Western Grey Kangaroo Macropus Fuliginosus Management Plan For Western Australia 2003 2007

Author : Christopher John Mayberry
Publisher :
ISBN 13 :
Total Pages : 272 pages
Book Rating : 4.:/5 (783 download)

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Download or read book Management of Isolated Populations of Western Grey Kangaroos (Macropus Fuliginosus Ocydromus) Through Fertility Control, in South-western Australia written by Christopher John Mayberry and published by . This book was released on 2011 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt: [Truncated abstract] This thesis explores the general hypothesis that management of isolated populations of western grey kangaroos (Macropus fuliginosus ocydromus) in south-western Australia by chemical fertility control through a capture, mark and treat approach is a practical alternative to culling, which is becoming socially unacceptable. For all live animal studies I used 'kangaroo muesli', a proprietary mix consisting mostly of steam-rolled lupins flavoured with molasses, and lucerne hay, to facilitate close approach to the kangaroos. To capture the kangaroos, I gave them an intra-muscular injection of tiletamine/zolazepam (Zoletil®), which induces unconsciousness rapidly. Unfortunately, it also has a prolonged recovery time, of up to four hours. While this is acceptable for a research situation it is not suitable for general field application. A practical alternative for minor procedures would be immobilisation of the kangaroos with succinylcholine, but there is no safe, efficacious dose known for kangaroos. To predict a safe, efficacious dose of succinylcholine for kangaroos, I compared plasma cholinesterase activity of western grey kangaroos with that of horses, sheep and cattle, for which succinylcholine dose rates are well established, and determined that as the plasma cholinesterase activity of kangaroos was similar to that of sheep and cattle, the succinylcholine dose should be too. I sequentially anaesthetised ten kangaroos with tiletamine/zolazepam and injected them with increasing doses of succinylcholine. An apparent antagonism between the succinylcholine and the tiletamine/zolazepam resulted in the succinylcholine failing to completely block the locomotory or respiratory muscles at any succinylcholine dose used, but instead, the succinylcholine induced an increased sensitivity to peripheral stimulation and clonic muscular contractions at higher doses. I used head measurements to estimate the age and calculate the dates of birth and conception of 136 kangaroo pouch young from two nature reserves and two golf courses in Perth, Western Australia. Seventy eight percent of all pouch young were conceived in the months of December - February, 11 % in November, 6 % in March, and less than 2 % in each of October, April and May. These results show that breeding by the western subspecies of the western grey kangaroo, M. f. ocydromus, is strictly seasonal. Thus, chemical fertility controls applied in October will provide a full year of birth control if they remain active for six months. To determine the level of any intervention into female fertility necessary to stabilise an isolated population of kangaroos, I used a non-linear mathematical model. At 90% adult female fertility and 10 % annual mortality for both adults and juveniles, as might exist on a golf course or a reserve after regular culling, the population would grow by 20 % per year, and female fertility would need to be reduced to 27 % to prevent population growth. In contrast, if adult mortality was 20 % and juvenile mortality was 50 %, as might occur on a reserve with no culling, the population would already be stable if female fertility remained at 90 %...