Advantages
Practicality
The main advantage with bioacoustics is that you can collect data without deploying a field team, making logistics simpler.
Flexibility
Field expeditions are sometimes compromised by adverse weather. With automated recording devices you have greater flexibility over which data to analyse.
Animal Welfare
Less disturbance: no need to handle sensitive wildlife.
Economic
In appropriate circumstances cost can be less than that of a field team.
Safety
When terrain is risky for night time work, recording devices can be deployed and then retrieved when they have collected the data.