A collection of monkeys is usually called a troop (not troupe!). However, tribe is other collective noun for monkey, and I once heard a professor of zoology refer to a 'mission of monkeys'. At the other end of the spectrum, I saw a stand-up comic use a gag about a 'circus of monkeys', but I think that he made up that collective noun.
The largest monkey is the mandrill (see fiercesome mug-shot opposite). Monkeys have tails, unlike apes like gorillas who have no such appendage.
It's true that monkeys spend most of their time in the trees, and the use their tail like a fifth limb. The higher a monkey climbs, the more you see of his behind. Joe Stillwell.
At the "Tigers” Sanctuary in Myrtle Beach, South Carolina, USA., this orang-utan, Suryia, was in the rescue centre and was not doing at all well. This old Blue Tick hound, Roscoe, wandered in, truly emaciated, and the orang-utan took to him from the moment the dog arrived. He stayed with the hound night and day until he was well and during the process found a reason to live. They are now inseparable friends.
A dog is not just a man's best friend, he's an orang-utan's friend too.
Barbary Ape Legend of Gibraltar
One of the most enduring legends about monkeys concerns the macaque, or Barbary ape. The legend has it that if these monkeys all die or are relocated, then the British will be forced to leave Gibraltar. (Despite their name and lack of tail, they are true monkeys.)
In the second world war the population dwindled to less than 10, and seemed unsustainable. Then in 1941 prime minister Winston Churchill personally ordered a secret mission. Two special task forces were despatched in 1942, one to Morocco and another to Algeria, they returned with about 20 Barbary apes. Today there are over 200 Barbary apes on Gibraltar and it looks like the British will be hanging on to this outpost on Spain's doorstep.
source = http://www.guy-sports.com/humor/pictures/picture_monkey.htm