Breeding

Pair Formation

Occurs, including copulation, within 1–2 wk of arrival at most breeding sites (Parmelee et al. 1967, Flint and Kondratiev 1977). Sexes return to breeding grounds independently (Flint and Kondratiev 1977).

Nest-Building

Starts within 1 wk of arrival (Flint and Kondratiev 1977).

First/Only Brood Per Season

Laying begins third week of May in Alaska, mostly completed by end of month (Kessel 1989). Most laying last week of May at Yukon-Kuskokwim, AK (Brandt 1943, Holmes and Black 1973). Mean nest-initiation date 14 Jun (range 6–21 Jun) over 4 yr in Kuparuk Oilfield, AK (C. Moitoret pers. comm.). First eggs about mid-Jun in 3 yr on Victoria and Jenny Lind islands (Parmelee et al. 1967). Laying during last third of Jun on Devon I. (Hussell and Page 1976). Incubation began at one nest on Banks I. on 18 Jun (Manning et al. 1956). Replacement nesting on Seward Peninsula, AK, if first clutch destroyed (O. W. Johnson pers. comm.). Clutch from renesting completed 8 Jul at Jenny Lind I.; eggs abandoned after 17 d, although fertile (Parmelee et al. 1967).

First hatching 23 Jun at Hooper Bay (Conover 1926), peaks during last third of Jun in Alaska (Kessel 1989). First young 18 Jul at Colville Delta, AK (Kessel and Cade 1958). One nest hatched 12 Jul on Banks I. (Manning et al. 1956). Hatching on Victoria I. 13 Jul–2 Aug, most on Jenny Lind I. mid-Jul, latest 26 Jul (Parmelee et al. 1967). Hatching mid- to late Jul on Devon I. (Hussell and Page 1976), last week of Jul on Bylot I. (Drury 1961).

First flying juveniles mid-Aug on Victoria I.; adults still show signs of parental behavior (alarm; Parmelee et al. 1967). Most young fledge no sooner than third week of Aug on Devon I.; nesting cycle shifts later in years of heavier snow cover (Hussell and Page 1976).

Selection Process

Male appears to choose nest site; no evidence for multiple scrapes.

Microhabitat

Typically open, in exposed spots (Parmelee et al. 1967, DRP).

Site Characteristics

Nest built on ground, with incubating adult usually entirely visible; probably long-distance view one of most important characteristics. Simple experiments on incubating male showed it would incubate eggs (1) if clutch was moved 0.3 m but not 1 m, (2) when nest-site was altered by addition of many objects, and (3) if scrape were hidden by plant matter, with eggs added on top (Höhn 1957).

Construction Process

Male makes a shallow scrape with both bill and feet, throwing rootlets and stones to one side or the other over its shoulder and often sitting in the scrape, probably as a stimulus to female. Female deepens and lines the scrape (Flint and Kondratiev 1977).

Structure And Composition

Nest essentially unlined on bed of lichens or moss (Brandt 1943) or lined rather scantily with lichens (including Cladonia, Cetraria, and Thamnolia), pebbles, bits of willow twigs, and various leaves (Walkinshaw 1948, Parmelee et al. 1967, Mayfield 1973, Flint and Kondratiev 1977).

Dimensions

Shallow cup, round to oval, with inside depth 2.5–6.5 cm and inside diameter 10–17 cm (Brandt 1943, Flint and Kondratiev 1977).

Microclimate

Completely exposed, no particular orientation.

Shape

Short pyriform to pyriform.

Size

Exceptionally large for size of female (egg ca. 16% weight of female). Mean length 52.8 mm (49.9–56.8) x mean breadth 36.6 mm (35.7–36.6), shell mass 1.93 g (1.66–2.24) (n = 80l; Western Foundation of Vertebrate Zoology [WFVZ], L. Kiff pers. comm.). Geographic variation in egg size presumably correlated with size cline in adults. Variable even at single locality: 51.4 (47.0–56.5) x 35.3 (34.0–36.7) on Victoria I. (n = 33; Parmelee et al. 1967).

Mass

Averaged 34.9 g on Chukotka Peninsula (n = 23; Flint and Kondratiev 1977), 35.2 g in 1 Alaska clutch (Walkinshaw 1948). Fresh eggs averaged 31.0 g on Devon I., lost 0.15 g/d during incubation, for total loss of about 18% (Hussell and Page 1976).

Color

Ground color variable: pinkish, greenish, or brownish (Brandt 1943). Ground color of fresh shells often with slightly greenish cast (fading after preparation), not seen in nearby American Golden-Plover eggs (Parmelee et al. 1967). Marked with medium-sized, usually distinct (some confluent), somewhat circular, brownish to black spots, heaviest around widest part of shell; sparse gray to violet-gray spots underlie primary spots (Brandt 1943). Well camouflaged, typically on substrate associated with speckled black and white lichens at Hooper Bay, AK (Brandt 1943).

Surface Texture

Smooth, matte, at 30x magnification with flat, irregular granules separated by narrow interspaces.

Eggshell Thickness

Eggs collected 1924–1947 with thickness 0.98 ± 0.004 mm (n = 22), 1948–1965 with thickness 1.00 ± 0.007 mm (n = 25) (Morrison and Kiff 1979).

Clutch Size

Virtually always 4, mean 3.97 (n = 113) from WFVZ and Slater Museum of Natural History egg slips. Clutch size in literature 1 (n = 1), 3 (n = 6), 4 (n = 128+), and 5 (n = 2) (H. W. Brandt in Bent 1929, Parmelee et al. 1967, Hussell and Page 1976, Flint and Kondratiev 1977). Extraordinarily, at least one 5-egg clutch laid by single female (Flint and Kondratiev 1977).

Egg-Laying

Begun after nest completion; every 1–2 d (Parmelee et al. 1967) or at about 36-h intervals (Hussell and Page 1976); fourth egg may be laid as much as 55 h after third (Flint and Kondratiev 1977). Some evidence that eggs are laid successively around noon, midnight, noon, and midnight (Hussell and Page 1976). Only males seen at nest during laying, including standing near nest on 7 occasions and incubating incomplete clutch on 5 occasions (Hussell and Page 1976).

One report of replacement clutch, when first clutch lost early in incubation (Cramp and Simmons 1983).

Onset Of Broodiness And Incubation In Relation To Laying

Incubation often begins before last egg laid, as hatching often asynchronous (Drury 1961, Parmelee et al. 1967, Hussell and Page 1976). Incubation of incomplete clutch by male only, probably because female needs to feed to produce eggs (Hussell and Page 1976).

Incubation Patches

Both sexes (Conover 1926) have 2 large incubation patches on either side of lower breast and belly.

Incubation Period

A puzzling dichotomy reported: 23–24 d (Brandt 1943, Höhn 1957, Flint and Kondratiev 1977) and 26–27 d (Drury 1961, Parmelee et al. 1967, Holmes and Black 1973, Mayfield 1973, Hussell and Page 1976). Variation may be due to ambient conditions and individual pairs, but in addition observers may have used variety of time points to determine incubation period.

Parental Behavior

Incubation about equally by both sexes on Victoria I. and in Chukotka (Parmelee et al. 1967, Flint and Kondratiev 1977, DRP), although males incubated much more than females at 4 nests on Bylot I. (Drury 1961) and were seen on and at nest more than females on Devon I. (Hussell and Page 1976). Female incubated 60% of time during afternoon watches at 1 nest on Bathurst I. (Mayfield 1973). Incubating bird always returned within 10 min after disturbing factor (predator) disappeared (Mayfield 1973). Male reported to approach nest more readily than female (Walkinshaw 1948, Parmelee et al. 1967), and greater frequency of observations of male incubating may be consequence of this (Hussell and Page 1976). In Siberia, however, Seebohm (1901) reported female more likely to return to nest first, no matter how long it takes, whereas male more likely to remain vigilant at 1 spot at a distance.

Male rolled back 1 of 2 and 1 of 3 eggs placed on nest rim but unable to retrieve 2 eggs outside rim or remove light covering of grass from nest (Höhn 1957).

For sexes combined, time on nest during incubation totals nearly 100% (Flint and Kondratiev 1977). Little information about timing of incubation in sexes; at one nest, both sexes incubated equally “day” (0800–2000 h) and “night” (2001–0400 h) (n = 11; DRP).

Change-over performed quickly. In typical interchange, male approaches on wing from distance, giving loud single note and typical flight call. Female flies directly from nest to several hundred meters distance and begins feeding. Male alights 20 m from nest and runs rapidly to it. Eggs untended <1 min (Mayfield 1973). After female calls from nest, male comes on foot from 150 m away (Walkinshaw 1948).

Hardiness Of Eggs

Eggs laid on Devon I. during temperature ranges of -4 to 8°C, averaging just above 0°C (Hussell and Page 1976). Temperatures of artificial eggs in one nest alternately warmed to about 20°C and cooled to ambient at 5–10°C during intermittent incubation before last egg laid, and maintained at 28–32°C during continuous incubation thereafter (Flint and Kondratiev 1977).

Preliminary Events And Vocalizations

Adult behavior changes 1–2 d before pipping, with increased standing and brief departures from nest. Chicks begin peeping during this time (Flint and Kondratiev 1977).

Shell-Breaking And Emergence

Eggs pip 2–3 d (Drury 1961, DRP) before hatching, at any time of day. Hatching typically over 2- to 3-d period (Drury 1961, Hussell and Page 1976, DRP). Hatching usually asynchronous, but siblings in 2 nests hatched in 12–16 h (Parmelee et al. 1967, Mayfield 1973). Hatching of individual eggs takes from 6 h to 1 d (Flint and Kondratiev 1977).

Parental Assistance And Disposal Of Eggshells

Both sexes carry away eggshells within minutes of hatching (Mayfield 1973). At 1 nest, female took shell of third egg, male of fourth egg (Hussell and Page 1976). Shells carried to about 100 m distance, in some instances pushed into depression or under vegetation (Flint and Kondratiev 1977).

Condition At Hatching

Average mass 21.4 g (n = 23), continue to lose weight for several hours after hatching, then regain it within 48 h (Hussell and Page 1976). Yolk sac provides nutrition for 1–2 d after hatching (Hussell and Page 1976). At hatching, tarsus 32.5 mm (32.0–33.4), culmen 12.3 mm (11.5–13.5) (n = 5; Parmelee et al. 1967, Hussell and Page 1976). Covered with down, white egg tooth prominent at hatching. Bill black, legs gray. See also Appearance: molts and plumages. Young alternate sleep and vigorous activity both in and out of nest; earlier hatchlings of brood venture as much as 20 cm out of nest (Mayfield 1973).

Growth And Development

Weights and measurements of known-age chicks in Hussell and Page 1976 . Five-day-old chick with tarsus 37.0 mm, exposed culmen 15.5 mm (Parmelee et al. 1967). During development, primaries grow most rapidly, then rectrices, then tarsus and culmen (Hussell and Page 1976). No Juvenal feathers at 5 d, wing quills barely visible (Parmelee et al. 1967). First primaries appear by day 6, first rectrix by day 10. Juvenal feathering all over by day 12–13, but appearance of juvenile not attained until day 18; down persists longest on nape, rump, and underparts (Hussell and Page 1976). Temperature control presumably achieved by 2–3 d, after which not brooded (Hussell and Page 1976).

All young out of one nest within 15.5 h of hatching of first, although could have been hastened by observer nest visits (Mayfield 1973). Young may spend 1 night in nest after all hatch (Drury 1961). Pluvialis chicks tend to stay in nest longer than those of other shorebirds (Nethersole-Thompson 1973), perhaps because of asynchronous hatching. Young may forage within 12 h of hatching; over brief period, peck at and finally capture midges and caterpillars; may forage up to 50% of time by 20 h (Hussell and Page 1976). Older young forage alone up to 40 m from nest and brooding adult until last-hatched young becomes active and nest deserted (Hussell and Page 1976). Chicks not assisted by parents when foraging; foraging behavior develops slowly but similar to adults (Hussell and Page 1976). Chicks run rapidly across irregular tundra when pursued (Brandt 1943).

Brooding

Begins soon after hatching and continues for 2–3 d after chicks leave nest. At 1 nest, male spent 12 h and 13 min brooding, female 7 h and 34 min. Male returned to nest 11 times after observers’ activities disturbed nest, female only once (Hussell and Page 1976). Both sexes are solicitous of newly hatched chicks (Parmelee et al. 1967), sometimes calling softly when approaching or covering them (Mayfield 1973). When young are dispersed, both sexes brood different young simultaneously (Hussell and Page 1976).

Adults act as sentinels, using alarm calls to warn foraging young of approaching danger. Young usually crouch motionless (Hussell and Page 1976).

Departure From The Nest

Young alert and active and covered with down feathers when they leave nest. Adults take entire brood from nest area to more richly vegetated habitats (Mayfield 1973). Broods usually remain within 1.5 km of nest site, one young moved to 3 km away (Hussell and Page 1976). Marked broods had moved 0 m on day 1 (n = 3), 0 m on day 2 (n = 1), 140 m on day 3 (n = 1), 400 m on day 5 (n = 1), and 400 m on day 10 (n = 1) (C. Moitoret pers. comm.). Flint and Kondratiev (1977) followed one brood for 1 mo in Chukotka. It moved about 200 m in 1 direction for 8 d, then reversed direction and went about 100 m past nest site by 13 d, turned sharply and wandered to about 1,000 m from nest by 27 d, then returned to within 250 m of nest by 31 d. Brood near lake or pond each of 15 times located.

Fledging period unusually short among larger shorebirds; about 23 d, when young reach growth asymptote; flight apparently not possible before that time (Hussell and Page 1976).

Association With Parents Or Other Young

Both sexes care for young; exact details sketchy but female reported to desert 10 d or 2–3 wk after fledging (Hussell and Page 1976, Flint and Kondratiev 1977).

Ability To Get Around, Feed, And Care For Self

Parents function primarily by guiding young to foraging areas and warning them of predators.

On Pacific Coast, cloacal bursa enlarged through at least first year: mean length Sep–Oct 18.8 mm (n = 4, Washington), Dec–Feb 13.4 mm (n = 10, California), May–Jun 14.6 mm (n = 16, Washington) (specimen data).