It’s raining kangaroos: the ups and downs of kangaroo management

Rain is encouraging kangaroos to breed, and making farmers nervous. Wombalano

Spokespeople for the Kangaroo Industry Association of Australia and some other pastoralist organisations, are warning that in the current land of “flooding rain”, landholders will be overwhelmed by burgeoning kangaroo numbers unless commercial offtake (or harvesting) is ramped up (with government support).

Should landholders be worried? Should we be commercially killing more kangaroos?

On the mainland, the commercial industry kills four species of large kangaroo – the red kangaroo, the eastern and western grey kangaroo and the common wallaroo. The offtake is from a mixed stock of four species of quite different biology, even though they are usually presented generically as “kangaroo” to consumers.

In 2011, the combined commercial quota for killing kangaroos is 3,730,710. The 30-year average total population of the four species of kangaroos in the commercial zones is about 27 million. The quota varies between species (highest for red kangaroos), state management programs and harvest zones and this distils down to about 14% of the combined population of the four species.

How quickly do kangaroo populations jump back with the rain?

The red kangaroo is noted for its quick reproductive response to drought-breaking rain. Even so, development is slow: it is about a year from conception to weaning. The common wallaroo is similar but the two grey kangaroos have slower development, taking about 18 months to weaning.

Fecundity, or the ability to reproduce, is increased in kangaroos because these animals have overlapping generations. In kangaroos, the uterus and pouch are rarely left vacant. Thus the red kangaroo will give birth in about a month and then mate and conceive 1-2 days later.

A female kangaroo can have (a) a joey just out of the pouch and (b) another on the nipple. Ulrike Kloecker