If you intend to use a bird scaring device, you must comply with the Audible Bird Scaring Devices Environmental Noise Guidelines. Devices covered by the guidelines include gas or electronic powered noise generating equipment that is used for the purpose of scaring birds from land. The guidelines recommend you develop a bird management plan for your property, the details of what this plan should cover are provided in the guidelines.
You should also consult with your local council to see if there are any further restrictions on the use of bird scaring devices in your local area.