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Yarn Registry BLOG: A Landfill is an Ecosystem Unto Itself, part V

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Mammalian abundance

Part 5 of a series investigating the many layers of life in the average landfill. This week’s entry discusses the myriad mammals that are able to live in a landfill, from small rodents to upper-echelon predators to human beings. Next week: the conclusion and some final thoughts!

Confession time: when I visited the Rumpke landfill and stared out at its considerable acreage, I envisioned animals living within the garbage itself — a civilization burrowing through alien waste, living in a maze of tunnels running through the picturesque mountains of trash. I pictured a community not unlike something from The Borrowers, in which insect and animals take what they need and return home to a burrow tastefully decorated with scavenged ephemera. Unfortunately (for the purposes of my own imagination at least), the reality of creatures in a landfill is not quite like this. Aside from the thriving microbial community, not much can live in the bowels of a trash mountain because its insides are largely devoid of oxygen. The garbage is so compacted that it lacks significant “void space” where oxygen could collect, while most oxygen that does remain is converted to methane gas by the microbial process described in a previous entry. “There’s no air there,” said Dr. Jean Bogren, a emeritus research professor at the University of Illinois in Chicago who has made a career out of landfill research. “There’s no advantage to living in garbage.” My trash burrow fantasy realm was cruelly compacted by reality.

But this isn’t to say that animals aren’t attracted to garbage, they may just not live directly in the piles. Many mammals inhabiting the Rumpke’s property prefer to reside in the grassy areas surrounding landfills. Studies have shown that the areas around landfills are typically populated by various species of mice, voles, shrews[7], rats, chipmunks, and possums. Skunks and foxes are also present, as are feral cats and dogs. Raccoons are sometimes brought to the landfill when dumpsters are dumped in the back of garbage trucks. Omnivorous species generally fare better in dumps, as opposed to strictly carnivorous or herbivorous species, whose specific diets don’t allow them to take full advantage of the smorgasbord.[8] The most populous mammal tends to be the white-footed mouse.

Some mammals travel to and from the landfill for food and supplies. White-footed mice, for example, have a range of over 1000 feet, while woodland voles have a 600 foot range. One study observed that mice made nests made of shredded paper and leaves in bottles, cans, and other containers from the dump.[9] Burrows on the peripheries of a landfill tended to be deep enough — from 10 to 36 cm deep — to provide cover from owls and hawks, which are their main predators. Predation by raptors and other animals discourages daytime feeding or foraging. The greenspace created on covered landfills features the predator-prey relationships one can assume. It is a grassland-like environment that often draws animals such as coyotes, foxes, and snakes that prey on other mammals. One landfill worker even reported that sometimes they’ll shoot and eat a deer or turkey that wanders onto the grassland.

Landfills have been shown to attract grizzlies, baboons, and other upper-echelon predators in areas where these creatures have become habituated to landfill use. Bears have been reported in landfills in Alaska and New York, and have even fed while trucks dump their haul. Grizzlies are capable of digging seven feet deep, and have excavated buried livestock. In one strange case, the fallout from eating garbage inadvertently helped temper the temper of a baboon troop. Baboons were dining on the scraps thrown in the bushes outside of a tourist lodge in Kenya and contracted tuberculosis from spoiled meat. These baboons were the alpha-male type who previously wouldn’t let anyone else get close to the meat. Incredibly, and this speaks for the innate benefits of the “can’t we all just get along” sentiment, when these baboons died from contracting tuberculosis, they weren’t replaced by the next-most aggressive males. The rest of the troop realized they didn’t have to fight for food, and were able to live communally and happily, replacing gestures of aggression with ones of affection, and having no problem welcoming new members into the fold.

Mammals, like birds, have to weigh the options of eating at a dump. Rats, for example, a frequent resident of landfills, need to eat around 35% of their body weight per day. Do they go for overall less nutritionally sound meals from the midden, or do they expend more energy traveling further for healthier meals? Does the convenience of ready food outweigh the presence of animals that would happily eat them? What about the danger posed by the garbage itself?

While the threat of a hungry coyote or possessive baboon is serious, the toxic composition of a landfill poses a grave threat to any creature that trudges through it. Leachate, that noxious juice that flows like lifeblood throughout the entirety of the landfill, is no less harmful to animals than it is to humans. Studies show exactly what happens when animals are exposed to it: an increase in cancerous legions and organ failure.[10]

In a typically cruel study, rats were injected for thirty days with different concentrations of a leachate concoction, comprised of leachate from twenty leachate wells in Nigeria. Within 24 hours of exposure, the rats showed discolored skin, un-groomed hair, and had difficulty breathing. During the second and third weeks, the rats were sluggish and ate less. Frequent sneezing, hair loss, and diarrhea occurred throughout the fourth week of the study. One rat had its eyeball bulge out of the socket, while others developed abscesses. Three rats died from the exposure during the tests, and another died a day after the tests were stopped. The pollution likely causes “direct chemical disruption of the organs.”

The study concluded that livers and kidneys are the organs most prominently affected by landfill pollution. Increased organ weight as body weight decreases, which the mice demonstrated, is a sign of toxicity, reflecting attempts to “sequester” these contaminants. Mice taken from landfills in Spain were shown to have heavier kidneys than mice from non-landfill sites, indicating their bodies’ attempts to flush out the accumulated toxins. Overall, kidneys fare a little better than most organs, reaching a “degree of tolerance or adaptation” to harsh substances, thanks to the kidneys’ deft detoxification process. Juvenile mice had elements such as lead in greater abundance, owing to higher energy requirements and the greater consumption of food this necessitates. Interestingly, shrews from the same landfills did not show an increase in some elements, highlighting differences in reaction to these elements in different species. Overall, carnivores are usually more exposed to metals and therefore accumulate more of these elements than omnivores and herbivores.

But perhaps the most pathos-inducing danger to mammals in a landfill is being accidentally injured or trapped in the garbage. One Florida veterinarian and wildlife rehabilitator described “skunks with yogurt containers stuck on their heads…Plastic items become intestinal blockages; baited fishing lines entangle limbs, hindering movement and causing dismemberment; and aluminum cans with leftover soda or beer turn into razor-sharp traps.” The most heartbreaking injury was a raccoon whose paws were stuck in beer cans. “The cans had been on his limbs for so long that he had tried to learn to walk with them, and both front limbs were completely damaged,” she said. She sedated the raccoon and took the cans off of his hands, which had no fur and no skin on them.

Humans, too, have been thrust into the ecosystem of a landfill. Economic and political conditions have pushed an estimated 15 million people into this strange new world. Many landfills in developing countries offer a form of refuge and employment, allowing people support themselves and their families by scavenging useful items. In some cases, selling plastics and metals to recycling companies, for example, can provide some semblance of income. Tens of thousands of people live inside individual landfills. Communities in landfills in countries such as Indonesia, Guatemala, Russia, and Senegal have their own schools, neighborhoods, and societies.

Living in landfills, humans have taken their customary place at the top of the ecological hierarchy, but this is obviously a Pyrrhic victory. Humans are subject to the same diseases, toxins, and dangers that afflict any creature that searches its way through a dump. Birth defects, tuberculosis, tapeworm, malnutrition, and fatal garbage landslides are a few of the many ubiquitous concerns. One man, who lives and works in a landfill in India, said that, due to the stench, he didn’t eat for over a week when he arrived, and vomited every day. But for better or worse, he has slowly become acclimated to life there, just as one might take to living in an unfamiliar area out of necessity. There are dangers inherent in any ecosystem, and hazards that creatures of every variety take into consideration. It’s all part of the game of life, and, as we’ve seen above, millions of organisms are somehow making it work.

[7] Special consideration was necessary for counting the short-tailed shrew. “The method of tagging by toe clipping is less reliable than ear tagging because of the possibility of shrews losing their toes to natural causes,” noted the authors of one study.

[8] One landfill in Virginia even attempted to introduce a new mammal to its grounds: goats. But, after a year, “officials realized that using farm animals to cut grass was not the easy solution originally imagined.” The situation did not improve even when sheep were brought in to augment the finicky goats. The final solution: officials acquired two lawn mowers to cut most of the grass on the landfill. “The same city official who initiated the goat project later proposed creating a mulching operation at the landfill. Supervisors rejected the proposal, but he purchased $500,000 of equipment without approval. He resigned in 2015 just before he would have been fired.”

[9] The authors noted that their study was conducted before an outbreak of Hauntavirus, and that they were not conducting a mammal survey at the time the study was published, which was apparently during the outbreak.

[10] Similar dysfunctions of the kidney have been reported in human workers associated with the treatment of industrial waste. A study done by the London School of Hygiene and Tropical Medicine suggests a possible increase in cancers and birth defects in humans who live near landfills.


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