Black Rhino extinction risk sharply increased by killing of specific
female rhinos

Date:
April 13, 2022
Source:
University of Manchester
Summary:
New research has examined data from the Critically Endangered Kenyan
black rhino populations which suggest that individuals really matter
when assessing the impact of poaching on species' survival chances.



FULL STORY ==========================================================================
New research from The University of Manchester, in collaboration with
Kenyan conservationists and scientists, has examined data from the
Critically Endangered Kenyan black rhino populations which suggest
that individuals really matter when assessing the impact of poaching on species' survival chances.


==========================================================================
The research published today in journal, Proceedings of the Royal Society B,demonstrates that poaching combined with individual rhino's reproductive variance, or how successful mums are at raising young, leads to a greater
than first thought risk to the survival of the black rhino.

In the case of these rhino, reproductive variance increased extinction
risk by as much as 70% when combined with poaching.

Within black rhino populations (and most likely in most animals), some individuals have more babies than others. This variation increases
existing estimates of extinction risk, especially when there is
poaching. This is because indiscriminate killing can lead to some of
these important animals which contribute a greater number of offspring
being removed.

Susanne Shultz, Professor of Evolutionary Ecology and conservation at
The University of Manchester said: "Preventing population declines is a
crucial step for stopping biodiversity loss. In this study, we identified
how losing key rhinos can make small populations very vulnerable,
which can help us design more effective conservation actions." The new research is important because it shows that we may underestimate risk
(or overestimate viability) if we do not recognise that some individuals contribute a lot more to the population (and their loss will have a much
bigger impact).

Lead author on the work, Dr Nick Harvey Sky said: "This study shows
that poaching has effects on rhinos beyond the death of targeted
individuals. The deaths of healthy females that would have gone on
to produce lots of calves can make whole populations more vulnerable
to extinction." Estimating the extinction risk faced by different
populations is vital for conservation. This can be affected by differences
in breeding success between individual females (called reproductive
skew), but reproductive skew is not often included in predictions
of future population growth because it requires detailed individual
breeding histories.

This information is available for the Critically Endangered eastern black
rhino because of intensive monitoring to protect them from poaching. The University of Manchester has collaborated closely with Kenyan rhino
managers, scientists and security teams who have meticulously recorded
births and deaths for decades. Across three Kenyan populations of black
rhinos on Lew Wildlife Conservancy, Ol Pejeta Conservancy and Ol Jogi
Wildlife Conservancy, the researchers found that there is significant
variation in breeding success between females, with many females not
breeding or doing so very slowly.

Dr John Jackson, Post-doctoral researcher at the University of Oxford
said: "For me, our study really highlights a deadly combination of
small populations, individual differences, and poaching for vulnerable populations. When working in combination, these factors can completely
reshape the fate of an endangered species." Crucially, variation in
female breeding success can exacerbate the effects of poaching, especially
on small populations. If key individuals, ones that breed very well,
are killed then it can make the whole population more vulnerable to
extinction. This highlights how important it is to protect rhinos from poaching. It may be possible to even out the variation in breeding success
by creating new rhino reserves, moving rhinos between current reserves,
or even creating more valuable habitat, but the causes of reproductive
skew must first be identified. Differences between individuals in their contribution of young to at risk populations is likely an issue across
many more species and should be evaluated when assessing their risk
of extinction.


========================================================================== Story Source: Materials provided by University_of_Manchester. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Nick Harvey Sky, John Jackson, Geoffrey Chege, Jamie Gaymer, David
Kimiti, Samuel Mutisya, Simon Nakito, Susanne Shultz. Female
reproductive skew exacerbates the extinction risk from poaching
in the eastern black rhino. Proceedings of the Royal Society B:
Biological Sciences, 2022; 289 (1972) DOI: 10.1098/rspb.2022.0075 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/04/220413104154.htm

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