Kiwi are a remnant of a group of ancient birds belonging to the group palaeognathae. There are five species one in the North Island (Brown Kiwi) and four in the South Island (Rowi, Tokoeka, Pukupuku and Roroa). The mating systems of these species vary from monogamy to cooperative breeding. We found that Brown Kiwi shows a diversity of mating systems from monogamy to polyandry and polygynandry. Interestingly Kiwi females are larger than males (sexual dimorphism) and in the Pukupuku and Brown Kiwi the male incubates alone (sex role reversal). This sort of behaviour is common in polyandrous species living in extreme environments where the females and males’ reproductive success depends on rearing as many offspring as possible, during a short and often hazardous breeding season. This does not seem to be the case for brown kiwi where females lay up to two clutches of two eggs per season and the life span is long (≥50 years). So, we have been fascinated by this unusual species and are studying several aspects of their breeding ecology. An intriguing aspect of a breeding system where males incubate is the hormonal environment of the males. We measured the levels of prolactin on male and female kiwi. Female prolactin concentrations increased at the time of oviposition, whereas male prolactin concentrations rose gradually between the pre-breeding and incubation periods. Male testosterone decreased during incubation. We are currently looking at whether females take male roles (sex role reversal) to match incubation of males. We will be measuring hormones that are involved in masculinisation in other species (androstenedione and testosterone). In addition, we are looking at breeding behaviours that could be mediated by such hormones. Finally, we have found that members of breeding units are less related to each other than expected suggesting that Brown Kiwi can detect kin. We are investigating whether kiwi can smell differences in individuals that allow them to select partners to avoid inbreeding. The variable mating system of kiwi as well as their potential ability to discriminate between relatives can provide benefits to management by decreasing inbreeding and maximising reproductive success.