There are mainly 3 types of monkeys here in Costa Rica and I've seen all 3. Spider monkeys, white faced monkeys (carablancas) and howler monkeys also known as "Congos".
They are very common in any forested area and sometimes you can see them right off the highways if you watch for them.
I have only seen the spider monkeys a few times but have seen the white faced and howler monkeys many times so they will be the subject of this post.
Around here we hear the howlers in the distance but haven't seen any nearby yet. (I am told we will!) They mark their territory by making a very loud "howling" sound. Think of movies where gorillas go "Hoo Hoo Hoo!" and that is similar to the sound of the Howlers. Though the Howlers are not dangerous and are not very big at all, really. About the size of chimpanzees.
They roam in families and if you find one you should be able to find up to a dozen more very near by! They will usually just hide from you but sometimes a bold one will throw some fruit at you or get right above you, perhaps to show his superiority.
When I lived in Montezuma years ago I would hear them every night about 50 feet from my cabin as a family of them would come by around 2-3am and wake me up with their hoo-hoo-hoo howling.
The 1st time I heard it, it scared me! I didn't know how big they were or anything about them and they sound much much bigger than they are. After I got used to them coming, I would just wake up, smile, wait for them to move on and go back to sleep.
They are very fun to watch! They tend to stay deeper in the forest and are a little harder to find than the white faced monkeys.
The white faced monkeys are everywhere and you can also see them in trees above the road, crossing the roads on branches, and in nearby farms.
They tend to be a little less scared of people, especially if they are living in an area where there are a lot of people around, and they may even try to get food from your plate or wherever once they are accustomed to living around people.
If they live in the back country they are less likely to hang around near people and will more likely run away and hide when people are nearby.
Yesterday for example we were driving home and we happen to see them in a tree up ahead. We stopped the car and got out and tried to get some pictures and it took us awhile but we succeeded. (Pictures to be posted soon.) But they were not at all accustomed to people and they hid from us. We only saw 3 or so but usually they travel in families of5 or more.
One day in the same area we saw a mom carrying a baby on her back, which was a real treat! But we were so excited by the time I thought to get my camera, they were gone!
For me it's a great treat to see and hear monkeys in my neighborhood! I am told sometimes they pass through our farm but I've yet to see them here. I did see one at the neighbor's farm one day though, so I'm sure it's just a matter of time til we see them right here.