Bonobos, foraging in small groups by day, must travel silently to avoid attracting predators. When a lead group of bonobos comes to a trail junction, they indicate which route they've taken by marking the trail with two broken plants or by placing a large leaf pointing in the direction of travel, indicating that bonobos may possess some understanding of mathematics and symbolic logic. Though the rate of Amazon deforestation is slackening from its peak in 1995, nearly 5000 square-miles of Brazil's unique forests were cleared in 1997. While the Brazilian government claims much of the credit for slowing deforestation, environmentalists say the decrease is due to 1997's heavy rains, which hampered the use of heavy machinery to clear the forest and build roads. Although fewer trees have been cut, much of the clearing is taking place in small patches, further accelerating the decline of the remaining forest through increased edge effect.
Ecosystems are most vulnerable to disruption at their edges.
A study published in Science magazine in February claims that over-fishing by industry is changing the global marine food web, and calls the changes unsustainable. These fish have been replaced by squid and other invertebrates, signaling a deterioration of the oceanic food web. The average age, weight and nutritional value of netted fish have also declined. The trawler Steinholm, fishing off Norway's northern coast, netted a huge catch of herring. When the crew tried to haul in the net, the entire school turned en masse and swam straight for the bottom, capsizing the ship.