Did you know that herons nest in colonies that are called rookeries? Well, technically they are called heronries, but that term has never really caught on in the U.S. A rookery is actually a nesting colony of rooks, a member of the crow family that lives in Europe and Asia. Whether you call it a rookery or a heronry, we have a big one at Iroquois NWR and earlier this month the refuge counted all the nests in it. This survey consists of staff and volunteers trudging through snow along transect lines counting the nests above them. This time of year the herons are spending their time in warmer climates to the south, so all of last year’s nests are empty, but still in the trees. With no leaves to get in the way, counting them is a breeze, assuming you don’t trip on a stick or fall through the ice while you are looking up and counting them.
A total of 637 nests were counted this year (compared to 618 in 2017 and a 5-year average of 592). Although not our highest count (2015 had 673 nests), the 2018 heron nest numbers show an upward trend in the nesting population since inhabiting this location. Mixed in with the heron nests are a small number of great egret nests. The nests of these two species look identical, so there’s no way to tell the difference when the birds aren’t in them.
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The refuge provides the ideal habitat for herons to nest, roost, and feed. They are always a visitor favorite to watch fly with their slow wing beats and prehistoric look and to watch hunt with their snake-like necks. Look for them on the refuge in spring, summer, and fall standing in the shallow edges of the marshes waiting for their next meal to swim, slither, or hop by.