Loons, known as divers in the UK and Ireland, are aquatic birds from the Gavia genus, found across North America and northern Eurasia. Resembling large ducks or small geese in size, loons are distinguished by their black-and-white patterned summer plumage and their unique call, different from the related cormorants. Both sexes have similar appearance, and it's challenging to differentiate between individuals, especially in winter when their plumage is less distinct. Adapted to aquatic life, loons are excellent swimmers with webbed feet, but they are somewhat awkward on land and struggle to walk, so they are more commonly found in the water except for nesting and mating. They primarily feed on fish by using their sharp bills and can dive deeply, often swallowing pebbles to aid in digestion. Unfortunately, loons are at risk of lead poisoning from ingesting lead fishing tackle. Loons are also migratory, traveling from northern freshwater habitats to coastal marine areas in winter, and they can tolerate saltwater thanks to specialized glands. Reproduction involves nest building near water with both parents incubating the eggs. Males select the nest site and fiercely defend their territories to maximize reproductive success. Interestingly, loon pairs do not typically mate for life. During migration, loons are capable of impressive long-distance flights, and research has documented flights of over a thousand kilometers in one day. In taxonomy, the origins of their common names include references to their awkwardness on land, and the genus name Gavia has been used since the 18th century. The evolutionary history points to Europe during the Paleogene, with a lineage that eventually spread to North America. Loons hold cultural significance in various regions: they are provincial birds, state birds, appear on currency, and have inspired both sports team names and music. Loons have an extensive fossil record, with nearly ten named prehistoric species within the Gavia genus, dating back to the early Miocene. Their diversification has followed a tendency towards larger size over time. In contemporary culture, loons are featured in indigenous myths, honored as symbols on currency, and celebrated by name in sports teams and popular media.