Tag Archives: Partnership rewilding

Under The Mistletoe

Keystone species ‘punch above their weight’, to use a popular metaphor. They contribute more to their ecosystems than their numbers would indicate. Charismatic top predators such as wolves and dingoes are great examples of keystone species. They generate the trophic cascades that enhance whole systems of life including the geophysical foundations (discussed here). But as the fascinating ecologist Stephan Harding tells us:

‘You never know who the big players are in the wild world.’

Native mistletoe at Edeowie Station, by Michelle Bartsch (CC)
Native mistletoe at Edeowie Station, by Michelle Bartsch (CC)

To my mind one of the least likely ‘big players’ is mistletoe. Can a parasite actually be a keystone? Surprisingly, the answer is ‘yes’. Not only is mistletoe good for kissing, this great cohort is a ‘keystone resource’.

Let us enter the entrancing world of mistletoe through symbiotic mutualism. A relatively non-technical definition is ‘two or more species that live together to their mutual benefit’. Although the idea of symbiosis was not the dominant paradigm for much of the 20th century, a growing body of research is showing that it complements competition and is utterly fundamental to life on earth and is part of how every creature lives. The great biologist Lynn Margulis declares:

‘We are symbionts on a symbiotic planet.’

Mistletoe, it turns out, is a highly eclectic and inclusive symbiotic mutualist. One of the main families all around the world, and a prominent player in Australia, is Loranthaceae – a family of mistletoe with about 1,000 member species. Most of them are ‘obligate, stem hemiparasites’. This means that they can only live by being attached to another plant (obligate), that they attach to stems (not roots), and that while they get water and some nutrients from their host, they are also able to photosynthesise.

The story of mistletoe mutualisms is all about entanglements of interdependencies, nutrient cycles, and seductions. Loranthaceae are themselves deeply dependent. First there is dependence on the tree or shrub on which they grow. No host, no parasite. Next, there is dependence on birds and bees to pollinate. No pollination, no seeds, no future generations. Then there is dependence on birds, in particular, to eat the fruits and disperse the seeds. No dispersal, very little chance of germination and growth. And there is dependence on the leaf-eaters: no browsing means too much mistletoe growth leading to multiple deaths and disasters.

Brushtail possums, by David Cook (CC)
Brushtail possums, by David Cook (CC)

If mistletoes are to survive they have to entice and nourish their mutualists. The brightly coloured flowers are powerful attractors of pollinators, and the nectar is not only high in sugars, but also fats. Some of the Australian Loranthaceae produce nectar containing droplets of pure fat. The berries are highly visible, abundant and full of nutrition. Worldwide, many ‘folivores’ eat the nutritious leaves: deer, camels, rhinoceroses, gorillas and possums, amongst many others.

Their adaptive edge goes beyond mere provisioning and involves dazzling abundance.

The most awesome interdependence is between mistletoes and their mutualist mistletoe birds. ABC Science journalist Abbie Thomas wrote a delightful account:

Many mistletoes continue to flower in drought or during winter, when few other blossoms are available. Indeed, they are often the only local source of nectar and pollen during hard times. Packed with sugar and carbs, mistletoe fruits are good tucker, not just for the ubiquitous mistletoe bird, but also for cuckoo-shrikes, ravens, cockatoos, shrike-thrushes, woodswallows, bowerbirds, and even emus and cassowaries.

The mistletoe bird plays an important role in the mistletoe plant’s life cycle. The life of most mistletoes begins when a viscous, gluey seed drops onto a branch from the rear end of the brilliantly coloured black, red and white Mistletoe bird. Found throughout Australia, these birds are highly mobile and go wherever mistletoe is in fruit. Once eaten, the seed of the fruit quickly passes through the bird, emerging just 10-15 minutes later. The sticky seed fastens onto the branch, although many seeds fail to adhere, and are lost.

Within days, a tiny tendril emerges from the seed, growing quickly and secreting a cocktail of enzymes directly onto the corky outer protection of the branch. Unable to resist the onslaught, the bark yields a small ulcer-like hole into which the tendril probes, seeking its way down into the sappy tree tissue until it hits paydirt: the water and mineral-rich plumbing of the tree.’

Male mistletoe bird, by Leo (CC)
Male mistletoe bird, by Leo (CC)

Mutualisms are entanglements of interdependencies. The host tree supports its mistletoes physically and nutritionally, and it also buffers them against the vicissitudes of climate uncertainty. So, too, mistletoes support other species and provide a buffer against fluctuations and uncertainties. A study from Australia shows that mistletoes have extended nectar and seed producing periods, and that within a given region nectar and fruit are available from one or another mistletoe species all year round. In addition, as mistletoes are host to so many insect species, the insect-eating birds also get the benefit. Mammals join the feast, eating leaves, seeds and flowers. Possums are amongst the main leaf eaters, and are seasonally dependent on mistletoe.

Along with all the creatures who consume mistletoes, there is yet another entourage that benefits. Some animals build their nests in the mistletoe where they get some protection from the elements and predators. The action of the mistletoe itself increases hollows in trees, and so all the creatures that nest in hollows get the benefit. A further benefit is that their presence in trees alters the forest canopy and reduces the severity of bushfires.

In life systems, what goes around comes around. The host tree or shrub gets a steady rain of litter, droppings, and other organic matter that become part of the nutrient cycle, benefiting both the host and other plants in the area. In short, the benefits of mistletoes pass through the lives and bodies of many species before turning into nutrients to be drawn up by hosts and tapped into by mistletoes.

The relationships work because of the extravagant generosity of interdependence: highly nutritious nectar produced by bright showy flowers; shiny seeds loaded with carbs and sugars; mistletoe birds with their gorgeous red feathers, lovely song, and fertile poop; gliders and possums; butterflies who visit, eat, and reproduce.

Mistletoe (Amyema) flowers, by Bill and Mark Bell (CC)
Mistletoe (Amyema) flowers, by Bill and Mark Bell (CC)

There is an association between songbirds and mistletoe, and as new evidence is showing that both groups have their origins in ancient Gondwanaland, perhaps there is more to this old and beautiful alliance than is yet properly understood. I found myself totally captivated by a story shared by Andrew Skeoch, a sound recordist specialising in the sounds of nature. He recorded a mistletoe bird in full song, and inadvertently also recorded the fact that this talented little creature was singing and pooping at the same time. Something about this bright little bird creating and performing musically, while depositing mistletoe seeds securely wrapped in glue and fertiliser seems almost magical in its joyfulness (listen to the birdsong here).

It is good to recall that there is an old European history of respect. Mistletoe is sacred to Druids (contemporary and ancient), and it is still a customary Christmas decoration. Hung over the threshold, it invites people to kiss. In earlier days it was said to be able to find buried treasure, keep witches away and prevent trolls from souring milk! It would be good also to recall that Aboriginal Australians respect mistletoe as a food for humans and for many other creatures. In North Australia, where so much of my learning has taken place, people give berries to children, but adults avoid them. Perhaps they are aware that growing children have a particular need for the high nutritional value of mistletoe.

At this time, many people think mistletoe is a pest. The term ‘parasite’ conjures negative imagery, but the larger issue, at least in Australia, is that in some areas mistletoes are over-abundant. Trees are dying, and something has gone askew because mistletoe cannot thrive if the host dies. The renowned science writer Tim Low tells us that the loss of possums, those folivores who love their mistletoe, is a key. “Foxes, by preying on mistletoe-munching possums,” set up conditions where mistletoes can grow out of control. Possums are only prey to foxes when they come down out of the trees. Along roadsides and on farms, they are at risk. Within forests where they can remain up in the trees possums thrive and mistletoe is contained.

Ringtail possum, by Visible Procrastination (CC)
Ringtail possum, by Visible Procrastination (CC)

So, what would partnership rewilding be like if the focus were on mistletoes and their ‘ground up’ trophic dynamics?

First, it would involve fewer foxes and more possums. Here the answer is readily to hand in the form of the dingo. As I have been reporting in other essays, the evidence is overwhelmingly clear that dingoes reduce the numbers of invasive species such as foxes and cats, and promote the viability of smaller native marsupials such as possums.

Second, it would involve on-going health and reproductive capacity of more extensive stands of trees. Here the answer is readily to hand in the form of flying-foxes. Their pollination is utterly crucial to the future of forests and woodlands in Australia, and their lives and livelihoods are central to partnership rewilding.

Third, it would involve changes in human thought and action. Not everyone thinks mistletoes are innate pests, but, as the great mistletoe scientist David Watson indicates, “pretty much all of the public’s perceptions about Mistletoe are fundamentally incorrect.” I want to be clear that Aboriginal people are not likely to hold these misperceptions. Here, as with other matters, the limitations of the mainstream public cannot readily be attributed to everyone. Having said that ~~

I want to set up camp, metaphorically at least, under the mistletoe. Here the kiss of life is sensuous, continuous, and diverse.

I hope others will join me, and I rather hope we won’t get pooped on! Let us open our lives to the great, complex, on-going, joyful, benefit-rich, exuberant and dazzling generosity that holds entangled interdependencies together. A camp in the midst of all these mutualisms is place of coming-forth for those whose flows of life and death are achieved together. These entangled partnerships have co-evolved over millions of years, and if the human newcomer can partner in with them, we may yet become part of ecosystems that will hold together in this time of flux and uncertainty.

© Deborah Bird Rose (2014)

This is the third in a series of essays on partnership rewilding. The others include: Partnership Rewilding with Flying-Foxes, and Partnership Rewilding with Predators. 

Resources

Most of the scientific information in this essay is drawn from David Watson’s outstanding work. One of his main articles is free online: http://rspb.royalsocietypublishing.org/content/early/2012/07/03/rspb.2012.0856.full

Another is not open access except for the abstract: http://www.annualreviews.org/doi/pdf/10.1146/annurev.ecolsys.32.081501.114024

Abbie Thomas’s article is available online: http://www.abc.net.au/science/articles/2004/03/05/2044992.htm

Lynn Margulis’s book is Symbionic Planet (a New Look at Evolution).

The book by Tim Low mentioned in this essay is New Nature.

Information on dingoes as top predators is available in previous essays, and is the subject of a recent article by Arian Wallach, published in The Conversation. (read here)

My essay on flying-foxes and the kiss of life is not freely available online but I am happy to share copies if asked.

Partnership Rewilding with Predators

Elk near Jackson Hole, Photo: Dave Rose
Elk near Jackson Hole,
Photo: Dave Rose

My father, Dave Rose, was fascinated with the elk that came down out of Yellowstone National Park during the winter months. He took us kids to Jackson Hole to see them, and he persuaded the guy with the hay to let us ride on the trailer while he went through the herd dumping fodder. Dad took slides (and more slides). Sometimes it seemed as if every slide show was all about elk!

Only much later did I learn that the National Elk Refuge was founded in 1912 by local ranchers who were concerned that this great herd might go extinct. Its migration routes were disrupted by ranches and the town.  Conflict between ranchers and elk over hay led to killing, and there was mass starvation.

The establishment of a winter refuge adjacent to Yellowstone, with funds for fodder, was an early action in America’s long and often odd conservation movement. For almost one hundred years wolves were persecuted. Herbivores were hunted. Still today at the National Elk Refuge, ‘both bison and elk populations are managed through refuge hunt programs. Permits specific to each hunt are required and are obtained online or through the Wyoming Game & Fish Department.’

When we went there all those years ago, it was pretty easy to see that this great migratory herd had nowhere to go. Problem and solution seemed pretty clear. But if Dad had read Aldo Leopold’s essay ‘Thinking Like a Mountain’ he might have suspected that there was more to the story. Leopold’s brief, influential essay starts with him killing a wolf, as people did in those days, and then working through the implications of predator loss, overabundance of deer, stripped vegetation, and barren ground.

American wolves in captivity
American wolves in captivity

For centuries mainstream European-origin culture has feared, despised, and sought to annihilate wolves and other predators. The outcome, if one can use such neutral term to describe the result of all this suffering, has been extinctions and extirpations. If Dad had asked about wolves, he would have come upon a story of vicious, cruel persecution that would have deeply saddened his kind and generous heart.

As if in counterpoint to all the death work that has gone into efforts to eradicate wolves, conservation biologists are discovering that the top carnivores have ecological roles that benefit numerous species of flora and fauna. This is counter-intuitive thinking for western peoples, but it is actually integral to indigenous peoples in many parts of the world. The novel Wolf Totem by Jiang Rong tells the story in the context of Mongolia: kill the wolves and you kill the grazing lands, and so you kill the herding way of life.

‘Trophic cascade’ is the scientific term for ecological processes that ripple from one species through others, and through whole ecosystems.

This process has been documented with the re-introduction of wolves into Yellowstone National Park after a seventy year absence. The consequences are completely stunning. A recent video narrated by George Monbiot tells the story in words and images (view here). It is helpful to know that Monbiot uses the word ‘deer’ where Americans would use the word ‘elk’ for the species Cervus elaphus. I don’t want to spoil the drama of the video, so I’ll just make the point that a trophic cascade starting with a top predator ripples through other animal species, plant species, and ultimately even through the physical geography of their ecosystem.

Furlined/Creative Commons
Furlined/Creative Commons

The re-introduction of wolves into Yellowstone is an example of the new thinking that is often called ‘rewilding’. It addresses ecosystem restoration on a large scale; there is no attempt at retrieving primeval ‘wilderness’ – that would be impossible, and if it were possible it would be counterproductive. Rather, rewilding aims to let ecological processes start up again.

The development of rewilding programs in the USA depends on three key strategies: cores, corridors and carnivores. The carnivores are the first key, as Monbiot narrates in the Yellowstone video. If they are healthy, the benefits flow on through the system.

The second key, then, recognises that the top predators require adequate range to sustain themselves across generations. The third key is corridors; it recognises the fact cores can become death traps unless the animals can move. This is so genetically, and equally because ecosystems and climate always offer the unexpected. With climate change, even more unexpected changes are (paradoxically) expected to occur. Animals need the versatility and flexibility in order to be able to respond to change.

Carnivores with ample area and ample connectivity will regulate ecosystems in ways that achieve complexity, diversity, and resilience.

So far, so good, but now the news turns alarming. An extremely important recent publication addresses these issues in the context of climate change and the accelerating extinction event now underway. A great number of the large carnivores that ecosystems need are themselves vulnerable to extinction or local extirpation. The authors state that in light of all the recent evidence ‘alongside climate change, eliminating large carnivores is one of the most significant anthropogenic impacts on nature.’

Photo: John Murray
Photo: John Murray

A good section of the study is dedicated to dingoes, and it summarises the work of Arian Wallach and the other dingo scientists whose work last year was awarded the Eureka Prize. Their conclusion: ‘Overall, the suppression of dingo has probably contributed to the endangerment and extinction of small marsupials and rodents over much of the continent.’ It has also enabled the expansion of a range of invasive species over much of the continent.

The biggest threat to large carnivores is the human species. Finding ways of co-existence is therefore absolutely crucial. Not only is the work that carnivores do ‘underappreciated’ (the authors’ words); in many areas, as is well known, predators are actively persecuted. Many pastoralists have formed the view that livestock and predators are incompatible. Having set up an ‘us or them’ opposition, they destroy the predators.

Dingo Barrier Fence
Dingo Barrier Fence

Here in Australia the conflict is between cattle and sheep farmers on the one hand, and dingoes on the other. I wish they would all read Wolf Totem, but that seems unlikely. Perhaps they will listen to the recent  Bush Telegraph radio report ‘Could dingoes actually help farmers?’ (listen here) The program starts with a fascinating interview with Lyn Watson of the Dingo Discovery Centre speaking about dingo physiology and behaviour. It concludes with Arian Wallach, the dingo research scientist and one of the authors of the influential study of carnivores and climate change. She carries out research on Evelyn Downs Station, a working cattle station (ranch) that is one of the few predator-friendly ranches in Australia.

In the radio interview Arian reminds listeners that dingoes are top predators here in Australia: ‘ …  the health of the ecosystemits biodiversity, its productivity, the condition of it’s soil, the rivers, the endangered speciesare all tightly linked up with the dingo.’ She then very precisely changes the story from ‘us vs them’ (pastoralists vs. dingoes) to interconnection. Rather than barriers, there are connections. Cattle and sheep need biodiversity, dingos sustain biodiversity, therefore pastoralists, livestock and dingoes are all interconnected and are, in effect, on the same side.

Cattle and Dingoes at Evelyn Downs (A. Wallach)
Cattle and Dingoes at Evelyn Downs (A. Wallach)

Arian and Lyn also discuss the problems that arise when dingo ‘control’ (poison, trapping, shooting) creates homeless, unsocialised creatures who are effectively out-of-control. It is a truly vicious circle, and one of our great challenges is how to break the cycle of violence without destroying either pastoralists, or livestock, or dingoes.

To return to partnership rewilding, therefore, I see hope in the idea that the best thing we humans can do for the earth at this time is to work in alliance with other creatures whose lives regulate, pollinate, and otherwise sustain flourishing ecosystems. In relation to flying-foxes I proposed the establishment of vast corridors or networks of flowering trees. ‘Rewilding’ the open savannah woodlands would enable flying-foxes to sustain themselves and continue their work of pollination. Those same corridors could also be habitat for dingoes and many other creatures, and as core areas are maintained, and more corridors are established, the country can become criss-crossed with edges and zones of co-existence.

Life on earth is not ours to destroy, and nor is it ours to engineer solely for ourselves.

Partnership Rewilding acknowledges and works with interconnections. At this time, most ecosystems are massively perturbed and there is a huge role for humans in working to re-establish favourable conditions. The ethics of multi-species alliances thus have several sides. Humans may at times be active partners, and at times may simply need to get out of the way so that others can do the work they are so beautifully evolved to do.

© Deborah Bird Rose (2014)

Postscript: Arian Wallach has just published and excellent article in ‘The Conservation’ (read here)

Her recent interview on Freedom of Species is also relevant and insightful. (listen here)

Resources:

Aldo Leopold’s essay is available online: http://nctc.fws.gov/resources/knowledge-resources/wildread/thinking-like-a-mountain.pdf

The horror of the violence against wolves is conveyed, along with much else, by Barry Lopez in his great book Of Wolves and Men.

Mongolian herders’ relationships with wolves are analysed in Natasha Fijn’s ethnography Living with Herds: Human-Animal Coexistence in Mongolia. She is a terrific film-maker as well, and films from her Mongolian experience are also available (view here).

Acknowledgements: Thanks to Ray Pierotti, author of Indigenous Knowledge, Ecology, and Evolutionary Biology, for the wolf photos and for clarification of the elk/deer nomenclature.