This post is written by Houston Zoo primate keeper, Helen Boostrom, who is in Belize right now. She is being supported by the staff conservation fund to do field work with Howler Monkeys in Belize. Please go here to learn more about the staff conservation fund. We will post these updates of Helen’s work as we get them, so stay tuned!
The howlers are tracked throughout the day and their movements are marked using a GPS so the process of their territory establishment can be recorded. This is sometimes difficult as the forest is quite dense and the howlers are adept at moving quickly through the trees. It is also really hard to spot them when they are high up in the canopy. If they are resting, you can walk right under them and not even know they are there. When the howlers travel, there is always the telltale sound of fruits and branches falling. A lot of the time on your head as you walk underneath them!
While keeping a close eye on the howlers high-up in the trees it is also important to watch the forest floor for snakes, such as the venomous fer de lance, poisonous plants like the poison wood, and various tripping hazards like vines and holes.
If that wasn’t enough to keep an eye out for, you must also record their behaviors as well as the plants they eat, including the specific type of tree as well as whether they are eating the fruit, the mature leaves, or the new leaves. This is the hardest part in my opinion. I spent the first few days just trying to learn how to correctly identify the plants found in the forests. Then just when you think you have it down, you realize that a lot of the trees have vines wrapped among the branches and even though they are sitting in the tree eating leaves it is the leaves of the vine and not the tree.
All of the information gathered from the study of these howlers in post release will help out in future releases of rehabilitated howler monkeys confiscated from the illegal pet trade. It will be used to assess future release areas in terms of the known food plants found in potential areas, the available space for establishing territories, and the availability of plants suitable for travel or rest. The information will also be used to improve rehabilitation protocols to increase the number of potential food plants the howlers are exposed to in the rehabilitation process and to better mimic the environment the howlers will experience in the forests, such as thin bendable branches and vines, throughout the rehabilitation process.
Keep checking back for more from Helen in Belize. If you want to read her previous posts scroll down or go here.