Certain species of swans, loons, grebes and ducks are a few examples of the various types of highly acquatic birds that tend to carry their young on their backs. Since these birds spend much of their time in water, the adults carry young on their backs as a way to transport and help care for them until they are able to swim for long periods of time on their own.
Black-necked swan, black swan, and mute swans are examples of three species of swans that carry their young on their back while swimming in water. Using the underside of the parent's wing and body as a type of ramp, the young climb onto the parent's back. According to a paper written by Paul A. Johnsgard and Janet Kear, sometimes the wings of the adult are slightly raised for the young to wedge themselves comfortably between the wing and body, otherwise the young stay aboard without help from the adult. Male black swans will often help incubate new hatchlings on their backs under the safety of both its wings.
Common loons breed near forested lakes and ponds and are usually found in the northern regions of North America as well as Greenland and Iceland. They nest on land near lakes and incubate their eggs for about a month. Loons spend much of their time in the water and eat mainly fish. Sometimes they dive up to 200 feet below the water's surface to hunt for food. Hatchlings walk on their own on their first day, however it takes about 11 weeks for a baby common loon to fly. In the meantime it rides on its mother's back while the mother swims.
Great crested grebes are great divers and do so to hunt for food and to escape predators. They nest near waterways like lakes, reservoirs and rivers and build nests out of floating water-weed. When the chicks are ready they climb onto their parent's back and stay there for at least a week. They remain on their parent's back even when the parent dives underwater for food or takes flight.
Musk ducks spend most of their time in water, even while they sleep, and seldom walk on dry land or fly. Usually one or two chicks survive the brood and hatch covered in down and ready to swim. However, they ride on their mother's back until they are able to swim for long stretches of time on their own. The young stay near the mother for at least several months even though they are able to dive after being a few days old. Seven other species of ducks are known to also carry young on their back such as Salvadori's duck and the Common ruddy shelduck.