Amazonian rivers and tropical rain forests are home to a large number of wildlife species. Protect hundreds of uncontacted indigenous groups and are considered “The Lungs of the Planet” (Fig. 1). A single Amazon tree can contain the same number of ant species all Britain has. Amazon basin covers around 40% of the South American territory and now is facing a massive battle against past and present anthropogenic activities.
Uncontrolled Fur Trade
Many pressures threaten this critical natural environment. Lots of studies have focussed on understanding how habitat loss and climate change risk this ecosystem. But now, there is new information of how overhunting historical events, like the fur hunting boom developed during the 20th century, affected animal populations to the present. Overexploitation like hunting, illegal trading and poaching in addition to natural habitat loss have given way to the so-called “empty forest syndrome” among the tropics
Overexploitation like hunting, illegal trading and poaching in addition to natural habitat loss have given way to the so-called “empty forest syndrome” among the tropics1. There are records of 89.000 extractivists in the central-western Brazilian Amazon by 1950, of which only 528 declared themselves as professional hunters. Most of them were opportunistic native people hunting mainly for meat and animal hides (Fig. 2). Human population increased and the unregulated commercial hunting practice grew that much that hunting effort never decreased, even when populations exploited declined, because by that time people were paid for whatever they could catch2.
During the last century, there were two peaks of extreme harvesting over Amazonian animals, between 1930s-1940s and the 1960s. It is estimated that during this period of time around 23.3 millions of wild mammals and reptiles, representing at least 20 species, were hunted for their fur. And this happened because the rubber trade in the Amazon developed during the early 1900s collapsed, forcing forests hunters to find replacement products. Illegal hunting and hide export continued in spite of the ratification of the Convention on International Trade in Endangered Species (CITES) in 1975, which put many of these species under the maximum protection against exploitation. But it was finally at the Rio Earth Summit, where international people turned against the use of wild animals skins in fashion and banned hunting in Amazonian forests2 (Fig. 3).
Ecosystem and Species Resilience
Now we can understand better how historical international trade in furs and skins affected the Amazonian ecosystem. Terrestrial and Aquatic animals were highly hunted over the last century. But aquatic fauna seems to be more vulnerable to hunters, especially in dry seasons, mainly because they don’t have the same spatial refuges to hide as terrestrial animals have within the forest. For most aquatic species, refuge size is lower than the area needed to for population recovery.
Amazonian people preferentially live on river’s banks and use the river system as their main way of transport. So hunting takes place mainly in rivers too. This is why animals like otters, caimans and manatees show a high level of population decline when comparing with collared peccaries, deer, ocelots and even jaguars, leaving the Amazon basin with “empty rivers”2 and populations collapsed. Most of these species are now at some risk of extinction category established by the IUCN Red List of Threatened Species and this is because their currently wild populations show a huge decline due to past overhunting practices (Fig. 4).
The resilience showed by terrestrial animals should not be taken as means of sustainable hunting as some people try to do. Some indices measuring hunting sustainability have been developed. They measure if the number of animals added to natural populations annually through ideal reproduction conditions is greater than the rate of animals removed by hunting. And for Amazonian species, the estimate of commercial offtake was higher than their recovery rate (maximum production), neither for aquatic or terrestrial species.
Besides all this iconic and well know species, there are many others commercially important species threatened by excessive bushmeat harvest. Among them, we have the Amazonian turtle (Podocnemis expansa), arapaima fish (Arapaima gigas), tambaqui (Colossoma macropomum) and catfish (Phractocephalus hemioliopterus). The loss of fauna affects the entire ecosystem functioning3. For example, it’s known that species like primates, tapirs, guans and curassows are hunted in the Amazon for meat trade. When these animals disappear from the forests, seed dispersal decreases and tree species start to decline as well. Every species is essential for ecosystems survival2.
How to revert the past
The resilience land animals presented does not mean they are safe in the rainforests. Illegal hunting keeps happening in some places, even in protected reserves, because there is no efficient control established in those areas. There are also many places within the Amazon with no hunting regulations at all and currently deforestation that gives hunters access to remote habitats4.
Populations continue declining and this creates the opportunity to demonstrate governments, with scientific evidence, that maintaining forests, with minimum road access and no disturbance, gives shelter for species to survive. More policies regulating hunting are needed, considering the actual status of the species hunted, their population numbers and managing ways to control that native people living in extractive reserves, who have the rights to use natural resources of the environment they live (territories where human livelihoods are protected by law5), hunt in a sustainable way. Working with local people has proven to be the best solution to conserve ecosystems. In this way, we can make the path again to have healthy ecosystems where people and animals live in harmony as they used to do.
- Camargo-Sanabria, A. A., Mendoza, E., Guevara, R., Martínez-Ramos, M. & Dirzo, R. Experimental defaunation of terrestrial mammalian herbivores alters tropical rainforest understorey diversity. Proc. R. Soc. Lond. B Biol. Sci. 282, 20142580 (2015).
- Antunes, A. P. et al. Empty forest or empty rivers? A century of commercial hunting in Amazonia. Sci. Adv. 2, e1600936 (2016).
- Peres, C. A., Emilio, T., Schietti, J., Desmoulière, S. J. M. & Levi, T. Dispersal limitation induces long-term biomass collapse in overhunted Amazonian forests. Proc. Natl. Acad. Sci. 113, 892–897 (2016).
- Kosydar, A. J., Conquest, L. L., Rumiz, D. I. & Tewksbury, J. J. Effects of Hunting and Fragmentation on Terrestrial Mammals in the Chiquitano Forests of Bolivia. ResearchGate 7, 288–307 (2014).
- Brockington, D. & Wilkie, D. Protected areas and poverty. Phil Trans R Soc B 370, 20140271 (2015).