REPRODUCTION
Many smaller dasyurids demonstrate semelparity (death of males after first breeding season) and show tight seasonality to breeding behaviour. Synchronicity of breeding in red-tailed phascogales in managed care was influenced by daylight length and social conditions (Foster et al.
2008). Signs of oestrus vary between species but may include changes in bodyweight, reduced appetite and development of the pouch (Foster et al. 2008). Assays of faecal oestradiol and progesterone were not useful indicators of oestrus detection in red-tailed phascogales housed in managed care (Foster et al. 2008). Measures of plasma and faecal androgens in male spotted-tailed quolls (Dasyurus macu- latus) and Tasmanian devils showed close correlation, and revealed seasonal variation in androgen levels, which increased in the period preceding female reproductive cycling (Hesterman and Jones 2009); however, there does not appear to be seasonal variation in sperm production in male Tasmanian devils (Lim et al. 2010). Pouch development in female Tasmanian devils and spotted-tailed quolls is a useful external indicator of reproductive activity and reflects changes in plasma levels of sex steroids (Hester- man et al. 2008).Storage of sperm has been demonstrated in females of some dasyurid species (Foster et al. 2008). Some species produce large quantities of offspring, more than the number of teats available for rearing, and many do not survive. Assisted reproduction techniques in dasyurids are largely still at the research and development stage. Techniques for preservation of germ-line material are currently in development. Sperm and oocyte cryopreservation techniques have been trialled with several species, including Tasmanian devil and fat-tailed dunnart (Sminthopsis cras- sicaudata), using a range of cryoprotectants and freezethaw programs (Czarny et al. 2009; Czarny and Rodger 2010a; Czarny and Rodger 2010b; Keeley et al. 2012). Sperm viability has been variable and is affected by a range of factors; our understanding of approaches to cryopreservation of sperm in dasyurids is improving. For additional information of reproduction in dasyurids see Chapter 5.
3.