Piping plovers find breeding habitat on Cat Island

The next time someone complains that deer don’t have a chance against forest predators such as coyotes, bobcats, wolves and black bears, tell them piping plovers would love to lead the whitetail’s pampered life.

When this sparrow-sized shorebird tries to build a nest and raise a brood in places like southern Green Bay, it first has to compete with egrets, herons, cormorants, herring gulls, Caspian terns, common terns, Forster’s terns and about 20 other shorebird species just to spread its wings, stretch its legs and forage for food.

Then, assuming it finds a mate willing to try nesting amid such competition, it must deal with the threat of high water, as well as nest-raiding assaults by air and ground, which includes gulls, skunks, foxes and raccoons.

And all that assumes the piping plovers even find suitable summer habitat. That task started getting easier in the lower southwestern corner of Green Bay when the Brown County Port and Resource Recovery Department in 2012 began reconstructing the 272-acre Cat Island Chain.

One pair of piping plovers accepted that daunting challenge this summer. They even raised three chicks into fledglings, a feat unknown in lower Green Bay since before World War II. The birds probably wouldn’t have succeeded without some human intervention, however, which included a protective wire cage that let the piping plovers come and go from the nest while keeping predators out.

The adult piping plovers have since migrated south. As of midweek, one of the fledglings had also flown the coop, and was spotted along Manitowoc’s shoreline. The other two fledglings are expected to head south at any time.

The human help goes beyond that protective cage, and started about four years ago. The sand, gravel and surrounding shorelands habitats are part of a 2.5-mile causeway built by the U.S. Army Corps of Engineers with materials dredged from Green Bay’s nearby ship canal to the east.

The dredgings and resulting beaches/wetlands are protected by a rock barrier to tame the bay’s waves, which destroyed much of the original island chain in the mid-1970s, a time marked by high water and severe spring storms during ice-out. The Corps will continue filling the island chain the next 20 to 30 years with dredgings. The chain will remain closed to the public while under construction.

The dredgings are tested for contaminants such as PCBs and heavy metals. Any materials with contaminant levels exceeding what’s already on the islands can’t be used. When completed, parts of the causeway will be removed to create a series of small islands separated from shore.

The island-restoration project is funded by several sources, including the Corps of Engineers, Great Lakes Restoration Initiative, a grant from the Wisconsin Department of Transportation’s Harbor Assistance Program, Fox River Natural Resources Damage Assessment settlement money, and revenues collected by the port of Green Bay.

Since construction began, biologists from the Department of Natural Resources, U.S. Fish and Wildlife Service and other conservation partners have worked onsite to assist habitat restoration and management. No one, however, has spent more time on the piping-plover watch than Green Bay’s Tom Prestby, who’s well-known in Wisconsin for his birding and bird-photography skills.

Prestby earned his bachelor’s degree in wildlife ecology at the University of Wisconsin-Madison, and recently earned his master’s degree by conducting shorebird research on 19 locations in lower Green Bay. So, if you’re wondering how someone happened to spot these tiny birds — which weigh about 1.4 ounces when wet, even as adults — credit this studious birder and our public universities.

Although this family of piping plovers is now famous for its nesting success on lower Green Bay, they aren’t the species’ Cat Island pioneers. On May 20, 2013, just after the Corps started building the Chain’s rock barrier, Prestby spotted a pair of piping plovers skittering around the shallows and shorelines. The shorelines were larger and wider three years ago because of low water levels.

Prestby could tell it was a male-female pair because the male was courting her. This ritual includes stone-tossing, flights with repeated dives, and quick-marching advances and foot-stomping while standing upright and all puffed up.

Yes, it’s a guy thing.

Unfortunately, the pair soon moved on without nesting. Prestby figured they simply couldn’t locate suitable habitat because the Corps had yet to dump any sand-and-soil dredgings, and the gulls and cormorants dominated the available habitat.

He spotted piping plovers again in spring 2014, but the water was higher and even less habitat was available. Then Prestby spotted some more in late August as they passed through while migrating south.

Prestby was optimistic when spring 2015 arrived. The island chain was taking shape as the Corps continued its work, and small cottonwood trees were taking root. Sure enough, the piping plovers returned in late April to mid-May. He identified them as three males, which defended individual territories while waiting for a female to show up.

Their wait wasn’t rewarded, however, and they eventually left. Prestby said the piping plover population in the Great Lakes “skews male.” Still, he remained optimistic, especially when a couple of new plovers stopped in during their August 2015 migration.

Biologists in the Great Lakes region estimate the region’s piping plover population at 75 pairs. That’s the highest it’s been since the species was listed as federally endangered in 1986, but still “critically” low. Most of them nest in Michigan, but five to six pairs have nested near the Apostle Islands on Lake Superior in recent years.

This spring Prestby’s vigilance paid off when three males again showed up, including one he first identified in August 2015 as a bird born on the Apostles. This time, however, a female born on North Manitou Island in northern Lake Michigan showed up, and the August 2015 male won her affections.

Prestby located the pair’s nest May 24 and photographed two eggs. He considers that sight the highlight of his 20 years of birdwatching. The nest eventually held four eggs, three of which hatched.

How did Prestby know the individual identity of the birds? He studied the leg bands, which biologists attach in various color combinations so birds can be identified at a distance.

And how will we recognize Green Bay’s piping plover fledglings? They’ll be the ones sporting green-and-gold leg bracelets.

“I got to choose the colors, and since you can see Lambeau Field from Cat Island, I thought the chicks should wear the Packers’ colors,” Prestby said.

Patrick Durkin is a freelance writer who covers outdoors for USA TODAY NETWORK-Wisconsin. Email him at patrickdurkin56@gmail.com.