The Science Behind Northport’s Gull Island

A tiny island near Northport with a gazillion gulls has a surprising science backstory. We head out with a research crew to hear the screeching up close, get pecked and learn how these gulls changed America. This Traverse Classic is featured in the May 2015 issue of Traverse, Northern Michigan’s Magazine. Get your copy.

Note: In order to protect the colony of gulls and especially their young, there is absolutely no trespassing allowed on the island. 


Like anybody else who has ever traced the Leelanau County coast north to Northport, I became curious about a tiny island that rises in the bay not far from the harbor. With the naked eye, I could make out remnants of a house there, just two chimneys rising from an otherwise barren scrape of land. I’d heard rumors of thousands of gulls that nested there, a colony that was so resilient it had outlasted the people who’d built the now-destroyed house.

Then a friend told me that the humble and now-protected isle—officially named Bellow Island, but locals call it Gull Island—was also involved in some of the most important and longest-running gull studies in the annals of Great Lakes research, and that herring gulls here were even instrumental in getting DDT banned. The gulls of Bellow are something like canaries in a coal mine—a top-of-the-food-web predator whose condition reveals the health of everything below it.

Check out this short video Jeff Smith shot while he was out on Northport’s Gull Island. 

I contacted Dr. William Scharf, a retired long-time biology instructor at Northwestern Michigan College and renowned Great Lakes bird researcher. For decades he had been making data-gathering trips to study one thing or another about the gulls on Bellow Island—subjects like population size, territory competition and chemical contaminants in eggs. “Spring of 2014 will be my 46th annual trip,” Scharf told me. He gave me permission to tag along, promised to fill me in on the island’s research pedigree. At the time it was winter, and we were to go in April when ice left the bay and eggs were in the nests.

But the winter brought record cold and dumped 22 feet of snow on Leelanau. A deep chill lingered long into spring, and all through April, ice encased Bellow Island. The trip date got bumped, and bumped again, delays that were very vexing to ornithologist Scharf.

[Curious about the house on Gull Island? Read the incredible tale.]

gull island northport

Aerial view of Gull Island shot by Ted Cline

When spring arrives in the north, life unfurls fast, and in the course of a single month, gull nests evolve from empty, to crowded with eggs, to teeming with hungry, cheeping chicks. Scharf knew that the herring gull eggs he needed to collect were already laid and—for his purposes any way—degrading by the hour.

Scharf’s research trip had multiple purposes, and one of the main missions was to gather 13 herring gull eggs whose yolks would be needed to test for man-made chemical contaminants. Yolk is the food source for a developing chick, and as the chick grows inside the egg, it consumes the yolk. Scharf had to reach the island before the yolks were too small to be of scientific value. The egg chemistry data contributes to a long-running Canadian/U.S., Great Lakes–wide gull egg study assessing the presence of harmful chemicals in the basin ecosystem, and the last thing Scharf wanted was a break in the line of data from Bellow.gull island northport

Scharf and his research crew—Jenee Rowe of the Leelanau Conservancy (which owns and protects the island—no trespassing, by the way), and Eric Olsen, a natural resources officer with the Grand Traverse Band of Ottawa and Chippewa Indians (which owns the boat)—pick May 5 for the 2014 sampling trip. Luck breaks their way. Enough ice has opened to allow passage, and though the day is foggy and cold, and black-gray clouds stuff the sky, the wind stays oddly calm, and the water lies flat.

About 7:30 a.m. crew and equipment are in the boat at Omena’s Kal Marina, and Olsen eases away from the dock, motoring slowly across the mile and a half to the island. The minute the boat is in the open water, Scharf puts binoculars to his eyes. He scans the horizon, scopes the gulls swirling above Bellow, zeroes in on a couple of birds bobbing in the water not far from the boat.

“Ice berg at 2 o’clock,” Olsen says of a small ice floe, and cheats a little to the left.

“Last year we saw Bonaparte gulls here. They normally nest on the Canadian Plains,” Scharf says. He suspects they were blown off course by a big wind, but nobody really knows—could it be a habitat loss issue? “Oh, hey, there’s a Bonaparte gull right there!” he says, his voice rising with the sight. Scharf is in his mid-70s, still strong, and he appears to have lost little of his lifelong passion for just plain seeing a bird, especially an unexpected one. Likewise he remains passionate about the research needed to make sure birds have a fighting chance as man continues to impact their habitat.

northport gull island

Olsen gentles the boat to an island landing, and it becomes obvious why locals can’t let go of the name Gull Island. From every direction comes the screeching, cawing, shrieking cacophony of gulls. Hundreds of gulls circle above. Hundreds more sit warming eggs in nests scattered across the barren scape of the little isle. Hundreds more gulls float near shore, their bright white bodies seem to glow against the calm, charcoal-gray water.

The annual research trip has three main goals, Scharf explains. One, the team will measure the size of eggs in 30 nests—a general indicator of egg health. Two, the team will count the number of nests occupied by herring gulls, ring-billed gulls and cormorants to track which species is growing and which is diminishing in the battle to control the island. And three, the team will collect one egg each from 13 nests, and the eggs will be tested for man-made chemicals, including DDT, PCBs, dioxins and furans.

Left to right: Scharf, Rowe and Olsen

Scharf stands on the gravelly shore and surveys the scene. “We are out here very late,” he says, more thinking out loud than making conversation. If ice had delayed their trip another week or two, “there’d be chicks inside the eggs, not yolks,” he says.

Scharf and Rowe pair up and head off to collect and measure eggs. They carry a 5-gallon bucket of water, calipers and a super-cushioned case for shipping the eggs. Olsen heads off on his own across the 7-acre island, a chrome click-counter in hand to record the number of cormorant nests in an enclave on the north shore.

As the crew walks among the nests, the gulls dial up their aggression. A gull swoops to peck Rowe’s head—she wears a hard safari hat for protection. “Whoa, that one was serious,” she says, readjusting her helmet. Scharf shares a story about a gull that pecked him through a slot in a bike helmet he wore one year. “That was a heckuva a poke!” he says.

Scharf and Rowe are looking for nests with three eggs. They will measure one and keep one to ship Fed-Ex that evening to a Canadian laboratory that is testing eggs from a dozen islands in the Great Lakes basin.

Scharf picks up an egg and fits the micrometer to it. “75.8 by 50.2,” he reads to Rowe.

“That’s a big one! Good job, Lady!” Rowe says. Then, per protocol, she repeats the numbers aloud and writes them in the log.

Next they float the three eggs in the bucket of water. The egg that sinks fastest will be the one chosen for shipping, because as a chick grows and the yolk shrinks, the egg has more air—floats better—and the team wants as much yolk as possible.

_I1A2835Other than gathering the eggs for the chemical analysis, Scharf doesn’t get involved with the contaminant part of the research. His research focuses on the population dynamics and territorial battles of the herring gulls and, in recent years, two bird invaders: ring-billed gulls and cormorants. He concedes that herring gulls are his favorites. “The earliest reports of the island, from the 1880s, show only herring gulls,” he says. He suspects that herring gulls colonized the island possibly thousands of years ago, maybe even immediately after the glaciers receded 11,000 years ago.

The story of the invading ring-billed gulls and cormorants on Bellow Island offers insight into the value of the often-unglamorous baseline research of the type that Scharf and his crew are doing this day. In the early aughts, the cormorant population exploded in the Upper Great Lakes. By 2007 Bellow had 1,541 cormorant nests. Their feces were killing the vegetation—herring gulls prefer thick vegetation for territorial boundaries—and the cormorants were outcompeting the herring gulls for nesting space. Making things worse for the herring gulls, ring-billed gulls also prefer more open nesting grounds and were also expanding into the herring gull turf on Bellow. Scharf’s decades of population data was able to clearly show the impacts of cormorants on herring gulls, and helped convince the federal government to approve a plan to reduce the cormorant population on Bellow. On this day, Olsen counted just 209 cormorant nests—13 percent of the peak.

The team wants to be off the island quickly to disturb the gulls as little as possible, so they move along. By 11 a.m., they have one task to complete. Scharf, Rowe and Olsen meet at the south edge of the island, stand about 10 yards apart and walk straight north clicking their chrome counters with every herring gull nest they see. As they step carefully through the heart of the island, gulls lift off their nests in a great, white, screeching, flapping, swarming multitude. Occasionally one swoops to peck a researcher.

The team wanders back to the boat, clambers back in. “How many nests did you count?” Scharf asks.

They compare numbers. “We didn’t get quite a thousand,” Olsen says.

A look of disappointment crosses Scharf’s face. “Back in the ’70s we had 1,650,” he says. This is the first time in his 46 years of study that Scharf has seen the herring gull nest number drop below 1,000. He’s concerned about the herring gull’s future. The herring gull eats primarily fish, a little bit of garbage, but not much. So if fish populations fall, that hits the herring gull hard. The ring-billed gull, though, is a scavenger, the gulls you see in the Wal-Mart parking lot squabbling over half-eaten Whoppers. “So the more people there are around Grand Traverse Bay, the more garbage there is, and the more food there is for the ring-billed,” he says. The habitat is shifting in the ring-billed’s favor.

Scharf is also concerned that chemical contaminants are causing a delay in when some gulls lay eggs. Later egg-laying results in more females and fewer males. Will that result in a long-term decline in population?

View of Gull Island house from the water

On the way back to the dock, I comment that Scharf’s string of 46 annual trips to Bellow is nearly unbelievable. He tells me the research history on Bellow actually goes way back beyond that. “You should talk with Jim Ludwig,” he says. “His family was banding birds there going back to the 1930s. They basically wrote the book on where gulls go in winter.”

Some time later I call Ludwig, and when I do, I learn that yes, it’s true that he comes from a renowned bird research family and that his grandpa, dad and uncle were banding on Bellow in the ’30s. He first banded birds there as an 8-year-old in 1949.

But then Ludwig reveals something much more remarkable on the Bellow Island research résumé. Here, as a young graduate student at the University of Michigan in the mid-’60s, Ludwig gathered the first solid data proving that the notorious pesticide DDT caused thinning in the shells of herring gull eggs. Thin eggshells cracked, embryos died, and populations collapsed throughout the bird kingdom, including among bald eagles. “Bellow, quite frankly, was a mess,” Ludwig says. “28 percent of the eggs were broken, cracked and leaking.” Just as Scharf’s baseline data was able to show clear reductions in gull population due to cormorant invasion, Ludwig’s long string of population data was able to show a sharp reduction in herring gull population due to the effects of the pesticide. In the early ’60s, “Bellow Island was the most productive herring gull colony in the Great Lakes,” Ludwig says. “And when DDT arrived everything reversed. It became the least productive colony in just two years.”

Ludwig’s Bellow study was among just a handful that persuaded Congress to ban the chemical, meaning the little island near Northport played a role in an environmental victory that still stands as one of conservation’s defining and most inspiring moments.

When I ask Scharf about the results of the Bellow chemical contaminant studies from our trip in 2014, he defers, saying I should talk directly to the lead researchers on that front, Dr. Keith Grasman, at Calvin College, who studies how the gulls’ immune system is affected by the chemicals and Dr. William Bowerman, at the University of Maryland, who tracks concentrations of chemicals in the eggs.

As for Grasman’s immune response research, he says one thing that makes Bellow interesting is that given its location far from heavy industry, it has surprisingly high levels of dioxin and furan compounds in the eggs. As suspected, researchers are seeing impaired immune response in the birds; in some cases, the immune response is half of what it should be. A reduced ability to fight infection and disease could in theory reduce the gulls’ prospects of survival. “That’s one of the interesting things to me, not just at Bellow Island, but others too, you can go to iconic, beautiful, scenic islands in apparently pristine environments, but in many of these sites, the birds suffer problems from chemical contaminants,” Grasman says.

I ask Bowerman to give an example of how the long-term research that Bellow Island is part of has affected environmental decisions recently. “Well, brominated fire retardants,” he says. “We found them in gull eggs, and because we had gull eggs archived (frozen and preserved), we could go back and see that those chemicals were doubling in the eggs every three to five years in the Great Lakes.” The compounds were banned and levels started to decline. “All because of the herring gull programs,” Bowerman says.

Gull Island house, side view

Overall, is Bowerman optimistic or pessimistic about chemical concentrations like those seen on Bellow Island? “I’m optimistic,” he says. “In the past 20 years we’ve seen about a two-thirds reduction in PCBs and about a 50 percent decline in pesticides in the eggs. Also, other than the brominated compounds, we are not seeing big new chemicals appearing in levels that would impact bird health.” He concedes, however, that the reductions have plateaued somewhat and now appear to be on a long, slow decline and that it could take decades before the levels of PCBs and other persistent pollutants drop to safe levels for birds.

For his part, Scharf remains cautiously optimistic about the future of herring gulls on Bellow Island. “I’m impressed at their resilience,” he says. He sees the main threats to their survival being other birds more so than contamination. “The ring-bills and the cormorants are moving in and they’re taking up a lot of territory that the herring gull used to occupy,” he says.

Little Bellow Island and its outsized role in Great Lakes bird research leads me to consider how such studies can go for so long and all the while seem mundane, boring, ho-hum, pointless and how they can easily become the target of budget cuts. But then suddenly a change appears, and that same research can become shockingly important. Tiny Bellow Island, rising so humbly within sight of the Northport dock, is a bellwether for many big things. Without people like Dr. Bill Scharf and his crew heading out to count nests with a clicker or collect a baker’s dozen of eggs for testing, the tale it has to tell would remain locked in secrecy.

And so I’m left with this image, of Scharf and Rowe measuring their 30 eggs on that cold, dark day in May 2014. Scharf, caliper on the egg, reading numbers to Rowe. She repeating them … “72.4; 59.2” … “72.4; 59.2” … “73.5; 50.1” … “73.5; 50.1” … “65.8; 50.0” … “65.8; 50.0” … “73.8; 48.7” … “73.8; 48.7” … “73.7; 48.2” … “73.7; 48.2,” and all around them as they do this tedious call and repeat, is the constant screech and caw and squawk of gulls.

Historic postcard of Gull Island

Get Gull Savvy

Four things to know about gulls.

  • As Dr. William Scharf likes to say, “There’s no such thing as a seagull,” meaning, no single bird is named seagull; it’s a common term that encompasses all gulls.
  • Ring-billed gulls are so named because they have a small black ring around their beak.
  • Herring gulls are about a third larger than ring-billed gulls.
  • Herring gulls have a little red dot on their beaks, and when a baby gull taps it, the parent regurgitates food into the baby’s mouth.

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Article Comments

  • Peregrino

    Interesting that nothing was said in the article about the estimated 150 million people who have died from malaria since the banning of DDT. Since when are people of less importance than scavenger pests?

  • mnelson19

    Here’s our family motorboat trip from around 1962, Alden to Northport, with our stop at Bellow (Gull) Island. https://www.youtube.com/watch?v=UYVsSn6A-sI