Australia: The Land Where Time Began

A biography of the Australian continent 

Red Kangaroo

The red kangaroo is the largest living marsupial, at 2.5 m from nose to tip of tail and weighing about 85 kg. They live in the arid parts of Australia, in the inland woodlands and deserts. Like other marsupials they are well adapted to their arid environment, shutting down their reproductive system when conditions are too dry to breed successfully, and rebooting it only when conditions improve. They are one of the most highly adapted animals to desert conditions, especially their reproductive strategy. The females usually have a production line of young, one out of the pouch but still drinking milk when necessary, a baby still developing attached to the other nipple, and a fertilised ovum that remains at the blastocyst stage of development until the young attached to the teat reaches the stage were it leaves the pouch, the blastocyst them recommences development. Each nipple varies the composition of the milk it produces to suit the stage of development of the young drinking from them. They don't have a definite breeding season, the female being ready to mate the next time there is a male nearby as soon as the blastocyst resumes development. This reproductive strategy, in which there are young at 3 stages of development allows the female to reproduce at maximum speed in good times and in drought, if she reaches a stage when she can no longer support young, the milk supply stops and, in the most severe conditions, 1 or both of the young feeding from nipples can die, following which the blastocyst resumes development. Each young takes 600 days to reach the stage where it can live independently, but in good times a female can have a young becoming independent every 240 days. There is a high mortality at the stage when they leave the pouch, but in good times they can build up their numbers rapidly.

They drink from stock watering places when available, but they are capable of surviving with no surface water to drink, getting all they need from their food. They usually feed between dusk and dawn, spending the hot part of the day resting in whatever shade they can find. They usually move around in groups of about 20 with a single dominant male. In the dry season mobs of several hundred are not uncommon. They can live more than 20 years, but most don't, many not getting past a couple of years. Their numbers fluctuate widely with the seasonal conditions. With the return of good conditions their reproductive strategy means they can breed up very rapidly in the good times.

Sources & Further reading

  1. Mary E. White, Listen...Our Land is Crying, Kangaroo Press, 1997
  2. Tyndale-Biscoe, Hugh, 2005, Life of Marsupials, CSIRO Publishing.
Author: M. H. Monroe
Last updated: 30/09/2011

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