Don´t put all your eggs in one basket - or all your horses on one pasture
December 2011. Winters in the Gobi desert are usually long and very cold but the winter of 2009/2010 was particularly severe, a condition Mongolians refer to as "dzud". Millions of livestock died in Mongolia and the re-introduced wild Przewalski's horse population crashed dramatically. Petra Kaczensky and Chris Walzer from the Research Institute of Wildlife Ecology (FIWI) of the University of Veterinary Medicine, Vienna have used spatially explicit loss statistics, ranger survey data and GPS telemetry to provide insights into the effect of a catastrophic climate event on wild horses, wild asses and livestock that share the same habitat but show different patterns of spatial use.
Extreme winter in Mongolia
In Mongolia, extreme weather conditions - droughts followed by cold and snowy winters - occur at irregular intervals. However, the dzud of 2009/10 was the most extreme winter Mongolia had experienced in the past 50 years. Fifteen out of Mongolia's twenty-one provinces were declared disaster zones and over 7.8 million livestock, 17% of the national stock, are believed to have perished.
Przewalski's horse reintroduction
Przewalski's horses have been re-introduced into Mongolia since 1992 and there are now free-ranging populations in Hustai National Park in central Mongolia and in the Great Gobi B Strictly Protected Area (SPA) in south-western Mongolia. Due to its special location at the fringe of the Dzungarian basin, flanked by high mountains, the Great Gobi B SPA received particularly high amounts of snowfall in the winter of 2009/2010. Most snow came with weather from the west and when the snow clouds hit the Altai Mountains on the eastern edge of the Great Gobi B SPA they discharged large amounts of snow, resulting in a strong east-west gradient in snow depth. The high, tightly packed snow made it hard for animals to gain access to the vegetation under the snow.
60% Przewalski's horses died
Herders in and around the Great Gobi B Strictly Protected Area were severely affected by the dzud and lost on average 67% of their livestock. Although herders are semi-nomadic, it was hard for them to escape the worst of the weather as competition for the available winter camps was high. Przewalski's horses were found to use three different winter ranges, two in the east and one in the west. Losses averaged 60% but mainly affected the groups wintering in the east, with the group in the west suffering almost no mortalities. As spatial use of Przewalski's horses is extremely conservative, groups did not attempt to venture beyond their known home ranges.
Wild asses suffered few losses
In contrast, Asiatic wild asses seem to have suffered few losses. These animals roam over much larger areas than Przewalski's horses and are not restricted to any particular wintering areas. Petra Kaczensky, the first author on the PLoS paper, says that "wild asses were obviously able to outrun the worst of the dzud by moving west. The long-distance movements and shifts in range highlight how important it is to manage migratory or nomadic species on a landscape level, including multi-use areas outside of protected areas. Fragmentation of their range will reduce their flexibility and can easily result in local population crashes such as the one seen for the Przewalski's horses."
Limited range an issue
The severe effect of this localized catastrophic event was largely due to the small size and limited range of the present-day Przewalski's horse population. A large and continuous population would be much more robust as it could counteract local population lows or extinctions via re-colonization. The dzud winter of 2009/2010 is a textbook example of how vulnerable small and spatially confined populations are in an environment prone to fluctuations and catastrophes. Losses of this magnitude are difficult to model or predict. As long as populations remain small and spatially confined, their survival cannot be guaranteed, necessitating a long term conservation commitment to ensure the species' future.
"The winter disaster really highlighted how dangerous it is to have all our eggs in one basket or in this case all the horses on a single pasture," says Petra Kaczensky. "The national strategy for Przewalski's horse conservation in Mongolia should continue to aim at multiple re-introduction sites with spatially dispersed populations. Ideally the sites should cooperate closely and if necessary also exchange animals on a national as well as international scale. Such steps have already been initiated in Mongolia and the recent down-grading of the Przewalski's horse in the IUCN Red List from ‘critically endangered' to ‘endangered' shows that this strategy is paying off."
http://www.wildlifeextra.com/go/news/Przewalskis-horse%20.html
Generally, it is not feasible, either technically or financially, to breed and re-introduce all endangered species, as has been done for the Przewalski's horse. Chris Walzer explains, "More promising strategies involve timely science-based measures to reduce threats to fauna and flora. These may include the establishment of protected areas but it is also important to maintain natural spaces and structures that make multi-purpose landscapes ‘permeable' for wildlife, so that wide-ranging species can roam, as Asiatic wild asses tend to do".
Their results are now published online in the international Journal PLoS ONE.
Showing posts with label Mongolia. Show all posts
Showing posts with label Mongolia. Show all posts
Sunday, January 1, 2012
Saturday, December 18, 2010
The snow leopard: ghost of the mountains
Nobody said anything, we just thought it: if the traps had been built yesterday, we might have got one. We might have joined the tiny number of people alive on this planet who have seen a snow leopard in the wild. This most elusive and mysterious of big cats comes along only slightly more often than a unicorn, and if you are not prepared you can regret it for the rest of your life.
The one person not troubled by regret was Johansson himself, for in the history of biological research into Panthera uncia no one has had more physical contact with wild snow leopards than this 33-year-old PhD student from Sweden. From 1982 to 2008 biologists succeeded in capturing only 15 snow leopards (for the purpose of attaching radio or GPS collars) in their natural habitat. In the past two years a further 12 have been caught by one man, Johansson, a research associate at the Grimso Wildlife Research Station, which is affiliated to the Swedish University of Agricultural Sciences in Uppsala. He is, in the words of Dr Koustubh Sharma, the conservation biologist supervising the Swede's groundbreaking work in Mongolia, a 'snow leopard catching machine'.
Johansson represents the sharp end of the world's first long-term ecological study into the charismatic leopard, about which far less is known than any other of the big cats. Co-sponsored by two US-based non-profit organisations, the Snow Leopard Trust and Panthera, the programme is now in its third year and scheduled to run for at least 15 years. In late August of this year – as summer in the high desert shaded into chilly nights and misty dawns – I joined Johansson and his backup team in their remote mountain camp.
The J Tserendeleg Snow Leopard Research Centre is located in a mountain range in Mongolia's South Gobi province. In the far south-west of the province the Gobi Desert rises and crumples into a series of east-west ridges and valleys known as the Tost Mountains. This area, 75 miles long and 10 to 20 miles wide, is hardly classic snow leopard country, being neither particularly high – about 7,000ft – nor heavily snowbound in winter. But, for reasons that are not entirely understood, it sustains a high density of snow leopards. Based on his work of the past two years, Johansson puts the figure at more than 20.
The snow leopard: ghost of the mountains
Nobody said anything, we just thought it: if the traps had been built yesterday, we might have got one. We might have joined the tiny number of people alive on this planet who have seen a snow leopard in the wild. This most elusive and mysterious of big cats comes along only slightly more often than a unicorn, and if you are not prepared you can regret it for the rest of your life.
The one person not troubled by regret was Johansson himself, for in the history of biological research into Panthera uncia no one has had more physical contact with wild snow leopards than this 33-year-old PhD student from Sweden. From 1982 to 2008 biologists succeeded in capturing only 15 snow leopards (for the purpose of attaching radio or GPS collars) in their natural habitat. In the past two years a further 12 have been caught by one man, Johansson, a research associate at the Grimso Wildlife Research Station, which is affiliated to the Swedish University of Agricultural Sciences in Uppsala. He is, in the words of Dr Koustubh Sharma, the conservation biologist supervising the Swede's groundbreaking work in Mongolia, a 'snow leopard catching machine'.
Johansson represents the sharp end of the world's first long-term ecological study into the charismatic leopard, about which far less is known than any other of the big cats. Co-sponsored by two US-based non-profit organisations, the Snow Leopard Trust and Panthera, the programme is now in its third year and scheduled to run for at least 15 years. In late August of this year – as summer in the high desert shaded into chilly nights and misty dawns – I joined Johansson and his backup team in their remote mountain camp.
The J Tserendeleg Snow Leopard Research Centre is located in a mountain range in Mongolia's South Gobi province. In the far south-west of the province the Gobi Desert rises and crumples into a series of east-west ridges and valleys known as the Tost Mountains. This area, 75 miles long and 10 to 20 miles wide, is hardly classic snow leopard country, being neither particularly high – about 7,000ft – nor heavily snowbound in winter. But, for reasons that are not entirely understood, it sustains a high density of snow leopards. Based on his work of the past two years, Johansson puts the figure at more than 20.
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