Aquabird of the North

Tuesday, May 20, 2025

Aquabird of the North

Today’s special animal friend is the common loon, Gavia immer. Also known as the “great northern diver,” this water bird is one of five species in the Gavia genus. They are found throughout North America and on the Atlantic coast of Europe. The common loon is migratory, breeding in the summer in the far north of the U.S. and throughout Canada and wintering in many areas of the U.S. as well as Mexico. Loons are known for their distinctive call:

It was a surprise to hear this call from the porch of our beach rental in Oak Island, NC. It turned out there was a bird rescue facility a short distance from the house, where they were caring for both a common loon and a red-throated loon (Gavia stellata) which had been injured during their migration.

The volunteers were hoping the loons would recover quickly, because caring for them meant risking bites and stabs from the loons’ long, very pointy, serrated bills. The bill allows them to catch fast-swimming fish underwater and swallow them without losing their grip. They also eat some other aquatic prey, such as crustaceans, snails, slugs, and insect larvae, but these are pursued only when water bodies are shallow, turbid, or short of fish.

The common loon is up to three feet long with a wingspan of up to 54 inches. They are a very heavy bird, weighing up to 16 lbs. This results in their being slow to get airborne, exposing them to injury from boats. In the summer, they have an attractive black-and-white houndstooth check pattern, while winter plumage is solid dark gray or brown on the back.

During breeding season, loon couples establish a large territory, often a whole pond or small lake or cove. Common loons are monogamish. A couple will stay together through multiple breeding seasons unless something intervenes. Sometimes one partner dies, and the other finds a new mate, but other times, another loon will drive one partner out of their territory. The remaining one will settle down with the newcomer. Young adults, both male and female, are the most likely invaders in this scenario.

Loons hatch one or two chicks per season. Both parents are involved in the care of the chicks, who can swim within two days. Although the reproductive rate is low, the hatching and survival rate of the chicks is pretty high. Pairs, led by the male, will return to a nesting site where they have successfully hatched chicks and raised babies. The male will choose a new site if eggs or chicks were lost to predators.

The common loon is a species of Least Concern. Adults have few predators and have a survival rate of over 90% per year until they are over 20 years old. Eggs and chicks are vulnerable to many terrestrial and aquatic predators, but they are guarded by the adults and their dangerous bills!