When comparing the sizes of loons and ducks, there are a few key factors to consider:
Average Size
On average, loons are larger than ducks. The common loon, the most widespread loon species, has an average length of 31-38 inches and weighs 8-14 pounds. Mallards, one of the most common duck species, average around 24 inches long and 2-3 pounds in weight.
Other loon species like the yellow-billed loon and red-throated loon are slightly smaller than the common loon but still measure over 2 feet long on average. Ducks in the same size range as loons, like eiders and long-tailed ducks, represent some of the largest duck species but are rarer than common, mid-sized ducks.
Differences in Proportions
Loons tend to have longer, more slender bodies than ducks. A loon’s body shape is optimized for diving and swimming underwater in search of fish, with long narrow wings and feet placed far back on the body to act as paddles.
Ducks have shorter, bulkier bodies and are more suited for swimming on the water’s surface. Their feet are located closer to the middle of their bodies, which provides better stability when tipping forward to feed on aquatic plants or small invertebrates near the surface.
Exception: Largest Duck Species
While loons are on average bigger than ducks, the very largest duck species outweigh all loon species. For example:
- The trumpeter swan has an average length of 4-5 feet and can weigh over 25 pounds.
- The mute swan measures 4-5.5 feet long and weighs 18-25 pounds.
- Tundra swans have an average wingspan of 6 feet and weigh 14-20 pounds.
By comparison, the yellow-billed loon is the largest loon with a maximum length of around 3 feet and weight of 16 pounds. So although ducks tend to be smaller overall, the biggest swan species exceed the maximum size of any loon.
Wingspan Differences
Another way to compare size is to look at wingspan. The common loon has an average wingspan of around 5 feet. Mallards and other mid-sized ducks have wingspans in the range of 2-3 feet.
Again, the trumpeter swan outweighs all with a maximum wingspan over 7 feet across. The wingspans of the biggest loon species top out around 5-6 feet at most.
Visibility on Water
When viewing loons and ducks on the water, loons appear larger thanks to their longer necks and stouter bills. A swimming loon’s body will ride higher on the water surface compared to a duck. Loons have very dense bones to help them dive, which also makes their bodies less buoyant than a duck’s.
Conservation Status Differences
Both loons and ducks face threats to their populations from habitat loss and environmental changes. However, loons are more sensitive to disturbance and human activity near their nesting sites.
All five loon species found in North America are considered at risk, with the yellow-billed loon in particular facing endangerment. Duck populations are more stable overall, although certain species like the long-tailed duck have declined in numbers.
Conclusion
In most cases, loons are larger and longer-bodied than ducks on average. But a few very large duck species like swans exceed the maximum size of any loon. What remains consistent is that loons’ proportions are adapted for deep diving, while ducks tend to be smaller, stockier waterfowl suited for swimming on the surface. Careful management of wetland habitats is crucial for supporting both of these iconic bird groups.
