What types of pests are primarily controlled through trapping?

Trapping is a method commonly used to control certain types of pests, particularly those that are smaller and can be effectively captured in traps. This includes species like squirrels, pocket gophers, and rats, which are all known for their ability to cause damage to crops, vegetation, and structures. Traps can be designed specifically to target these animals with the goal of reducing their populations in a specific area safely and effectively.

In contrast, options that include deer, rabbits, or large mammals typically require different management approaches due to their size and behavior, which may not be as effectively controlled through trapping alone. Birds and insects also present unique challenges that often necessitate alternative control methods, such as baits, sprays, or habitat modification, instead of trapping. Thus, the best fit for the pests primarily controlled through trapping is indeed the smaller animals mentioned in the answer choice.