Depending on the nature of the project, the custom object detection and classification model would vary. For example, camera traps that are meant to detect a certain species would be slightly different than the ones meant for general observations.
For this project, the model was trained to detect 17 classes, which are all the classes of animals that I was able to manually detect in the MegaDetector demo video.
The classes are Armadillo, Bear, Bird, Bull, [Car], Cat, Cattle, Deer, Dog, Fox, Monkey, [Person], Pig, Raccoon, Sheep, Tiger, and [Truck]. I also added a few classes in [brackets], just in case someone would find the model useful as is. Cars and trucks are typically good indictors of nearby poachers.