Wetland wanderer: Little blue heron is a rarity in this area

In 1970, the Grateful Dead released a song called “Truckin’.”

A line from that song occurred to me as I was writing this article:

“What a long, strange trip it's been.”

This song would have to be near the top of a young little blue heron’s playlist.

Yes, I realize this calls for an explanation.

Little? blue heron

Compared to its larger relative, the great blue heron, the little blue heron (Egretta caerulea) is seldom seen in our local area. This is not because its size makes it difficult to spot. In fact, it is just under 30 inches tall and has a wingspan that is a little more than 40 inches. For comparison, a great blue heron stands 38 inches tall with a 70-inch wingspan. It is rarely seen because it is rarely here.

An endangered rarity

Typically, when you hear of scarce herons or egrets, you might think of the fact that egret feathers were used to decorate hats late in the 19th century. More than 40 native bird species were identified decorating hats during the height of this unfortunate craze. The preferred feathers brought a much higher price per pound than gold.

In particular, it was the decorative male breeding plumes, called aigrettes, of great blue herons, snowy egrets and great egrets that were in the highest demand. Because of the incredible hunting pressure brought to bear on these wading bird species, the newly formed National Audubon Society, dedicated to bird conservation, chose the great egret as its symbol.

Now you might be expecting me to write that the little blue heron suffered during this era. Actually, it was not a favorite target. Fortunately for the species, male breeding little blues do not sport showy aigrettes.

One of the reasons the little blue heron is listed as endangered in the Land of Lincoln is because its range within our state boundaries was always limited.

The species frequents freshwater swamps, sloughs, and other shallow waters, from New England coasts and the tip of Illinois southward down the Mississippi River Valley and throughout the southern Atlantic states. It frequents wetlands all the way along the coasts of South America. In the northern portions of its range, the species regularly heads south for the winter.

A white little blue visits Stillman

During the summer of 2023, an immature little blue heron was a “regular” here at Stillman’s pond. How could we tell it was a first-year bird? It wasn’t blue, it was white.

Being white when young and turning a dark color as an adult is an unusual development pattern among the herons and egrets. In fact, the little blue is the only heron that exhibits what ornithologists call chronological white-dark dimorphism.

Other all-white egrets include the cattle egret, snowy egret (also endangered in Illinois), and the great egret. Here at Stillman, we often see the great egret, which, at 38 inches in height, is relatively easy to separate from the shorter little blue. We did enjoy watching both these birds do their shopping at our pond. The questions are, why were these white blue herons here and why are these juvenile birds white?

It seems that every few years, after the breeding season is concluded, these young blue herons suffer from wanderlust. They disperse hundreds of miles from where they were hatched. The birds usually head inland in a northerly direction. During this post-breeding dispersal, the white little blues can fly as far as southern Canada. Lucky for us, one stopped here at Stillman.

Where and when they disperse is not entirely predictable. Before last year, we hadn’t seen one at Stillman for 11 years. Little blue herons were also spotted at other Chicagoland wetlands. The reasons for this avian equivalent of the Amish rumspringa is still under investigation.

Why are young little blues white?

Research into the juvenile birds’ color offers some interesting possible answers.

Apparently, some of the larger white egrets bully the adult little, actually blue, heron. Being white makes you less of a target and it allows you to travel in mixed flocks composed of other white herons and egrets. As the old saying goes, there’s safety in numbers.

Also, as the heron is learning the hunting skills it will need as an adult, it can practice out in open water. The white feathers help you blend in with the white clouds or bright sky overhead. Remember, possible prey are looking up from the water. That prey includes crustaceans, invertebrates along with small fish and amphibians. The blue adult heron hunts closer to shore with darker vegetation and overhanging branches as a backdrop.

The white feathers also reflect more sunlight. So, when you’re in the nest, you are less likely to overheat. Where do little blue herons nest? Where don’t they! Based on research done across its range, here is a partial list of plants where this heron’s stick nests have been found: pine, black gum, bald cypress, Osage orange, buttonbush, poison ivy, blueberry, honey locust, phragmites, and cattails.

When will they return?

Now that I think of it, I’m not sure when I’ll see a little blue heron hunting at our pond again. Ten years from now? A dozen years? It is probably somewhere around there, but nobody knows for sure. I do know one thing. The next little blue heron will arrive before the next solar eclipse does.

Mark Spreyer is the executive director of the Stillman Nature Center in Barrington. Email stillmangho@gmail.com.