Final answer:
A compensating control offsets the absence of a key control in a system, providing alternative ways to achieve the same objectives and ensure accurate experimentation.
Step-by-step explanation:
A compensating control is a control elsewhere in the system that offsets the absence of a key control. In the context of experimental design, particularly in conservation biology, a control is an experimental unit that is not subjected to the treatment being tested. This allows for a comparison against the experimental group to understand the treatment's effect. However, when a key control cannot be implemented, compensating controls are utilized instead to mitigate risk and provide alternative ways to achieve the same objectives that the key control was supposed to provide.