Demography and Populations

Age At First Breeding; Intervals Between Breeding

Sexual maturity said to be 2–3 yr (Glutz von Blotzheim et al. 1975), but probably most if not all breed at 2 yr, as 1-yr-olds common in summer south of breeding range but birds older than 1 yr not found. Fat yearlings with enlarged gonads on northward migration in Washington (DRP) and specimens of that age from breeding grounds (specimen data) almost surely indicate breeding at that age. Breeds annually, from limited data on marked birds (O. W. Johnson pers. comm.).

Clutch

See Breeding: eggs.

Annual And Lifetime Reproductive Success

Proportion of eggs hatched 67.2% (2.7 young/nest, nest n = 17) over 4 yr on Devon I; at 11 fertile nests not taken by predators, mean young 3.7/clutch (Hussell and Page 1976). Successful nests (hatching all young) 58% (nest n = 12) over 5 yr in Kuparuk Oilfield, AK (C. Moitoret pers. comm.). Variation in percentage of juveniles in migrating and wintering flocks probably indicates annual variation in breeding success (Glutz von Blotzheim et al. 1975, B. Harrington and S. Groves pers. comm.). Survival rate of eggs 54.7% over 27-d incubation period; hatching success of eggs surviving incubation period 97.5% (Hussell and Page 1976).

Number Of Broods Normally Reared Per Season

One.

Longest life span reported in Americas 12.7 yr (Clapp et al. 1982), in Europe 20.3 yr (Holland 1992). Survivorship on Tees Estuary, U.K., averaged 86% in adults over 6 yr (range 68–100%) and 91% in 2-yr-olds and 63% in juveniles over 3 yr (respective ranges 73–100% and 61–67%) during same period (Evans and Pienkowski 1984).

Endoparasites reported from adults include acuarioid nematodes (Wong and Anderson 1990a, b).

Rather poorly known. One of 16 nests (6.3%) destroyed by snow-melt water (Flint and Kondratiev 1977).

Exposure

Thirteen marked birds that disappeared during 2 severe winters at Tees Estuary, U.K., shown to have lost weight when strong winds interfered with feeding; presumably died from starvation and/or exposure (Evans and Pienkowski 1984). At least 200 died in severe winter at The Wash, U.K., with mortality heaviest among juveniles; many more males than females perished (Clark and Davidson 1986), perhaps because more males present in winter. Six of 122 shorebirds found killed by golfball-sized hailstones in England were Black-bellied Plovers (Mawby 1984). Estimated 2% mortality of one wintering population from severe weather—exposure and/or starvation (Whitfield 1985).

Predation

Five of 16 nests (31.2%) taken by predators at Devon I. (Hussell and Page 1976). Two of 16 nests (12.5%) taken by arctic foxes in Chukotka (Flint and Kondratiev 1977). During population high, arctic foxes destroyed virtually all early nests on Taymyr Peninsula; probable renesting produced some broods (Pienkowski 1983b). Of 61 birds radio-tagged at Teesmouth, 16 (18%) found dead; 5 not taken by predators, 4 in first week may have suffered handling effects, and 7 presumed taken by predators (6 foxes, 1 raptor), although not known if actually killed by predator (Townshend 1984). Estimated 2% mortality of one wintering population by predators (Whitfield 1985).

Initial Dispersal From Natal Site

One record of philopatry: fledgling banded 25 Jul 1968 on Bathurst I., Northwest Territories, recovered there, presumably breeding, 24 Aug 1971 (BBL). Only 5 band recoveries and recaptures at same site in North America through 1993 (BBL).

Fidelity To Breeding Site And Winter Home Range

Males probably show greater fidelity to their breeding site. All males (n = 4) but only 33% of females (n = 6) returned to breeding grounds 1 yr after capture in Kuparuk Oilfield, AK; both of 2 males but neither of 2 females returned for a second year; and a single male returned for a fourth year. No male disappeared from the area during the study (C. Moitoret pers. comm.). In a small, disjunct breeding population near Nome, AK, however, high site fidelity shown by both sexes (O. W. Johnson pers. comm.).

In Kuparuk Oilfield, breeding males moved mean distance of 252 m (116–436, n = 6), females 276 m (116–436, n = 2) in successive years; males moved about the same distance whether in intact pair (276 m, 116–436, n = 2) or with new mate (267 m, 231–303, n = 2) (C. Moitoret pers. comm.). Recognizable individuals in Chukotka nested within 30–100 m of previous year’s nest (Flint and Kondratiev 1977).

Three banded individuals recovered at same wintering site in subsequent years in California, 1 in Florida (BBL). Numerous marked adults sighted at same locality in subsequent winters in England (Townshend et al. 1984).

Numbers

Breeding Season. Only estimate of a breeding population: 45,000 on Banks I. (Manning et al. 1956). Typically 1 to a few pairs/km²on breeding grounds, e.g., 1.9–2.3 pr/km²(1 yr) at Hooper Bay (Brandt 1943); 1.0–2.9 pr/km²at 2 plots (4-yr means 1.8 and 1.9) in Kuparuk Oilfield, AK (C. Moitoret pers. comm.); 0–2 pr/km²(4-yr mean 1.25) on sedge-moss meadow, 0–1 pr/km²(4-yr mean 0.125) on dry upland on Bathurst I. (Mayfield 1983); 0.3–1.0 pr km²(4-yr mean 0.6) on Devon I. (Hussell and Page 1976); 0.4–0.8 pr/km²on Victoria I., 1.2–2.3 pr/km²on Jenny Lind I. (Parmelee et al. 1967).

At 2 sites in n. Alaska, least year-to-year variation in population size among 6 most common breeding shorebirds (C. Moitoret pers. comm.).

Nonbreeding Season. Christmas Bird Counts (CBCs) in 1992 totaled 32,342 for Canada and U.S. (Atlantic Coast 4,974; Gulf Coast 6,249; Pacific Coast 21,119); apparently much more common on Pacific than Atlantic coast. Few figures available for Middle America and West Indies, although several hundred tallied on few coastal CBCs in these regions. Winter censuses in South America tallied 27,300 birds, with 62% on north coast of Brazil, 14.5% in Suriname, and remainder spread along all coastal countries (Morrison and Ross 1989).

Winter density estimates include 51.0/100 ha at Bolinas Lagoon and 18.4/100 ha at Limantour Estuary, CA (means of 5 and 10 seasons, respectively; Page et al. 1979). Winter densities averaged 2.2/km (maximum 9.6) over 17 yr on 11.8-km beach transect on Texas coast (A. F. Amos pers. comm.).

Winter numbers varied less than 2-fold over 8 yr (peak winter counts 65–104) at Totten Inlet, WA (Buchanan 1988), and 3-fold over 5 yr (mean yearly censuses 110–304) in central California (Page et al. 1979). Five-year means of CBCs varied 2- to 3-fold over 15 yr in British Columbia (105–251 at Ladner), Washington (249–691 at Grays Harbor, 214–377 at Sequim, 114–309 at Leadbetter Point), and Oregon (150–289 at Coos Bay) (Paulson 1993).

Density estimates during fall migration include 52.8/100 ha at Bolinas Lagoon and 13.3/100 ha at Limantour Estuary, CA. High counts at single localities include 4,000+ on 21 Sep 1976 at Monomoy, MA (Veit and Petersen 1993), and 5,000 on 11 Aug 1984 and 4,000 on 6 Sep 1971 at Boundary Bay, British Columbia (Paulson 1993). Spring density estimates include 49.9/100 ha at Bolinas Lagoon and 3.8/100 ha at Limantour Estuary, CA (means of 5 seasons at Bolinas and 10 at Limantour; Page et al. 1979). High counts at single localities include 6,200 on 27 May 1927 in New Jersey (Bent 1929); 6,000 on 30 May 1954 in Nassau County, NY (Bull 1974); 6,500+ on 19 May 1976 at Newburyport, MA (Veit and Petersen 1993); and 5,000 on 24 Apr 1985 at Delta, British Columbia (Paulson 1993).

Relative abundance compared with other shorebirds greatest on Atlantic Coast, e.g., second-most abundant shorebird of 22 species (10.0% of 161,563) in fall in St. Lawrence River system, Quebec (Maisonneuve et al. 1990); second-most abundant of 31 species (17.5% of 230,122) over 1 yr at Jamaica Bay, NY (Burger 1984); sixth-most abundant of 28 species (1.3% of 838,470) in Apr in the San Francisco Bay system, CA (Stenzel and Page 1988); and about tenth-most abundant of 20 species (0.27% of 939,087) in Jan in Sonora and Sinaloa, Mexico (Harrington 1993).

Trends

No apparent historic change in abundance in Pacific Northwest, although CBC totals increased slightly from 1974 to 1988 (Paulson 1993). A Texas coastal survey showed no change during 1978–1994 (A. F. Amos pers. comm.). Atlantic Canadian and American migrants showed nonsignificant declines during 1972–1991 (Howe et al. 1989, Morrison et al. 1994); Veit and Petersen (1993) noted no change in Massachusetts since the 1930s.

Most Black-bellied Plovers probably territorial throughout the year, on breeding and wintering grounds and during migration, but spacing behavior may be active or passive. Predation rate on both adults and nests apparently low, but little known about survival during first year of life. Winter mortality well documented in northerly wintering populations. Mortality on The Wash greater during spring/autumn than winter, only one of 8 shorebirds to show this pattern (Goss-Custard et al. 1977a), perhaps indicating that migrations contribute strongly to mortality.