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Thanks to one primate species, most others in the world are facing oblivion

Some 75 percent of species are already in steep decline, and trends suggest 60 percent could be gone in 25 to 50 years.

Ring-tailed lemur numbers are estimated to be in the thousands.
REUTERS/Heinz-Peter Bader

I learned a new word over the weekend and wished I hadn’t: defaunation, meaning the removal of animal species from ecosystems. Not just extinction or extirpation but all the progress toward those outcomes, typically steady and usually directed by our own terminating species.

It came up in the context of a new study reaching the awful conclusion that in the next quarter- to half-century, nearly two-thirds of the world’s apes, monkeys, lemurs, lorises and other primate species will disappear from the face of the earth.

This is not in the least guesswork; the data show that some 75 percent are already in steep decline. It’s not an impact of climate change, not yet, although that too is remaking ecosystems and will probably not be good for primates either, should they be lucky enough to survive that long.

The principal problem is people and a range of mostly industrial activities that are wiping out our primate cousins through habitat destruction to produce more crops, timber, minerals, and fuel, and, more directly, by commerce-based hunting for their meat. (Also, to sell them for pets, or turn their body parts into folk medicines, for the pleasure of people who really ought to know better by now.)

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Most MinnPost readers, living on a continent where humans are the only primates (outside a modest portion of Mexico), may imagine instinctively that these loss rates are so large because primate numbers are so small. Not so.

There are, for the moment, more than 500 species of primates spread across 16 families and 79 genera; among mammals, this diversity is exceeded only by rodents (2,256 species) and bats (1,151).

Taken together these creatures are also, of course, our closest biological relatives, and some our closest rivals in intelligence as we tend to measure it. An everyday demonstration of this proximity is the fact that nearly all primates seem to be interesting or attractive, or both, to most humans.

Which makes their currently dim prospects for survival perhaps all the harder to bear.

Living where the resources are

The new paper, “Impending extinction crisis of the world’s primates: Why primates matter,” appears to be the broadest and bleakest report to date about the conservation status of the world’s primates. Prepared by 31 of the world’s top primatologists, it is a meta-analysis of current statistics from the gold-standard International Union for Conservation of Nature, matched up with many studies of primates and the perils facing them.

It loses no time getting to the big picture: Primates have the mixed fortune to be abundant in a generally warm-climate swath around the globe, and the plain misfortunate to be concentrated especially in portions that are rich in certain resources precious to their sapient but ravenous cousins. Key excerpts:

The large majority of primates inhabit tropical moist lowland forests, but they also occur in tropical dry forests, mangrove vegetation above hightide levels, moist montane forests, high-elevation (from 1000 to >4000 m) deciduous and broadleaf temperate forests, savannas, grasslands, inland wetlands, rocky areas, and even deserts.

[They] are present naturally in 90 countries; however, two-thirds of all species occur in just four countries—Brazil, Madagascar, Indonesia, and the Democratic Republic of the Congo (DRC).

The main threats to primate species are loss of habitat due to agriculture (76% of species), logging and wood harvesting (60%), and livestock farming and ranching (31%), as well as direct loss due to hunting and trapping (60%). Other threats, such as habitat loss due to road and rail construction, oil and gas drilling, and mining, affect 2 to 13% of primate species, and there are also emerging threats, such as pollution and climate change.

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 Globally, agriculture is the principal threat, but secondary threats vary by region. For example, livestock farming and ranching negatively affect 59% of primate species in the Neotropics. In contrast, in mainland Africa, Madagascar, and Asia, hunting and trapping affect 54 to 90% of the species. Logging is the third greatest threat to primates in all regions.

Destruction for export markets

The paper acknowledges more than once, and sympathetically, that another misfortune of the primates is to be located in zones of human poverty, where any changes in conservation policy would face an immediate and steep financial challenge. But it would be a misreading to think that the threatening activities resemble subsistence farming, rather than industrial-scale commodity production, or woodcutting for home cookstoves rather than the hardwoods export market.

In the 20 years from 1990 and 2010, expansion of ag land into primate territory ran to some 1.5 million square kilometers, “an area three times the size of France.” Some of this, in Asia, is about growing rice for hungry populations. A lot of it is about producing palm oil for export in Africa and South America, or establishing new rubber plantations in China and India.

Modeling the overlap between primate species’ distributions and forecasted future agricultural production for the 21st century indicates that regions predicted to undergo the greatest agricultural expansion over the next decades comprise 68% of the global area currently occupied by primates.

Oddly, forest clearing is also credited as a driver of new species recognition among primatologists (along with advances in genetic study); they have lengthened the list of species from 376 to 504 since 2005, in part because apes and monkeys driven from their forest homes are easier to spot on the cleared landscape. Some have the flexibility to adapt to open country; most do not.

And so the discussion about possible new conservation responses just fails to persuade when it contemplates new regulatory regimes in places where poor people are clearing land as fast as they fan to produce new products for the wealthy outside world.

Ditto the suggestion of setting aside more protected areas for threatened primates; the paper discusses a dual trend in which nations have continued to extend protections to ever more acreage, without finding means to enforce the new rules.

Indeed, newly protected areas can become especially attractive sites to harvest, say, rosewood in Madagascar — or the monkeys and apes themselves.

Although bushmeat hunting is difficult to track, reports indicate that about 150,000 primate carcasses from 16 species were traded annually as bushmeat in urban and rural markets at 89 sites in Nigeria and Cameroon. In Borneo, between1950 and 3,100 orangutans are estimated to be killed annually (including 375 to 1,550 females), a level that far exceeds the maximum sustainable offtake for population viability.

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Because only a relatively small number of primates live inside protected areas … populations outside protected areas are declining rapidly; the consequent increase in rarity raises the price of primate meat, making it more worthwhile for poachers to risk encroaching into protected areas to hunt.

And despite the look-on-the-bright-side discussion of possible responses laid out in the text, co-author Paul Garber was less sanguine in an announcement of the paper[RM1]  from the University of Illinois, where he is professor emeritus of anthropology, about the odds of changing “needlessly destructive and unsustainable practices” of resource extraction and agriculture:

Agricultural practices are disrupting and destroying vital habitat for 76 percent of all primate species on the planet. In particular, palm oil production, the production of soy and rubber, logging and livestock farming and ranching are wiping out millions of hectares of forest.

This truly is the eleventh hour for many of these creatures. Several species of lemurs, monkeys and apes — such as the ring-tailed lemur, Udzunga red colobus monkey, Yunnan snub-nosed monkey, white-headed langur and Grauer’s gorilla — are down to a population of a few thousand individuals. In the case of the Hainan gibbon, a species of ape in China, there are fewer than 30 animals left.

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The full paper as published in Science Advances can be read here without charge.