natural chicago
by Sheryl DeVore Baker’s Lake rookery, in Barrington.
S
enior wildlife biologist Chris Anchor has been studying rookeries—places where egrets, herons and cormorants nest communally—for decades. Like no other species in the region, these birds offer humans a chance to watch them court, build nests and raise young. “There’s so much interesting bird behavior to see from spring through summer at a rookery,” says Anchor, who works for the Forest Preserve District of Cook County (fpdcc.com). Sometime in March or early April, herons, egrets and cormorants arrive at the rookery and begin carrying long twigs to build or tidy old nests in trees. “There, you’ll hear a lot of noise and competition and see males displaying for the females,” Anchor says. “They lift their wings and show off their plumage. It’s gorgeous.” As the season progresses, the eggs hatch and the young demand food and constant attention from their busy parents that fly for miles to bring them regurgitated fish and other aquatic delights. Herons and egrets wade in shallow water to find fish and frogs, while cormorants swim 38
Chicago
NAChicago.com
and dive for fish. Several large rookeries exist for the public to visit in the Chicago region, including Baker’s Lake, in Barrington, and Lake Renwick, in Plainfield. Types of species have changed over the years at these rookeries, and numbers of nests have risen and declined for various reasons. Many smaller rookeries can also be found throughout the Chicago region; some can be seen while driving, while others are nestled in hidden places. Herons, egrets and cormorants nest in colonies from several to thousands of nests. They feel protected from predators when they’re in large numbers. “It’s like a big school of fish in the ocean,” Anchor explains, noting, “Herons and egrets are near the top of the food chain, so when you have a rookery, that indicates your environment is in good shape.” Five types of herons and egrets, plus one cormorant species, have nested in small to large rookeries in Cook County. The fairly common, but secretive green heron and the rare Left: Black-crowned night-heron
Photo by Jeff Nelson
Reveal Lives of Herons, Egrets and Cormorants
Photo by Jeff Nelson
Rookeries
