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Context. Overabundant native wildlife can pose serious challenges for managers. The most direct, immediate way to reduce density-dependent impacts is by culling, but lethal control often lacks public support. Fertility control offers a non-lethal management alternative. Aims. We conducted two fertility-control projects on eastern grey kangaroos (Macropus giganteus), a common and widespread species in Australia. We aimed to evaluate three key components of an integrated fertility-control project, namely, delivery efficiency, contraceptive efficacy and population-level outcomes. Methods. The two study sites on the urban fringe of Melbourne, Australia, were small reserves. Both had undergone an irruptive peak and subsequent crash, with negative impacts on animal health. Gresswell Forest (52 ha) is open forest habitat enclosed by a kangaroo-proof fence. Serendip Sanctuary (250 ha) is grassy woodland and retired pasture, with a boundary allowing kangaroo movement onto neighbouring properties. We captured kangaroos with a dart gun at night and treated all healthy adult females with subdermal levonorgestrel implants. Key results. Delivery efficiency (catch-per-unit effort) was greater from a vehicle at Serendip Sanctuary than on foot at Gresswell Forest, with only a marginal decline over successive nights at both sites. Background fecundity was 91% at Serendip Sanctuary, but close to zero at Gresswell Forest. Treatment efficacy was high, being 86–100% infertility at Serendip Sanctuary and 96–100% at Gresswell Forest. At Serendip Sanctuary, the proportion of females treated never reached 75%, whereas only one female at Gresswell Forest remained untreated after 3 years. Population density at Serendip Sanctuary exceeded the target range 3 years after culling and fertility control. No culling occurred at Gresswell Forest, but fertility control apparently held population density at a moderate level, albeit much higher than the density target. Conclusions. Future management at Serendip Sanctuary and Gresswell Forest will require a sustained fertility-control effort. Further culling may also be required to complement fertility control at Serendip Sanctuary, the larger, open site. Implications. Contraceptive efficacy of levonorgestrel is high in kangaroos and implants can be delivered efficiently, but achieving control of a large, open population will be challenging. [ABSTRACT FROM AUTHOR]

Age is an essential attribute in studies of animal development, survival and reproduction. Here we evaluate the age estimation technique of molar progression devised for kangaroos in 1965. We used 71 wild eastern grey kangaroos (Macropus giganteus) that were first captured and aged as pouch young at Wilsons Promontory National Park, Victoria, and subsequently found dead between the ages of 1 and 14 years. We expected that the original equation, derived from captive kangaroos in Queensland, would not estimate age correctly due to differences in diet and/or clinal variation in skull morphology. We found no difference in rate of molar progression between males (n = 44) and females (n = 27). Our overall regression of age on molar index (MI) was log10 (age, days) = 0.284 (MI) + 2.51 1, r² = 0.97. The slope of this equation was indistinguishable from that of the original one, meaning that molar progression in the wild was equivalent to that originally developed on captive kangaroos, despite likely differences in diet and morphology. [ABSTRACT FROM AUTHOR]