For observers near lakes, evening and nighttime choruses
may include the haunting vocalizations of the Common Loon. These loons
breed on lakes with clear water, abundant fish, and lots of small islands
(which often serve as nesting sites). Common Loons are capable of a number
of vocalizations including wails, yodels, and tremolos. Pairs will often sing
duets comprised of all these vocalization types just after sunset and sometimes into the night. Birds are highly territorial in the early weeks of the
breeding season during which territorial vocalizations (yodeling) and fighting between individuals may be observed. Pairs of loons can be observed foraging together by day prior to incubation. Both pair members assist in the creation of their nest sites constructed at the water’s edge and both members incubate eggs once laid. Chicks leave the nest with their parents within 24 hours of hatching and are initially completely dependent on their parents for food (such as crayfish and small fish). Young loon chicks may be carried on the back of their parent.

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Safe Dates: May 15th to July 20th (applicable for only the S or H codes).

Breeding Evidence: If you hear Common Loon wails or tremolos within the safe dates, use code S and upgrade to S7 if heard at the same location 7 or more days later. For a silent bird on a potential breeding lake, a loon may be considered in appropriate breeding habitat (H) if within the safe dates. Nest sites may be obscured by vegetation and difficult to see. In such cases when a loon is observed visiting a probable nest site, you can use code N. Common Loons may be observed courting, displaying, or copulating on open water (code C). If territorial defense (which may consist of yodeling vocalization and physical altercations) is observed, use code T. Once hatched, chicks are always in the presence of their parents and can be highly visible (code FL). When a chick is discovered, behaviors such as feeding young (code FY) can often be observed.