Study documents huge wildlife loss after Amazon "Rubber Boom"

Researchers have documented the killing of millions of animals in Brazil's Amazon Basin for their hides following the collapse of the Rubber Boom in the 20th century, causing the collapse of some aquatic species.

The findings, published this week in the journal Science Advances, were the first by the researchers, including lead author Andre Pinassi Antunes of Brazil's Wildlife Conservation Society, who examined cargo manifests of the steamships, port registries and other documents that reported hide export data.

"There was a massive international trade in furs and skins taken from the Amazon in Brazil during much of the 20th century, yet surprisingly no previous studies documented the exploitation of the animals or the resilience of the ecosystem," said Taal Levi, a wildlife ecologist at Oregon State University (OSU) and co-author of the study.

Beginning in the late 19th century, about half a million colonists entered the Amazon region to extract rubber across all the major river basins.

A fleet of steamships was built for transport and trade and a network of river merchants purchased forest products from extraction industries. When rubber prices collapsed in 1912 because of competition from Malaysian plantations, the enterprises that did not go bankrupt sought other products.

Thus began the international trade in Amazonian animal hides, which persisted for decades until Brazil passed a faunal protection law in 1967, severely restricting hunting for many of the affected species, and the Convention on the International Trade in Endangered Species (CITES) was ratified in 1975.

The research team estimates that between 1904 and 1969, at least 23 million animals representing 20 species of mammals and reptiles were hunted for hide and registered through export records.

Acknowledging that these figures vastly underrepresent the total number of animals killed since many were hidden to avoid taxes and others were wounded or killed and never made it to the steamships, the team documented the greatest losses to aquatic species, causing the widespread collapse of giant river otter, black caiman, and manatee populations.

Among the researchers' estimates for the period of 1904 through 1969:

-- more than 4.4 million black caimans were killed, with the harvest during the last five years dwindling by 92 percent from the peak;

-- 110,504 manatees were killed, reducing the harvest by 91 percent from the peak;

-- 386,491 giant otters were killed, reducing the harvest by 88 percent from the peak;

-- 793,133 capybaras were killed, reducing the harvest by 75 percent from the peak.

"The aquatic animals were more vulnerable because rivers were easily accessible and the animals were in essence trapped there," Levi said in a news release from OSU.

"There wasn't as much effort spent hunting animals on land, thus the terrestrial species in general were affected less by commercial hunting." And most land-based species appear to have survived the carnage.

"The international trade in hides peaked during World War II, when the United States sought Amazonian rubber to replace the rubber from Malaysia that the Japanese had captured," noted Levi. "A second peak of animal hide exports came in the 1960s when exotic furs became fashionable."

However, "research by other ecologists is showing that some of these species are beginning to recover, including the black caiman, which is the second largest crocodilian species in the world," Levi said.

"They can grow up to 20 feet (6.1 meters) long. But prior to this, we've never been sure just how resilient animals were to high harvests in the past." Endit