Feral desert donkeys are digging wells, giving water to parched wildlife

Erick Lundgren, University of Technology Sydney; Arian Wallach, University of Technology Sydney, and Daniel Ramp, University of Technology SydneyIn the heart of the world’s deserts – some of the most expansive wild places left on Earth – roam herds of feral donkeys and horses. These are the descendants of a once-essential but now-obsolete labour force.

These wild animals are generally considered a threat to the natural environment, and have been the target of mass eradication and lethal control programs in Australia. However, as we show in a new research paper in Science, these animals do something amazing that has long been overlooked: they dig wells — or “ass holes”.

In fact, we found that ass holes in North America — where feral donkeys and horses are widespread — dramatically increased water availability in desert streams, particularly during the height of summer when temperatures reached near 50℃. At some sites, the wells were the only sources of water.

Feral donkeys and horses dig wells to desert groundwater.
Erick Lundgren

The wells didn’t just provide water for the donkeys and horses, but were also used by more than 57 other species, including numerous birds, other herbivores such as mule deer, and even mountain lions. (The lions are also predators of feral donkeys and horses.)

Incredibly, once the wells dried up some became nurseries for the germination and establishment of wetland trees.

Numerous species use equid wells. This includes mule deer (top left), scrub jays (middle left), javelina (bottom left), cottonwood trees (top right), and bobcats (bottom right).
Erick Lundgren

Ass holes in Australia

Our research didn’t evaluate the impact of donkey-dug wells in arid Australia. But Australia is home to most of the world’s feral donkeys, and it’s likely their wells support wildlife in similar ways.

Across the Kimberley in Western Australia, helicopter pilots regularly saw strings of wells in dry streambeds. However, these all but disappeared as mass shootings since the late 1970s have driven donkeys near local extinction. Only on Kachana Station, where the last of the Kimberley’s feral donkeys are protected, are these wells still to be found.

In Queensland, brumbies (feral horses) have been observed digging wells deeper than their own height to reach groundwater.

Some of the last feral donkeys of the Kimberley.
Arian Wallach

Feral horses and donkeys are not alone in this ability to maintain water availability through well digging.

Other equids — including mountain zebras, Grevy’s zebras and the kulan — dig wells. African and Asian elephants dig wells, too. These wells provide resources for other animal species, including the near-threatened argali and the mysterious Gobi desert grizzly bear in Mongolia.

These animals, like most of the world’s remaining megafauna, are threatened by human hunting and habitat loss.

Other megafauna dig wells, too, including kulans in central Asia, and African elephants.
Petra Kaczensky, Richard Ruggiero

Digging wells has ancient origins

These declines are the modern continuation of an ancient pattern visible since humans left Africa during the late Pleistocene, beginning around 100,000 years ago. As our ancestors stepped foot on new lands, the largest animals disappeared, most likely from human hunting, with contributions from climate change.

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Giant marsupials once migrated across an Australian Ice Age landscape

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If their modern relatives dig wells, we presume many of these extinct megafauna may have also dug wells. In Australia, for example, a pair of common wombats were recently documented digging a 4m-deep well, which was used by numerous species, such as wallabies, emus, goannas and various birds, during a severe drought. This means ancient giant wombats (Phascolonus gigas) may have dug wells across the arid interior, too.

Likewise, a diversity of equids and elephant-like proboscideans that once roamed other parts of world, may have dug wells like their surviving relatives.

Indeed, these animals have left riddles in the soils of the Earth, such as the preserved remnants of a 13,500-year-old, 2m-deep well in western North America, perhaps dug by a mammoth during an ancient drought, as a 2012 research paper proposes.

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From feral camels to ‘cocaine hippos’, large animals are rewilding the world

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Acting like long-lost megafauna

Feral equids are resurrecting this ancient way of life. While donkeys and horses were introduced to places like Australia, it’s clear they hold some curious resemblances to some of its great lost beasts.

Our previous research published in PNAS showed introduced megafauna actually make Australia overall more functionally similar to the ancient past, prior to widespread human-caused extinctions.

Donkeys share many similar traits with extinct giant wombats, who once may have dug wells in Australian drylands.
Illustration by Oscar Sanisidro

For example, donkeys and feral horses have trait combinations (including diet, body mass, and digestive systems) that mirror those of the giant wombat. This suggests — in addition to potentially restoring well-digging capacities to arid Australia — they may also influence vegetation in similar ways.

Water is a limited resource, made even scarcer by farming, mining, climate change, and other human activities. With deserts predicted to spread, feral animals may provide unexpected gifts of life in drying lands.

Feral donkeys, horses (mapped in blue), and other existing megafauna (mapped in red) may restore digging capacities to many drylands. Non-dryland areas are mapped in grey, and the projected expansion of drylands from climate change in yellow.
Erick Lundgren/Science, Author provided

Despite these ecological benefits in desert environments, feral animals have long been denied the care, curiosity and respect native species deservedly receive. Instead, these animals are targeted by culling programs for conservation and the meat industry.

However, there are signs of change. New fields such as compassionate conservation and multispecies justice are expanding conservation’s moral world, and challenging the idea that only native species matter.

Erick Lundgren, PhD Student, Centre for Compassionate Conservation, University of Technology Sydney; Arian Wallach, Lecturer, Centre for Compassionate Conservation, University of Technology Sydney, and Daniel Ramp, Associate Professor and Director, Centre for Compassionate Conservation, University of Technology Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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On dangerous ground: land degradation is turning soils into deserts

Abbas El-Zein, University of Sydney

If any of us still has the slightest doubt that we are facing an ecological crisis on an unprecedented scale, then a new report on land degradation, released this week by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), provides yet another piece of evidence.

Land degradation can take many forms, but always entails a serious disruption of a healthy balance between five key ecosystem functions. These are: food production; fibre provision; microclimate regulation; water retention; and carbon storage.

Its impacts can be far-reaching, including loss of soil fertility, destruction of species habitat and biodiversity, soil erosion, and excessive nutrient runoff into lakes.

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The immense challenge of desertification in sub-Saharan Africa

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Land degradation also has serious knock-on effects for humans, such as malnutrition, disease, forced migration, cultural damage, and even war.

At its worst, land degradation can result in the desertification or abandonment of land (or both). Protracted drought and loss of fertile land may have been contributing factors in the wars in Sudan and Syria.

According to the new report, 43% of world populations live in regions affected by land degradation. By 2050, the report estimates, 4 billion people will be living in drylands. These are defined by the United Nations as land with an “aridity ratio” of less than 0.65, meaning that the amount of water lost far outweighs the amount received in precipitation.

Such areas are highly vulnerable to food and water insecurity, especially in sub-Saharan Africa and the Middle East.

A global threat

It would be wrong to infer that land degradation is purely a problem for developing countries. Overall, land is generally more degraded in the developed world – as shown, for example, by greater declines in soil organic carbon content, a measure of soil health. However, in richer nations the rate of degradation has slowed, and people in these regions are generally less vulnerable to its effects.

It is in sub-Saharan Africa, Asia and South and Central America that the problem is growing most rapidly. But climate change, especially where droughts and forest fires are becoming more frequent, can cause land degradation even in affluent places such as California and Australia.

What’s more, a decline in the overall availability of agricultural land is bound to affect food prices globally. By 2050, the report states, humans will have transformed almost every part of the planet, apart from uninhabitable stretches such as deserts, mountains, tundra and polar regions.

Perhaps most chillingly, the report predicts that the combined effects of land degradation and climate change will have displaced between 50 million and 700 million people by 2050, potentially triggering conflict over disputed land.

Some of this migration will inevitably be across international borders – how much is impossible to tell. While the impacts on migrants are almost always devastating, the ripple effects, as we have seen recently with the Syrian war, can spread far and wide, affecting electoral outcomes, border controls and social security systems throughout the world.

Globalised causes

The two most significant direct causes of land degradation are the conversion of native vegetation into crop and grazing lands, and unsustainable land-management practices. Other factors include the effects of climate change and loss of land to urbanisation, infrastructure and mining.

However, the underlying driver of all these changes is rising per-capita demand from growing populations for protein, fibre and bioenergy. This in turn leads to more demand for land and further encroachment into areas with marginal soils.

Market deregulation, which has been a global trend since the 1980s, can lead to the destruction of sustainable land management practices in favour of monocultures, and can encourage a race to the bottom as far as environmental protection is concerned. The vast geographical distance between demand for consumer goods and the land needed to produce them – between, in other words, the cause of land degradation and its effect – makes it much harder to address the problem politically.

Sadly, the timid history of attempts to create global governance regimes over the past century – from human rights, to conflict prevention, arms control, social protections and environmental treaties – has seen more failures than successes.

On the positive side, success stories in land management are well documented: agroforestry, conservation agriculture, soil fertility management, regeneration and water conservation. In fact, the new report states that the economic case for land restoration is strong, with benefits averaging ten times the costs, even when looking at very different types of lands and communities of flora and fauna. A common feature of many of these success stories is major involvement by indigenous populations and local farmers.

And yet these achievements remain far short of the scope of the problem. Significant obstacles remain – including, according to the report, increasing demand for land, lack of awareness of the extent of land degradation, fragmented decision-making within and between countries, and increased costs of restoration as time goes by.

On the other hand, the report’s authors emphasise that a host of existing multilateral agreements, including conventions on desertification, climate change, biodiversity and wetlands, provide a strong platform for combating land degradation. However, whether these agreements will be successful in overcoming the obstacles mentioned above remains to be seen.

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If the world’s soils keep drying out that’s bad news for microbes (and people)

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What can we do as citizens, especially those of us who live in cities and have little direct interaction with the land? The most obvious action is to eat less meat and, more generally, to inform ourselves about the sources and impacts of the food we buy – including its packaging, fuel and transport.

But the problem is not just about individual choices, important as these are. Underlying systemic causes need to be addressed, including deregulated international trading systems, lack of protection for local communities powerless to resist global market forces, ideologies of unfettered growth and perverse incentives for more consumption.

Arguably, what is needed is a broadening of the active scope of national politics, from an almost exclusive concern with short-term economic well-being to the making of global futures. Next time you meet your local representative, ask them what they are doing to protect the interests of your children and grandchildren. Or, even better, inform yourself, talk to others about it, form your own opinion about what should be done, then try to make it happen.

Abbas El-Zein, Professor of Environmental Engineering, University of Sydney

This article was originally published on The Conversation. Read the original article.

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