The Greater Yellowlegs and Lesser Yellowlegs are two closely related species of shorebirds in the genus Tringa. They can be difficult to distinguish in the field, as they are very similar in appearance. However, there are some key differences between the two species that can be used to tell them apart.
Identification
The most noticeable difference between Greater and Lesser Yellowlegs is size. As their names suggest, Greater Yellowlegs is the larger of the two species. Specifically:
- Greater Yellowlegs measures 12-15 inches in length with a wingspan of around 30 inches.
- Lesser Yellowlegs measures 8-10 inches in length with a wingspan of around 20 inches.
So if you see a large yellowlegs, it’s likely a Greater. If it’s small, it’s probably a Lesser. However, size alone isn’t always diagnostic, as larger Lesser Yellowlegs can potentially overlap in size with smaller Greater Yellowlegs.
Looking at more subtle differences in proportions can help confirm the identification:
- Greater Yellowlegs has a proportionally longer and thicker bill than Lesser Yellowlegs. The bill of a Greater may be up to 2.5 inches long.
- Greater Yellowlegs has proportionally longer legs than Lesser Yellowlegs. The legs of a Greater Yellowlegs appear noticeably long compared to the body.
- Lesser Yellowlegs has a smaller head and thinner neck compared to the chunkier Greater Yellowlegs.
Plumage
Both species have largely gray and white plumage in breeding and non-breeding seasons. However, there are some subtle plumage differences as well:
- Greater Yellowlegs has more extensive white barring and flecking on its gray back feathers compared to Lesser Yellowlegs.
- Lesser Yellowlegs often shows a faint white eye-ring, which is usually absent in Greater Yellowlegs.
- Lesser Yellowlegs may show faint streaking or necklace-like markings on the chest, which are absent in Greater Yellowlegs.
These plumage differences can be helpful when the two species are seen side by side. But again, they may be difficult to discern at a distance or individually.
Behavior
There are some behavioral and ecological differences between Greater and Lesser Yellowlegs that may provide additional clues to their identification:
- Greater Yellowlegs is less likely to be found in freshwater habitats than Lesser Yellowlegs. Greater Yellowlegs is more often seen in tidal areas.
- Lesser Yellowlegs is more gregarious and forms larger foraging flocks. Greater Yellowlegs is more solitary.
- Greater Yellowlegs has a more deliberate feeding action, taking slower, deliberate steps between probes. Lesser Yellowlegs tends to dart about more actively.
- The flight call of Greater Yellowlegs is a mellow whistle of 2-3 notes. Lesser Yellowlegs’ call is a faster, higher 3-4 note whistle.
Range and Habitat
The breeding and wintering ranges of Greater and Lesser Yellowlegs also differ and can provide helpful clues:
- Greater Yellowlegs breeds primarily in boreal forest and tundra habitats in Canada and Alaska. Its winter range extends along the coasts of North America, Central America, and northern South America.
- Lesser Yellowlegs breeds at more southerly latitudes in prairie and taiga habitats in central Canada and the northern USA. It winters along the Pacific and Atlantic coasts of the Americas.
- During migration, Lesser Yellowlegs uses more inland freshwater habitats like marshes, ponds, and flooded fields. Greater Yellowlegs is more likely to stopover along coasts.
So during spring migration, Lesser Yellowlegs is more likely to be found at inland habitats across the USA and Canada. Greater Yellowlegs becomes more prevalent along the coasts.
Spotting Tips
Here are some helpful pointers for distinguishing between Greater and Lesser Yellowlegs in the field:
- Size – If it’s really large with long legs and neck, it’s likely a Greater. Smaller size suggests Lesser.
- Bill – Thicker, longer bill indicates Greater.
- Plumage – Look for more extensive back barring and lack of eye ring or chest streaks for Greater.
- Behavior – Solitary and tidal habitats means probable Greater. Flocks and freshwater suggests Lesser.
- Voice – Slow, mellow whistle is Greater. Fast, high whistle is Lesser.
- Range – During migration, inland freshwater indicates Lesser, coastal areas suggest Greater.
With good views and ideal conditions, an experienced birder can confidently separate the two species. But many individuals may still prove too ambiguous. So it’s perfectly acceptable to leave a sighting as simply “Yellowlegs sp.” when the identification remains uncertain.
Table Comparing Features
| Feature | Greater Yellowlegs | Lesser Yellowlegs |
|---|---|---|
| Size | 12-15 in. length 30 in. wingspan |
8-10 in. length 20 in. wingspan |
| Bill | Long, thick | Shorter, thinner |
| Legs | Long | Shorter |
| Plumage | More extensive back barring No eye ring or chest streaks |
Less back barring May show faint eye ring or chest streaks |
| Behavior | Solitary Coastal tidal habitats |
Gregarious, flocks Freshwater habitats |
| Voice | Slow, mellow 2-3 note whistle | Faster, higher 3-4 note whistle |
| Range | Breeds in boreal forest and tundra Winters along North American coasts |
Breeds in prairies and taiga Winters along Pacific and Atlantic coasts |
Conclusion
Telling Greater and Lesser Yellowlegs apart can be tricky. Size and structural differences like bill length, neck thickness, and proportions provide the most reliable clues. But plumage, behavior, voice, and distribution can also help in identification. Familiarity with both species takes practice. So don’t feel discouraged if Yellowlegs identification remains difficult at first. With experience, the differences will become easier to recognize. Just enjoy observing the beauty of both species!
