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| Photo: Mark Thiessen/National Geographic Creative |
Whenever I present Food Foolish
to a live audience, I always try to end on a hopeful note, saying that if we are
smart and diligent, we can reduce food waste. And when we’re successful, the result
will be good for everyone: less hunger, reduced carbon emissions, a stable agricultural
footprint, more available fresh water, and greater food security for
populations around the world. Nobody loses.
I usually see people nod in agreement until one evening at a local
college, someone asked, “What about birds?”
“Birds?” I asked.
“What,” she explained, “would happen to birds that had come to depend
on landfills if we stopped wasting food?”
It was a good question. In the
United States and other developed countries, much of the food we waste shows up
in landfills. Unfortunately, I had no
answer at the time. Recently, I decided to
try to figure it out: How dependent are birds on human
food waste, and what happens if we reduce it—as so many individuals,
corporations, and governments are now committed to doing?
It’s Complicated
The intersection of birds and food waste turns out to be a puzzle. In Spain and Portugal, for instance, white
storks are avoiding their annual winter migration to Africa because of a
growing dependence on landfills. “White storks used to be wholly migratory,”says Aldina Franco, a conservation ecologist at the University of East
Anglia. “During the 1980s, the
first individuals started staying, and now we see those numbers increasing
exponentially." The resident
population of white storks in Portugal has grown more than ten-fold in the last
twenty years, with 80 percent of the 14,000 resident population feasting on
landfills.
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| Ringed White Stork By Soloneying [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)] from Wikimedia Commons |
In Germany, researchers outfitted 70 newborn white storks from
locations around Europe and Asia with miniature GPS tags and watched to see
what would happen. Just as in Portugal,
some migrated while others wintered on landfills. Those that chose to migrate were, ironically,
more likely to die. Landfill feeding
turned out to be, at least in the short term, nutritious, plentiful, and reliable. But there are many unanswered questions. Why do some storks migrate while others
remain, for instance? Do those that
remain have advantages or disadvantages over their migrating cousins? And most important for the “homebody” storks,
what happens if Europe closes its open-air landfills, as it is now trying to
do. Do the storks accustomed to an easy
meal resume their migration, or do they perish?
Similar questions revolve around species like the western gull (Larus occidentalis) in western North
America, whose population growth is a direct result of landfills. The Environmental
Protection Agency has estimated that 22 percent of every landfill in the US is
food waste, more than any other single material. And in 2015, the EPA and USDA announced a national goal of reducing food waste by half by the year 2030. If successful, what happens to the population
of North America’s western gull?
In the case of Bald eagles, it appears that young birds can adapt
quickly to landfills—from red meat and bones to rats—and become “landfill specialists.” Some even watch for the
trucks to roll in, knowing that their garbage will be “fresh.” Will this new-found specialization make them
or their offspring less effective hunters if the landfills close and they are
forced back into their more traditional habitat?
A study published in 2003 examined the influence of landfills on the
diet of the adult Yellow-legged Gull off the southeastern coast of France. Researchers studied the pellets of six
colonies and determined that up to 74 percent were consistent with foraging in
landfills. “Indeed,” the report says, “high
refuse dump accessibility leads to a poorly diversified diet dominated by
refuse. In contrast, when refuse dump accessibility is low, Yellow-legged Gulls
broaden their trophic niche, with an increased exploitation of alternative
foraging habitats, such as terrestrial habitats.” In other words, the landfill diet is like a
human filling up on fast food, skipping the fruits and vegetables. Researchers concluded that, if nothing else,
Yellow-legged Gulls are opportunistic and adaptable—factors that may work in
their favor as landfills are closed.
A 2016 report led by Professor Iain Gordon of James Cook University in
Australia examined in qualitative terms the impact of reducing agricultural
loss (in the field and during distribution) and waste (in landfills) on a
number of wild species, including birds.
“A question that animal conservation scientists should be asking,”
Gordon says, “is will a reduction in food waste, to meet the increasing demands
for food, have a positive or negative impact on biodiversity and which species
will be winners and losers? For example,
a number of bird species rely on grain spilled during harvest; if more efficient
harvesting techniques are introduced, what impact will this have on this
predictable food supply? More effective
vaccines and medicines used to improve livestock yield in developing countries
can reduce carcasses that scavengers such as vultures rely on. Likewise, more attention to waste reduction
by fishing vessels can reduce the food supply of surface-feeding seabirds.
The fact that scientists aren’t entirely sure why about 15 percent of
the world’s 10,000 species migrate in the first place complicates the
puzzle. A study published earlier this year hypothesizes that it’s a question of optimizing “the balance between energy
acquisition and energy expenditure.” In
other words, bird migrate if they can ultimately spend less energy to eat in
the face of seasonal changes and competition—even if it means a 10,000-mile
flight. The report adds, “our
mechanistic model provides a tool for predicting how ecosystems will respond to
global anthropogenic change”—one such obvious anthropogenic change being the
creation of landfills. If the
researchers’ hypothesis is true, the expansion and contraction of landfills
will have a significant impact on the migration choices of species.
Some landfills, like the Brevard County Central Disposal Facility in
Cocoa, Florida, and the landfill in Tullytown, Pennsylvania, are considered birders’
paradises. Want to see a Tamaulipascrow? Despite being a Mexican bird with
a limited range, it likes to dine at a landfill in Brownsville, Texas. In the October 2016 Audubon magazine, birder Nicholas Lund tells readers that you have
to “learn to love landfills and sewage treatment plants.”
Answering the Question
In summary, when it comes to the relationship between birds and
landfills, there’s not enough research available to determine anything
conclusively. Landfills encourage some birds to stay but others still
migrate; we’re not sure why, though a sophisticated internal energy calculation
might be at work. Those birds that dine
on waste tend to do better in the short-term—at least in the case of white
storks—but the long-term consequences of dining on food mixed with plastics and
potential toxins remains unknown. One unanticipated consequence of white storks dining at landfills might be an overabundance of
locust and other pests on which storks normally feed. If true, this explosion of pests could reduce
crop yields, diminishing the food supply long even before it has the chance to
reach a landfill.
At least we can say with certainty that landfills change the behavior
of some migratory birds, who are smart and adaptable, and are no less likely to
pass up a free lunch than a birder. Beyond
that, there is more unknown than known. Professor
Gordon’s research suggests we simply need more information about how humankind’s
food waste agenda is likely to impact the biodiversity of the planet. “Fundamental food web studies would be a good
place to start,” he says, and one such study by DA Bohen and others is
attempting to create theories about the system-level behavior of agroecosystems. “Network structure and dynamics have
substantial impacts on ecosystem performance,” Bohen writes, “but evidence from
agroecosystems lags behind network theory.” Scientists will be called upon
increasingly to answer questions about the consequences of our food supply on
species around the world. “Waste has
been ignored for too long,” Gordon concludes.
“The food security agenda will bring it to the front of mind, and
conservation scientists need to respond quickly if we are not to be left
feeding from the scraps under the table.”
Which is an eloquent way of answering the question I received that
night about what happens to birds if landfills close: We just don’t know.