Recycling, reusing, and the harms caused by littering were the first environmental issues I learned about in elementary school. We went on several field trips to recycling centers and participated in art workshops where we painted and glued together empty containers. Back then, the words “climate change” and “global warming” were foreign to me — not to mention “biodiversity,” a term that is still foreign to many. I used to berate anyone who used polystyrene or disposable products and was able to recite by heart how much time each material required to break down.
Today, when the awareness of recycling is much greater than it used to be, and “biodegradable” and “made of recycled materials” are strong selling points (although many are greenwashing marketing ploys), we have many other pressing issues on our environmental plate. While the importance of recycling is often either pushed aside, debated or overemphasized, waste disposal is still crucial: greater awareness of the amount of waste we produce has not negated our societies’ ever-growing overconsumption. The more we produce, the more important it is to find ways to clear our Earth of leftovers — and to protect wildlife from its harms.
Yet, I am not here to discuss turtles becoming deformed or suffocating from the plastic bags floating our oceans. I am also not going to talk about repurposing waste, tossing each type of waste in the appropriate bin, or replacing plastic straws. You know all this. What may come as a surprise, however, is that animals can be recruited to aid us humans in the task of waste disposal.
Collecting
A start-up in Södertälje, near Stockholm, had a creative idea. They placed a mechanical box in a local park and taught the local New Caledonian crows a simple task: place a cigarette butt in the machine, get yummy seeds. The choice of crows to perform this cleanup is due to their remarkable intelligence, which is also linked to ensuring their safety when participating in the project: unlike other species, they do not eat the cigarettes. While this does not solve the long-term problem of the cigarettes’ safe disposal, it does aid in removing the dispersed litter that poses a threat to urban biodiversity and, of course, is unpleasant to people. This form of waste collection has been found to be 75 percent more efficient economically than previous clean-up methods, saving the municipality resources for other uses.
Arguably more surprising is the discovery that the incorporation of cigarette butts into bird nests (specifically, those of sparrows and finches) has been found to promote bird health, since the toxins act as natural parasite repellents. While many birds know that adding some fresh herbs to the nest can repel parasites, cigarettes appear to be more efficient, and researchers have found a negative link between the amount of cellulose acetate (found in cigarette filters) and parasites in the nest.
This is of course not to say that cigarette litter is desirable; but much like empty container-based art workshops for children, repurposing existing waste can reap some benefits. The problem is, however, that repurposing does not dispose of the waste, but makes it someone else’s problem (in the art case, the parents’). All of this waste still ends up in a landfill, and while this is better than being left spread across natural land and marine habitats and urban areas, landfills are generally not safe for surrounding wildlife (although this impact varies greatly between different species and types of waste; compare, for example, the findings of this study in North Carolina and this one in Florida).
Think about the apocalyptic vision in the movie WALL-E: the prospect of a future with mountains of waste is very grim indeed. Can animals, then, assist in the actual decomposing — rather than the mere collection — of waste?
Separating
Artificial, human-made substances are difficult to get rid of, since they are not naturally found in nature. Much like invasive species, they appear in an ecosystem with no natural predators and their breakdown takes a very long time. Yet, all materials also originate from natural sources if you track them far back enough, and this fact can be utilized in certain cases. For example, waxworms, the caterpillars of Galleria mellonella moths, voluntarily feed on polyethylene, namely, plastic. Since this process was found to be supported by gut microbia, it might even be possible to use waxworm microbes on their own to break down polyethylene.
Another possible form of recycling is inspired by mussels. Neodymium is a rare earth element that can be used for clean-energy production and medical equipment, but its extraction is highly polluting and harmful to marine habitats. Inspired by the stickiness in water of the adhesive material used by mussels to glue themselves to rocks, scientists are now working on a glue that can extract neodymium from electronic waste and industrial wastewater. While this does not repurpose the waste directly in its entirety, it does efficiently recycle important and rare materials that have already been extracted and used industrially. Still, the holy grail is decomposing of waste and returning it to the ecosystem.
Recycling
I arrived there early in the morning. It was a small temple at the foot of a hill, and I decided to explore it while waiting. There were thousands of thin stone slabs with inscriptions and decorations—gravestones without graves.
And then the “burial” began. Incense was lit next to the temple, and old women dressed colorfully began singing and mourning loudly. An enormous group of vultures arrived out of nowhere and filled the sky: at least 200 huge birds of prey that seemed to have known what was coming.
A group of men took the dead body to the middle of the hill and began dissecting it with axes. I remained at a distance… Then the vultures arrived, surrounding the men and eventually coming between them, trying to reach their feast. The men moved back and left the vultures to play their part. They were crowding around. Every now and then one of them would leave the group holding something; sometimes they fought over bits. After several minutes nothing was left on the hill.
The men returned to collect the bones, crushing them very thinly with their axes, making sure they left nothing lying around. The vultures were scattered across the hill with their giant wings spread, sunbathing in the pleasant morning sun and leisurely digesting their meal.”
The above description is of a “sky burial,” as told by my partner, Itamar Goldstein, who witnessed one in Litang (Garzê Tibetan Autonomous Prefecture). The idea might make us feel nauseous; many of us do not like thinking about what happens to our bodies. It is much more convenient to place them in a coffin or wrap in fabric, and bury them away. But even then, corpses do not stay intact: they become part of the ecosystem again through the relentless work of creatures hidden in the soil.
Once upon a time, all forms of litter were biodegradable. All you had to do was bury or hide it, and nature would do the rest. But what does it mean for “nature to do the rest”? Nature is not one entity, graciously taking the garbage away. It is through the contributions of different species and microorganisms, working efficiently to feed, as all creatures do, that our leftovers are consumed and the Earth is cleaned. Despite their bad reputation and frequent portrayal as villains in popular culture (remember the hyenas in Walt Disney’s 1994 Lion King or the vultures in 1937 Snow White and the Seven Dwarfs?), scavengers perform an almost sacred duty: they clean up the carrion in our world and the diseases it harbors, essentially recycling the body to support life.
Just like the creatures we fear are part of biodiversity, so are the creatures whose instinctive nature we are disgusted by and whom we view as inferior to both humans and the animals we find cute or admirable. If human aversion to scavengers is due to our tendency to find decaying flesh repulsive, we should perhaps be more thankful to the creatures that quietly and efficiently remove it from our environment. The multitude of scavenger species on the planet — vertebrate, invertebrate, and microbe — all work in tandem to clean our surroundings and provide a vital service to their ecosystems. This includes even our mortal enemies, despised and hated by almost all: cockroaches.
Reusing
Unfortunately, the increasing frequency and scale of animal mass-mortality events, for example, due to diseases, natural disasters and attempts to control invasive species, is overtaxing the natural process. Necrophagous species — those that feed on dead biomass — are unlikely to be able to keep up with the increasing supply. While those events are difficult to study due to their unpredictability, researchers have been able to assess that the process of carrion removal is significantly reduced when dealing with large amounts.
While we like to imagine that the majority of the decomposition process occurs underground by small creatures, hidden away, studies have found that vertebrate scavengers play an equal if not greater role. Their job extends further than simple cleaning, since decomposition contributes in turn to the health of the soil and the stability of the ecosystem. Vertebrates, including mammals and birds of prey, consume moderate amounts of carrion; leftovers are consumed by invertebrates such as insects. Their interaction with carrion allows microbes to easily access the material, recycle and reintroduce nutrients into the ecosystem. Therefore, when the amount of carrion is too much for vertebrates and invertebrates to consume, less will be accessible to microbes until abiotic processes break down the dead tissue over time. This means fewer nutrients will re-enter the ecosystem, and disease and carrion will accumulate.
In fact, composting — very common in many households today — is also performed by necrophagous microorganisms. When organic waste finds its way into landfills it not only expands in volume, its decomposition in anaerobic conditions contributes to the emission of the greenhouse gas methane. Through the process of composting, many species — from microbes to worms — aerobically decompose organic waste, not only keeping it away from landfills and preventing the production of methane, but also repurposing it as beneficial nutrients for the soil and human agriculture.
Rebuilding
Recycling is not a human invention made for plastic bottles; it is just how the ecosystem works. “One man’s trash is another man’s treasure” is a law of nature: no resource is wasted, and every bit of biomass is used by one creature or another. Unlike artificial machines built specifically for the collection and repurposing of garbage, these creatures use it to fuel their own life.
Novel ways of encouraging animals to clean up the environment, such as the cigarette collection by crows, are inspiring strategies for decreasing the overload on our cities, parks, and cleaning systems. Yet, the garbage we produce still ends up in landfills and is not reintroduced to the life cycle. The relentless work of the quiet, uncharismatic dwellers of our environment, who dispose of the garbage we hate the most — dead biomass —can inspire us to think about waste in circular, rather than linear terms. We may need to seek out more solutions for working with, and not against, the species we dislike and might even consider pests, from crows and hyenas to even cockroaches and bacteria.
When you donate to TiME, you save an ecosystem in all of its glory: the majestic, the “dirty” and the ugly, all working together to keep our world clean. The next habitat we protect may also save a species that inspires the next great idea to help humans clean up our own mess.
Author: Noga Syon
Editor: Liat Radcliffe Ross
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