
Species Identification:
This tiny heron keeps well-hidden amongst cattails and bushes. At about 30 cm tall, they are the smallest heron in the western hemisphere. The Least Bittern is light brown along their sides with a white throat and belly, and darker feathers on their back. They have a large, long yellow bill and yellow legs. The male’s head and back are much darker than the female and juvenile, and they are more frequently heard than seen. Their common call is a gentle, “coo, coo, coo,” and when alarmed they give a rapid, “rik-rik-rik-rik”.
Diet:
The Least Bittern primarily eats small fish by stabbing them with their long bill. They also eat leeches, small mammals, frogs, crayfish, small snakes, and large insects. They will often build platforms in shallow water to hunt off of. They hunt by standing patiently by the water, and may even hang off vegetation to reach down into the water, or quietly stalk their prey.

Biology and Behaviour:
Adults arrive back to their nesting sites starting in late April. Male displaying behaviour takes place for about six weeks starting early May. This is the best time to hear their calls and to detect them using call playbacks. Amongst dense vegetation, the male will build a nest platform by piling dry plant stalks onto bent marsh vegetation. 4-5 eggs are laid on average and incubated for up to 20 days. After about a month of being fed by their parents, the young transition into hunting for themselves, and then disperse in late summer. The fall migration starts in late August to late September.
Adults are preyed on by snapping turtles and raptors. The young are also vulnerable to snakes, raccoons, minks, corvids, and other herons. The Least Bittern has low tolerance to habitat changes, making them susceptible to illness and diseases. They also have low tolerance for fluctuating water levels.

Similar Species:
- American Bittern is similar to the Least Bittern, but they are larger and less colourful
- The Black-crowned Night-heron and the Yellow-crowned Night-heron juveniles differ from the Least Bittern since they have dark brown underparts

Conservation and recovery strategies:
The Provincial and Federal recovery strategies have so far focused on filling in information gaps on the Least Bittern through monitoring and research projects. Survey protocols have been established for their breeding season. So far 54 critical habitat sites have been identified in Ontario, but more habitat analysis needs to happen. In Ontario, Species at Risk at the Threatened level have all habitats automatically protected.
Additional Resources:
- Cornell Lab of Ornithology page
- Georgian Bay Biosphere reserve page
- COSEWIC 2009 Assessment and Status Report

Sources:
COSEWIC. 2009. COSEWIC assessment and update status report on the Least Bittern Ixobrychus exilisin Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vi + 36 pp. (www.sararegistry.gc.ca/status/status_e.cfm).
Ontario Ministry of Natural Resources and Forestry. 2016. Recovery Strategy for theLeast Bittern (Ixobrychus exilis) in Ontario. Ontario Recovery Strategy Series. Prepared by the Ontario Ministry of Natural Resources and Forestry, Peterborough, Ontario. v + 5 pp. + Appendix.