Exploding kangaroos: assessing problems and setting targets.

Grey kangaroo populations in south-eastern Australia can increase to the point where they are considered overabundant. In such populations, the management problem is too often oversimplified as high population density. A more useful approach is to identify the key, underlying problems associated with kangaroos and set clear objectives for them. Kangaroo-related problems may include road accidents, attacks on people, zoonotic disease, contamination of water supplies, lost crop production and competition with threatened species, as well as affects on kangaroos themselves, such as poor body condition and heavy juvenile mortality. Once specific problems have been identified, managers should set objectives that are clear and realistic. Population targets then have to be set for the density required to meet management objectives. Currently, some approaches to this are inadequate: basing targets by comparing density with other populations ignores site-specific differences in productivity and habitat structure; calculating the ecological carrying capacity considers only food resources and neglects other effects; constructing grazing exclosures provides no data on intermediate densities. The relationship between the problem and the population can be explored by analysing time-series data, but is most effectively elucidated by experimentally manipulating population density and measuring responses in the level of the problem. [ABSTRACT FROM AUTHOR]