FOR MORE THAN A DECADE, Jan Reese has ridden a bicycle down the dusty dirt roads of Poplar Island year-round, at least once every two weeks. His mission: try to count every single bird on this 3.5-mile-long island and record its species name.

Over the course of one day's visit, Reese makes his way from one diked section to the next. He brings high-powered scopes to see the birds. And he carries hand-held clicker counters. "I have a clicker on one hand, another clicker on another, and another in my head," he says.

Reese, an environmental consultant and long-time birder on the Eastern Shore, was contracted in 2002 by Maryland Environmental Service, which manages Poplar Island, to do regular counts. The project's monitoring committee wanted to track the numbers as one of several indicators of progress in the multiyear effort to rebuild the island in the Chesapeake Bay. Reese was a fitting choice because his experience on Poplar goes back much further — he studied birds there starting in the 1960s when it was a natural island.

Providing this habitat for shorebirds, waterfowl, and other birds in the Bay was one of many reasons that the Maryland Port Administration and its partners decided in the 1990s to build up Poplar Island using dredged sediments. Secluded islands like this provide valuable space for nesting and migratory birds, but such islands have steadily disappeared in the Chesapeake because of rising sea level, sinking land, and erosion. By the time construction began in 1998, Poplar had shrunk to only a few acres.

So far, Reese's figures have helped to show that bird populations there have vastly increased, according to wildlife scientists involved in the project. More than 175 different species have been observed, up from about 50 before the project began, says Peter McGowan, a wildlife biologist with the U.S. Fish and Wildlife Service who oversees wildlife management activities on Poplar Island. Many of these are migratory birds that touch down on the island awhile to rest and eat.

Of that total, about 25 species have been seen nesting on the island, up from ten before the project. These included species whose numbers have declined in the Bay. In 2012, there were an estimated 300 pairs of common terns, which are not known to nest anywhere else in the Maryland portion of the Bay. Also counted were about 45 pairs of American black ducks, a species popular with hunters and diners. The birds, scientists say, are one indicator that this manmade island is beginning to function like a natural ecosystem.

"[The numbers are] a huge success for us at this point," McGowan says. "And we're expecting more species to move in." Located about two miles from the nearest part of the Eastern Shore mainland, Poplar offers relatively few predators and good supplies of food.

"God, what bird wouldn't want to nest there?" Jan Reese says during a recent interview at his home in Saint Michaels.

Priority Bird Species on Poplar Island^*

Species	2002	2004	2006	2008	2010	2012
Common Tern	380	809	504	361	509	c.300**
Least Tern	40	50	35	112	175	75
Osprey	5	7	5	11	7	17
Snowy Egret	5	45	50-60	55	68	85
Black Duck	0	?	3-4	3-4	3-4	45

*Figures represent estimates and counts of the number of nesting pairs
** Range of 270-330 estimated

Five "species of concern," including snowy egrets and ospreys (above), have been chosen by wildlife managers to track on Poplar Island because their numbers are dwindling and they were known to feed and nest on the island before reconstruction. Figures reported by Jan Reese and other observers are included in the table above. Credits: Osprey, Maryland Environmental Service; Table source: Michael Erwin, U.S. Geological Survey

For Reese, 75, counting the island's birds has been not just a job but also a passion for much of his life. With his tall and slender frame and thin features, he resembles a shorebird himself.

Reese grew up on Tilghman Island, not far from Poplar, and when he was a young man, one of his high school teachers introduced him to birding. Reese was hooked. He educated himself about birds, later studying the reasons for the decline of ospreys. He pursued the subject through formal study, earning master's degrees in wildlife management and avian ecology.

To pay his bills, he worked in the construction industry on the Eastern Shore but kept active in bird research by collaborating with scientists at the Patuxent Wildlife Research Center in Laurel, Maryland. In 1990, he started his own consulting business, primarily conducting environmental assessments required for land developers.

Reese had visited Poplar to observe birds as the original island steadily lost acreage to the Bay. As the island disappeared, so did the birds. After work began to rebuild the island, Reese returned in 2002, this time as a consultant.

"It's one reason I like this job — I saw Poplar Island die, and then I saw it reborn," he says.

"In terms of the biology out there, I think he's got the best feel of anyone familiar with the project," says Michael Erwin, an emeritus professor at the University of Virginia and a former research wildlife biologist with the Patuxent Wildlife Research Center who has collaborated with Reese. "He's usually the first one to find species that have taken up residence on the island."

Erwin and federal and state wildlife managers have paid attention to counts of five "species of concern" that they especially wanted to establish on Poplar: common terns, least terns, snowy egrets, ospreys, and black ducks. Wildlife managers wanted to track these species for several reasons. These species were chosen because they frequented the Poplar Island area for nesting, feeding, or both before the restoration project began. In addition, scientists had good historical data on those species' populations in the Bay. And as a result of habitat loss, McGowan says, those numbers showed declining populations.

Reese counts species of concern and also many others during his rounds on Poplar. His favorite that he's spotted so far is the piping plover, a sand-colored, sparrow-sized shorebird that is increasingly rare on the East Coast and is federally listed as a threatened species. This plover does not nest on the island but probably visited while migrating, he says.

Reese's approach to counting bird populations — a comprehensive census — is accepted by wildlife biologists, but this method and others each have pros and cons, Erwin explains.

Reese's method may miss some birds of some species, like egrets and ducks, that are difficult to see because they hide among marsh grasses, Erwin says. Erwin instead relies on sampling a portion of the total population. He and his colleagues have periodically counted a limited number of tern nests on Poplar Island and used statistical methods to extrapolate from that to estimate the total number — a result called a Lincoln-Peterson Index.

An index approach can yield more accurate results than a complete census, Erwin says. But it is more time consuming, typically requiring two or more observers to be accurate. Reese's census approach is probably sufficiently accurate to help inform understanding about progress in building Poplar's bird populations, Erwin says.

"The fact that he is doing it the same way and repeating it month after month, year after year, I think is extremely valuable," Erwin says.

Predators — especially owls — have presented one of the bigger challenges to the bird restoration effort.

Great horned owls are probably the principal reason that terns have largely failed to reproduce on the island, scientists say. Terns nest in wide-open sandy areas at Poplar where marsh grasses have not yet been planted and other vegetation is sparse. That makes them easy pickings for sharp-eyed nocturnal raptors. When the owls swoop in, the adult terns not killed abandon their nests, and their eggs fail to hatch. As a result, population numbers have varied widely from year to year.

"Whenever you start concentrating birds, such as at Poplar Island, it can be devastating because the owls are pretty quick to find that location and cause a lot of damage," Erwin says. "Terns and owls typically don't get along very well."

The U.S. Fish and Wildlife Service collected airtight evidence of that — a remote, motion-controlled video camera recorded images of a nocturnal owl's attack on a tern colony. In 2009 the agency removed a pair of horned owls from Coaches Island, a small nearby island, and found that the terns' rate of reproduction later improved. But scientists also found signs that more owls have taken their place on Poplar. In addition, agency managers suspect that other predators such as great blue herons, crows, blackbirds, and Coopers hawks may also be taking a toll on the terns.

Diseases and toxins that afflict birds present another threat. Many birds on Poplar Island have died or become sickened at times from avian botulism, caused by bacteria. Another cause of death and illness has been microcystin, a toxin produced by a common species of blue-green algae called Microcystis aeruginosa. The 2012 season was the deadliest so far; more than 750 animals were killed or sickened, mostly from botulism, during a 15-week period. The creatures affected included 35 species of birds and one species of mammal, muskrats.

Both the botulism-causing bacteria and Microcystis prefer to grow in shallow, warm bodies of water on Poplar, fueled by hot summer temperatures and an abundance of nutrients. It's a mystery why the particular strain of Microcystis found on Poplar Island has prospered in the relatively salty water there, McGowan says — the toxin-producing algae typically inhabit water that is fresh or relatively low in salinity.

A team of scientists led by the Chesapeake Research Consortium has begun studying this strain, work that may help inform how the bodies of water on the island are managed, says Kevin Sellner, the consortium's director. The research may also indicate under what conditions this strain might grow and present a threat in other brackish parts of the Bay, he says.

It's an indication of how Poplar Island has become an important laboratory for a range of studies, McGowan says. Other researchers are examining, for example, the reproductive biology of osprey and other waterbirds.

Meanwhile, Jan Reese has continued his rounds, moving up from his old bicycle to an all-terrain vehicle provided by project managers in 2012. That's made it easier for him to get around on the island and continue counting the return of the birds.