Red-throated Loons are flat gray with tiny, scaly, white speckles on its back and has a white and gray, slender head and neck. This regal, elegant and solitary loon floated like a miniature, cargo-laden freighter. It then dove close towards the jetty. Under, gone, up, low in the water, gone, under, up again, diving, and then slowly resurfacing…
This foot-propelled swimmer can dive deeply. The fully webbed toes are on strong, large feet that are set back at the rear of a streamlined body and function as paddles. Loons paddle both feet at once with ease. Like all loons, the Red-throated is graceful and agile on water but ever so awkward and vulnerable on land.
Their eyes are adapted for both aerial and underwater vision. As visual feeders, they often peer below the surface of the water [snorkel] just prior to diving.As fish eaters [piscivorous] that chase their prey underwater, they grab it with their bills. Red-throated Loons eat small fish, frogs and other aquatic invertebrates. They are well adapted to waters both fresh and salt.
Compared to an elongated Common Loon at 32 inches, the diminutive Red-throated Loon measures in at 24 - 25 inches. Its body seems to slope back toward the rear. The slim head is smaller with a tapered forehead and is carried on a short neck. This floating aristocrat with an angled up head is equipped with a long, sharp bill.
Red-throated Loons weigh an average of 3 pounds with males being slightly heavier and larger than females. The Red-throated Loon rides low in the water. The plumage is dense and provides great warmth.
The large oil gland [uropygial gland] aids in waterproofing. Proctor and Lynch's "Manual of Ornithology" reports loons having 16 - 20 tail rectrices. In water, loons appear to be without a tail even though they have very short, stiff tail feathers. The uropygial gland at the rump is located above those rectrices. Puzzled by why I've rarely seen Red-throated Loons in flight in winter, I consulted Roger Pasquier's "Watching Birds, An Introduction to Ornithology", and he mentions that loons have a flightless stage on their wintering grounds where they can escape danger just by diving.
Sibley's "Bird Life and Behavior" mentions their bones being denser than other birds' bones to help them dive. Chris Leahy's "Birdwatcher's Companion" states that loons' bones are less pneumatized or heavier. While in Alaska, I enjoyed those Red-throated Loons that had brick-red, arrowhead-like patches on their throats, and those arrowhead points faced up toward the lower mandible. My observation of them was limited to isolated, freshwater, shallow pools and ponds. They took flight to forage in the coastal area and returned with fish for their young. In their nests, I saw one or two chicks. The young were not carried on the adults’ backs as I've witnessed with Common Loons. I recall the adults being whiter on the belly and quicker on the wing than Common Loons. Unlike the larger, heavier Common Loons, they took flight effortlessly, not running along the water's surface.
Frank Gill's "Ornithology" states: "Specialized water birds such as loons, auks, gulls, ducks, cranes, and petrels invaded aquatic niches during the Eocene epoch, 37 to 54 million years ago." Wow, that brings the terms "ancient divers" and "primitive" into perspective...