We’re in the midst of an ecosystem brain drain

A paper just published in the journal Nature [1] has reviewed hundreds of studies on the impact of humans on the movement of birds, mammals, reptiles, amphibians, fish and arthropods. The study found that in two-thirds of cases, animals were having to move up to 70% further to find food. Disturbance from recreation and hunting, had stronger impacts on animal movement than habitat modification, such as logging and agriculture. Not knowing where to find food, means we are in the midst of an ecosystem brain drain.

As we’ve discussed elsewhere in this blog, migration is really important for nutrientA substance that contains the raw materials for life. At a chemical level, these are contained inside compounds that are absorbed into the body and essential energy-containing molecules are extracted, so that energy can be transformed into other chemical processes that use the energy for living. More transfer(of nutrients) the thing that sets animals apart from plants, is that they can move. Some of the biggest migrations on Earth every day, are the movement of insects like caterpillars, from the stem of a plant to a leaf and back, before turning into butterflies and transferring the energy elsewhere. Large-scale migration of grazing animals and migratory songbirds moves More and it’s the trait that sets animals apart from all other lifeforms. It’s also one of the principle reasons we need other animals –human beings aren’t very mobile. We can’t walk more than a short distance every day and we no longer act as as hunter-gatherers, so even our short migrations to moderate resources like meat and fruit, has been replaced with car-trips to the supermarket.

It’s the reason animals are critical to stabilising 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 and enabling human life support. Migration happens for a reason and it’s not always on a massive scale. The daily movements of insects to and from flowers or the vertical movement of lantern fish from the deep ocean at night, are all migrations.

Think about wild animals as awesome remote sensing machines, but ones that self-replicate and learn for millennia, through a constant cycle of life and death. Moreover, they both take from the environment and give back to it. If you’re an animal in a pristine landscape, you move places you know where to find food and while you’re there, you prune the vegetation and lightly fertilise it, so it reappears strongly next year when you return.

Animals knowing both where to find food, being part of cultivating it and being able to move between seasonal patches, is what makes ecosystems stable and diverse. Animals are coupled to the process being both givers and takers but the knowledge they need, is based on an evolved survival strategy.

When we interfere with those processes and restructure them by building roads, cutting down forest or polluting habitat, we are not only impacting on the animals’ survival, we’re also impacting on the ecological functioning of the landscape. It’s this function(Of an ecosystem). A subset of ecosystem processes and structures, where the ecosystem does something that provides an ecosystem service of value to people. More that delivers 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, meaning all the things we need for a habitable Earth. We need to be aware that our impact on animals will come full circle and affect our own survival, if we allow it to get out of control.

The guidance systems animals use for nutrition are based on information they store in their brains about where and when they expect to find food. Some of this is physical and predetermined and some is learnt. You can break the process of ecosystem stability by either altering their environment or removing animals themselves. This is why it s harder to rehabilitate ecosystems, the longer animals have been absent (see Cingolani, 2005 in the following link).

A paper published in the journal Science compared the movements of real reintroduced, radio-collared bighorn sheep in North America, to a theoretical modelThe process, either mathematically or in the human brain, of creating an internal version of something that we can refer to, to better understand how it functions and our place within. Scientific modelling is where we take the best knowledge we have and build a version of what will happen, if we assume certain parameters. For example, we might model More they created. The model had one herd doing random movement and another that knew precisely where green vegetation occurred (the omniscient herd). Researcher Matthew Kauffman from the University of Wyoming described the results online in The Atlantic:

Some of the recently translocated herds tracked the green wave no better than the ones that wandered randomly,” says Brett Jesmer, who led the work. The older herds did far better—“not as well as the omniscient ones, but closer,” he says.

In other words, these animals lose their local cultural knowledge of where to find food, if they are removed from the land. Between 65 – 100% of wild bighorn sheep migrate but fewer than 9% in translocated herds. The only ones that did better, were translocated into existing herds and able to pick up some of the cultural knowledge.

Newly-reintroduced animals begin, as you’d expect, wandering aimlessly looking for food. The scientists found that only after “several decades, newly established herds were better able to track the emergence of vegetation in the environment”. In Chernobyl, a herd of domestic cows have been found to have rediscovered their wildness and started behaving socially, like the herds of wild turs that they are related to. During COVID, animals moved back into cities very quickly, showing us that our mere presence is enough to force them away. Perhaps this is a hopeful sign that animals can step in and start to rebuild ecosystems for us quite quickly.

It makes me wonder though, how long it would take for animals to create the level of knowledge needed, not only to start redeveloping migration patterns but stabilise ecosystems? The “omniscient” herds described in the scientists’ models (above) are likely to be similar to herds in a pristine ecosystem.

It isn’t the mere presence of animals that creates life support, it’s their connection to country and this information process can take an extraordinarily long time to recreate, especially when the supporting environment is in a state of chaos(Of energy and ecosystems). Ecosystems are thermodynamically driven. Disorder occurs when energy dissipates and becomes more chaotic. For example, the release of hot air into the atmosphere results in that energy is freer to disperse (maximum entropy). The opposite is true when energy is locked into biological processes, when it is stored inside molecules (minimum entropy). Stability in ecosystems occurs More.

You see, if we were dealing with a stable landscape and reintroducing animals, that would be simple– unfortunately, this is largely how we currently think about animal 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.

We don’t realise that we’re dealing with a landscape that is destabilised because animals were removed and we are imposing other impacts as well, such as fossil-fuel-driven climate change. We have two systems that have to reach alignment, both of which are in a state of chaos and can only ultimately be reformed by adding animals and letting natural processes happen.

As a world, we haven’t yet worked out that animals are this essential for a habitable Earth and the biodiversity processes they drive (that deliver clean water, food security and stable climate), are the consequence of the interaction they have with the landscape.

1. Doherty, T.S., Hays, G.C. & Driscoll, D.A. Human disturbance causes widespread disruptionThe result of an action that creates a sudden change in the stability of an ecosystem or process. This tends to create a gap where there is free surplus energy and organisms will move in to fill the space. Disruption might be a tree fall, or the application of pesticide to farmland. Disruption is important to maintain dynamics in ecosystems More of animal movement. Nat Ecol Evol (2021). https://doi.org/10.1038/s41559-020-01380-1 https://www.nature.com/articles/s41559-020-01380-1
2. Jesmer, Brett & Merkle, Jerod & Goheen, Jacob & Aikens, Ellen & Beck, Jeffrey & Courtemanch, Alyson & Hurley, Mark & McWhirter, Douglas & Miyasaki, Hollie & Monteith, Kevin & Kauffman, Matthew. (2018). Is ungulate migration culturally transmitted? Evidence of social learning from translocated animals. Science. 361. 1023-1025. 10.1126/science.aat0985.

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