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the Colorado is in Costa Rica, the Greytown branch in Nicaragua, and there are constant bickerings between the two states respecting the outlet of this fine river, which makes any well-considered scheme for the improvement of it impracticable at present. A sensible solution of the difficulty, would be a federation of the two small republics, but the heads of the political parties in the two countries see in this a danger to their petty ambitions, and will not risk the step, and so the boundary question remains an open one, threatening at any moment to plunge the two countries into an impoverishing war. If the Colorado were not to be interfered with by man, it would, in the course of ages, carry down great quantities of mud, Sand, and trunks of trees, and gradually form sand-banks at its mouth, pushing out the delta further and further at this point, until it was greatly in advance of the rest of the coast; the river would then break through again by some nearer channel, and the Colorado would be silted up as the Tower San Juan is being at present. The numerous half-filled-up channels and long lagoons throughout the delta show the various courses the river has at different times taken. Our boatmen paddled on until nine o’clock, when we anchored in the middle of the stream, which was here about one hundred yards wide. Distant as we were from the shores, we were not too far for the mosquitoes, which came off in myriads to the banquet upon our blood. Sleep for me was impossible, and to add to the discomfort, at midnight the rain commenced to come down in torrents. We had an old tarpaulin with us,
Ch. II.] BOAT JOURNEY UP THE SAN JUAN. 15.
but it was full of holes, and let in the water in little streams, so that I was soon soaked to the skin. Altogether, with the streaming wet and the mosquitoes, it was one of the most uncomfortable nights I have ever passed. The waning moon was sufficiently high at four o'clock to allow us to bring the long dreary night to an end, and to commence paddling up the river again. As the day broke the rain ceased, the mists cleared away, our spirits revived, and we forgot our discomforts of the night in admiration of the beauties of the river. The banks were hidden by a curtain of creeping and twining plants, many of which bore beautiful flowers, and the greenery was further varied here and there by the white stems of the cecropia trees. Now. and then we passed more open spots, affording glimpses each into the forest, where grew, in the dark shade, slender-stemmed palms and beautiful tree-ferns, contrasting with the great leaves of the Heliconiae. At seven we breakfasted on a sand-bank, and got our clothes and blankets dried. There were numerous tracks of alligators, but it was too early to look for their eggs in the sand; a month later, in March, when the river falls, they are found in abundance, and eaten by the canoe-men. At noon we reached the point where the Seripiqui, a river coming down from the interior of Costa Rica, joins the San Juan about thirty miles above Greytown. The Seripiqui is navigable by canoes for about twenty miles from this point, and then commences a rough mountain muletrack to San José, the capital of Costa Rica. We paddled on all the afternoon with little change in the river. At eight we anchored for the night, and although it rained heavily again, I was better prepared for it, and, coiling myself up under an umbrella beneath the tarpaulin, managed to sleep a little. We started again before daylight, and at ten stopped at a small clearing for breakfast. I strolled back a little way into the gloomy forest, but it was not easy to get along on account of the undergrowth and numerous climbing plants that bound it together. I saw one of the large olive-green and brown mot-mots
(Momotus marţii), sitting up on a branch of a tree, moving its long curious tail from side to side, so that it was nearly at right angles to its body. I afterwards saw other species in the forests and savannahs of Chontales. They all have several characters in
Ch. II.] FORAGING ANTS. 17
common, which are linked together in a series of gradations from species to species. One of these features is a spot of black feathers on the breast. In some species this is edged with blue, in others, as in the species mentioned above, these black feathers are nearly obsolete, forming only a small black spot nearly hidden amongst the rust-coloured feathers of the breast. Characters such as these, very conspicuous in some species, shading off in others through various gradations to insignificance, if not extinction, are known by naturalists to occur in numerous genera; and so far they have only been explained on the supposition of the descent of the different species from a common progenitor. As I returned to the boat, I crossed a column of the army or foraging ants, many of them dragging along the legs and mangled bodies of insects that they had captured in their foray. I afterwards often encountered these ants in the forests, and it may be convenient to place together all the facts I learnt respecting them.
ECITONs, OR FORAGING ANTs.-The Ecitons, or foraging ants, are very numerous throughout Central America. Whilst the leaf-cutting ants are entirely vegetable feeders, the foraging ants are hunters, and live solely on insects or other prey; and it is a curious analogy that, like the hunting races of mankind, they have to change their hunting-grounds when one is exhausted, and move on to another. In Nicaragua they are generally called “Army Ants.” One of the smaller species (Eciton predator) used occasionally to visit our house and Swarm over the floors and walls, searching every cranny, and driving out
the cockroaches and spiders, many of which were caught, C
pulled, bitten to pieces and carried off. The individuals of, this species were of various sizes; the smallest measuring one and a quarter lines, and the largest three lines, or a quarter of an inch. •
I saw many large armies of this, or a closely allied species, in the forest. My attention was generally first called to them by the twittering of some small birds, belonging to several different species, that follow the ants in the woods. On approaching, a dense body of the ants, three or four yards wide, and so numerous as to blacken the ground, would be seen moving rapidly in one direction, examining every cranny, and underneath every
fallen leaf. On the flanks, and in advance of the main
body, smaller columns would be pushed out. These Smaller columns would generally first flush the cockroaches, grasshoppers, and spiders. The pursued insects would rapidly make off, but many, in their confusion and terror, would bound right into the midst of the main body of ants. At first the grasshopper, when it found itself in the midst of its enemies, would give vigorous leaps, with perhaps two or three of the ants clinging to its legs. Then it would stop a moment to rest, and that moment would be fatal, for the tiny foes would swarm over the prey, and after a few more ineffectual struggles it would succumb to its fate, and soon be bitten to pieces and carried off to the rear. The greatest catch of the ants was, however, when they got amongst some fallen brushwood. The cockroaches, spiders, and other insects, instead of running right away, would ascend the fallen branches and remain there, whilst the host of ants were occupying all the ground below. By-and-by up would come some of the ants, following every branch, and