The risk of black rhino extinction is significantly increased with the killing of specific female rhinos.

In collaboration with conservationists and Kenyan scientists, examines data from a population of the critically endangered Kenyan black rhino that shows that individuals are critical in assessing the impact of hunting on the survival of the species.

Royal Society B suggests that poaching combined with individual rhino reproductive variation or how successful mothers are at raising their young results in a greater-than-expected survival risk. For these rhinos, reproductive dispersal combined with hunting increases the risk of extinction by up to 70%.

Some individuals have more babies than others in black rhino populations (and likely in most animals). This variation increases the estimated risk of extinction, especially from hunting. This is because indiscriminate killing could result in the loss of some of these important animals, which contributes to more offspring.

Susanne Schultz, Professor of Evolutionary Ecology and Conservation at the University of Manchester, said: "Preventing population decline is an important step in halting biodiversity loss. In this study, we discovered how the loss of essential rhinos could make small populations extremely vulnerable, which could help us design more effective conservation measures.

This new study is critical because it shows that if we don't realize that some individuals contribute more to the population (and their loss will have a much more significant impact), we may underestimate risk (or overestimate profitability).

Lead author Dr. Nick Harvey Skye said: "This study shows that poaching impacts rhinos beyond the deaths of individual targets. The end of a healthy female, which will produce many calves, can make the entire population more vulnerable to extinction.

Assessing the risk of extinction for different populations is very important for conservation. This can be affected by differences in reproductive success between females (called reproductive bias). Still, reproductive bias is often not considered in future population growth projections as it requires a detailed individual breeding history.