Demography and Populations

Age At First Breeding; Intervals Between Breeding

In Alaska, 8% (3/37) of banded fledglings were resighted on breeding grounds as yearlings (2 confirmed breeding); 19% (4/21) of fledglings first resighted on breeding grounds as 2 yr olds (1 confirmed breeding; TLT unpubl.). Individuals not known to skip breeding seasons.

Clutch

See Breeding: eggs, above.

Annual And Lifetime Reproductive Success

In s. Alaska, hatching success (% pairs hatching ≥1 young) 78% in 1996 (n = 27 pairs), 91% in 1997 (n = 30). Fledging success (% broods fledging ≥1 young) 34% in 1995 (n = 32 broods), 28% in 1996 (n = 53), and 27% in 1997 (n = 60; TLT unpubl.). No data from other regions.

Number Of Broods Normally Reared Per Season

No evidence for >1 brood raised/season.

Proportion Of Total Females That Rear At Least One Brood To Independence

No estimates avail-able.

No data on mean longevity. Record of 5 yr 11 mo (Kennard 1975) later corrected to 4 yr 9 mo (Clapp et al. 1982).

Diseases

Carries antibodies to eastern encephalitis in blood (Herman 1962). Following an outbreak of avian botulism, censuses of a portion of Delta Marsh, Manitoba, yielded 10 of 54 Lesser Yellowlegs with symptoms of infection (Manuwal 1967). In Regina Waterfowl Park, Saskatchewan, 25 birds found dead from an outbreak of botu-lism (Sanderson 1962).

Body Parasites

Internal parasites include a cestode (Kowalewskiella totani) found in the small intestine of spring migrants in Kansas (Self and Janovy 1965) and a trematode (Cyclocoelum brasilianun) found in abdominal air sacs of 18 of 75 birds from Iowa, S. Dakota, and Wisconsin (Taft 1971). External parasites include a bird louse (Quadraceps falcigerus; Malcolmson 1960) and 2 nasal mites (Neoboydaia philomachi; Clark 1964 and Rhinonyssus coniventris; Strandtmann 1951).

Known causes of mortality include predators (see Behavior: predation), botulism (see Diseases and body parasites, above), pesticide poisoning, crushing by vehicles, and hunting (see Conservation and management: effects of human activity, below). A few cases of newly hatched young dying, apparently of hypothermia, during unseasonably wet, cold weather (TLT).

Initial Dispersal From Natal Site

Of unsexed fledglings in Alaska, 7 of 37 (19%) were resighted within 12 km of their natal sites in subsequent 1 or 2 yr (TLT unpubl.) (see Measures of breeding activity, above).

Fidelity To Breeding Site And Winter Home Range

Of 100 color-banded adults in Alaska, 67% were resighted in the subsequent 1 or 2 yr following banding; 62% bred within 5 km of their previous breeding sites and 5% between 5 and 15 km of previous sites. On a smaller scale, 11 of 12 males and 6 of 15 females nested in the same general area they had occupied the previous year (TLT unpubl.). No information on fidelity to winter home range.

Dispersal From Breeding Site Or Colony

No information.

Home Range

Courting and incubating adults traveled to shared feeding areas up to 13 km from their nesting sites in coastal Alaska (TLT). Adults with broods were found up to 3 km from their nesting sites (TLT).

Numbers

Population estimated to be about 500,000 birds (Canadian Shorebird Conservation Plan, Can. Wildl. Serv., unpubl.). In n. Ontario, breeding density estimated to be 1–10 pairs in about two-thirds of the 10-km squares where detected, and 11–100 pairs in most of the remaining squares (Cadman et al. 1987). Breeding densities (territories/10 ha) varied among different habitats in the Tanana River valley, AK: low and medium shrub thicket (1.6), tall shrub thicket (1.4), white sprucebirch woodland (0.3), black spruce bog (1.2; Spindler and Kessel 1980). On Breeding Bird Survey routes sampled 1985–1991, the average number of birds per route was 30.8 and 28.0 on 2 routes in the Northwest Territories and 23.3 on a route in Manitoba (Price et al. 1995). High single counts have been recorded at fall staging areas, e.g., 13,600 at Big Quill Lake, Saskatchewan (Gollop 1986) and 23,000 at Duda Farm, FL (Sykes and Hunter 1978). A total of 91,000 yellowlegs (majority probably Lesser Yellowlegs) were counted during aerial survey of the entire South American coast (Morrison and Ross 1989). Regional winter estimates include 3,700 ± 1,600 SE in coastal Texas (Jan; G. T. Muehl, J. T. Anderson, and T. C. Tacha unpubl.); and 50,000 each at Bigi Pan, Wia-Wia, and Coppename in Suriname (Wetlands for the Americas unpubl.).

Trends

Breeding Bird Survey data indicate significant decrease in numbers between 1980 and 1996 along 25 routes surveyed in Canada in the last 30 yr (Sauer et al. 1997). However, these routes sample a very small percentage of the breeding population and results should be interpreted with caution. International Shorebird Survey data (1972–1983) suggested no trend in number of fall migrants at 43 stopover sites along the Atlantic coast (Howe et al. 1989). Christmas Bird Count data suggest an increase (1959–1988) in the U.S. wintering population, particularly in Florida (Sauer et al. 1996). Trends for wintering populations outside of the U.S. unknown.

Predation and exposure appear to be major sources of chick mortality. Hunting and contaminants may be important sources of adult mortality during migration and winter. Needs study (see Conservation and management, below).