Mastering the Identification of Greater and Lesser Yellowlegs
Master the identification of Yellowlegs (Greater vs lesser)
Identifying Greater Yellowlegs (Tringa melanoleuca) and Lesser Yellowlegs (Tringa flavipes) can be challenging, especially when these shorebirds are seen feeding in the same wetlands. With practice, though, you can confidently distinguish the two using size, shape, behavior, and vocalizations. This guide breaks down their key differences for birders of all levels.
Why It’s Important to Differentiate Yellowlegs
Accurate identification helps:
Enhance Your Birding Skills: Recognizing subtle differences sharpens your observation abilities.
Contribute Reliable Data: Proper IDs improve eBird entries and contribute to better research.
Enjoy the Challenge: Mastering these lookalikes adds depth to your birding experience.
Key Differences Between Greater and Lesser Yellowlegs
1. Size
Greater Yellowlegs: Larger, with a body length of 36-41 cm (14-16 in) and a wingspan of 70-80 cm (28-31 in). They appear more robust.
Lesser Yellowlegs: Smaller, measuring 27-30 cm (11-12 in) with a wingspan of 55-60 cm (22-24 in). They have a more delicate, slender build.
Tip: When both species are present, size comparison is the easiest way to differentiate them.
2. Bill Shape and Length
Greater Yellowlegs:
Bill is thicker, slightly upturned, and longer than the head (1.5x head length).
Often has a bluish-gray/yellowish base.
Lesser Yellowlegs:
Bill is thin, straight, and about the same length as the head.
Uniformly dark in color.
Field Note: Focus on the bill shape and proportions, especially if size is hard to judge.
3. Plumage and Pattern
Greater Yellowlegs:
Heavier streaking on the breast and flanks during breeding season.
Winter plumage is still more heavily marked than the Lesser.
Lesser Yellowlegs:
Finer, less extensive streaking on the breast.
Appears cleaner and lighter overall, especially in non-breeding plumage.
5. Behavior and Posture
Greater Yellowlegs:
Often moves more deliberately, with a purposeful stride.
Feeds by sweeping its bill side to side in deeper water.
Lesser Yellowlegs:
More active and quick, with daintier movements.
Prefers shallower water and pecks at prey on the surface.
6. Vocalizations
Greater Yellowlegs:
Louder and more insistent, giving a clear, ringing "tew-tew-tew" in three notes.
Lesser Yellowlegs:
Softer, more mellow "tew-tew," typically in two notes.
When Observed in Flight
Wing Patterns
Both species show dark wings with no striking patterns. However, in flight, size and structure differences become apparent:
Greater Yellowlegs: Longer wings and more robust appearance in flight.
Lesser Yellowlegs: Shorter, quicker wingbeats, giving them a lighter look.
Tail and Rump
Both species have white rumps with barred tails. The tail pattern is not a reliable distinguishing feature.
- Comparison Table
| Feature | Greater Yellowlegs | Lesser Yellowlegs |
|---|---|---|
| Size | Larger (36-41 cm; wingspan 70-80 cm) | Smaller (27-30 cm; wingspan 55-60 cm) |
| Bill | Thicker, slightly upturned, >1.5x head length | Thinner, straight, = head length |
| Plumage | Heavier streaking | Finer streaking |
| Behavior | Deliberate, sweeps bill | Quick, dainty movements |
| Call | Loud, three-note "tew-tew-tew" | Softer, two-note "tew-tew" |
Tips for the Field
Observe Multiple Features: Relying on a single trait, like size, can lead to misidentification.
Watch Behavior: Feeding styles and movement patterns often reveal the species.
Use Binoculars: A pair of 8x42 or 10x42 binoculars helps pick out fine details.
Take Notes: Record observations of size, bill shape, and vocalizations for later review.
Quick recap: Greater Yellowlegs are larger, with thicker, upturned bills and louder calls. Lesser Yellowlegs are smaller, more delicate, and have softer vocalizations. By focusing on size, bill shape, and behavior, you’ll soon master the identification of these elegant shorebirds.
Happy birding!
- Laurent Bédard