[Next-door Nature] Leftovers

Features - Next Door Nature

Urban wildlife are adept exploiters of the humans with whom they live. And easy access to consistently plentiful human-produced food waste is a primary reason for the success of many wild species in urban and suburban habitats.

October 23, 2013
Kieran Lindsey

Editor’s note: This article originally appeared on www.nextdoornature.org. Copyright 2013 Kieran Lindsey. To subscribe to this blog, visit www.nextdoornature.org.

According to the U.S. Environmental Protection Agency, Americans throw out 34 million tons of food each year. That’s an average of 93,000 tons a day and some experts estimate the amount triples on Thanksgiving and Christmas. Food for thought while making another trip to the garbage can following our national day of feasting. Waste not, want not — so the proverb goes. But does anything digestible really ever go to waste? Perhaps only if you think food is wasted when humans don’t consume it...

We live on a planet where, if someone can eat it, bet your bottom dollar someone does eat it.

Within a biotic community there are three basic trophic (feeding) levels: producers, consumers and decomposers. You can think of them as meal plan options. Producers transform energy from the sun into sugar (and everything consumed by anyone is broken down into sugar by the digestive process) — that’s the work of green plants. Primary consumers eat the plants and secondary or tertiary consumers eat the animals that eat the plants. Decomposers transform dead plants and animals back into their abiotic components (e.g., water, nitrogen, CO2). All three groups work together to create food, move it through the community and return the abiotics back to the environment for another trip through the system.

No matter which meal plan you choose, at some point you are either moving nutrients through the community or you are nutrients...with the exception of modern humans in the “developed” world, primarily due to our funeral laws and customs.

You can visualize food traveling through the community by means of chains and webs. A food chain is the most simple model for illustrating the relationship between a community’s trophic levels. For example:

Sun > violets > caterpillars > black-capped vireo > sharp-shinned hawk > black vulture > bacteria

The food web is a more realistic and complex model of the relationship between members of the biotic community, taking into consideration that most consumers eat more than one thing — vireos don’t just eat caterpillars, they eat a variety of insects, insect larvae and spiders; sharp-shinned hawks eat all kinds of songbirds, plus some small mammals and an occasional large insect; black vultures will eat almost any kind of meat, although they seem to prefer it well “aged.” Even though large portions of the human population have disentangled themselves from food webs, but we remain an indirect source of nutrition for many non-human animals, and not just those we feed intentionally, such as our companion animals and livestock. Easy access to consistently plentiful human-produced food waste is a primary reason behind the success of many wild species in urban and suburban habitats. Garbage is also one of the main sources of conflict between wildlife and humans. This is due, largely, to the fact that — and I’m sorry, but I don’t know how else to say this — the human race has some control issues when it comes to food.

The concept of owning food even after you no longer intend to eat it yourself seems to be uniquely human, as is the idea that we should be able to stipulate who gets access to calories we paid for in some way or another, including future food (crops and livestock), non-human food (purchased from Petco or Wild Birds Unlimited) and former food (garbage).

Skeptical? How many times have you heard a bird-feeding acquaintance complain when squirrels help themselves to the backyard smorgasbord? Or even when the wrong kind of bird drops in for a snack? How about the U.S. Department of Agriculture, which spends millions of dollars annually on research to reduce or eliminate wild species that like to avail themselves to a helping of the harvest? Consider, also, the time, money and energy spent trying to keep wild creatures out of garbage cans and Dumpsters so their contents can be transported to the landfill and buried to prevent other non-humans from turning our waste into a meal.

Of course, there are valid reasons for managing food waste, including aesthetics and hygiene. Garbage stinks, there are disease-prevention concerns and no one wants to live in the midst of a kitchen midden. You may be willing to share your cast-off cuisine with resourceful furred and feathered recyclers, but human neighbors tend to be less than forgiving about garbage-strewn lawns. Picking chicken bones and greasy bits of aluminum foil out of the Zoysia grass isn’t all that fun; even less so when you’re running late for work. It’s mornings like these when homeowners begin to formulate battle plans.

Some may even seek vigilante justice against an individual opossum, raccoon, crow or seagull. It’s a war we’ll never win. At its core, this is a first-come-first-serve, finders-keepers-losers-weepers kind of world, especially when it comes to food. Sure, a brief détente may be achieved through an exclusion technology arms race.

But victory will be short-lived. There will always be more mouths that need filling, in part because our leftovers are the raw materials from which the next generation of wild Dumpster divers are created. Successful urban wildlife species are generally adaptive, creative, resourceful and fecund. They are adept exploiters of the humans with whom they live.

Still, in most ways it’s a symbiotic relationship. They take the food we no longer want and, in exchange, add to our quality of life in ways that are easy to recognize and hard to measure. Moreover, by refusing to accept that we are masters of the universe, they keep us humble.

And for that, I am thankful.


Dr. Kieran Lindsey loves looking for wild things in all the wrong places…so she became an urban wildlife biologist. She also has way too much fun as the official Animal-Vehicle Biologist for NPR’s “Car Talk.” Read her blog at www.nextdoornature.org. Contact her at klindsey@giemedia.com.