Khulan, a species of wild ass living in the Gobi Desert,
travel over extremely long distances to find food and water, a recent study has
shown.
The asiatic wild ass or khulan (Equus hemionus) used to be found
throughout the arid lands of Central Asia and Mongolia, but their range is
being limited by encroaching human activity.
As part of a long-term study into these animals, researchers
at the Research Institute of Wildlife Ecology (FIWI, Conservation Medicine
Unit) at Vetmeduni Vienna have been tracking their activity. Analysis of the data
has not only revealed new insights into the behaviour of these animals, but it
has also provided a new way of identifying water sources. The work has been
published in Scientific Reports.
The world’s largest remaining khulan population, in
Mongolia’s South Gobi Region, provided the subjects for the study. Using GPS
collars to track the animals in the 100,000 km² study area, the researchers identified
367 waterpoints. Of these, 53 received intensive and repeated uses by many
different khulan over multiple years and so seem to be of high importance for
the entire khulan population.
However, the researchers point out that the large number of
less visited waterpoints are also important as they provide “stepping-stones”
to switch between areas and allow for maximal movement flexibility.
According to the researchers, khulan drink nearly every day,
with daily requirements of 12-15 litres, rising to 24 litres on hot days. The
low water content of their plant resources further increases the animals’ need
to drink.
In the Mongolian Gobi, khulan roam over thousands of square
kilometres, a range among the largest reported for terrestrial mammals. These
large nomadic movements are a consequence of the availability of pasture and
water changing within and between years.
To survive and thrive in such landscapes, movement
flexibility is key but may be threatened by increasing human impact on the
khulan’s habitat resulting in habitat fragmentation. The researchers point out
that, as in many other of the world’s drylands human exploitation of water for
agriculture, industry, and domestic uses increasingly affects the availability
of and access to water for wildlife.
Khulan tend to use pastures within 7 km of water and areas
beyond 15-20 km of water become functionally inaccessible. “Hence, blocking
access to water excludes khulan from the landscape and Identifying important
waterpoints in arid landscapes like the Gobi Desert is therefore essential for
wildlife-friendly land-use planning,” says John Payne.
According to the researchers, the most important variable
for the seasonal variation in choice of water sources is snow cover (or the
lack of it). In the deserts of Central Asia and Mongolia, a lack of snow, the
low water content of the vegetation, and the freezing of small and stagnant
water bodies can result in drought conditions during winter. In extreme cases,
these factors can result in winter die-offs of local wildlife populations.
The khulan´s highly mobile lifestyle is a coping strategy
during localized catastrophic weather events, but this requires habitats that
allow large-scale movements – which in turn necessitates maintaining landscape
connectivity. The researchers emphasise the urgent need for regional
conservation strategies so the khulan can continue to find the hidden liquid
treasure of the Gobi Desert in the future.
Petra Kaczensky concluded: “Our results provide important
data that can help guide a regional khulan conservation strategy, allow
predictions for other khulan populations, and illustrate the overall importance
of waterpoints for dryland herbivores.”
For more
details, see:
Hidden
treasure of the Gobi: understanding how water limits range use of khulan in the
Mongolian Gobi
John C.
Payne, Bayarbaatar Buuveibaatar, Diana E. Bowler, Kirk A. Olson, Chris Walzer
& Petra Kaczensky
Scientific
Reports (2020) vol 10, Article number: 2989
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