A rough-legged hawk hunting over the Fermilab grounds.
Photo: Ryan F. Mandelbaum

We drove past the perfect-circle frozen pond delineating the Booster—the second in a sequence of Fermilab’s particle accelerators—and then onto the 2-mile ring road that traces the tunnel that houses the Main Injector accelerator. Along the road are unfrozen ponds filled with water used for cooling research equipment, where Canada geese have taken up residence by the hundreds. We stopped to scan for any rarer geese that might have joined the flock as several crows flew overhead.

The crow population has plummeted due to the West Nile virus, Fermilab physicist Peter Kasper explained to me. The crows turned their attention to a larger bird of prey, which flew our way. Its bright white underside and long tail revealed it to be a male northern harrier, a marsh-loving hawk with an owl-like face. We continued following a road along the berm delineating the proton beam, arriving at where, in the past, it would have entered the the now-decommissioned Tevatron accelerator. We stopped to appreciate the stark contrast between the green head, yellow eye, and white body of a small diving duck called a common goldeneye.

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A common goldeneye in a pond near Fermilab’s Main Injector.
Photo: Ryan F. Mandelbaum

Kasper works on the laboratory’s Mu2e experiment, which will probe the fundamental rules of particle physics—the Standard Model—by seeing whether a particle called the muon can decay into an electron. If the decay occurs more frequently than the incredibly rare rate at which it’s presently predicted, it might be a sign of undiscovered particles—particles that could explain outstanding mysteries like dark matter. But Kasper has gained notoriety for his side project: He has birded Fermi National Accelerator Laboratory in northeastern Illinois since joining the lab’s accelerator division in 1986.

Kasper has been bird-obsessed since he was in fourth grade in Australia, when he saw a friend’s bird eggshell collection. He bought a field guide to understand eggs himself but was soon wowed by all the fascinating birds, birds he could go outside and see for himself. He’s since seen over 4,500 of the world’s 10,000 bird species, and he has become the de facto steward of Fermilab’s birds. Today, the lanky, long-haired physicist leads surveys of the site’s avian diversity; he and others have observed a total of 291 species on the 10-square-mile campus. I visited Fermilab this week for reasons unrelated to birds, but my press handler, knowing that I, too, am a bird-fanatic, budgeted time for me to observe the wildlife around the lab with Kasper.

A coyote on a barren field on Fermilab’s campus.
Photo: Ryan F. Mandelbaum
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After our waterfowl search around the Main Injector—where magnets and radiofrequency cavities turbocharge protons from the Booster and Recycler and send them to other experiments—we traced the Tevatron’s 3.9-mile ring, which once further accelerated and collided protons. A pair of experiments called CDF and DØ monitored those collisions and discovered the top and bottom quark, the heaviest two of a sextet of subatomic particles. Fermilab decommissioned the experiment in 2011, as the more powerful Large Hadron Collider at CERN in Switzerland came online. The ring encases a tallgrass prairie and a reedy lake. It’s a perfect summertime habitat for waterfowl, marsh birds, and, in dry years, migrating sandpipers.

Lakes freeze over during the frigid Illinois winter, so we’d hoped to find grassland specialists like the northern harrier and the northern shrike, a robin-sized bird famous for impaling its prey onto sticks, thorns, or barbed wire. We failed to spot one, but a small falcon called an American kestrel flew over the car, making a fine consolation prize. We completed the circuit and turned onto the road bordering the lab’s respectable grasslands.

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One of Fermilab’s resident bison.
Photo: Ryan F. Mandelbaum

Less than 0.01 percent of Illinois’ original 22,000,000 acres of tallgrass prairie remains today. In the 1950s and 60s, biologist Robert F. Betz of Northeastern Illinois University worked to protect this habitat. When he heard that Fermilab architect and Manhattan Project physicist Robert R. Wilson was looking for ways to manage the site’s vacant land, Betz met with Wilson and explained the importance of the prairie ecosystem and the threats it faced, though he cautioned that the project would take 40 years to complete. Wilson replied, “If that’s the case, we should start this afternoon,” according to a paper on the results of their project.

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Wilson was already famous for guiding the lab’s distinctive appearance, Fermilab archivist Valerie Higgins explained to me over lunch. Wilson put a herd of American bison on the site in 1969 as an attraction to complement the prairie restoration. Today, prairie breeders like meadowlarks, bobolinks, and even rare Henslow’s sparrows summer in the grasslands.

A short-eared owl hunts just after sunset, with Fermilab’s Wilson Hall in the background.
Photo: Ryan F. Mandelbaum
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We kept our eyes peeled for rough-legged hawks, Arctic-breeding birds that spend the winter patrolling America’s prairies in search of prey. Kasper pointed out a place where I could later see the short-eared owl, a grassland specialist that hunts for meadow voles and can be seen around sunset. I warned Kasper that I needed to be back soon for an interview with a physicist about quantum technology, but then I mentioned that I’d never seen a Lapland longspur, a sparrow-like bird that favors barren agricultural fields. Kasper said this was a fine excuse to be late. We turned past the whimsical, Wilson-designed pi-shaped power lines and onto an iced-covered road bordered by farmland where Kasper had seen the longspurs this past weekend.

A pair of horned larks, another barren-ground lover with a yellow face, fed on grit and seeds by the side of the road; so too did flocks of American tree sparrows, a small brown bird with a red cap and a bicolored bill who happens to favor treeless habitats. Wind over the empty landscape chilled us both; neither of us were wearing a coat, despite the below-freezing temperatures. No Lapland longspurs showed themselves during our drive—but another consolation prize, one of the site’s resident coyotes, slunk in front of our car.

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A horned lark on Fermilab’s campus.
Photo: Ryan F. Mandelbaum

We turned around and returned to Wilson Hall, the 200-foot-tall concrete tower that stands solitary over the prairie. We accidentally scared a red-tailed hawk out of a tree as we entered the parking lot. In just 45 minutes, we’d tallied 13 species, a respectable list for wintertime birding. I retraced our circuit later and the next day (my press handler warned security that a harmless 20-something with binoculars would be driving slowly around areas labeled “Authorized Personnel Only”), catching views of the short-eared owls hunting over the prairie, a duck called a redhead, and, finally, a flock of Lapland longspurs.

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Kasper has seen all but six of the site’s 291 recorded birds, including a neotropic cormorant, rare to the state of Illinois. He’s jealous of another birder’s decades-old observation of a garganey, a small European duck, and wishes he could see a snowy owl on the site’s plains.

Like other long-time birders, Kasper has observed a decline in the number of birds at Fermilab. The area’s annual Christmas Bird Count survey has counted fewer and fewer birds over the years. Formerly large flocks have dwindled, and while spring migration might once have brought Fermilab 20 species of colorful warblers in a day, today Kasper struggles to see 10. America has lost almost 3 billion birds since the 1970s, 29 percent of its total avifauna. Veteran birders notice.

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“The data is horrific,” Kasper said, noting that it’s become normal for him walk through the lab’s woods and not hear a single bird chirp. “The first time that happened to me, I was shocked. I thought, ‘what’s going on, where are all the birds?’ The woods were never quiet.”

A pair of Lapland longspurs in a field.
Photo: Ryan F. Mandelbaum
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Fermilab’s grassland visitors show the importance of protected habitats to a healthy ecosystem. The hundreds of bird species that visit the campus are drawn to its diverse habitats—today, it combines woods, creeks, lakes, and prairies into a relatively small area near a well-known migratory route. Kasper’s hobby has brought him recognition from birders around the world, and his bird logs have drawn more birders into the area. Birders call this phenomenon the Patagonia picnic table effect, where rare bird sightings can turn a seemingly unremarkable patch into a birding hotspot, as more birders come to the area and report more rare sightings of their own.

“There are much better places to find birds in the Chicago area than Fermilab,” he said. “But we keep looking [here].”

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Senior writer covering physics / Founder of Birdmodo

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