Pennant's red colobus monkeys only live on Bioko Island near Africa's west coast. Their population declined by over 40% in two decades after a luxury bushmeat market opened on the island. Hunters killed about 550 red colobus for bushmeat in 2004. Although the monkeys live only in special reserves on a small part of the island, they're not protected enough to prevent the massacre.

Forest patches alongside a 60 kilometre stretch of Kenya's lower Tana River are the only place where Tana River red colobus live. Less than 1,000 of the monkeys remain. An influx of people and farming has escalated since 1990, leaving only half of the original riparian forest habitat and degrading the rest. Another monkey that's also restricted to these forests, Tana River mangabey (Cercocebus galeritus), is just as scarce and endangered.

Biologists have extensively and repeatedly searched for Miss Waldron's red colobus monkey since 1993, but have failed to see a single one alive. They found one skin in 2002 in the hands of an Ivory Coast hunter. If not already gone, this red colobus is on the verge of extinction.

Scientists first became aware of kipunji in 2003, which turned out to be not only a new species but also a new genus of monkey. Fewer than 1500 kipungi survive in two mountain forests separated by 350 kilometres. One site has less than 200 individuals. Their continued existence is threatened by hunting and tree cutting.

Two subspecies of this monkey, also known as simakobu, live only on an island cluster off the west coast of Sumatra. Forests for this tree-dweller are being logged and people are moving into the area, causing its numbers to decline. These changes are also endangering three other primates unique to the Mentawai island forests, a gibbon, a macaque and another langur.

No more than 250 Delacour's langurs remain in the limestone mountains of northern Vietnam. The monkeys live in 19 isolated groups, most with fewer than 20 individuals. Some subpopulations have declined by 20% in the last five years. The traditional medicines trade drives the killing of 30 or more of these animals a year.

Langurs once densely populated the 140 square kilometre Cat Ba Island of northeast Vietnam. In the 1960s they numbered around 2500. Hunting for traditional medicines reduced the total to 53 individuals by 2000. With better protection they increased by 2007 to around 65 monkeys. But just three of the seven isolated groups are producing offspring, because males are scarce. Recently only one or two golden-headed langurs have been born each year.

The population of this native Sri Lankan langur has declined by 80% in recent years to around 10,000 monkeys. Expanding human settlement and forest loss over the past half century has reduced the habitat suitable for this monkey to three unprotected forests.

This recently identified douc species numbers 600 to 700 in central Vietnam. It may also live in Laos and Cambodia. Hunting the monkeys with snares continues, even in parks and nature reserves. Their habitat is also declining due to illegal logging and expanding agriculture.

Fewer than 150 of this large colobine monkey remain in four locations of northern Vietnam. One population in a nature reserve that previously numbered 70 individuals had less than 40 by 1992. A 2006 survey there found none, although local residents suggest perhaps a dozen still exist. Hunting and deforestation have decimated the species in recent decades.

Both subspecies of variegated or brown spider monkey are critically endangered. There are no surveys of where exactly they remain. Much of their forest habitat was destroyed and is now farmed. Some spider monkeys have also been hunted or captured to sell as pets.

A small number of brown-headed spider monkeys are left in two areas of Ecuador. Hunting and deforestation have removed the tree-dwelling monkeys from most of their former range, including the country's central coast. It's not known how many exist, nor whether any survive in Columbia.

Not much is known about Peruvian yellow-tailed woolly monkeys, except that they're disappearing. There are no estimates of the numbers or where in Peru's Andes they still live. Illegal selective logging that goes on even in protected areas is enough to cause the monkeys to leave. Clearing of the mountain forests that woolly monkeys rely on continues at an alarming rate. They're also illegally shot for trophies.