June 10, 2023 – More often heard than seen are those secretive herons of the marshlands, the American bittern, and the smaller and less common Least bittern. The peculiar calls of the American bittern remind one of the sounds of liquid pouring from a large jug with a small neck and have been aptly described as a repeating oonk-ga-chonk, oonk-ga-chonk, earning the bittern nicknames like mire-drum, thunder-pumper, and stake-driver. The American bittern has a status in Illinois as an endangered native, and the loss of wetlands has reduced nesting habitat and contributed to the decline of this species over the years, which continues even today across its range from pollution, climate change, and habitat loss. The Least bittern is about half the size of the American bittern at about 13 inches, making it the smallest heron in the Americas. The little heron is listed as threatened in Illinois, suffering from the same environmental challenges as many wetland birds. The smaller bittern has several calls that are familiar sounds in the marshes and bogs with shallow water and tall cover, high-pitched clucking, and springtime mating calls of coo-coo-coo-coo heard in the wetlands are sometimes mistaken for the sounds of frogs or the songs of other birds like the Black-billed cuckoo. Once a common summer bird in Illinois, their decline began with a reckless assault on the land in the late 1800s. The destruction of wetlands by the draining of shallow lakes and ponds that once dotted Northern Illinois had a devastating impact on the local and migratory wildlife. With the encroachment of man determined to tame the land for other uses, the Least bittern is now seen or heard only in the limited areas of its favored habitat. Traveling at night during the migration Least bitterns begin arriving from Central and South America in April. The little herons build their nests among the tall, dense vegetation, where they interweave a platform above the water from dead plants. They will produce four or five eggs with two broods each year. Spring migration of the American bittern starts in March and April, and this might be the best opportunity for a lucky person to get a glimpse of this secretive and well-camouflaged bird. Although nesting does occur in Illinois in the limited marshes and sloughs, the American bittern is considered an uncommon summer resident. More widespread nesting occurs in the vast dense wetlands of our northern border states, continuing into southern Canada.