Volunteer in Australia

Conservation Volunteers Australia (CVA)
CVA has been organizing short- and long-term voluntary conservation projects, including tree planting, walking trail construction, and wildlife surveys in Australia since 1982. "Each year, Conservation Volunteers involves over 10,000 volunteers, plants 1 million trees and trains 1,000 groups and individuals."

Discover Corps
Volunteer Vacations with a Purpose in Australia
Volunteer vacations for adults and families in Australia. Immerse yourself in a different culture while giving back, engaging in hands-on cultural workshops, and connecting with fascinating people. Volunteer doing wildlife conservation.1 to 2 week all-inclusive packages.

WWOOF — Australia (World Wide Opportunities on Organic Farms)
Distributes the Australian WWOOF app, with the addresses of about 1,800 member farms in Australia looking for short- or long-term voluntary help. Membership costs AU$70 (which includes accident insurance and an app) and includes a list of farms and volunteer work opportunities.