Great Blue Heron Rookery in Sanilac County

By: Jackie Salowitz
Tribune Recorder Leader

“Although the Great Blue Heron is not on the Threatened and Endangered Species List the MNFI (Michigan Natural Features Inventory) does record and monitor locations of rookeries throughout the state.” (MNFI)

Sanilac County is fortunate to have a rookery, with the Blue Heron nesting in a wooded area on private property, returning to the same location every year.
According to MNFI, “The Great Blue Heron is vulnerable because of their colonial nesting behavior and the availability of suitable nesting is declining.”
They went on to say, “The Great Blue Heron is mostly a colonial nester. colonies are typically found in lowland swamps, islands, upland hardwoods and forests adjacent to lakes, ponds and rivers. Nests are usually in trees and may be as high as 98 feet or more from the ground. The same nests are used year after year.”
The MNFI says that “The Great Blue Herons in Michigan are largely migratory, almost all leave the state during the winter months. Most leave by October and return early to mid-March.”

“Courtship and nest building commences from early April in southern Michigan to early May in extreme northern portions of the state. Both sexes are involved in the nest building process, with males primarily gathering sticks from the ground, nearby trees, or unguarded nearby nests. Males pass sticks to females who then place them on the nests” – (Cottrille and Cottrille 1958, Palmer 1962, Mock 1976).
(Butler 1992) – “Both sexes take a turn at incubation with females incubating mostly at night and males during the day. Between 3-7 eggs are laid, with an incubation period of 25-29 days.”
According to Barrows 1912, Butler 1992, “Main food items include fish, crayfish and frogs, but many other animals are taken including snakes, salamanders, insects, small mammals and birds.”
The Great Blue Heron makes a distinctive call, and once I went into the woods, I just followed the noise, and within minutes of looking up high in the trees, nests were found. The birds were spotted in the tree branches and also found flying in a nearby farm field.