Even though it’s the smallest member of the North American branch of the heron family, being dubbed the ‘Least’ anything isn’t exactly a compliment. How about the ‘tiny but plucky’ bittern, or the ‘adorable’ bittern? Nope, Least Bittern it is, and has been since the late 18th century.
It is unlike most other herons in that it does not wade through the water on stilt-like legs searching for food, but climbs and clings to cattails and reeds, thanks to its long toes. It is also slightly built, and because of its small size (body length 28 to 26 cm, wingspan 41 to 46 cm) slips easily through the vegetation, making it also hard to spot unless it’s flying.
Its plumage is brown and beige with larger, chestnut-coloured patches on its wings. Males have a black back and top of the head, while for females it’s significantly lighter in tone.
Males of the Least Bittern species select the nest and also build it. They tend to do so close to the water’s edge, in vegetation (generally reeds) anywhere from six to 30 inches above the surface of the water that can be anywhere from just three to more than 38 inches deep.
Nests are only about six to eight inches wide and two to five inches deep, and they’re sometimes built using the foundation of a nest from a previous year. Males also help repair the nest, even if its mate is still incubating the eggs. Females can have one to two broods a year, laying from two to six eggs on average each time. Incubation of the pale blue or green eggs takes between two and three weeks.
Both parents take part in feeding the young, through regurgitation, and both parents also protect the nest from predators. They will puff themselves up and spread their wings to look bigger and more menacing.
Young Least Bitterns develop quickly, as there have been examples of them leaving the nest as early as six days after hatching when disturbed (ordinarily, they stay for about two weeks, and then stay close to the nest for about another week.)
The nests are elevated, and close to the water to allow for more convenient and effective foraging. The Least Bittern’s diet consists primarily of small fish (minnows, juvenile Perch and Sunfish), frogs, tadpoles, salamanders, slugs, crayfish, shrews, mice, dragonflies and leeches. Their long, pointy bill, keen eyesight and sharp reflexes make them efficient hunters as they either stand motionless in the water, or hang off a branch or reed overlooking the water, jabbing at prey rapidly. Sometimes they will flick their wings open and shut to startle prey into moving, making them sitting – or floating – targets.
In the early fall, Least Bitterns head south, migrating to the southern United States, Mexico and parts of Central America. Travel is conducted mostly at night, with the return journey to northern climes happening in mid spring.
The species is considered to be ‘Threatened’ as human activity has destroyed great swaths of its wetland habitat. There are almost no examples of the Least Bittern in one of its former strongholds, southwestern Ontario, due to encroachment on their habitats. Thus, they are now concentrated in the central and eastern parts of the province, including the Cataraqui Region, south of the Canadian Shield.
- Sources: Province of Ontario, Cornell Lab (All About Birds), Wikipedia, National Geographic, Audubon Society.