The Kangaroo

The sound is most like that made by the jew's harp. The back of the tongue is pressed up against the soft part pf the palate. By increasing and decreasing the size of the mouth cavity, you can create a note which 'hops up and down', and is reminicent of a kangaroo hopping over the key note.
The true rhythm of this way of playing can be learnt best by looking at some kangaroos hopping about.
The Dingo

Imitating the sound of the dingo starts with barking while you are playing, and the barking then changes into the howling of a wolf. You will not manage this without help of your abdominal muscles. Make sure that you keep vibrating your lips.
Emu (The Trombone Sound)

You have to purse your lips and then keep them tightly pressed together. It is easier with a narrow mouthpiece, or even a didgeridoo with a smaller diameter. The short double sound, " TOO TOO", indicates a change in the rhythm of traditional music or the end of a song. You can produce a really jazzy sound when you learn to alternate the key note and the trombone sound rapidly so that a percussive style results.
The Kookaburra

It is quite difficult to imitate its song on the didge. A great deal of air and a lot of 'abdominal support' are required to produce the appropriate sound. As regards the pitch of the note, the imitation starts in the middle regions and then moves up to the higher regions. This can only be achieved by using the larynx. The first syllables are short and seem to be cut off, but towards the end they become longer and longer 'cuccacoo, cuckoo, cacacacuckoo, cacaa, caa, caaa, caaaaaaa!' Pbviously the key note has to keep sounding at the same time.
text and images from: DIDGERIDOO Ritual Origins and Playing Techiniques DIRK SCHELLBERG
ISBN 90-74597-13-0