Kings of the swingers: see in World Monkey Day with five super simians

For any primate fans, 14 December is one of the most important days of the year – it’s World Monkey Day! 

This unofficial holiday started as a bit of "monkey business", instigated by American art students Eric Millikin and Casey Sorrow in 2000 as a recurring motif in some of their comic artwork. The anniversary has since been embraced by conservationists and animal-lovers alike, as an opportunity to promote the cause of endangered primates and to generally celebrate all things simian.

Japanese macaque

Excluding humans, no other primate lives farther north than the Japanese macaque, making these Old World monkeys the Most northerly primates. Their range extends to the mountainous region of Jigokudani in Nagano Prefecture, central Honshu, Japan. 

To help endure the cold winters, when temperatures plummet as low as -15°C (5°F), snow monkeys have learned to take advantage of natural hot springs where the geothermal water reaches a toasty 40+°C (104+°F). 

A hot bath isn’t the only method used by Japanese macaques to keep warm – in playful moments, they’ve sometimes been known to roll snowballs too (see video below).

Mandrill

It’s a common misconception that gorillas are the Largest monkeys, but technically gorillas, chimps and orangutans and their kin belong to the closely related but separate ape group (Hominoidea). This means that although all monkeys and apes are primates, the terms “monkey” and “ape” are not interchangeable.

Today, eastern lowland gorillas are the Largest primates overall (at around 1.75 m/5 ft 9 in tall), but the largest member of the monkey family is the mandrill. Native to the rainforests of West Africa, males have been known to weigh in excess of 50 kg (110 lb) and stand as tall as 60–80 cm (1 ft 11 in–2 ft 7 in) on all fours – about the same as a Rottweiler dog.

This baboon-like monkey is instantly recognizable thanks to the males’ vivid faces and rear-ends. The vibrancy of the colouration indicates status within its troop, or “horde”. Standing out is important when a typical horde can number more than 600 individuals, occasionally exceeding even double that.

Pygmy marmoset

At five times the length and as much as 40 times the weight, a mandrill would truly dwarf its pygmy marmoset cousin – the Smallest monkey. Full-grown adults of these pint-sized primates could comfortably sit in a human hand – a newborn, meanwhile, is only about the size of a thumb! 

Fortunately for the latter, the two will never meet naturally as pygmy marmosets live on the other side of the Atlantic to mandrills, in the Amazon region of Brazil, Peru, Bolivia, Ecuador and Colombia. 

Given their size, pygmy marmosets are a popular would-be snack for many rainforest predators, including eagles, snakes and wild cats. So to better their odds, pygmies favour dense vegetation and have mastered the emergency escape; some have been known to jump nearly 40 times their own body length in a single leap to evade enemies! 

Surprisingly, as small as they are, pygmy marmosets are not, in fact, the Smallest primates…

Proboscis monkey

There’s a very good reason that these monkeys have been named after their hooters… In elder male specimens, the prodigious proboscis can reach lengths of 17.5 cm (6.8 in) – about the same as a medium-sized banana. This makes it easily the Longest primate nose. 

Biologists believe that this distinctive feature helps the males of this species attract females by increasing the volume of their calls in the thick forests of Borneo. 

The super-snout is double the size of the Longest human nose – a record currently held by Mehmet Özyürek of Turkey whose nose measured 8.8 cm (3.5 in) in 2010.

Yunnan snub-nosed monkey

From one bizarre nose to another... Many of the world’s monkeys live in tropical rainforests, which tend to occur at lower elevations. The black snub-nosed monkey – native to coniferous forests of the Chinese province of Yunnan and Tibet – is an exception. 

It’s been documented at heights of up to 4,700 m (15,419 ft) – sometimes even venturing beyond the treeline of the Trans-Himalayan peaks where it lives. Indeed, it’s the Highest-living primate, aside from humans. 

The diet of this species has adapted to its high-altitude and cold-climate habitat, unusually consisting predominantly of lichen.

Fun fact

Monkey fans don’t come much bigger than Wang Lingxian (China). As of 2005, she'd amassed 5,680 monkey-related items, which she had been collecting for 35 years.

For more really wild record-breakers, be sure to check out our new book GWR Wild Things, out now in shops and on Amazon.