Poachers and Poaching

VII.

HOW THE WORLD IS FERTILISED

In approaching the subject of the geographical distribution of animals and plants, one is struck with the marvellous methods which nature adopts for the dispersal of her types. If the seeds of forest trees were merely shed to the ground immediately beneath, they would be in an environment precisely the least likely to further the reproduction of their kind. Instead of this, many of the seeds of forest trees are furnished with wings, an adaptation which allows them to be easily wafted by the wind, and thus fits them for wide dispersal. It is only by possessing some such advantage as this that certain species could survive at all. It is true that acorns and other kindred fruits do not possess this advantage, but then they are largely fed upon by birds, and birds, as will presently be shown, are an admirable means of dispersal. The crop of a wood-pigeon, which burst when the bird fell to the ground when shot, was found to contain sixty-seven acorns, besides a number of beech mast and leaves of clover. In this connection imagine the possible rate of multiplication which would follow the accidental dissemination of a single head of red poppy. If left undisturbed it would, under ordinarily favourable circumstances, ripen forty thousand seeds, each capable of producing a successor. It has been stated by a competent authority that one red poppy could produce plants enough in less than seven years to occupy every inch of the thirty and odd million acres of the United Kingdom.

Ocean currents have not unfrequently been the means of connecting the floras of different continents, and seeds and fruit are sometimes picked up on the western coasts of Britain which have been wafted across the whole Atlantic Ocean. It is also known that certain birds of long and sustained powers of flight cross the Atlantic unaided, and what this may possibly mean will presently be shown. Even land animals are known to cross straits between island and island upon rafts—drift-wood or bits of floating bark.

A quaint instance of transportation of fish spawn is given by an old writer. Izaak Walton believed that pike were bred from pickerel-weed; though he seems to have had some suspicion of this piece of unnatural history, and qualifies his statement by saying that if it is not so "they are brought into some ponds some such other ways as is past man's finding out." But one of his contemporaries attacks this heterodoxy, and "propounds a rational conjecture of the heron-shaw." He thinks it quite likely that while fishing the heron might "lap some spawn about her legs", in regard to adhering to the segs and bull-rushes near the shallows, as myself and others without curiosity, have observed. And this slimy substance adhering to her legs, and she mounting the air for another station, in all probability mounts with her. When note, the next pond she haply arrives at, possibly she may leave the spawn behind her, an observation now known to be strictly accurate. Herons are not the only birds which are aids to dispersal. Although the feet of birds are generally clean, Darwin in one case removed sixty-one grains, and in another twenty-two grains, of dry argillaceous earth from the foot of a partridge, and in the earth there was a pebble as large as the seed of a vetch. The same naturalist had sent to him by a friend the leg of a woodcock, with a little cake of dry earth attached to the shank, and weighing only nine grains; this contained seeds of the toad-rush, which not only germinated but flowered. But perhaps the most interesting case of all was that of a red-legged partridge forwarded by Professor Newton. This had been wounded, and was unable to fly; and a ball of hard earth adhered to it, weighing six and a half ounces. The earth had been kept for three years, but when broken and watered, and placed under a bell-glass, no fewer than eighty-two plants sprang from it.

American passenger pigeons are frequently captured in the State of New York with their crops still filled with the undigested grains of rice that, according to Mr. Howard Saunders, must have been taken in the distant fields of Georgia and South Carolina, apparently proving that the birds had passed over the intervening space within a few hours. It is known that at certain seasons thousands of these beautiful pigeons are killed, not only by man, but by predatory animals and birds; and their long migratory journeys as a possible means of dispersal becomes at once evident. As bearing on this particular subject, Darwin has proved that the hard seeds of fruit pass uninjured through even the digestive organs of a turkey. In the course of two months he picked up in his garden twelve kinds of seeds out of the excrement of small birds which seemed perfect, and some of them germinated. The crops of birds do not secrete gastric juice, and consequently do not in the least injure germination. Darwin forced many kinds of seeds into the stomachs of dead fish, and then gave them to fishing eagles, storks, and pelicans in the Zoological Gardens. The birds, after long intervals, either ejected the seeds in pellets or passed them; after which several kinds still retained the power of germination. In the tropics countless swarms of locusts sometimes suddenly make their appearance, and as suddenly vanish. They cover every leaf-bearing thing, and occasionally denude whole districts of their greenery. So great are their powers of flight that they have been seen at sea nearly four hundred miles from nearest land. In Natal the farmers, rightly or wrongly, believe that the locusts introduce injurious seeds upon their grass lands, and the following would seem to show that their belief is well founded. A Mr. Weale, who was in their way of thinking, collected a packet of dried pellets and sent them to England. When closely examined under the microscope they revealed a number of tiny seeds from which plants of seven kinds of grasses were ultimately raised.

In comparatively few years a small island in mid ocean had quite an important addition to its flora, merely from the fact that the grave of an officer was dug with a spade that had been used in England. The seeds from which these sprang were embedded in the dry earth adhering to the spade. Floating driftwood is quite an important means of dispersal, as can easily be understood; and the natives of some of the coral islands in the Pacific procure stones for their tools solely from the roots of drifted trees, the stones being a valuable royal tax. In this connection Darwin made the following interesting experiments. He found that when irregularly-shaped stones were embedded in the roots of trees, small parcels of earth were frequently enclosed in their interstices or behind them, so perfectly that not a particle could be washed away during the longest transport. Out of one small portion of earth thus completely enclosed by the roots of an oak about fifty years old three dicotyledonous plants germinated. It is well known that in many cases a few days' immersion in sea-water is sufficient to kill seeds, but a number taken out of the crop of a pigeon which had floated on the water for thirty days nearly all germinated. Other aids to dispersal already referred to are wading birds, which frequent the muddy edges of ponds, and, if suddenly flushed, would be the most likely to have muddy feet. "Birds of this order wander more than those of any other, and they are occasionally found on the most remote and barren islands of the open ocean; they would not be likely to alight on the surface of the sea, so that any dirt on their feet would not be washed off; and when gaining the land they would be sure to fly to their natural fresh-water haunts. I do not believe," says Darwin, "that botanists are aware how charged the mud of ponds is with seeds; I have tried several little experiments, but will here only give the most striking case. I took in February three tablespoonfuls of mud from three different points, beneath water, on the edge of a little pond; this mud when dried weighed only six and three-quarter ounces. I kept it covered up in my studio for six months, pulling up and counting each plant as it grew. The plants were of many kinds, and were altogether five hundred and thirty-seven in number; and yet the viscid mud was all contained in a breakfast cup. Considering these facts, I think it would be an inexplicable circumstance if water birds did not transport plants to unstocked ponds and streams, situate at very distant points. The same agency may have come into play with the eggs of some of the smaller fresh-water animals."

The manner in which the ubiquitous brown rat obtrudes itself everywhere is only paralleled by the like qualities in the British sparrow. Our weeds have migrated to the colonies, and certain kinds have almost overrun them. In New Zealand the common dock is now widely disseminated, the original seeds being sold by a lively British tar as those of the tobacco plant.

1

For several interesting facts concerning the flight of insects, especially the dragon-fly, I am indebted to the late Dr. Gough.

2

"Sometimes while stealing along in a quiet deep channel but a few yards wide, worn through the rock, or between it and the green bank opposite, the spectator would marvel at the broad expanse of shingle or barren sand. Little would he wonder if, after a week's rain, he sought the same spot, when Tweed was coming down in his might, and every tributary stream, transformed for the nonce into a river, swelled the mighty flood. Then timber trees, sawn wood, dead animals, farming implements, even haystacks would come floating down, and the very channel of the river would be diverted, sometimes never to return to its ancient course. Sad was the havoc occasioned among the embryo spawn; torn from its bed, it would be carried down stream, to be devoured by the trout or the eel, or to perish amid the waste of waters. We felt on these occasions pretty safe. Our principal enemies were dispersed: the gulls sought worms in the ploughed uplands; the kingfisher and the solitary heron flew away to the smaller streams, where the less turbid water permitted them to see their prey. The cold, slimy, cruel eel, alone of all our enemies, was then to be dreaded. Crawling along at the bottom of the water, his flat wicked head pressed against the gravel, so as to escape the force of the stream, the wily beast would insinuate himself into every crevice or corner, where a small fish might have taken shelter, or a drowned worm be lodged, and all was prey to him." The Autobiography of a Salmon.

3

"One had better throw open his pond or river to all the poachers in the district than indulge in a taste for swans. If any one doubts this, let him row up the Thames from Weybridge to Chertsey, or on to Laleham, during the latter end of the month of April or early in May, and take particular and special notice of what the swans are doing. If he has still any doubt, and likes to kill one or two and cut them open, he will solve his doubts and do a service at the same time; he may be fined for it, but he will certainly suffer for a good action and in a good cause. A swan can and will devour a gallon of fish-spawn every day while the spawn remains unhatched, if he can get it; and it is easily found. I leave the reader to calculate what the few hundreds (I might almost say thousands) on the Thames devour in the course of two or three months. Their greediness and voracity for fish-spawn must be witnessed to be believed. If this were not so, the Thames ought to swarm to excess with fish, whereas it is but poorly supplied. Here is a little calculation. Suppose each swan only to take a quart of spawn per diem, which is a very low average indeed; suppose each quart to contain fifty-thousand eggs (not a tithe of what it does contain). I am not speaking of salmon and trout here, their ova being much larger; suppose only two hundred swans (about a fourth, perhaps, of the number really employed) are at work at the spawn, and give them only a fortnight for the period of their ravages. Now what is the result we get? Why, a little total of one hundred and forty million. One hundred and forty million of eggs! Suppose only half of those eggs to become fish, and we have a loss of seventy millions of fish every year to the River Thames—a heavy price to pay for the picturesque, particularly when the reality may perhaps be doubled, or trebled, or even quadrupled." Francis Francis.

4

"Then the kingfisher, with rufous breast and glorious mantle of blue, would dart like a plummet from his roost, and seize unerringly any little truant which passed within his ken. The appetite of this bird was miraculous; I never saw him satisfied. He would sit for hours on a projecting bough, his body almost perpendicular, his head thrown back between his shoulders; eyeing with an abstracted air the heavens above or the rocks around him, he seemed intent only upon exhibiting the glorious lustre of his plumage, and the brilliant colours with which his azure back was shaded; but let a careless samlet stray beneath him, and in a twinkling his nonchalant attitude was abandoned. With a turn so quick that the eye could scarce follow it, his tail took the place of his head, and, falling rather than flying, he would seize his victim, toss him once into the air, catch him as he fell, head foremost, and swallow him in a second. This manœuvre he would repeat from morning till night; such a greedy, insatiable little wretch I never saw!"—The Autobiography of a Salmon.

5

"In this neighbourhood I escaped, by pure good fortune, a danger that I afterwards learnt proved fatal to thousands—nay, tens of thousands—of my young companions. The stream had apparently divided, and whilst I followed the course of the right-hand one, the greater number passed down the wider but less rapid left-hand division. Here they speedily encountered a terrific mill-wheel, and, dashing on one side, they found their progress stopped by a small net, which being placed under them, they were landed literally by bushels. My informant, who escaped by passing under the mill-wheel at the imminent risk of being crushed to death, assured me that the bodies of our unlucky brethren were used as manure! And, degrading as the suggestion is, it seems not impossible, for the numbers taken could not be sold or used for food."—The Autobiography of a Salmon.

6

1890.

7

Dr. T. Gough.