This past weekend I had the pleasure of hearing Kenn Kaufman, a naturalist and bird expert, speak at the Smith Nature Symposium. He is somewhat of a “rock star” in the birding world. His novel, Kingbird Highway, chronicles a personal adventure hitchhiking around the country at the age of 16 on a quest to find birds—a story that has reached the status of folklore. Many years later, and surely a much longer “life list,” his keynote address at Ryerson Conservation Area focused on warbler migration: the phenomenon of these teeny tiny birds in every hue of the rainbow that travel thousands of miles across entire continents each spring and fall. He presented complicated doppler maps and in-depth scientific research on these migratory dynamos, but by the end of the discussion the focus had shifted to something more simple: the children from his young birders club.
Late that evening, as I settled down with one of his many guide books, Field Guide to Advanced Birding, I was struck by this same theme of simplicity. Kaufman urges folks to slow down and focus not on looking for the birds, but instead to spend time looking at the birds. He stresses getting to know the common birds of an area very well. By doing so, we are well on our way to knowing when a rare bird may enter the scene. This concept brought to mind one of the best places to take a long look at one common bird of Lake County, Illinois: a great blue heron rookery.
Most of us have likely seen a great blue beron (Ardea herodias) cross our path, whether it flew over you with its immense wingspan or it was seen slinking around in a wetland in search of its next meal. Great blue herons are sometimes confused with sandhill cranes (Grus canadensis), a larger and more rare sight in Lake County, but a bit more knowledge can help even a beginning birder notice the differences with ease. Start by comparing the photos below. The two pictures on the left show a great blue heron, and the two on the right are of a sandhill crane. In the upper left photo, notice the heron’s posture and feather details when standing—3 to 4.5 feet tall with frayed feathers on the chest. The lower left photo illustrates a heron in flight with its neck curved like an “S.” The upper right photo shows a larger, 5- to 6-foot tall, sandhill crane feeding in a field, and the lower right photo illustrates its posture while flying: a straight neck. Also, notice the crane’s red “cap,” white cheek, and fluffy bottom, which are helpful distinctions from the heron.
Once you have learned to identify a great blue heron you may begin to notice them everywhere, but by far the best place to watch this prehistoric-looking bird in action is at a rookery. While sandhill cranes nest atop piles of plants in marshy areas, great blue herons nest in concentrated treetop colonies near or surrounded by water. Many heron rookeries are used for decades and contain dozens of nests that are tidied up each year. Herons return from migration in the early spring, and their first call to action is sprucing up last year’s nest with the addition of new twigs, grasses and leaves. Males collect these vegetative “gifts” and offer them to a female, who in turn weaves the new materials into a saucer-shaped nest up to four feet in diameter. These heron mates will stay monogamous for the season, potentially selecting a new partner each year.
Soon after nest renovations are complete, the female lays two to six eggs over the course of a week. Both parents incubate their clutch, taking turns for hours at a time. The pair exchanges spots with elaborate ceremony, the incoming parent offering a stick to the brooding parent, after which the birds “clapper” their bill tips together in greeting. Scientific studies have reported that the male is the main bird bringing the sticks to the female, although folks at the Cornell Lab of Ornithology have observed differently while watching a pair nesting on their lIve great blue heron nest cam.
Incubation of the eggs takes about a month, and during that time both parents can be seen rolling the eggs around in the nest to keep them evenly warmed and prevent the embryos from sticking to the inside of the shell. The eggs do not hatch at the same time, resulting in different sizes of nestlings. Like siblings everywhere, the chicks are in constant competition, fighting for a meal regurgitated by their parents straight into their squawking mouths. Often the older, stronger chicks will reign victorious in these food fights, occasionally resulting in the starvation of the weaker nestlings. By the time they are eight weeks old, the surviving babies are roughly adult sized and fledge from the nest to fend mostly for themselves, coming “home” for about three more weeks for a free meal.
Rookeries are evolving places. Over time, the dead trees in rookeries standing directly in water begin to fall, changing the landscape. This has begun to happen at Almond Marsh Forest Preserves, one of the most accessible heron rookeries in the Lake County Forest Preserves. Together with the Lake County Audubon, we began erecting artificial nesting platforms in February 2009. Read about the success of this program here. Better yet, come out and see this rookery buzzing with action at Almond Marsh. Our dedicated rookery volunteers open the preserve to visitors every Saturday from 8AM-12PM, April through June. Volunteers supply high-power viewing scopes, binoculars and a vast knowledge of Lake County birds. They help visitors identify the herons, as well as other amazing wildlife that frequents the marsh. Another very active rookery can be viewed from the marina area at Fox River Preserve in Barrington. Take a long moment and truly watch.