UConn researcher gets a rare look at the elusive American bittern
When Laurie Doss’s students at Marvelwood School in Kent first heard it last May — described in field guides as sounding like BLOONK-adonk and oonka-lunk — they weren’t sure what it was.
“They were asking, ‘What is that sound’?” said Doss, chair of the school’s Science Department.
Thanks to the wonder of the Merlin Bird ID app, the kids learned that the loud bull-froggy voice belonged to an American bittern tucked away on the edge of the school’s small pond.
They were lucky to make the ID. Bitterns — a speckled brown bird in the heron family — are secretive, solitary, expert at camouflage, and in Connecticut, endangered.
They are also underscrutinized. They are birds of freshwater ponds and marshes, but nobody has studied those spots for bitterns. They migrate through the state in spring and summer, but no one knows how long they stay or whether they breed here.
Sam Merker is working to fill in at least some of those gaps.
Merker, a researcher at the University of Connecticut’s School of Ecology and Environmental Biology, spoke to the Litchfield Hills Audubon Society about the American Bittern Project, an undertaking he started to learn bittern ways.
“I like to study unstudied birds and bitterns certainly are that,” he said. “We know very little about their natural history and biology.“
We do know that in the 19th century, they were commonly seen in the state. By the 20th century, they had begun to fade from the scene.
The simplest explanation is that humans did away with their habitat, filling in marshes and swamps to make real estate.
But Min Huang, a migratory bird program leader at the state Department of Energy and Environmental Protection, said that may be too simple.
Bitterns winter along the southern Atlantic coast and the Gulf of Mexico. Changes there may be contributing to bittern decline as well.
“We need good information about their habitat throughout their whole life cycle,” Huang said.
Bitterns are a bird apart. They have thicker bodies, thicker throats and shorter legs than other herons.
Unlike their more showy kin, they don’t stalk around in open water, staying instead on the edges, where their streaky brown-andwhite plumage hides them perfectly in reeds and brambles. They feed on frogs, salamanders, small fish, small snakes and big insects such as dragonflies.
When approached, they stand with their heads and bills pointing straight up, which blends them into the reeds even more.
They’re also solitary
birds. Unlike many herons, which nest in colonies, mother bitterns go off by themselves to build a nest, lay and hatch eggs, and rear their young. Male bitterns, rather than acting as faithful fathers, are polygamous, mating with several females.
The only confirmed successful bittern mating and nesting in the state in recent years was at Wiminsink Swamp in Sherman around 2014.
“We saw their babies moving around that June,” said Angela Dimmitt, of New Milford.
Their Latin name — botaurus lentiginosus — can be loosely translated as speckled ox-bull.
The ox-bull part comes from their deep, odd Tuvan throat-singing call, which the males sound during the
mating season and to defend their territory, which they do, zealously.
It’s also why they have earned other onomatopoeic nicknames, such as Bog Bull, Thunder-Pumper and Belcher-Squelcher.
Like other marsh birds, bitterns are shy, preferring to be heard, not seen. They are crepuscular, active at dawn and dusk.
Male bitterns oonk-alunk to announce themselves during the day. Merker was able to use this territorial imperative to his advantage.
He built a wire cage, equipped with a mirror inside and a small broadcasting unit on top. He then would wade out into the marsh, and set the cage up, then sound the bittern call.
Males bitterns in the area would gather in. They
would see themselves in the mirror and walk into the cage to fend off what they thought was an invader “I caught five,” he said. He then attached radio collars around their necks, and was able to track them around the state, to parts north, then south to Florida, where two died.
Huang, from DEEP, said Merker’s work on The American Bittern Project this year may learn that some of the collared birds return to the same places this spring. These secretive birds may become a little less so.
“With the older technology we had, we never, ever, could have gotten this information before,” Huang said.