I can only tell you about UNSW.
At UNSW, you can do double majors. Although there is no such thing as an "Ecology major", but majoring in "Biological Science" or "Environmental Science" will cover ecology and much more. You can also major in Psyc for your second major (which doesn't require you to do maths subjects at all
). Then, if you wish, in your fourth and optional year, you can Honours in either one of your specialisation.
I don't know what withoutaface is talking about UNSW being less flexible, because in B Sc at UNSW, you can basically do whatever subjects you want as long as they are in the Science faculty for your majors, as well as other faculties for your minor if you don't want to do a second major.
All 3 unis are great. It's really a personal preference
Good luck!