Is calling deer an invasive pest, a self-defeating strategy?

What we call invasive species are often animals taking advantage of free energyThe energy of a system that is emitted as waste and is not part of ecosystem processes. There is always some free surplus energy as this creates the basis for evolution where new species exploit gaps in the ecosystem where free energy becomes available. Surplus energy can occur as a result of disruption or disturbance. When free surplus energy reaches More in a system we’ve broken. The longer we don’t have any animals to suppress that free energyEnergy and nutrients are the same thing. Plants capture energy from the Sun and store it in chemicals, via the process of photosynthesis. The excess greenery and waste that plants create, contain chemicals that animals can eat, in order to build their own bodies and reproduce. When a chemical is used this way, we call it a nutrient. As we More, the more it builds up, so culling animals to maintain ecosystemsHow ecosystems function An ecosystem is a community of lifeforms that interact in such an optimal way that how ecosystems function best, is when all components (including humans and other animals) can persist and live alongside each other for the longest time possible. Ecosystems are fuelled by the energy created by plants (primary producers) that convert the Sun's heat energy More can become self-defeating. Eventually the bubble bursts. What we should be doing is addressing the root cause of the build up by reintroducing sustainable animal populations (an abundance of all wildlife in correct proportions) as this controls free energy. Deer are examples of animals that move in to alter environments, either those that are regrowing or where other native animals have been destroyed. The question we always need to ask ourselves before we jump to conclusions and start killing animals, is: is this in our best interest or not? What if deer as an invasive pest is a self-defeating strategy?

Deer in landscapes without native herbivores

In the forests of southwest Ireland there are oak trees dripping with moss and lichen. Introduced Sika Deer from Japan clip emerging shoots and there is little sign of regeneration. On the other side of the planet in Australia, Indian Sambar Deer have become so numerous around Melbourne that I’ve started to see them commonly at night on country roads. Like in Ireland, forests are apparently suffering from their constant browsing.

Are our ecosystems suffering or are we watching the slow re-establishment of something new? The persecution of animals for doing what comes naturally pervades our cultures and conservationWhy is animal conservation important? Animal conservation is important, because animals are the only mechanism to create biodiversity, which is the mechanism that creates a habitable planet for humans. Without animals, the energy from today’s plants (algae, trees, flowers etc) will eventually reach the atmosphere and ocean, much of it as carbon. The quantity of this plant-based waste is so More science but is it worth pausing before we start culling?

Ask any conservationist in Australia about deer and it immediately raises hackles. It’s a mood-changer and the default rhetoric is about non-native species ‘destroying the bush’.

Conservationists world-wide unite in a fear that deer are destroying our forests – indeed, it’s one of the only things I vividly remember from my University field trip to Ireland’s Killarney National Park in 1997. I can recall damp earth smells, the crowns of ancient gnarled trees cloaking bright green saplings in the shadows, neatly snipped off leaving just the stems exposed above the mulched leaf litter below my feet. Now I am beginning to think that I may have been misled.

Animals and rewilding

Isabella Tree in the incredible book Wilding speaks of the absence of browsers from European countryside causing the gradual reforesting of a continent. Tree challenges the view that the natural state is climax forest and in fact, Europe would once have been covered in a grassy landscape, dotted with a rich mosaic of ancient trees and scrub. A huge biomassThe weight of living organisms. Biomass can be measured in relation to the amount of carbon, the dry weight (with all moisture removed) or living weight. In general it can be used to describe the volume of energy that is contained inside systems, as the size of animals relates to their metabolism and therefore, how much energy they contain and More of browsers like deer, Elk, Bison, predatory Wolves, Brown Bears and Lynx, plus neolithic humans, would have maintained diverse and dynamic ecosystems.

Tree traces our mistaken modern views of ecosystems back to bias inherent in pollen studies that promulgated decades of misconception about how ecosystems behave. The linear succession from grassland to forest is clear if you remove animals from the equation but that’s not the natural way of things. The chaos-reduction processes that drive ecosystem development are more sophisticated and biodiversityWhat is the definition of biodiversity? When we ask, what is the definition of biodiversity? It depends on what we want to do with it. The term is widely and commonly misused, leading to significant misinterpretation of the importance of how animals function on Earth and why they matter a great deal, to human survival. Here I will try to More can’t be achieved without animals.

Animal-rich ecosystems are needed for humans to exist.

Forests aren’t dynamic enough

That’s not to say we don’t need to protect remaining primary forest but we do have to change our attitudes to abundant wildlife we may regard as ‘pests’ taking over habitatsWhat is habitat for animals and people? Habitat, hence the word "habitable" describes the natural surroundings in which any animal (or human) lives, that houses basic needs, such as food and shelter. Vegetation, for example, is habitat for animals. On its own, habitat is not necessarily stable or sustainable, which is why it differs from an ecosystem. Habitat in disrepair More that we may regard as ‘wasteland’.

Gammage in the book The Biggest Estate on Earth describes the same consequence of Aboriginal humans and herbivores maintaining grassy-woodland habitat in Australia. It seems Europe and Australia had similar style ecosystems, packed full of animals far more numerous than today.

Imagine if you took all the grazing animals off the African plains, they would quickly turn into forest, but we wouldn’t think that’s natural would we? If people lived in Australia before Aborigines arrived, they would have been appalled to have the land burnt, megafaunaThe largest animals that represent the top of the trophic pyramid. These are the final building blocks in ecosystem structures for maximum entropy production. Megafauna can be measured at any spatial scale. The largest animal that ever lived on Earth is the Blue Whale. In a grassland, spiders could be considered megafauna The term is generally reserved for animals larger More wiped out and an influx of millions of kangaroos … yet that’s the environment we took over when Europeans settled and we regard as our benchmark for ‘biodiversity’ today.

Globally, we don’t look beyond tree-planting to solve climate change because science has led us to imagine forests as the be all and end all of landscapes. Yet it’s only the rebuilding of animal populations that keeps forests under control and will save us from the worst climate excess. Climate scientists haven’t realised this yet–that unmitigated vegetation growth contributes to ecosystem collapse. The natural state of things is not completely dominated by forest, at least not in temperate regions of the world.

Nature and nurture

Our first impression of any animals that are more abundant than we’ve seen before; or any animals we consider to be changing the character of an environment we grew up with, is to assume they are doing destructive things … because as soon as animals are introduced, they set about modifying the environment for their own gain.

In the absence of fire management in Australia, what if deer are doing vital forest clearing?

I realise this is a controversial thing to say but we can’t burn enough of the Australian landscape to replicate pre-European conditions and even when we try, we light indiscriminate management fires to protect human infrastructure. Also, we’re deliberately killing native kangaroos for the same reasons.

The ABC reported that WA’s environment department fire-bombed Perup Sanctuary, one of the last remaining strongholds for threatened Numbats. There is little or no benefit to burning unless it helps wildlife populations, because without them, there are no habitable ecosystems.

Much of our burning these days risks wiping out wildlife that’s actively resetting ecosystem imbalance, unless we are very careful about where and when we do it–at the whole of landscape scale, we lack the resources or knowledge to do this with precision. If we keep halting this progress, we can set ecosystem recovery back thousands of years.

What if deer are responding to the free energy that exists in habitats where there are no longer native animals or Aborigines living in abundance?

In the case of Australia, there are no longer abundant human communities or native mammals in the bush, where once there were millions. In Europe, there are no longer abundant grazing animals. Deer have moved in to take over where native animals once existed and we aren’t going to be able to wipe them out. Their numbers are now so large, is there anything we can do about it? Science doesn’t have the magic bullet necessary to alter what we’ve already created.

“It is interesting how, in delegitimising or denying ourselves a role as vectors for other species – be it intentional or unintentional – we exclude ourselves from the rest of the animal kingdom”

Isabella Tree, Wilding

Is it right to manage invasive animals?

The irony is, that the more we do to try to kill ‘invasive’ animals, the more we risk maintaining the free energy that gives them advantage. If we’re not careful, we can easily set back the clock on conservation.

I’m not saying that there is any fix-all or indeed, condoning the broad-scale acceptance of introduced species … successful rat eradication on seabird islands is crucial to global climate and fisheries, for example.

But removing animals does change the potential for re-invasion. And when we do analyses on the costs of invasive species ‘management’, we might ask, what would be the situation if we still had native animals to fill the gap? I realise this is a circular argument, because often eradicating a pest is the first step.

Without abundant animals, the amount of free energy gets bigger by the day until the bubble is so large, we lose all hope of dealing with the consequences when it finally bursts. This is why, to tackle invasive species, we should really be putting more animals into the system with them, not killing the ones that are there already – and that goes for native species. It seems ironic that we’re trying to manage invasive pests in Australia while killing kangaroos. How does that make sense?

Wildlife has a way

As a sidenote, from Tree’s book Wildling, did you know that Europe has ‘17,000 [Brown Bears] compared with just 1,800 grizzlies in the United States – an area twice the size of Europe … Wolves number 12,000 – almost double the number in the US’? Tree attributes this to the unprecedented release of marginal land from agriculture … the animals are moving in and ready to take on the job of rebuilding our biodiversity.

Perhaps all we need to do, is allow creatures room to breath and we could solve many of our world’s ecological problems? It’s more cost-effective than heavy-handed intervention that too often creates conflict with natural processes.

Deer won’t wipe out all forests but they will favour some over others. There will be trees that can’t be reached because they are surrounded by scrub and others that will be distasteful, so gradually the deer will create clearings and that may end up to the advantage of other Australian native mammals like kangaroos, that were once far more numerous. With abundance of mammals restored, there will once again be fertile soils, clean water and carbon cycles will be restored.

There is no doubt that feral animals are causing enormous damage to existing ecosystems and this costs our economy but maybe only because we have developed lifestyles based on an ecosystem that we have destroyed – we have pulled the rug out from under our own feet. It pains me to even think this because I also know the damage these newcomers are doing to populations of once common native species.

However, to think that we can hold back nature’s interminable desire to reset imbalance is to greatly exceed expectations of our own influence on the planet. Trying to work against those forces is what got us into this predicament in the first place and every year we use the same tactics of killing more animals to try to keep things as they are–it’s mostly a process doomed to failure and in many cases, will be counter-effective.

Rule number one of all wildlife conservation and any ecosystem or landscape biodiversity management, should always be to avoid killing animals at all cost. At the very least we should be thinking before we act. We assume that change is bad but what if the action of animals is the thing most likely to bring systems back into a state where they deliver clean water, food and stable climate?