Breeding

Pair Formation

Some pairs probably form on wintering grounds or during migration, but other individuals arrive at breeding sites unpaired (Sordahl 1984, JAR and LWO). In Hawaiian Is., birds can appear to be paired at any time of the year, although less frequently in winter (Coleman 1981).

Nest-Building

Nest building completed immediately prior to egg-laying.

First/Only Brood Per Season

Figure 5 (ne. California and Hawaiian Is.); also see data for n. Utah in Sordahl 1996b . At Salton Sea, CA: earliest egg-laying 2 Apr, median egg-laying 15 May, median hatching 14 Jun, latest active incubation 16 Aug (Grant 1982). At McKay Bay, Florida: adults arrive mid-Mar, with peak hatching during last week of May (Dinsmore 1977). At Cache Co., UT: arrival in late Mar, copulations 11 Apr–6 Jun, nests with eggs 23 Apr–10 Jul, hatching 20 May–6 Jul, latest clutch initiation 9 Jun, flightless young until 5 Aug (Sordahl 1981). In Great Salt Lake Valley, UT: arrival late Mar (Paton et al. 1992), nesting begins late Apr, latest clutches initiated mid-Jun (T. A. Sordahl pers. comm.). At Lassen Co., CA: arrival in late Mar, copulations begin mid-Apr, nests with eggs 18 Apr–19 Jul, hatching 14 May–20 Jul, latest clutch initiation 22 Jun, flightless young until 17 Aug (1992–1994; JAR and LWO). In ne. Venezuela (where birds are resident), breeds Apr (beginning of rainy season) through Jul (McNeil 1971). For Hawaiian Stilts, mid-Feb through late Aug with peak nesting varying among years (mid-May 1978, late Mar 1979, O‘ahu; Coleman 1981).

Selection Process

Selected jointly by the pair.

Microhabitat

Appendix 1 . Nest scrape in soft substrate of alkali flat, dike or island. Often over water on small islands or vegetation clumps (JAR and LWO; for Hawaiian Stilt, Telfer 1975). Although nests often completely in the open, at some sites nests surrounded by a mean of 56% vegetative cover (n = 47 nests), mostly glasswort and frakenia (Frankenia grandifolia; at Bolsa Chica, CA; James 1995). In tidal impoundments with 95% open water, flooded salt-meadow cordgrass (Spartina patens) and saltgrass (Distichlis spicata, in Delaware, north of the usual breeding range). Along water’s edge of impoundments in clumps of barnyard grass (Echinochloa crusgalli var. crusgalli) or Bermuda grass (Cynodon dactylon; Texas; J. M. Cys pers. comm.). On dead remains of cattails protruding above the waterline (nw. Nevada; JAR). Short emergent vegetation stubble over water and on dikes, islands, or high spots with sparse vegetation, particularly glasswort and saltgrass (Distichlis stricta; Sordahl 1996, unpubl. data).

Site Characteristics

Often slightly elevated (2–10 cm) from surrounding substrate. In Utah, 74% of nests in vegetation, others in the open (n = 23, Sordahl 1996b). Nests studied by Hamilton (1975) tended to be on the leeward side of the dike.

Islets are highly preferred for nesting (Coleman 1981, JPS). In Tulare Lake Basin, CA, 100–150 nests found on each of several small (0.1 ha) islets (JPS). When wavebreak islands were removed at one agricultural evaporation pond in Tulare Lake Basin, nest attempts declined by 75% and nest predation increased 25-fold within two breeding seasons (JPS). No nests found by 8th postremoval breeding season (H. T. Harvey and Associates 1996).

For distances to water, see Appendix 1 . Additional data: Salton Sea, CA, 15.9 m ± 21.6 SD (range 0–91.4, n = 128; Grant 1982); Salton Sea, CA, 13.6 m (n = 66; R. A. James, Jr., unpubl.); Ventura, CA, 18.1 m ± 22.5 SD (range 1.2–45.7, n = 5; Grant 1982); Bolsa Chica, CA, 1.1 m (n = 47; R. A. James, Jr., unpubl.). Distance to water in Hawaiian Is. (O‘ahu), range of means for 4 sites 1.05–2.34 m (1.49–5.61, n = 319; Coleman 1981).

A dike or island used in one year may not be used in the next, even though conditions appear to be sim-ilar (JAR and LWO). Occasional nests constructed over water on floating algal mats (JAR and LWO), woven floating water hyssop (Bacopa monnieria, Hawaiian Stilt, Coleman 1978), or dead tules and marsh grasses (Wolfe 1931). Successful Hawaiian stilt nests built on floating wooden platforms (Morin 1994) and on bare lava rock next to an aquaculture facility (M. Morin unpubl. data).

Construction Process

Either sex scrapes with breast and feet while mate observes nearby; then tosses small pieces of lining materials over its back. Adds lining throughout incubation, particularly when mates switch incubating. If water rises, nests are built up by both sexes sticking pieces of dead vegetation beneath the nest lining. Mean height 1.2 cm ± 2.5 SD (n = 253; O‘ahu; Coleman 1981). In Waiwa, O‘ahu, a nest was built up from an original height of 12 cm to a height of 25 cm in 2 d using dead saltwort (Batis sp.) twigs (Coleman 1981). Nests also built up using pieces of plastic trash (JMR). The process of adding materials to the nest can move the nest location horizontally up to 50 cm (Coleman 1981).

Structure And Composition Matter

Degree of lining varies from none to fully lined (see Appendix 1) with objects found nearby including grasses, other vegetation, pebbles, shells, feathers, mud chips and bones. Hawaiian Stilt nests also range from bare to fully lined with woven grass. Lining materials include pebbles, saltwort, Brachiaria, dry grass and snail shells (Coleman 1981, JMR). Lining material used is that nearest nest; most lining material added during incubation (Hamilton 1975; Hawaiian Stilt, Coleman 1981).

Dimensions

Salton Sea, CA, diameter 132.0 mm ± 12.4 SD (range 100–160, n = 111); depth 25.6 mm ± 11.0 SD (range 0–51, n = 111; Grant 1982). Salton Sea, CA, diameter 170.0 mm (n = 66; R. A. James, Jr., unpubl.). Ventura, CA, diameter 132.1 mm ± 11.1 SD (range 110–145, n = 7); depth 15.7 mm ± 15.1 SD (range 0–40, n = 7; Grant 1982). Bolsa Chica, CA, diameter 120 mm (n = 470; R. A. James, Jr., unpubl.). McKay Bay, FL, diameter 214 mm (n = 5; Dinsmore 1977). Nu‘upia, O‘ahu, diameter 140 mm; depth 38–51 mm (n probably = 7; Saito 1975). James Campbell NWR, O‘ahu, diameter 190 mm ± 42 SD (n = 254); depth 30 mm ± 17 SD (n = 254; Coleman 1981).

Microclimate

Mean air temperatures in nests with complete clutches, Salton Sea, CA: during day, 37.1°C ± 3.1 SD (n = 361); at night, 32.5°C ± 1.9 SD (n = 11; Grant 1982). For incomplete clutches: during day, 36.9°C ± 3.0 SD (n = 47; Grant 1982).

Maintenance Or Re-Use Of Nests, Alternate Nests

Nests built earlier in season by American Avocets or Black-necked Stilts sometimes used later by another pair of avocets or stilts (JAR, JPS, LWO). Sequential use of nest cups most common on islands (JPS). In Hawaiian Is., same nest reused by different individuals in same year; nest cup also known to be used by the same individual in subsequent years (Coleman 1981).

Nonbreeding Nests

Scrapes without eggs are recorded regularly (JAR, LWO, JPS; Hawaiian Stilt, e.g., Ohashi and Telfer 1977, Dougherty et al. 1978). Some pairs probably construct multiple scrapes during the nest site selection process (although this has not been documented for individually marked pairs). Other scrapes may represent nests that were depredated and abandoned before being found by researchers.

Shape

Pyriform. Rarely oval. Four eggs of clutch fit snugly in nest cup with small ends together. Larger clutches (see below) do not fit well, and eggs often roll out of nest.

Size

Tulare Basin, CA: length 4.35 cm ± 0.18 SD (range 3.68–5.06); width 3.09 cm ± 0.11 SD (range 2.61–3.55); 1 randomly selected egg measured from each nest, and species confirmed by embryo examination (n = 270 nests; JPS). Nw. Nevada and ne. Cali-fornia, length 4.34 cm ± 0.13 SD (n = 33); width 3.04 cm ± 0.11 SD (n = 32; JAR and LWO). Salton Sea, CA, length 4.38 cm ± 0.17 SD (n = 222); width 3.05 cm ± 0.10 SD (n = 222); surface area 36.2 cm²± 1.6 SD (n = 29; Grant 1982).

Runt eggs from central California measure 3.83 cm ± 0.02 SD × 2.78 cm ± 0.05 SD (n = 3). Both measurements differ significantly from measure-ments of normal eggs at the same site (length, t = 4.93, p < 0.00001; width, t = 5.03, p < 0.00001; df = 271 for both; JPS). Incidence of runt eggs 0.113% (6 of 5,302 eggs examined in 1988 and 1989, Tulare Basin, CA; JPS).

Mass

Fresh egg mass 21.0 g ± 1.4 SD (n = 29); volume 19.9 cm³± 1.3 SD (n = 29); density 1.055 g/cm³± 0.001 SD (n = 29; Grant 1982).

Color

All colors identified (and numbered) according to Smithe (1975). Base color Tawny Olive (223D) to Light Drab (119C), occasionally as dark as Sayal Brown (223C) or as light as Drab Gray (119D). Surface speckled and mottled to varying degrees in 2 layers of intensity: underlying markings Army Brown (219B) to Natal Brown (219A); overlying markings Sepia (119) or Vandyke Brown (221). Occasionally, overlying markings are no darker than Dark Drab (119B), rarely they are nearly absent. Pattern of markings varies from blotching to spotting to irregular squiggles. Markings usually evenly distributed across egg, but rarely more dense at large end or around widest part.

For Hawaiian Stilt, Coleman (1981) noted that the initial base color was a dull mint green, which faded to tan 1 day after laying.

Surface Texture

Smooth without any gloss.

Eggshell Thickness

Churchill Co., NV (1991): 0.234 mm ± 0.022 SD (range 0.21–0.28, n = 18; JAR). Salton Sea, CA (1976): 0.224 mm ± 0.017 SD (n = 22; Grant 1982).

Clutch Size

Usually 4. Reported mean clutch sizes: Salton Sea, CA, 3.9 eggs ± 0.4 SD (range 2–5, n = 152; Grant 1982), 3.5 eggs ± 1.0 SD (range 1–4, n = 64; R. A. James, Jr., unpubl.); Ventura, CA, 3.8 eggs ± 0.4 SD (range 3–4, n = 9; Grant 1982), Bolsa Chica Reserve, CA, 3.2 eggs ± 1.0 SD (range 1–4, n = 38; R. A. James, Jr., unpubl.); Cache Co., UT, 3.9 eggs (range 3–4, n = 17, excluding single eggs and one 6-egg clutch; Sordahl 1996b); Stillwater NWR, Churchill Co., NV, 3.6 eggs ± 0.7 SD (range 2–4, n = 8; USFWS unpubl.); Churchill Co., NV, 3.4 eggs ± 0.96 SD (range 1–4, n = 13; JAR); Lassen Co., CA, 3.8 eggs ± 0.73 SD (range 1–6, n = 252; JAR and LWO). For Hawaiian Stilts, James Campbell NWR, O‘ahu, 3.6 eggs ± 0.9 SD (range 2–7, n = 366; Coleman 1981); Nu‘upia, O‘ahu, 3.8 eggs (n = 47; Ueoka et al. 1976).

Supernormal/supernumerary clutches (clutches of ≥6 eggs) can be found occasionally when 2 females lay in the same nest cup (Sordahl 1996b; Hawaiian Stilt, Coleman 1981); 5-egg nests probably also involve ≥1 female. When ≥6 eggs are in a nest cup, 2 distinct patterns on eggs suggest laying by 2 females (Rohwer et al. 1979, C. L. Gratto-Trevor unpubl., JAR, LWO). Incidence of supernumerary clutches: Churchill Co., NV, 0% (n = 16, 1991, JAR); Lassen Co., CA, 0.36% (annual range 00.93%, total n = 278 nests, 1992–1994, JAR and LWO). Incidence of 5-egg nests: Lassen Co., CA, 0.72% (annual range 0–2.5%, total n = 278 nests, 1992–1994, JAR and LWO). In Tulare Basin, CA, in-cidence of supernumerary clutches 0.23% and incidence of clutches with ≥5 eggs 0.73% (annual incidence range of all clutches with ≥5 eggs 0.7–1.1%, total n = 2,195 nests, 1987–1989; JPS).

On the northern edge of expanding range (see Distribution: historical changes, above), laying by 2 females appears to be more common than else-where; incidence in Brooks, s. Alberta, where breeding has only recently been documented, 2 of 8 nests (1995–1997; C. L. Gratto-Trevor unpubl.); incidence in Washington range expansion, 1 of 5 nests (1973 and 1977, Rohwer et al. 1979).

Rarely, supernormal clutches include both American Avocet and Black-necked Stilt eggs. In Lassen Co., CA, 2 cases (0.98%, n = 278 total stilt nests ob-served) each with 7–8 total eggs and 34 eggs per species; avocets incubated the clutch (JAR). In Tulare Basin, CA, 4 nests containing 1–2 avocet eggs in addition to Black-necked Stilt eggs (0.18%, n = 2,195 total stilt nests observed); all 4 were incubated by stilts (JPS).

Dropped eggs (single eggs laid on ground without evidence of scraping) also noted (Sordahl 1996b, JAR, JPS, LWO; Hawaiian Stilt, e.g., Ohashi and Telfer 1977, Coleman 1981).

Egg-Laying

Four eggs laid in 4–5 d. Time between laying third and fourth egg was 25 h 42 min for one female (Grant 1982).

Onset Of Broodiness And Incubation In Relation To Laying

Incubation may begin as soon as first egg is laid, but depends on local ambient temperatures (see below).

Incubation Patches

Developed by both sexes.

Incubation Period

When temperatures are moderate, incubation probably begins with penultimate egg (in Alameda Co., CA, eggs were cold until third or fourth egg was laid; Hamilton 1975). When ambient temperatures warm, first eggs begin developing immediately after being laid without parental incubation. When ambient temperatures hot, parental attention needed to cool eggs from the time first egg is laid. In hot conditions at Salton Sea, CA, eggs incubated from the time laid and for at least 10 h each day; first egg maintained near incubation temperatures for minimum of 30 h before 4th egg laid (Grant 1982). Days from known date first egg was laid to known date first egg hatched: Lassen Co., CA, mean 26.0 d ± 1.4 SD (range 24–29, median 26, n = 16; JAR and LWO); Tulare Basin, CA, 25.0 d ± 2.0 SD (range 21–30, median 25, n = 43; JPS). For comparison with intervals normally reported for shorebirds (from day clutch is complete to day first egg hatches) these data can be adjusted by subtracting 3 d for laying of first 3 eggs. Other reported incubation periods: Alameda Co., CA, range 22–27 d (n = 2, from day last egg laid to day last egg hatched in 4-egg clutches; Hamilton 1975); Hawaiian Is.: 23–26 d (Berger 1967, Ueoka et al. 1976, Coleman 1981).

For fresh (confirmed by high intensity candling) stilt eggs artificially incubated at 37.5°C, mean time to pipping (small cracks in shell) 20.2 d ± 1.2 SD (median = 20, range 1822, n = 13); mean time to hatch 23.1 d ± 0.9 SD (median = 23, range 21–24, n = 20; JPS).

Parental Behavior

Both sexes take turns incubating day or night (Grant 1982, Sordahl 1996b; Hawaiian Stilt, Woodside 1979b, Coleman 1981). In very hot environments, incubation behaviors serve to cool eggs rather than to warm them. Parents soak belly-feathers in water before sitting on nest to facilitate evaporative cooling and to maintain nest humidity, and periods off nest are reduced to minimum (not observed for Hawaiian Stilts, Coleman 1981). Due to belly soaking, eggs often become encrusted with salt and mud. Belly-soaking was most common during periods of high solar radiation loads (not high ambient temperatures), and egg temperature was not the proximate stimulus (Grant 1982). At Salton Sea, CA, no eggs were left uncovered for >1 min from 09:00 to 18:00 (Grant 1982). Incubating birds orient themselves to face into wind, pant and fluff feathers on back to regulate body temperature in hot environments (Grant 1982; Hawaiian Stilt, Coleman 1981).

Male and female usually alternate throughout day; incubation bouts become shorter as shaded ambient temperature increases (Grant 1982). Sexes equally likely to be incubating at any time (James 1991; Hawaiian Stilt, Coleman 1981). Mean incubation bout length: in Alameda Co., CA, male 64.6 min (n = 11), female 82.0 min (n = 10; Hamilton 1975); at Salton Sea, CA, male 21.3 min (n = 199), female 19.4 min (n = 201; Grant 1982); Ventura, CA, male 37.6 min (n = 16), female 44.3 min (n = 16; Grant 1982); Bolsa Chica, CA, male 45.5 min (n = 15), female 41.4 min (n = 15; James 1991); Kaua‘i, Hawaiian Is., male 55 min (n = 34), female 51 min (n = 34; Stejneger 1887). Percent of time nest was incubated: 95.4% (Hamilton 1975), 95% (Hawaiian Stilt, Coleman 1981).

During changover, relieving bird alights in water near nest and walks toward incubating individual. On approach of relieving bird, incubating bird stands and walks toward water. Occasionally departing bird tosses bits of material similar to nest lining over its back as it leaves the vicinity of nest (Hamilton 1975; Hawaiian Stilt, Coleman 1981).

Hardiness Of Eggs

Normal egg temperatures during incubation: at Salton Sea, CA, day 37.9°C ± 2.1 SD (n = 586, complete clutches) and 34.8°C ± 4.7 SD (n = 96, incomplete clutches); night 35.2°C ± 2.6 SD (n = 44, complete clutches); Ventura, CA, day 37.2°C ± 1.3 SD (n = 58, complete clutches; Grant 1982). Egg temperature increases with ambient temperature (see Grant 1982 for relationships between ambient temperature and incubated egg temperature). Eggs hardy to high ambient temperatures—hatched after reaching temperatures of up to 42.9°C for 15 min to 3 h, and a few minutes at 46°C; 47.7°C was lethal to embryo (Grant 1982). Eggs in early stages of development also hardy to cold temperatures. At Tulare Basin, CA, eggs at 3–5 d of incubation were refrigerated at 16°C for up to 36 h without any loss of viability upon subsequent artificial incubation (JPS).

Preliminary Events And Vocalizations

Chicks begin to vocalize and small fractures appear at large end of egg approximately 1–3 d before hatching. Three vocalizations described for prehatch and young chicks: Peep Call, clicking sounds at 1–7 kHz, and “Whine Call” (sonograms in Sordahl 1980). Distinct hole (4–15 mm) appears in broad end of egg 1–2 d before hatching.

Shell Breaking And Emergence

Nestmates usually hatch within a 24–48 h interval: 46.2% of broods hatch within 1 d, 37.8% over 2 d, 14.2% over 3 d and 1.7% over 4 d (n = 119 broods; JAR and LWO). Hawaiian Stilts usually hatch within 24 h, occasionally to 36 h and rarely 48 h (Coleman 1981). Egg tooth on upper mandible and small egg tooth on lower mandible disappear approximately 24 h after hatch.

Parental Assistance And Disposal Of Eggshells

Shells are removed by parents immediately after hatching, and often sunk in nearby water (Sordahl 1994). If shells become crushed in nest and white insides are not visible, they are not removed.

Departure From Nest

Chicks stay in nest not >24 h after hatching of last chick. If nest disturbed, may move within hours of hatching of last chick. If nest is on an island, parents call chicks to swim to shore, which they do with difficulty. Broods are led to areas of shallow water with vegetation for cover. In general, either (1) vegetation shorter than adult, but taller than the chick with small openings to allow chicks to move freely, or (2) vegetation taller than the adult with unvegetated pathways that can be used by the chick.

Most broods move only once when they leave hatch site and go to brood territory. Straight-line distances between nest and brood territory: 80–950 m (n = 4; Sordahl 1996b), 10–20 m (Hawaiian Stilt, Coleman 1981), several hundreds of meters (Hawaiian Stilt, JMR).

Condition At Hatching

Chicks precocial and downy; dry and able to leave nest within 1–2 h, but walk awkwardly for first day. Bill short.

Growth And Development

Crouches silently when parents give Alarm Call, usually in vegetation unless caught in the open; run when caught in the open; running only slightly more prevalent as chicks mature (Sordahl 1982). Measurements of known-aged chicks (T. A. Sordahl unpubl.): Age 1 d (≤24 h): mass 13.6 g ± 1.2 SD (range 12–15, n = 10), exposed culmen 11.4 mm ± 0.8 SD (range 10–12, n = 7), tarsometatarsus 28.4 mm ± 0.8 SD (range 27–29, n = 7), wing-chord 14.7 mm ± 1.3 SD (range 13–17, n = 7); age 3 d (n = 2): mass 17–18 g, exposed culmen 14–15 mm, tarsometatarsus 31–32 mm, wing-chord 16–17 mm; age 4 d (n = 3): mass 21.7 g ± 2.1 SD (range 20–24), exposed culmen 16.3 mm ± 0.6 SD (range 16–17), tarsometatarsus 33.3 mm ± 1.5 SD (range 32–35), wing-chord 17.3 mm ± 1.2 SD (range 16–18); age 5 d (n = 1): mass 28 g, exposed culmen 18 mm, tarsometatarsus 38 mm, wing-chord 18 mm; age 17 d (n = 3): mass 68.7 g ± 3.05 SD (range 66–72), exposed culmen 29.3 mm ± 1.2 SD (range 28–30), tarsometatarsus 54.7 mm ± 3.8 SD (range 52–59).

Measurements of known-aged Hawaiian stilt chicks (Reed et al. in press): Age 1 d (24 h): mass 15.6 g ± 1.1 SD (n = 33). Mass of older chicks, exposed culmen, tarsus length, and wing-chord measurements presented graphically by Reed et al. (in press).

Males more likely than females to be present with the chicks, although difference is not great (males present 86.4%, females 76.7%, p = 0.01). Parents significantly closer to chicks in first week than in third week posthatching, but males and females do not differ in proximity to chicks (James 1991).

Brooding

Only during first week except during overcast mornings or evenings (through 3 wk, James 1991; Hawaiian Stilt, as late as 2 wk, Coleman 1981). Brooding prior to departure from the nest is similar to incubation. On land, parent rests on its tibiotarsi, and the young stand beneath. In cold weather, older chicks are sometimes brooded in shallow water. Parent stands with wings loosened, and young wade beneath. Coleman (Hawaiian Stilt, 1981) also reported brooding during hot sunny periods, but this was not observed in California or Nevada (JAR and LWO; also see information on aggression toward foreign broods under Behavior: Agonistic behavior, above.)

Feeding

Feeding of young has never been observed in the wild, and young stilts survive in captivity with-out parents (M. Rubega pers. obs., JPS; Hawaiian Stilt, Coleman 1981). Lint (1959) reported chicks <1 wk old being fed exclusively by parents in a zoo setting, and parents becoming more tame with the presence of chicks.

Nest Sanitation

Not necessary because young do not remain in nest long after hatching and are mobile enough to defecate away from it.

Parental Carrying Of Young

None observed.

Association of nonbreeding adults with a breeding pair not observed (JAR and LWO).

Eggs of Black-necked Stilts and American Avocets found in same nest twice in Lassen Co., CA; in both cases avocets incubated eggs and reared young (JAR and LWO). Although intraspecific nest parasitism and brood-mixing are fairly common in American Avocets (Hamilton 1975, JAR and LWO), the greater degree of nesting territoriality, brood territoriality, and aggression to foreign chicks usually prevents occurrence in stilts (JAR, LWO; Hawaiian Stilt, Coleman 1981; see Eggs: clutch size, above). Hawaiian Stilt nests with up to 7 eggs reported; presumed to be from multiple females (Dougherty et al. 1978).

Departure From Nest

Fledglings depart from nest 1–24 h after hatching of last chick. Short, hopping flights can begin at 22–23 d (JAR and LWO). Capable of sustained flight 27–31 d posthatching (Sordahl 1980, JAR and LWO; Hawaiian Stilt, Coleman 1981).

Association With Parents Or Other Young

As noted by Wetmore (1925) family groups remain intact well beyond the time when young can fly. However, the degree of association appears to depend on location. In Utah, 100% (n = 9) of downy broods, but only 52% (n = 79) of juvenile broods were attended by both adults; in 87% (n = 38) of cases where only one parent was present, it was the male (Sordahl 1996b). In California, 39.2% of downy broods were attended by both adults (30.4% by male parent only, 17.4% by female parent only, 13.0% by neither, n = 23 marked broods; JAR and LWO). When first noted as flighted, groups of banded fledglings were accompanied by both parents 31.9% of the time (29.8% male parent only, 19.1% female parent only, 19.1% neither, n = 47 marked broods; JAR and LWO). In 75% of cases where brood was abandoned by one parent, the male remained (n = 16; JAR and LWO). Sibling Hawaiian Stilts observed in groups with 2 adults as late as Feb in the year after hatch (JMR).

Juveniles congregate in small groups prior to departure from breeding areas. Siblings and/or family groups sometimes migrate together (Robinson and Oring 1996).