I thought of a concrete example. The types of mitigation are really of two types. Some of them are during the construction phase and some of them are permanent. During the construction phase, there could be a concern that nesting birds are going to be disturbed. The scientists would tell you at what stage the birds are nesting and then would require the proponent to commit to not carrying out any construction activities during that period, say May 1 to June 30.
Mitigation measures can be very specific to a specific time in the year. They can be about how to replace a stream that's been damaged or about how to provide alternative habitat.