Female reproductive skew exacerbates the extinction risk from poaching in the eastern black rhino

Variation in individual demographic rates can have large consequences for populations. Female reproductive skew is an example of structured demographic heterogeneity where females have intrinsic qualities that make them more or less likely to breed. The consequences of reproductive skew for population dynamics are poorly understood in non-cooperatively breeding mammals, especially when coupled with other drivers such as poaching. We address this knowledge gap with population viability analyses using an age-specific, female-only, individual-based, stochastic population model built with long-term data for three Kenyan populations of the Critically Endangered eastern black rhino (Diceros bicornis michaeli). There was substantial reproductive skew, with a high proportion of females not breeding or doing so at very low rates. This had a large impact on the projected population growth rate for the smaller population on Ol Jogi. Moreover, including female reproductive skew exacerbates the effects of poaching, increasing the probability of extinction by approximately 70% under a simulated poaching pressure of 5% offtake per year. Tackling the effects of reproductive skew depends on whether it is mediated by habitat or social factors, with potential strategies including habitat and biological management respectively. Investigating and tackling reproductive skew in other species requires long-term, individual-level data collection.

Borrowing from Peter to pay Paul: managing threatened predators of endangered and declining prey species

Conservation policy and practice can sometimes run counter to their mutual aims of ensuring species survival. In Kenya, where threatened predators such as lion deplete endangered prey such as Grevy's zebra, conservation practitioners seek to ensure species success through exclusive strategies of protection, population increase and preservation. We found strong selection for the endangered Grevy's zebra by both lion and hyena on two small fenced conservancies in Kenya. Despite abundant diversity of available prey, Grevy's zebra were selected disproportionately more than their availability, while other highly available species such as buffalo were avoided. Lions were therefore not alone in presenting a credible threat to Grevy's zebra survival. Conservation practitioners must consider interlinked characteristics of prey selection, resource availability and quality, the interplay between carnivore guild members and landscape scale population trends performance in wildlife management decisions.

Stimulation of rotavirus IgA, IgG and neutralising antibodies in baboon milk by parenteral vaccination

A rhesus rotavirus vaccine adjuvanted with ISCOMs was injected intramuscularly to 5 pregnant baboons, with repeated doses 1-2 and 14 weeks after delivery. Maternal blood and milk samples and blood samples from their babies were collected at 2-weekly intervals until 26 weeks after parturition. Samples were assayed for rotavirus antibodies by ELISAs and neutralisation tests. Vaccination produced statistically significant increases in maternal serum IgG and neutralising antibodies, and in milk IgA, IgG, and neutralising antibodies. Control baboon mothers sampled from 12 weeks after delivery had lower serum and milk antibody titres, but responded to vaccination at 16 weeks by producing a similar antibody profile in serum and milk to those previously vaccinated. Because of the endemic nature of human rotaviral infections, similar maternal vaccinations have potential as a means of increasing milk antibodies to a level at which they may be protective to infants.