Study Tries To Understand How To Improve Captive Rhino Breeding
European Zoo’s may be about to experience a renaissance in rhino reproduction as researchers seek to improve the success rate of these animals mating in captivity according to a new study.
The Black Rhino is endangered because it is illegally hunted for its horn and also has a very low birth rate in captivity the researchers said.
In order to find out why some species of captive rhinos breed very easily whilst others never reproduce, English researchers undertook a detailed study of 39 captive rhinos which constitute roughly 90 per cent of the European rhino population.
“This species is of high conservation importance, so understanding what could be limiting breeding in certain individuals and how we could make improvements is a priority,” Katie Edwards, who led the research as part of her Ph.D. studies at the University of Liverpool, said in a statement.
The researchers needed to obtain biological samples so they used rhino droppings taken from 11 zoos across Europe. Samples were collected every other day for as long as 6 years. The study’s authors looked at hormone levels in samples that were used to examine the rhino’s reproductive cycles.
Of the rhinos that were part of the study, 15 failed to give birth whilst 17 bore offspring. 7 rhinos were not sexually mature and it was found that in female rhinos who had not reproduced, irregular ovulation cycles were more common.
“Our analyses showed that females who had never bred were more likely to exhibit irregular oestrus [ovulation] cycles, indicating that underlying physiology is involved in differences in breeding success,” Ms. Edwards said.
Observations of behaviour yielded very little information because female rhinos which were not breeding do not necessarily display when they are ready to mate which makes the management of breeding very difficult Ms. Edwards added. Instead zoos could use hormone analysis to predict when females are more receptive to mating.
Hormone analysis has already been a factor in the birth of three rhinos over the last three years in England. Additionally the study identified a number of other factors which might also increase the success rate of breeding.
Rhinos which do not participate in breeding tend to weigh more than rhinos that do breed which suggests that zoos should think about exercise and diets for animals held in captivity. Non breeding females also tended to be more temperamental.
Increasing the birth rate of rhinos held in captivity may well help the species survive experts say. Poaching is an existential threat to rhinos which means it is very important for scientists to understand the factors which may make reproduction successful.
