What is the difference between stilt sandpipers and Yellowlegs?

Stilt sandpipers and yellowlegs are two types of shorebirds that can be found along muddy shorelines, marshes, and wetlands across North America. Though they occupy similar habitats and bear a resemblance to one another, there are some key differences between these two species.

In this article, we will explore the characteristics, behaviors, appearance, habitat, diet, and identification tips to distinguish stilt sandpipers and yellowlegs. Understanding the nuances between these birds takes some practice, but a few tricks can help any birder or nature enthusiast tell them apart.

What are Stilt Sandpipers?

The stilt sandpiper (Calidris himantopus) is a small to medium-sized shorebird species in the Scolopacidae family. They breed in the subarctic regions of North America before migrating in large flocks to wintering grounds across South America.

Some key facts about stilt sandpipers:

– Length: 7-9 inches
– Wingspan: 16 inches
– Weight: 1.5-2.5 oz
– Plumage: Distinctive grey plumage in breeding season with white underside, brown speckled back. Nonbreeding plumage is grey-brown above and white below.
– Bill: Long, slightly upturned, and black in color
– Legs: Yellow to olive-green in color with long legs in proportion to body (giving the “stilt” appearance)
– Behavior: Gregarious, often found in large flocks. Wades belly-deep and probes mud to find invertebrate prey.
– Habitat: Marshes, mudflats, shorelines, flooded fields
– Range: Breeds in northern Canada and Alaska. Winters in southern South America. Migrates through central North America.

Identification Tips

– Long legs – True to their name, stilt sandpipers have noticeably long legs compared to other shorebirds
– Bill shape – Long, thin, and slightly upturned bill used for probing
– Feeding method – Wades into belly-deep water and probes down into mud with bill
– Flock size – Often in large, dense flocks of 20+ birds
– Nonbreeding plumage – Plain grey-brown above, white below

What are Yellowlegs?

Yellowlegs refers to two closely related species of shorebirds – the greater yellowlegs (Tringa melanoleuca) and lesser yellowlegs (T. flavipes). They are classified in the Scolopacidae family along with sandpipers, snipes, and other shorebirds.

Here are some key facts about yellowlegs:

– Length:
– Greater yellowlegs: 11-15 inches
– Lesser yellowlegs: 9-11 inches
– Wingspan:
– Greater yellowlegs: 25-30 inches
– Lesser yellowlegs: 18-22 inches
– Weight:
– Greater yellowlegs: 4-7 oz
– Lesser yellowlegs: 2-3.5 oz
– Plumage: Grey above, white below with distinctive yellow legs
– Bill: Long, straight, and black in color
– Legs: Yellow in color, gives the birds their name
– Behavior: Wades more cautiously. Jabs and picks at prey.
– Habitat: Marshes, mudflats, ponds, flooded fields
– Range:
– Greater yellowlegs: breeds in Canada and Alaska, winters from Gulf coast south to Argentina
– Lesser yellowlegs: breeds across Canada and Alaska, winters from southern U.S. to South America

Identification Tips

– Leg color – True to their name, yellowlegs have yellow legs
– Bill shape – Long, straight bill (not slightly upturned like stilt sandpiper)
– Foraging style – Wades more cautiously, picks at prey while stilt sandpiper probes
– Flock size – Usually alone or in smaller groups
– Nonbreeding plumage – Grey-brown above, white below

Differences in Appearance

While stilt sandpipers and yellowlegs have grey and white plumage patterns, there are some subtle differences in appearance that can help distinguish them:

Some additional notes:

– Stilt sandpipers have a distinctly small-headed, slender look aided by their long legs and neck
– Yellowlegs have a chunkier body and head shape by comparison
– Greater yellowlegs are noticeably larger than lesser yellowlegs
– Breeding plumage offers better color contrast – stilt sandpipers show more grey, yellowlegs show more white

Behavioral Differences

Observing how stilt sandpipers and yellowlegs move and feed can offer more clues to tell them apart:

Foraging Style

– Stilt sandpipers wade belly-deep and vigorously probe downwards into mud to find prey
– Yellowlegs wade more cautiously and pick at prey items on the surface or in shallow water

Movement

– Stilt sandpipers teeter back and forth while wading and probing
– Yellowlegs move steadily and don’t teeter as much

Flocking

– Stilt sandpipers usually travel and feed in much larger flocks, often 20+ birds
– Yellowlegs are more solitary or in smaller groups, often 5 birds or less

Waryness

– Stilt sandpipers will allow a closer approach by observers before taking flight
– Yellowlegs tend to be more wary and flush more readily when approached

So in summary, stilt sandpipers probe busily in dense flocks while yellowlegs pick delicately and are more solitary. Focusing on foraging behavior and flocking tendencies can be helpful identification clues.

Habitat Preference and Range

Stilt sandpipers and yellowlegs frequent many of the same habitats during migration and wintering periods, particularly coastal marshes, mudflats, shorelines, and flooded fields. However, their breeding ranges differ:

Stilt Sandpiper

– Breeding: Subarctic regions of Alaska and Canada
– Migration: Central plains of North America
– Wintering: Coastal South America from Peru to Tierra del Fuego

Yellowlegs

– Breeding: Canada and Alaska
– Migration: Throughout North America
– Wintering:
– Greater yellowlegs: Southern U.S. through South America
– Lesser yellowlegs: Southern U.S. to northern South America

So during the breeding season, stilt sandpipers are confined to the farthest northern latitudes while yellowlegs have a more expansive breeding distribution across Canada and Alaska. Wintering ranges can offer a clue too – stilt sandpipers are only found in South America while yellowlegs overwinter from the southern U.S. onward.

Diet and Feeding Behavior

Diet and feeding techniques also show distinct differences between stilt sandpipers and yellowlegs:

Stilt Sandpiper

– Diet consists mainly of small aquatic invertebrates like insect larvae, mollusks, crustaceans
– Probes rapidly and deeply in belly-deep water to find prey hidden in mud
– Uses sensitive bill tip to detect prey buried in substrate
– May feed at night in addition to daytime

Yellowlegs

– Feeds on insects, small fish, and crustaceans
– Wades cautiously in shallow water to visually hunt for prey at or near surface
– Walks steadily, jabbing bill into water to capture observed prey
– Does not probe into sediment like stilt sandpiper

So stilt sandpipers employ a tactile hunting strategy using their bills to probe deeply, while yellowlegs rely more on visual hunting in shallow water. These techniques align with each species’ specialized bill structure and foraging preferences.

Conservation Status

Both stilt sandpipers and yellowlegs are currently abundant shorebird species with stable populations, though habitat loss on migration routes and wintering areas remains an ongoing concern:

Stilt Sandpiper

– Population: 150,000
– Conservation status:
– IUCN: Least concern
– Audubon: Climate threatened – may lose nonbreeding habitat by 2080

Yellowlegs

– Population:
– Greater yellowlegs: 350,000
– Lesser yellowlegs: 500,000
– Conservation status:
– IUCN: Least concern
– Audubon: Climate threatened – may lose nonbreeding habitat by 2080

Wetland conservation throughout North America will benefit these and many other migratory shorebird species that all depend on these sensitive habitats. Monitoring is important to detect future population declines that could warrant increased protections.

Conclusion

Telling stilt sandpipers apart from yellowlegs does take practice, but by paying attention to plumage patterns, size, bill shape, leg color, foraging behaviors, and flocking tendencies, identification becomes much easier. Stilt sandpipers probe mudflat sediments in large flocks while slender yellowlegs pick at surface prey more cautiously and in smaller groups. Regional range and habitat can provide additional clues between these often look-alike shorebirds. While currently still abundant, both would benefit from ongoing wetland habitat conservation across North America.