Squirrels are the first animals I met in Costa Rica. There are a lot of them in the countryside, and in the forest, and even in the city. Usually they are reddish with a gray fluffy tail.
When we lived in the Mora area, I first heard the squirrels screaming. Very often they could be seen on a guava tree, which grew near our rented apartment. They jumped on branches, plucked and gnawed the fruits, the remnants threw down and made quite loud chirping sounds. Especially in the silence of the night, squirrels screaming and falling fruit rumble on the roof.