The Greater Scaup and Lesser Scaup are two closely related species of diving ducks that can be found across North America. They are very similar in appearance, which can make differentiating between the two challenging. However, one noticeable difference between these ducks is their size.
The Greater Scaup is larger and bulkier than the Lesser Scaup. Understanding the size differences between these two species can aid birdwatchers and hunters in properly identifying them. In this article, we will compare the sizes of Greater and Lesser Scaup ducks by looking at various physical features and measurements.
Weight
One of the most telling ways to distinguish a Greater Scaup from a Lesser Scaup is by looking at their weight. On average, male Greater Scaup weigh around 2.2-3.2 lbs (1000-1450 g), while females weigh slightly less at 1.8-2.5 lbs (800-1150 g). Lesser Scaup are noticeably lighter, with males weighing about 1.5-2.2 lbs (675-1000 g) and females weighing 1.1-1.8 lbs (500-800 g).
Species | Sex | Average Weight Range |
---|---|---|
Greater Scaup | Male | 2.2-3.2 lbs (1000-1450 g) |
Greater Scaup | Female | 1.8-2.5 lbs (800-1150 g) |
Lesser Scaup | Male | 1.5-2.2 lbs (675-1000 g) |
Lesser Scaup | Female | 1.1-1.8 lbs (500-800 g) |
As the weight ranges show, there is some overlap between large female Greater Scaup and small male Lesser Scaup. However, in most cases the Greater Scaup will be noticeably heavier than the Lesser Scaup.
Length
The length of Greater and Lesser Scaup provides another useful metric for comparison. Greater Scaup measure about 18-21 inches (46-54 cm) long. Lesser Scaup are smaller, ranging from 15-19 inches (38-48 cm) in length.
Looking at the average wingspans also shows the size difference. Greater Scaup have an average wingspan of 30-34 inches (76-86 cm). Lesser Scaup wingspans are smaller on average, measuring 26-29 inches (66-74 cm).
So in general, Greater Scaup are about 3-5 inches longer than Lesser Scaup in terms of both body length and wingspan. This makes the Greater Scaup appear distinctly larger in flight and swimming.
Bill Size
The bills of Greater and Lesser Scaup also provide some subtle clues about their size differences. Greater Scaup have longer, bulkier bills that are around 1.5-2 inches (3.8-5 cm) in length. Their bills also show a more pronounced hooked tip.
Lesser Scaup have smaller bills of about 1.25-1.5 inches (3.2-3.8 cm) long. Their bill lacks the long hooked tip of the Greater Scaup.
When seen up close, the larger bill size of the Greater Scaup is a good indicator of the overall larger body size compared to the Lesser Scaup. However, bill size can be harder to judge at a distance.
Plumage and Markings
The plumage pattern of Greater and Lesser Scaup is extremely similar. Both species have a dark head and back with a light belly. The male Greater Scaup has more extensive iridescent green on the head during breeding plumage compared to the Lesser Scaup. However, thisdifference is subtle and not necessarily a reliable way to distinguish size.
One marking that may indicate size is the white speculum pattern on the back of the wing during flight. This white patch tends to be longer and more pronounced on the Greater Scaup. The longer wing feathers and speculum of the Greater Scaup can add to its overall look of greater size compared to the Lesser Scaup. However, the speculum pattern is more useful for telling the two species apart, not necessarily determining size differences.
Species Ranges
Interestingly, the breeding ranges of Greater and Lesser Scaup also provide clues about the differences in their sizes and habitat preferences.
Greater Scaup tend to breed farther north than Lesser Scaup, primarily in Alaska, northern Canada, and into the tundra regions. The larger size of Greater Scaup allows them to better conserve heat and survive in extremely cold climates. Their larger body mass may also provide an advantage for migrating longer distances.
Lesser Scaup breeding habitat extends a bit farther south in the northern United States and into the southern Canadian provinces. The smaller size of Lesser Scaup may restrict them from breeding as far north into the tundra regions where their smaller bodies would be less equipped to handle the extreme cold.
So the more northerly range of the bulkier Greater Scaup coincides with their larger overall body mass, which is adapted for the coldest environments.
Habitat Preference
Differences in preferred habitat during migration and wintering periods also relate to the size differences between Greater and Lesser Scaup.
Greater Scaup tend to prefer larger, deeper lakes and reservoirs as well as coastal marine habitats like estuaries and bays. Their larger size allows them to dive deeper to find food. Greater Scaup have been recorded diving to depths over 60 feet (18 meters)!
Lesser Scaup occur more often on smaller wetlands, ponds, and lakes that don’t require as much diving depth. Lesser Scaup are still capable divers, just not quite as specialized for deep diving as Greater Scaup.
So the larger body size of Greater Scaup allows them to exploit deeper water habitats with abundant food sources that the smaller Lesser Scaup may not be as well equipped to access.
Diet
The diets of Greater and Lesser Scaup also support the differences in their sizes and diving abilities.
Greater Scaup consume large mollusks like clams, mussels, and snails which they obtain from deep dives. Their powerful bill allows them to crush the shells of these mollusks. Greater Scaup will also eat insects, crustaceans, and some small fish.
Lesser Scaup have a diet consisting more of insects, crustaceans, mollusks, and plant material. With their smaller bills, Lesser Scaup are less specialized for consuming larger mussels and snails. Lesser Scaup will eat small clams when available, but do not consume the large mollusks as frequently as the bigger Greater Scaup.
The ability of the larger Greater Scaup to access more of the large mollusks provides them an advantage in aquatic habitats where this high-protein food source is abundant.
Mating and Hybridization
An interesting behavioral difference that further separates Greater and Lesser Scaup is that they do not typically interbreed. This reproductive isolation likely allows each species to retain its unique adaptations and size differences.
However, hybridization between Greater and Lesser Scaup can occasionally occur. When it does, the resulting offspring tend to be intermediate in size between the two parent species. This provides further evidence that Greater Scaup are larger than Lesser Scaup, since the hybrids are not as large as pure Greater Scaup or as small as pure Lesser Scaup.
The rarity of hybridization shows that Greater and Lesser Scaup have likely evolved distinct sizes linked to their diving abilities, habitat preferences, and other adaptations optimal for capturing their preferred foods.
Identification Tips
When observing scaup ducks, here are some helpful tips to distinguish Greater Scaup from Lesser Scaup based on size:
– Look for weight and bulk – Greater Scaup appear distinctly heavier than Lesser Scaup
– Note length – Greater Scaup are 18-21 inches long, Lesser Scaup 15-19 inches
– Check wingspan – Greater Scaup wingspans are 30-34 inches, Lesser Scaup 26-29 inches
– Watch the speculum – The white wing patch is longer on Greater Scaup
– Consider bill size – Greater Scaup have longer, thicker bills (1.5-2 inches) compared to Lesser Scaup (1.25-1.5 inches)
– Know habitat preferences – Greater Scaup favor deeper lakes and coastal areas, Lesser Scaup smaller wetlands and ponds
– Remember ranges – Greater Scaup breed farther north in cold climates compared to Lesser Scaup
Using a combination of these size factors will help distinguish between a larger, bulkier Greater Scaup and a smaller, more compact Lesser Scaup. With practice, size can provide a reliable field mark. Being able to identify these similar duck species is an important ID skill for birders to develop.
Conclusion
In summary, Greater Scaup are distinctly larger than Lesser Scaup across many measures of size including weight, length, wingspan, and bill size. Their larger size allows Greater Scaup to exploit deeper lakes and marine habitats, make longer migrations, and consume larger mollusk prey. Lesser Scaup are smaller, occupy more southerly breeding ranges, prefer shallower wetlands, and do not consume large mollusks as frequently. Paying attention to various size factors can help distinguish these two look-alike species in the field. Understanding the differences between Greater and Lesser Scaup provides fascinating insight into how their specialized sizes link to their ecology and behavior.