I used to live in Bullsbrook, a bit north of Perth, and close to where the Avon River comes down onto the coastal plain through the Darling Range. Mulgas are not common on the Perth coastal plain, but I removed quite a few from dwellings/yards/chookpens in the Pearce/Bullsbrook/Gingin region. They seem to follow along the river in the Avon Valley to that part of the coastal plain, from the wheatbelt in the Northam region. Mostly they were fairly dark, with greenish scale-bases - very pretty when disturbed and doing the flattening expansion thing so you could see the two-tone scales. Not always appreciative of the help I was offering either!
Jamie