The Rio Negro teemed with a species of piranha. They are deep-bodied and blunt-nosed, and the jaws are armed with sharp, triangular teeth. Although they grow to a length of eighteen inches in the Orinoco and some of the other large South American rivers, those we found in the Rio Negro did not exceed eight inches in length; but they travelled in enormous schools, and made up in numbers what they lacked in size. During the hours of late afternoon, when our day’s work was over, I tried many experiments with the piranhas. They have a bad reputation and are known to attack animals much larger than themselves, and even human beings who enter the water. Usually they are slow to attack unless their appetite has been whetted by a taste of blood from a wound; then, however, their work is done with lightning-like quickness, and unless the luckless victim succeeds in reaching the shore immediately nothing but the skeleton will remain within a very short time. If I fished with a hook and line baited with any kind of raw meat the fish would scarcely wait for the bait to sink below the surface of the water. The number caught depended entirely upon the amount of time spent in fishing. The bodies of large mammals, such as monkeys, after we had skinned them, were thrown into the stream; instantly the ravenous hordes charged the spot and tore greedily at the bloody flesh; so great were their numbers that they threw one another out of the water in their mad struggles to reach the gory repast. On several occasions I threw dead or stunned individuals of their species into the midst of the frenzied mob, but, strange to relate, they floated on the surface of the water untouched. Unplucked birds were not molested, either. A struggle in the water seems to attract the fish, but I must admit that their behavior is very erratic. While washing my hands in the edge of the stream one day a piranha snapped a piece out of a finger; a few days later a man in passing over the river on a bridge dropped his purse into the water in almost the exact spot where I fished, and where the piranhas were most abundant; he stripped, waded out very slowly and cautiously so as not to create a disturbance, and felt about with his toes for the lost article; although the water was over four feet deep and he remained in it fully fifteen minutes, he remained untouched.
It is in the dark swamps dotting the chaco like low, glossy islands that the precious quebracho-trees grow. It was also from these same swamps that clouds of ravenous mosquitoes issued with the first signs of failing daylight, and drove us to the refuge of our net-covered hammocks. There we sweltered through the long hours of the night, listening to the angry buzzing of our outwitted assailants, which was not unlike the sound produced by a swarm of enraged bees. I could distinguish a number of different pitches and qualities in the music, blending harmoniously in one general chorus. The varying size of the insects, which ranged from individuals nearly an inch long to the small infection-bearing Anopheles, doubtless accounts for the different tones produced by the vibrations of the wings. Brockets were seen occasionally; they left the forest morning and night to feed. In the tall pampas-grass cavies abounded. They came out into the opening beside the railroad just before sunrise and ran about, or sat motionless, when they resembled clods of earth or shadows. Ocelots had worn well-defined paths through the fields in their nightly raids on the cavy community. In the trees we found black howlers, night-monkeys, and giant weasels (Tayra); opossums and various species of small rodents held sway on the ground.
Fort of Coimbra on the Rio Paraguay.
While there was no scarcity of birds, they were largely species already known to us, and one day one of the men brought in an anaconda ten feet long, that he found basking on the river-bank.
After spending a week on the Rio Negro we returned to Asuncion, where we were joined by the commissaries who had just arrived with the equipment. Two days later we boarded the comfortable little steamer Asuncion and started for Corumbá.
The four and a half days’ trip up the Paraguay was most interesting, although the heat and insects at times were troublesome. We had entered the great pantanal country, and the vast marshes teemed with bird-life. As the Asuncion fought the strong current and moved slowly onward countless thousands of cormorants and anhingas took wing; lining the pools and dotting the marshes were hordes of wood and scarlet ibises, together with a sprinkling of herons and spoonbills; egrets covered the small clumps of trees as with a mantle of snowy white, and long rows of jabiru storks patrolled both shores. Scarcely a moment passed in which we did not see hundreds of birds. Some of the passengers were armed with rifles and revolvers, with which they kept up more or less of a fusillade on the feathered folk; but fortunately their aim was poor so that little injury was inflicted.
The day before reaching Corumbá we passed an interesting old landmark. It is the fort of Coimbra, built on a rocky hillside with a cluster of thatch-roofed huts nestling against the base. As Coimbra is near the Bolivian border, the fort figured prominently in several of the bloody controversies of bygone years between the neighboring republics.