In 1995 and 1997, NASA sent me to Brazil to measure the
atmosphere during the tropical burning season. One day the smoke
was so thick at a remote camp on the Cristalino River that no
ultraviolet sunlight could be measured on the forest floor.
Something else was missing, because no birds could be heard or
seen. All that changed back at the river's edge. There was still
plenty of smoke, but birds were singing, and iridescent
butterflies were everywhere. Three bird watchers at the camp
were having a great time adding new species to their notebooks.
The sharp increase in the abundance of animal life along the
river was an example of what ecologists call the edge effect.
Before that experience in Brazil I had noticed the edge effect
while riding a bicycle from Albuquerque, N.M., to the Padre
Island National Seashore. We saw only antelopes in New Mexico
and coyotes in West Texas. But there was an obvious increase in
animal activity in the Hill Country where the road crossed
rivers and streams and sliced through the