Please use this identifier to cite or link to this item: https://hdl.handle.net/1959.11/6997
Title: Increased reproductive success in older female red kangaroos and the impact of harvesting
Contributor(s): Pople, AR (author); Cairns, Stuart C  (author); McLeod, SR (author)
Publication Date: 2010
Handle Link: https://hdl.handle.net/1959.11/6997
Abstract: Wildlife harvesting has a long history in Australia, including obvious examples of overexploitation. Not surprisingly, there is scepticism that commercial harvesting can be undertaken sustainably. Kangaroo harvesting has been challenged regularly at Administrative Appeals Tribunals and elsewhere over the past three decades. Initially, the concern from conservation groups was sustainability of the harvest. This has been addressed through regular, direct monitoring that now spans > 30 years and a conservative harvest regime with a low risk of overharvest in the face of uncertainty. Opposition to the harvest now continues from animal rights groups whose concerns have shifted from overall harvest sustainability to side effects such as animal welfare, and changes to community structure, genetic composition and population age structure. Many of these concerns are speculative and difficult to address, requiring expensive data. One concern is that older females are the more successful breeders and teach their daughters optimal habitat and diet selection. The lack of older animals in a harvested population may reduce the fitness of the remaining individuals; implying population viability would also be compromised. This argument can be countered by the persistence of populations under harvesting without any obvious impairment to reproduction. Nevertheless, an interesting question is how age influences reproductive output. In this study, data collected from a number of red kangaroo populations across eastern Australia indicate that the breeding success of older females is up to 7-20% higher than that of younger females. This effect is smaller than that of body condition and the environment, which can increase breeding success by up to 30% and 60% respectively. Average age of mature females in a population may be reduced from 9 to 6 years old, resulting in a potential reduction in breeding success of 3-4%. This appears to be offset in harvested populations by improved condition of females from a reduction in kangaroo density. There is an important recommendation for management. The best insurance policy against overharvest and unwanted side effects is not research, which could be never-ending. Rather, it is a harvest strategy that includes safeguards against uncertainty such as harvest reserves, conservative quotas and regular monitoring. Research is still important in fine tuning that strategy and is most usefully incorporated as adaptive management where it can address the key questions on how populations respond to harvesting.
Publication Type: Journal Article
Source of Publication: Australian Zoologist, 35(2), p. 160-165
Publisher: Royal Zoological Society of New South Wales
Place of Publication: Australia
ISSN: 2204-2105
0067-2238
Fields of Research (FoR) 2008: 060809 Vertebrate Biology
Socio-Economic Objective (SEO) 2008: 960805 Flora, Fauna and Biodiversity at Regional or Larger Scales
Peer Reviewed: Yes
HERDC Category Description: C1 Refereed Article in a Scholarly Journal
Publisher/associated links: http://www.rzsnsw.org.au/index.php?/Journals/Australian-Zoologist/australian-zoologist.html
Appears in Collections:Journal Article

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