Jouan & Rius / Koala (Phascolarctos cinereus) juvenile in tree, Otway National Park, Victoria, Australia

Steven David Miller / Young Koala (Phascolarctos cinereus) on tree branch. Captive, part of breeding program due to threat from disease. Hartley's Creek Zoo, Cairns, Queensland, Australia.

Steven David Miller / Western grey / Black-faced / Mallee kangaroo (Macropus fuliginosus) joey looking out of pouch, Flinders Ranges National Park, South Australia, June

Roland Seitre / Gray Short-tailed Opossum (Monodelphis domestica) babies suckling, Moscow Zoo, Russia. Captive

Inaki Relanzon / Koala (Phascolarctos cinereus) with young in tree, Great Otway National Park, Victoria State, Australia.

John Cancalosi / Common brushtail possum {Trichosurus vulpecula} newborn young suckling in mother's pouch, New Zealand, captive

John Cancalosi / Common brushtail possum baby suckling in pouch {Trichosurus vulpecula} New Zealand, captive

Roland Seitre / Greater bilby (Macrotis lagotis) baby in pouch, vulnerable species, captive, at breeding station, Australia

Steven David Miller / Black-footed / Black-flanked rock wallaby (Petrogale lateralis) joey looking out of mother's pouch, Heavitree Gap, Alice Springs, Northern Territory, Australia, June

Roland Seitre / New-born baby Koala (Phascolarctor cinereus) in pouch. Mikkira Station, Port Lincoln, South Australia.

Andy Rouse / Agile wallaby (Macropus agilis) female with joey in pouch, Bamarru Plains, Northern Territories, Australia

Dave Watts / Bennett's Wallaby (Macropus rufogriseus) female with joey in pouch, Tasmania, Australia.