Other Information
SE
Arizona Rare
Bird Alert
(520) 798-1005
Report
Rare Birds
(520) 798-1005
Email
a report
Nature Shop
(520) 629-0510
Agua Caliente Shop
(520) 760-7881
Mason Audubon
Center
(520) 744-0004
Membership
(520) 629-0757
AZ IBA Program
(520) 628-1730
Education Program
(520) 622-2230
Habitat Restoration
(520) 206-9900
Development
(520) 622-5622
Executive Director
(520) 622-5622
|
Birding home | Access updates | RBA | Dastardly Duos | AZ/NM listserv | Tucson area |
Tucson Audubon Society
Dastardly Duos
Greater and Lesser Yellowlegs
Text by Larry Liese
Illustration by George C. West
(Article first appeared in the September 2001
Vermilion Flycatcher newsletter. To receive the newsletter in the
mail, become a member of the Friends of Tucson
Audubon.)
 |
Shorebird migration is upon us once again, and this fall I’m looking forward to finally mastering what has been a truly dastardly duo for me: the Greater and Lesser Yellowlegs. I can vividly remember anguishing over this one bird at the Bolsa Chica State Ecological Reserve in southern California; first, I’d decide Lesser ... No! ... Greater, then back again. I stood there for twenty minutes before giving up. I then walked a hundred yards further and saw one of each standing next to each other. It was sooo obvious! If this has happened to you, you’re not alone.
One good thing, it is fairly easy to realize that a given bird is a Yellowlegs. Both have long, slender, bright yellow legs. They have slender bodies and move gracefully, actively pursuing insects and small fish. They can sometimes be seen walking forward swinging their bill back and forth below the water surface. In flight, their bold white rumps and lack of wing bars help to rule out other similar sized birds.
Though similarities between the two seem to dominate, there are differences. Overall size, bill size and shape, and voice are the dominant ones. For those who want an additional challenge, some seasonal plummage differences are nicely detailed in Kevin Zimmer’s The Western Bird Watcher, a well-known birder’s reference.
Seen together, differences in size and bulk are obvious: the Greater Yellowlegs is 30% larger and has twice the mass. A few Lesser Yellowlegs were present at the Snyder Hill Sewage Ponds recently. Their slender body shape was quite noticable. My latest method of using this difference is to think of how big of a meal the bird would appear to be to a predator. If a Peregrine or Harrier caught the bird for lunch, would it still be hungry afterwards? More scientific would be to compare size to the other shorebirds around, but that can’t always be done.
Bill size and shape differences take practice to get comfortable with. The often mentioned ratio of bill length to head length is good, but don’t expect to become adept in one day. The Lesser’s bill is thin, straight, all dark, and only slightly longer than the front to back head length in line with the bill. The Greater Yellowlegs’ bill is thick at the base and sometimes two-toned (paler at base). It is about 1-1/2 times the head in length and often perceptibly upturned.
Now to get our tu tu’s straight. I must admit this is new ground for me, but birders familiar with the calls of these two have no problem separating them. The most frequently heard call of the Lesser Yellowlegs is a usually two (tu?) noted call that is lower pitched, more rapid, and much less resonant than the Greater Yellowlegs’ three or four note teu or deew. Whew! It sure would be easier if birds spoke English!
So get out there to your favorite mudflat and try these tips. The furthest pond at the Avra Valley Wastewater Treatment facility on Snyder Hill Road west of town is one of the best. Good luck!
Bird questions? Check Birding | General questions? Contact: Tucson Audubon Society | Webmaster: Email
This page was updated on 02/21/06