Rare Black-Crowned Night Herons Thrive at Zoo ... As Visitors

By Justin Breen on May 13, 2013 6:21am | Updated on May 13, 2013 7:47am

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 Black-crowned night herons nest at the Lincoln Park Nature Boardwalk just south of Lincoln Park Zoo.
Black-Crowned Night Herons
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LINCOLN PARK — One of the rarest birds in Illinois is actually quite common in the heart of urban Chicago.

The black-crowned night heron, which is considered endangered in the state, has created a rather large colony on and around the Lincoln Park Zoo grounds, although they are not in captivity.

Mason Fidino, the zoo's coordinator of wildlife management, conducts routine morning counts of the birds, which he said numbered 403 on Thursday.

Fidino said between half and three-quarters of the herons currently are building nests, the majority of which exist in a line of ash and linden trees just south of the Lincoln Park Zoo Nature Boardwalk.

"We likely have the largest nesting colony in the state," Fidino said. "People love asking us about our small endangered celebrity that comes every year."

The zoo has been keeping track of herons' breeding numbers since 2007, when most nested on the island surrounded by the zoo's South Pond. As numbers increased, the herons, which have been endangered in Illinois since 1977, ventured south to the row of trees.

Many of the Lincoln Park birds likely originally nested at Lake Calumet on the city's South Side, Fidino said.

Last week, fencing provided by the Illinois Department of Natural Resource's Illinois Wildlife Preservation Fund was being installed around the main nesting site. Fidino said the fencing in part protects heron fledglings who may fall out of the nest when trying to fly.

The herons average about 25 inches in length and weigh 28 ounces. They have a black cap and back, gray wings and a white underside. Fidino said each nesting pair could lay as many as seven eggs, although most chicks don't survive.

Most of Lincoln Park's herons travel to southern states for the winter, and the birds' range extends to South America. But Fidino said 15 of the herons stayed on zoo grounds over this past winter.

The birds eat fish, lizards, mice and even turtles.

"Anything they can get their beaks on," Fidino said.

Seth Magle, the director of the zoo's Urban Wildlife Institute, said the herons are a great example of a species adapting to changing environments.

"If they're able to use some of these new patches we've created in these urban areas, than that's very exciting," Magle said.

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