Even in highly “improved” places like Iowa, nature still has a few secrets, and I got to steal a peek at one last week.
Having fished with great blue herons most of my life, I have long admired their grace, stealth and beauty and appreciated their company as they slip downstream just ahead of a slow-moving angler.
Of all the wild sounds, few are as distinctive as the squawk of a startled heron with its resemblance to the clearing of a badly congested throat.
In those many encounters, only once have I witnessed the coiled-steel speed and power of a stock-still heron hurling its dagger beak at an unsuspecting fish. It’s the definition of sudden.
While most of us have seen the elegant birds foraging in public along rivers, streams and wetlands, few have witnessed their private domestic life in their treetop nesting colonies.
At the invitation of a long-time friend who knows and shares my interest in nature’s secrets, I have finally checked that item off my bucket list.
Realizing nesting herons can be easily spooked and could abandon the colony if disturbed, the landowner observes the heronry sparingly and from afar. He guided me to it with the understanding that his identity and the colony’s location would not be disclosed.
The heronry consists of at least two dozen stick nests in the crowns of a cluster of tall trees in the middle of a timber far from the nearest road.
The location suits the birds’ preference for privacy as well as proximity to sources of food, which consists primarily of fish and amphibians.
The birds and their nests, sturdy despite their slapdash appearance, can best be seen in early spring before the trees leaf out.
The landowner said the colony has slowly expanded since he first noticed it three years ago.
During our brief mid-morning visit, herons came and went, while others sat in nests and roosted on nearby branches. We saw no signs of adults regurgitating their catch, which is how chicks are typically fed. Given the date, April 24, it seems likely they were incubating eggs rather than tending their young.
Though the herons were quiet during our visit, the landowner said they are typically more vocal in the evening.
The birds themselves are common in Iowa, but mystery surrounds the size, number and locations of their nesting colonies.
In a 2014 annual report on colonial water bird rookeries, the Department of Natural Resources said efforts to track colonial nesters through the Volunteer Wildlife Monitoring Program was hampered by the survey’s lack of structure and emphasis.
Under the federal Migratory Bird Treatment Act of 1918, it is illegal to capture, possess or harm a great blue heron, its nest or its eggs.