Parasitism: There is no brood parasitism reported for Greater Yellowlegs, however, parasites are associated with this species. Spring fluke infestations may determine if a bird migrates. Nematodes and helminthes have also been found in association with Greater Yellowlegs.
Mortality: The main causes of adult mortality on breeding grounds include nest predation, freezing or starving during unexpected freezing weather and nest predation. These birds, however, also fall prey to avian botulism and avian cholera.
Molting: Greater Yellowlegs are known to molt before and during migration, which may be the reason that the birds take breaks in their migration. Individuals that do not leave the wintering grounds to migrate north delay or fail to undergo a premigratory molt.
Vocalizations: The Greater Yellowlegs' call has been described as a loud, clear and ringing, with no evidence of regional dialects. The song typically consists of three descending notes, but has many variations within these notes. The birds use the many different variations of this call for different purposes. These include alarm calls, breeding calls, take-off and landing calls, migratory calls and "conversational murmuring." Both sexes make these calls and neither sing.
(Anderson and Bartlett 1996, Elphick and Tibbits 1998, National Geographic Society 1999, Secord and Canaris 1993)
Perception Channels: visual ; tactile ; acoustic ; chemical
Greater Yellowlegs were considered an important game bird in the early 20th century, due to its difficulty in being found. This hunting greatly reduced its numbers until the introduction of the Migratory Bird Treaty Act in 1918. Since 1927, this bird has been fully protected in the United States and Canada under this act. It is assumed that population numbers have increased since then, though this is not certain. DDE and PCBs have been studied in this species and have not been found to have an effect on the population numbers. Heavy metals have also been studied and selenium has been found to be the only one of concern. The main threat these birds have to their habitat is the loss of wetlands throughout their wintering range. The population numbers of the Greater Yellowlegs is thought to be stable and of little conservation concern, but there is little accurate data on this.
(Elphick and Tibbits 1998)
US Migratory Bird Act: protected
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: least concern
None known.
The Greater Yellowlegs is a tentative species, so it is difficult to observe. Many birding tourists will go to both its breeding and wintering grounds in order to view it.
The Greater Yellowlegs primarily eat small aquatic and terrestrial invertebrates, small fish, frogs and seeds or berries. Greater Yellowlegs will, at times, eat insects along the shore or snatch them out of the air.
(Elphick and Tibbits 1998)
The Greater Yellowlegs breeds throughout a band in central Canada, from Newfoundland and eastern Nova Scotia to eastern British Columbia. The breeding range also extends into Alaska, along the southern Pacific coast. Though it has not been confirmed, it is believed to extend past these areas, farther into the Northwest Territories and south into Oregon.
This species winters along the ocean coasts of North America, from New York south along to the Gulf of Mexico and from California south to Central America.
Vagrant individuals of this species have been observed in Europe, with sightings recorded in Belgium, Denmark, France, Norway and Spain. Rare observations of the species have been reported from Russia, Japan, Micronesia and once in South Africa.
(Elphick and Tibbits 1998)
Biogeographic Regions: nearctic (Native )
In its breeding range, the Greater Yellowlegs can be found throughout the boreal zone in wet bogs with small islands and in coniferous forests with many clearings. They are found in wet areas, covered with mosses and lichens. The breeding areas usually have many small lakes and ponds and trees to be used as perches. Subarctic tundra and subalpine scrub, however, may also serve as breeding sites.
In its wintering range, this species may be found in a variety of wetland habitats, both freshwater and saline. When the feeding habitats are tidal, a Greater Yellowlegs will roost on offshore rocks and reefs. Greater Yellowlegs that have settled along the coast are often found on shallow lagoons and tidal flats. Inland in the southern United States and into South America, these birds will use flooded rice fields.
Elphick, Chris S. and T. Lee Tibbits. 1998. Greater Yellowlegs. The Birds of North America 355:1-23.
Terrestrial Biomes: taiga
The Greater Yellowlegs is a medium-sized (approximately 36 cm long) shorebird with distinctive long, bright yellow legs. Its white tail is crossed with thin, black bars, adding to its cryptic coloration. It has a long, thin, slightly upturned, dark bill with a paler base. The bill length is about 1.5 times the length of the head. Males and females look alike and the juveniles have plumage like that of the adults.
Adults in basic (winter) plumage have pale heads and necks with a few brown streaks on them. The breast and flanks are spotted and streaked grayish-brown. Greater Yellowlegs have a dark brown back with lighter featheredges.
Adults in alternate (breeding) plumage have their heads, necks and chests streaked with black. The bill is also black. Their pale flanks are barred with black. The white belly has sparse dark bars. The back and upperwings are dark brown, spotted with black and white. They also have off-white supercilium (line above the eye) and eye-ring, and smoky-colored lores.
This species is often confused with the Lesser Yellowlegs, Tringa flavipes. The most obvious difference between the two is that of size, with the Greater Yellowlegs weighing 171 grams versus the Lesser Yellowlegs at 81 grams.
(Elphick and Tibbits 1998, National Geographic Society 1999)
Average mass: 171 g.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
There is little data on the reproductive behavior of Greater Yellowlegs, but the mating system is presumed to be monogamous with an even sex ratio. The courting male runs in circles around a female and poses while quivering its up-held wings. In an established pair, the male does this for only a few seconds, while the "dance" must be done longer when attempting to create a pair. Eventually the male mounts the female's back and copulation occurs.
There is also no information on the duration or maintenance of the pair bond. There is evidence of joint care of the young, which indicates that the pair persists at least into the chick-rearing period. This bird has one brood per season and has 3-4 eggs in its clutch. There is no evidence of a second brood in the season, though individuals may renest after losing a clutch. The incubation period is 23 days while it takes 18-20 days to fledge.
There is no information on nest building, however, nest location has been studied. The nests are generally found on the ground at the base of short, coniferous trees and are placed in a moss-covered hummock. The nest structure is a scrape or depression in the moss, sometimes lined with leaves. Shrubs and small trees generally shade these nests.
The eggs are ovate pyriform in shape and have variable color. The background colors range from smoky-gray to an olive color. The spots are always some shade of brown, from light to dark. The spots are irregularly shaped and vary in size. They have a slightly glossy surface texture.
(Elphick and Tibbits 1998)
Key Reproductive Features: iteroparous ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous
