Like Noah collecting for his ark, Chicago zoo workers cheated the rising waters of the Missouri River in June, rescuing eggs of a graceful, nearly extinct bird whose call once filled Illinois shores.
Clutches of piping-plover eggs were snatched from the river in North and South Dakota by Lincoln Park Zoo birdkeepers Anita Cramm and Sue Maher, along with a team from the Milwaukee County Zoo.
Piping plovers are delicate, robin-sized birds with near-perfect camouflage for their sandy homes. Their mottled brown eggs and brown colorations as downy chicks and feathered adults often allow them to blend in along rivers, lakes and seashores.
Because of their low visibility, they used to be called the “ghosts of the sandbars.” People could hear their distinctive call, peep peep peeplo, like a musical pipe, but had difficulty spotting them.
At last count in 1991, only 34 Great Lakes piping plovers were left. In Illinois, where industry, housing development and recreation have either altered or destroyed virtually every dune along Lake Michigan, there may be none left.
For that reason, Cramm was happy when Lincoln Park Zoo and the Milwaukee County Zoo were offered the chance to rescue flood-threatened eggs of the piping-plover species that inhabits the Missouri River basin.
Each zoo came back with 15 eggs. Lincoln Park was able to successfully hatch 13 in incubators. Milwaukee hatched 11.
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Because piping plovers never have been collected or displayed by zoos, the two zoos are obliged to learn as much as they can as quickly as they can about the species.
“These are the first ones we know of to have been artificially incubated and hatched,” Cramm said recently at the zoo’s birdhouse offices.
Five of the sparrow-size chicks were in two towel-lined rectangular glass aquariums near Cramm’s desk.
The youngest and least-experienced chicks were chasing tiny crickets released on the towels. The eight other slightly larger and more mature plovers are on display in the flamingo dome on the zoo grounds.
“We don’t know a lot about how to deal with them,” Cramm said. “I suppose we are sort of writing the book on them as we go along.”
There are only about 5,500 piping plovers in the world. For that reason, they are not normally collected from the wild for study or zoo display.
The chicks at the zoo, however, never would have hatched if the eggs had not been rescued in a joint operation between the two zoos and the Army Corps of Engineers.
The corps oversees the operation of giant hydroelectric dams built along the Missouri, controlling the flow and volume of water that passes through the dams. By law, the corps also must monitor and protect endangered species along the river, including piping plovers that nest on sandbars just a few feet above the normal river levels.
Early this summer, the corps calculated that unusual amounts of rain and melted snow from mountains upstream were piling up to a dangerous level behind the dams.
When that happens, “we’ve got to release the water or endanger the dam structure,” said Casey Kruse, the corps’ endangered-species biologist in Yankton, S.D.
Kruse said the corps knew water levels downstream would rise above the areas where plover mothers and fathers still were sharing incubation duties atop their eggs. So the corps called in the zoos.
“We figured, if these nests were going to be lost anyway, we could still learn a lot from them,” Kruse said. “We seized the opportunity and salvaged as many eggs as we could.”
Even in normal years, the birds don’t reproduce very successfully, he said. Only about one-tenth of those hatching reach maturity in a good year.
Since the dams were built in the 1950s, about 80 percent of the birds’ natural habitat along the river has been destroyed.
“With just 20 percent of the natural habitat left,” Kruse said, “all of the birds left are compacted into a much smaller area.
“If one predator, like a mink, finds and destroys the eggs in one breeding ground, now it has destroyed 50 percent of the population, rather than 5 percent when there was more habitat spread over a larger area. A localized hailstorm, which in the past might have destroyed four nests, might now destroy 40 nests.”
The zoo operation to save eggs from this year’s flooding was a one-day whirlwind.
A corporate jet lent for the operation by a wealthy zoo patron picked up Milwaukee and Lincoln Park staffers before sunrise June 2, flying them to Yankton.
From there, they made shorter hops up the river during the day as they collected eggs, storing them in special crates lent by the International Crane Institute in Baraboo, Wis. By nightfall, each zoo had 15 eggs in incubators back home.
“The first couple of places we got to, we were too late,” Cramm said. “The water had already destroyed the nests.”
When the zoo party arrived at sites where the eggs still were safe, the plover parents put on elaborate displays in a futile attempt to ward off the rescuers.
“In a way, it was heartbreaking to take the eggs while the parents watched,” Cramm said. “But, of course, the eggs were going to be destroyed soon if we didn’t take them.”
The corps later in the month went out and collected 230 more eggs, 114 from doomed piping-plover nests, and 116 from nests of another endangered riverbank species, the least terns. Of those, 96 plovers and 67 terns hatched successfully.
Like chickens, plover chicks are precocial.
That means they emerge from their shells covered by protective downy feathers and are almost immediately mobile and adept at finding and catching food. Within a week, the parents begin leaving them to fend for themselves.
The corps is raising those birds so they can be released back into the wild this summer, an undertaking never tried before with either species.
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The zoos aren’t raising the birds for wild release, at least for now. Instead, Cramm said, they will try to figure out what husbandry techniques work best for captive breeding and maintenance.
“We made surrogate mothers for them out of socks and feather dusters. We take them outside into the sunlight for a while every day to protect them from a metabolic bone disease they are prone to.”
Before the summer is out, they will molt and develop adult feathers, allowing them to fly.
In two years, if all goes well, they will be mature and breeding.
The corps hopes that the zoos will learn a lot about the plovers, Kruse said.
“If it came down to a situation in the wild that they were about to go extinct and we needed to bring whatever was left for captive breeding, we’d like to know beforehand how to best do that,” Kruse said.