Seasonal anoestrus in western grey kangaroos (Macropus fuliginosus ocydromus) in south-western Australia

Abstract

Public opposition to culling has generated interest in wildlife management through fertility control. Temporary, non-invasive methods of fertility control, such as by xenobiotics, can be best employed with an understanding of the target species’ breeding cycle. We used head length to calculate the conception date of 136 pouch-young of western grey kangaroos (Macropus fuliginosus ocydromus) from four sites around Perth, Western Australia, between May 2006 and October 2008: Thomsons Lake Nature Reserve (n = 80), Harry Waring Marsupial Reserve (n = 11), Melville Glades Golf Club (n = 29), and Marangaroo Golf Course (n = 16). In total, 78% 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. We examined the ovaries of 134 females culled from Thomsons Lake Nature Reserve during the months of May–July 2006. Only seven ovaries had a follicle of at least 5 mm and none had an active corpus luteum. These data indicate that the breeding activity M. f. ocydromus is restricted almost exclusively to the months of November–February. A practical application of this finding is that temporary fertility controls applied early in October will provide a full year of birth control if they remain active for seven months.