Ethan Linck’s Cataclysms to Desolate the World is a beautiful piece of nature writing about the loss of forest birds on Guam and the impact that introduced tree snakes have had on the ecology of these remote islands.
I was particularly struck by this quote:
Though I knew they were coming, the sheer volume of spiderwebs still took me by surprise, stretching from the boughs of low trees to knuckles of sharp karst only partly buried in leaf litter. On Guam, the forests have no birds, and nature abhors a vacuum.
It’s a nice reminder of two key components of Animal ImpactWhat is Animal Impact? Without wildlife, Earth would not be habitable for humans, because it's animals that stabilise ecosystems. It’s a fundamental law of nature that animals (and humans) exist because we are the most likely lifeforms to minimise environmental chaos. Animal impact, therefore, is a measure of how much all wildlife is collectively responsible for creating a habitable Earth. The More.
The first is how, when you destabilise trophic pyramidsThe gradual reduction in energy content, increase in body size and reduction in number of animals, that occurs the higher you go up the food chain. At the base of the pyramid are a vast number of high-metabolism, tiny creatures and at the summit, are the top predators. To be stable, the pyramid has to have creatures at all levels. More by removing a whole tranche of animals, it’s like caving a hole in the side of a roof. Water floods into areas it shouldn’t.
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 pooled somewhere new, after Guam’s birds went extinct. The surplus has led to a fresh, chaotic condition, a flourish of activity which will remain while the structure is brought back into alignment (a process that could take millennia). In Guam’s case, the spiders appear to have taken over, making use of the free surplus 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 extinct birds left behind, when they stopped eating insects.
The second point is this. Spiders are a conspicuous reminder of the action and reaction that occurs between animals and their environment, as they struggle to reach counterbalance.
I think it’s why we have loads of spiders in our houses–they are the frontline top-predators for the first wave of animals that move in, to restore damaged 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.
Every day, the spider takes its web down and rebuilds afresh. The fine silk is built from energy they extract out of the ecosystem … the spiderwebs Linck talks about, strung between the branches of plants on Guam, are how the spiders alter the environment to suit their own survival. They modify the world, bringing it into line with their predatory expectations. This is how and why animals are critically connected the ecosystem stability.
Over a long period of time, the spiders will eventually exhaust the free surplus energy and that will place greater selection pressure on remaining animals, including the snakes, forcing them to adapt and diversify, if they are to survive. Perhaps the snakes will eventually go extinct, replaced by successors of the island’s native wildlife, or they will become the new normal. Guam’s future contingent of wildlife will start as a cover version of what it once was, before gliding back towards a state of maximum diversity of ecosystem processes, as species multiply to fill the gaps.
Ignoring the devastation that introduced tree snakes have caused the island’s wildlife, the outcome is quite elegant to learn about. It’s as though the island’s essence is being redistilled into the threads of a new beginning, woven by spiders.
Spotlight
Trapdoor Spiders on Kangaroo Island
Jess Marsh is working on trapdoor spiders on Kangaroo Island. Spiders are 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 at their own scale. Rewilding 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 may depend on them … as might the recovery and resilienceReferring to an ecosystem’s ability to maintain a steady stable-state. The need to build resilience is entirely anthropocentric and symptomatic of ecosystems that are damaged or declining, leading to loss of ecosystem services on which humans depend. More of ecosystems like Kangaroo Islands’ following bushfires.
Reintroduction of Guam Kingfisher
The Guam kingfisher has been extinct in the wild for more than 30 years but thanks to intense 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 efforts, it now stands on the brink of being released back into the wild. Read more here … (thumbnail by John Ewen)
