to remain during winter. Even in these movements it is largely influenced by instinctive considerations of food. Evidently the temperature has but little to do with their migrations, as they not unfrequently move northward in large columns as early as the 7th of March, with a thermometer twenty degrees below the freezing-point. In the spring of 1872 a large accumulation of these birds took place early in March, in the eastern portion of New York. They were present in the forests about Albany, and were taken in such immense numbers that the markets of New York and Boston were very largely supplied with them.
As early as the 10th of March they were ascertained to have in their ovaries full-grown eggs, ready for exclusion. In Kentucky they have been known, according to Audubon, to remain summer and winter in the same districts for several successive years, in consequence of the great abundance of food, while in other parts of the State none were to be met with. They suddenly disappeared as soon as the beech-mast had become exhausted, and did not return for a long period.
The Wild Pigeons are capable of propelling themselves in long-continued flights, and are known to move with an almost incredible rapidity, passing over a great extent of country in a very short time. It is quite a common and well-ascertained fact that Pigeons are captured in the State of New York with their crops still filled with the undigested grains of rice that must have been taken in the distant fields of Georgia or South Carolina, apparently proving that they must have passed over the intervening space within a very few hours. Audubon estimates the rapidity of their flight as at least a mile a minute.
The Wild Pigeons are said to move, in their flight, by quickly repeated flaps of the wings, which are brought more or less near to the body, according to the degree of velocity required. During the love-season they often fly in a circling manner, supporting themselves with both wings angularly elevated. Before alighting, they break the force of their flight by repeated flappings.
Their great powers of flight, and the ability thus given to change at will their residence, and their means of renewing a supply of food, are also thought to be seconded by a remarkable power of vision, enabling them to discover their food with great readiness. Mr. Audubon states that he has observed flocks of these birds, in passing over a sterile part of the country, fly high in the air, with an extended front, enabling them to survey hundreds of acres at once. When the land is richly covered with food, or the trees well supplied with mast, they fly low in order to discover the part most plentifully supplied.
Several writers, who have witnessed the occasionally enormous flights of these Pigeons, have given very full and graphic accounts of their immense numbers that seem hardly credible to those who have not seen them. Mr. Audubon relates that in 1813, on his way from Henderson to Louisville, in crossing the barrens near Hardensburg, he observed these birds flying to the southwest in greater numbers than he had ever known before. He attempted to count the different flocks as they successively passed, but after counting one hundred and sixty-three in twenty-one minutes he gave it up as impracticable. As he journeyed on, their numbers seemed to increase. The air seemed filled with Pigeons, and the light of noonday to be obscured as by an eclipse. Not a single bird alighted, as the woods were destitute of mast, and all flew so high that he failed to reach any with a rifle. He speaks of their aerial evolutions as beautiful in the extreme, especially when a Hawk pressed upon the rear of a flock. All at once, like a torrent, and with a noise like that of thunder, they rushed together into a compact mass, and darted forward in undulating lines, descending and sweeping near the earth with marvellous velocity, then mounting almost perpendicularly in a vast column, wheeling and twisting so that their continued lines seemed to resemble the coils of a gigantic serpent. During the whole of his journey from Hardensburg to Louisville, fifty-five miles, they continued to pass in undiminished numbers, and also did so during the three following days. At times they flew so low that multitudes were destroyed, and for many days the entire population seemed to eat nothing else but Pigeons.
When a flight of Pigeons discovers an abundant supply of food, sufficient to induce them to alight, they are said to pass around in circles over the place, making various evolutions, after a while passing lower over the woods, and at length alighting; then, as if suddenly alarmed, taking to flight, only to return immediately. These manœuvres are repeated with various indications of indecision in their movements, or as if apprehensive of unseen dangers. During these manœuvres the flapping of their many thousand wings causes a reverberation suggestive of distant thunder. When at last settled upon the ground, they industriously search among the fallen leaves for the acorns and the beech-mast, the rear flocks continually rising, passing over the main body, and realighting. These changes are so frequent that at times the whole collection appears to be in motion. A large extent of ground is thus cleared in a surprisingly short space of time, and cleared with a completeness that is described as incredible. They are usually satiated by the middle of the day, and ascend to the trees to rest and digest their food. On these occasions the Pigeons are destroyed in immense numbers, and their abundance in large extents of the country has been very sensibly reduced.
In its movements on the ground, as also when alighted on the branches of trees, the Wild Pigeon is remarkable for its ease and grace. It walks on the ground and also on the limbs of trees with an easy, graceful motion, frequently jerking its tail and moving its neck backward and forward.
Mr. Audubon states that in Kentucky he has repeatedly visited one of the remarkable roosting-places to which these birds resort at night. This one was on the banks of Green River, and to this place the birds came every night at sunset, arriving from all directions, some of them from the distance of several hundred miles, as was conjectured from certain observations. This roost was in a portion of the forest where the trees were of great magnitude. It was more than forty miles in length, and averaged three in breadth. It had been occupied as a roost about a fortnight when he visited it. Their dung was several inches deep on the ground, covering the whole extent of the roosting-place. Many trees, two feet in diameter, had been broken down by their weight, as well as many branches of the largest and tallest trees. The forest seemed as if it had been swept by a tornado. Everything gave evidence that the number of birds resorting to that part of the forest must be immense. A large number of persons collected before sunset to destroy them, provided with torches of pine-knots, and armed with long poles and guns. The Pigeons began to collect after sunset, their approach preceded, even when they were at a distance, by a noise like that of a hard gale at sea sounding in the rigging of a vessel. As the birds passed over him, they created a strong current of air. The birds arrived by thousands, fires were lighted, and the work of destruction commenced. Many were knocked down by the pole-men. In many cases they collected in such solid masses on the branches that several of their perches gave way and fell to the ground, in this way destroying hundreds of the birds beneath them. It was a scene of great confusion and continued until past midnight, the Pigeons still continuing to arrive. The sound made by the birds at the roost could be heard at the distance of three miles. As day approached, the noise in some measure subsided; and long before objects were distinguishable the Pigeons began to move off, and before daylight all that were able to fly had disappeared. The dead and wounded birds were then collected and piled into heaps by those who had assembled for the purpose.