Breeding

Over entire range, breeding documented throughout year. In Texas and Louisiana, breeds early spring through summer (Apr–Jul or Aug; Oberholser 1938, 1974, Martin and Lester 1991; see Fig. 4). On mainland Florida, breeds winter through spring (late Feb or early Mar–Jun), but in Florida Bay normally fall–winter (Nov–Mar), but timing has become more irregular during last 2–3 decades (Allen 1942, Bjork and Powell 1994, Frederick and Towles 1995, R. Paul pers. comm., J. Ogden pers. comm.). If colony failure occurs in Dec–Feb; then may renest in Feb–Mar, extending season in bay through Jun (J. Lorenz and R. Bjork pers. comm.). Allen (1942) considered groups on mainland and at Florida Bay separate populations because of different breeding schedules (see Demography and populations: range, below). Environmental correlates of breeding chronology are not well understood.

Pair Formation

Varies geographically. Birds usually congregate at colony or vicinity approximately 1–2 mo before pairing (Allen 1942, White et al. 1982). In Texas, pairs form in Apr; in Florida Bay, early Nov–mid-Dec (Allen 1942). No dates from Louisiana. Pair formation and nest initiation occur simultaneously or within a few days of each other, but this information is based on few observations (see Behavior: sexual behavior, above; Allen 1942).

Nest-Building

The following is based on 1 pair in Texas (Allen 1942). Courtship and nest-building proceed together for about 20 d, until first egg is laid. Major construction continues at least through copulation, or 13 d after building begins; nest is well formed after 8 d. Birds may continue to add material, especially just before hatching. Initiation dates vary considerably in time and space; at same colony, highly synchronous within years but variable among years; 3–5 wk earlier in northeast than in northwest colonies in some years. Average at Tern Key over 11 seasons (1974–1992): Nov 29 ± 13.5 d SD; yearly average ranging from 15 Nov–27 Dec (42 d); extremes almost 2 mo apart (calculated from Bjork and Powell 1994). Initiation at Tern Key over 11 seasons not correlated with drying rate in foraging habitat (Bjork and Powell 1994). In Texas, nest initiation dates varied among years, but fewer annual data available: 27 Apr 1940 (1 pair; Allen 1942); 5 May 1978, average 15 Apr in 1979 and 1980 (White et al. 1982). No dates from Louisiana.

First/Only Brood Per Season

See Figure 4 for Texas and Louisiana. Reported egg collection dates in Louisiana, 18 May–2 Jun and Aug; in Texas, 8 Apr–24 Jun (Bent 1926, Oberholser 1938, 1974). In Texas, first eggs: at Galveston Bay, 30 Apr 1977 (clutch completion by mid-May); at Nueces Bay, 20 May 1978 (average laying date 25 Apr in 1979 and 1980); in San Antonio Bay, 15 May 1940 in 1 pair (Allen 1942, Chaney et al. 1978, White et al. 1982). Average dates of clutch com-pletion in Nueces Bay not reported; see Eggs, below. No specific laying dates for Louisiana. Usual hatching period in Texas is mid-May–mid-Jun; in Louisiana, may be slightly later (Oberholser 1938, Allen 1942, Ramsey 1968, Chaney et al. 1978, White et al. 1982). On basis of 6 wk to fledging, nestling period in Texas usually ends in Jul, but can end as early as 2 May (Oberholser 1974). Late egg dates of 24 Jun in Texas and 2 Jun in Louisiana suggest that nestling stage continues until about mid-Aug. Young remain in colony until about 2 mo old (see Fledgling stage, below). In Texas, adults and young begin to disperse in Aug (White et al. 1982).

Egg dates for mainland Florida: mid-Jan (Big Cypress, 1910, 1913) to 29 May (Cuthbert Lake, 1908; Stevenson and Anderson 1994). Historically, nesting season extended from Jan to Jun (Howell 1932). In Florida Bay, eggs laid mainly Nov and Dec (Ogden 1978b, Powell and Bjork 1991); after colony failure events in Jan or Feb, eggs noted in mid-Mar–end of Apr; dates between clutches in one year (1995–1996) were 24 Nov and 15 Mar, or about 16 wk (J. Lorenz and R. Bjork pers. comm.). Hatching dates in Florida Bay reported as mid- to late Dec (Allen 1962). During 1986–1987 to 1990–1991, eggs hatched at Tern Key approximately 15–21 Dec in 3 yr; 1 Jan and 18 Jan in 2 yr (Powell and Bjork 1991). Young usually fledge in late Jan or Feb; approximate dates at Tern Key were 21 Jan–25 Feb, 1986–1987 to 1990–1991 (Powell and Bjork 1991). Young disperse in Feb and Mar (Powell and Bjork 1990). Nestling period from mid-Mar through Jun when renesting after colony failure (J. Lorenz and R. Bjork pers. comm.).

Outside of U.S., information is sketchy and often outdated. In Mexico (Yucatán Peninsula), extreme egg dates 18 Jan–18 Apr at Sian Ka’an Biosphere Reserve (Ornat-Lopez and Ramo 1992). In Colombia, female observed laying eggs 31 Mar, in s. Bolívar (M. A. Carriker, Jr. in Hilty and Brown 1986).

Second/Later Brood(S) Per Season

None; see Demography and populations: measures of breeding activity, below.

Selection Process

Poorly understood, see Phenology, above, and Behavior: sexual behavior, above.

Microhabitat

Usually on islands (natural or human-made) or over standing water where access by terrestrial predators is limited. Adjacent shallows for fledglings to feed and adjacent roosting area are considered essential (Allen 1942). Roosts usually at edge of colony in larger trees and shrubs. Microhabitat varies geographically, depending on available vegetation.

In Florida, mangrove of natural mangrove keys (Florida Bay, Tampa Bay) or of spoil islands (Tampa Bay, Kennedy Space Center; Smith and Breininger 1988, Bjork and Powell 1996, R. Paul pers. comm.). Nests usually are built in dense cover of red or black (Avicennia germinans) mangrove; grouped together well inside mixed-species rookery in densest and shadiest area of colony, with water or soft mud underneath (Bent 1926, Allen 1962, Ogden 1978b, Smith and Breininger 1988). In Florida Bay, built along inner lagoons of mangrove keys or with shallow pooled water underneath (Allen 1947, Bjork and Powell 1996). In Tampa Bay, also in exotic Brazilian pepperbush (Schinus terebinthefolius) on spoil islands (R. Paul pers. comm.). In inland freshwater Everglades, in southern willow (Salix caroliniana) hammocks (Frederick and Towles 1995). Once in tall cypress (Taxodium distichum), about 15–25 m above ground (Phelps 1914). Red mangrove may be preferred over black mangrove because it provides better cover (Allen 1942; see Nest, below). Will nest in dead mangrove killed by hurricane; such sites lack the usual dense cover of leaves over nest (Allen 1962).

On Texas coast, on natural and dredge-material islands using variety of vegetation (trees, shrubs, herbaceous), nests on ground. Nests in the following shrubs: sea myrtle (Baccharis halimifolia), marsh elder (Iva frutescens), mesquite (Prosopis glandulosa), huisache (Acacia farnesiana), prickly pear (Opuntia lindheimeri), oleander (Nerium oleander). Also nests in small trees, including southern elder (Sambucus simpsonii), hackberries (Celtis mississippiensis; desert hackberry [C. pallida], C. lindheimeri), prickly-ash (Zanthoxylum clava-herculis); in taller salt cedar tree (Tamarix gallica) and willow oak (Quercus phellos); in vines and herbaceous plants such as morning glory (Ipomoea sp.), panic grass (Panicum amarulum), and reeds (Phragmites; Allen 1942, 1962, Palmer 1962, Oberholser 1974, Chaney et al. 1978). In Galveston Bay, in treetops of salt cedar with Great Blue Herons or below Olivaceous Cormorants in treetops (Chaney et al. 1978). In inland forested swamps, in small trees and shrubs like buttonbush (Cephalanthus occidentalis) under canopy of hardwood trees such as water oak (Quercus nigra) and elms (Ulmus spp.; Bent 1926, Texas Colonial Waterbird Society 1982).

Site Characteristics

Height of nest variable; 0–5 m, depending on vegetation. Texas: at Nueces Bay, mean 23.9 cm ± 2.4 SE (n = 28) in low vegetation (<0.5 m), 70.6 cm ± 13.3 SE (n = 12) in trees and shrubs (1–3 m; White et al. 1982). At Lavaca Bay, mean height of nest 61 cm, maximum height of vegetation 3.5 m (sea myrtle); at Redfish Bay, mean nest height 70 cm, maximum height of vegetation 4 m (salt cedar); in Argentina, mean height 38 and 47 cm, maximum height of vegetation 3 m (sedges; sample sizes unknown; Burger 1978). Mangrove (red, black, Avicennia nitida), 1.2–5 m above ground (Bent 1926, Allen 1957, Haverschmidt 1969, Dunstan 1976, Smith and Breininger 1988, Stiles and Skutch 1989, Baltz 1997).

Construction Process

The following is based on observation of 1 pair (Allen 1942). Female does most nest construction; male collects most material and presents it to female (see Behavior: sexual behavior, above). Flurry of building activity and copulation oc-curs together; during 55-min period, male brought in nest material very rapidly (11 trips) and 1 copulation occurred.

Structure And Composition Matter

Base is a bulky, loose platform of large sticks. Top consists of lining of finer plant material, such as small twigs, stems, leaves, bark strips, and moss, with shallow depression for eggs (Bent 1926, Allen 1947, Oberholser 1974). Uses plant material that is abundant in vicinity (White et al. 1982). In Texas, base is a crude platform about 6 cm deep, composed of large dead twigs of saltbush (Baccharis angustifolia), paloverde (Cercidium macrum), and retama (Parkinsonia aculeata) loosely fitted together (White et al. 1982). Top consists of live and dead stems of sea oxeye (Borrichia frutescens), saltbush, and grasses (Paspalum) coarsely intertwined into a lining with a wide shallow depression that formed eventually from activities of the birds. In Florida, nests are lined with dead leaves of red mangrove (Bent 1926), dried mud (Smith and Breininger 1988), and sea grass (Thalasia; J. Lorenz pers. comm.). Other materials re-ported include horsehair and feathers (Raffaele et al. 1998).

Dimensions

In Texas (Nueces Bay), mean external diameter 55.6 cm ± 1.8 SE (range 43–71, n = 16); external depth 10.7 cm ± 0.3 SE (range 10–13, n = 10; White et al. 1982). In Florida (Cuthbert Lake, 1908), 1 nest measured 40.6 cm in external diameter, 17.8 cm in internal diameter, about 5 cm in depth (Bent 1926). One oblong nest at Kennedy Space Center measured 61 × 51 cm (Smith and Breininger 1988).

Microclimate

Cover varies from dense to open, depending on vegetation. No data on temperature or humidity inside nest. Egg and chick mortality during cold winter rain may be higher in black mangrove than in red, since the former provides less cover (R. P. Allen in Palmer 1962).

Maintenance Or Reuse Of Nests, Alternate Nests

Constructs new nest each year (Allen 1942). Uses abandoned nests of earlier-nesting White-faced Ibis in Buenos Aires Province, Argentina (Weller 1967).

Nonbreeding Nests

None reported.

Shape

Ovate to elliptical ovate or elongate ovate (Bent 1926, Oberholser 1974).

Size

Length x breadth: In U.S. (no specific location), mean 65 × 43.9 (range 60.2–71.5 × 41.0–47.0, n = 40; Bent 1926). One egg each from 20 clutches (15 in Florida, 4 in Texas, 1 in Louisiana): mean 64.96 mm ± 2.54 SD × 44.19 ± 1.72 SD (Palmer 1962). One egg each from 70 clutches, Nueces Bay, TX, 1977–1980: mean 64.4 mm ± 0.3 SE × 43.7 ± 0.1 SE (range 56.9–71.2 × 41.3–47.9; White et al. 1982).

Mass

Of 1 egg each from 70 clutches at Nueces Bay, TX, 1977–1980: mean whole-egg mass 62.1 g ± 0.5 SE (range 52.4–77); volume 61.8 ml ± 0.5 SE (range 52–75.4); shell weight 5.7 g ± 0.1 SE (range 3.8–7.0; White et al. 1982). Order laid (first to fourth eggs) did not affect these egg measurements. Significant changes in egg mass during incubation period mainly due to water loss; eggs incubated >16 d averaged 5.5 g less than fresh eggs incubated 0 to <5 d. Other variables, percent lipid content, dry shell weight, similar between fresh and advanced eggs.

Color

Ground color dull or dirty white, dull cream color, pinkish white, or pale greenish blue. Evenly covered with spots and small blotches of various shades of brown; occasionally markings are concentrated around thick end. Sometimes brown spotting combined with dashes and spots of lavender, purple, and drab (Bent 1926, Palmer 1962, Oberholser 1974).

Surface Texture

Roughly granular; no gloss (Bent 1926).

Eggshell Thickness

No significant difference found in eggshell thickness between pre-DDT (pre-1947) and post-DDT (1947–1980) eras (Ohlendorf et al. 1979, White et al. 1982). Mean thickness pre-1947: in Florida, 0.425 mm (n = 32 clutches); in Texas and Louisiana, 0.427 mm (n = 15 clutches). Mean thickness 1947–1973: in Florida, 0.419 mm (n = 7 clutches); in Texas and Louisiana, 0.427 mm (n = 22 clutches). In Texas, eggs had the same average of 0.44 mm ± 0.01 SE from 1923–1924 (n = 11 clutches) and in 1980 (n = 25 clutches; White et al. 1982). Average thickness 5% thinner in 1977–1979 than in 1920s (0.42 mm ± 0.01 SE, n = 50 clutches), but within range of intraclutch variation (11%). No significant difference in shell thickness among eggs at different stages of development.

Clutch Size

See Demography and populations: measures of breeding activity, below.

Egg-Laying

Generally begins after nest is nearly completed; for 1 pair, 6 d elapsed between flurry of copulation and nest-building activity and first egg (total of 19 d from nest initiation; San Antonio Bay, TX, 1940; Allen 1942). At Nueces Bay, TX, generally 10–15 d from nest initiation until first egg laid (White et al. 1982). Deposition rate: 1 egg every other day, with no variation from this pattern reported (n = 29 nests; White et al. 1982). No data on time of day eggs laid. For replacement clutches, see Phenology, above.

Onset Of Broodiness And Incubation In Relation To Laying

Incubation begins the day after first egg laid (n = 29 nests; White et al. 1982). See Parental behavior, below.

Incubation Patch(Es)

No information.

Incubation Period

Lasts 22 d for each egg (n = 29 nests; White et al. 1982). Allen (1942) stated tentatively 23–24 d because unsure of when incubation began and of deposition rate of eggs.

Parental Behavior

The following is based on Allen 1942 . Both sexes incubate eggs. No information on relative contribution of sexes, or on differences in time of day that sexes incubate. Pairs alternate attendance at nest, one parent remaining at nest continuously (on basis of few observations); no reported guarding by male. No information on effective incubation (development) period, but regular hatching sequence of eggs (in order laid, separated exactly by deposition interval) suggests that incubation is steady (development progresses) after first egg laid (see White et al. 1982). No information for other spoonbills (Cramp and Simmons 1977, Hancock et al. 1992).

Incubating pair switched places at least 2–3 times during daylight hours in San Antonio Bay, TX, in 1940 (Allen 1942). Nest Relief Display includes a greeting and call (see Behavior: sexual behavior, above, and Sounds: vocalizations, above). Not well documented relative to time of day; first observed nest relief throughout colony occurs about 1 h after sunrise; occurs again about 3 h later. Longest stretch by 1 individual ≥8 h; emitted low cackling and clucking sound and assumed associated posture 9 times during last 4 h (see Sounds: vocalizations, above). Other behaviors observed during incubation shift include standing, tugging at nest twigs, shaking twigs in bill, preening, stretching, drooping wings while either standing or sitting to shade eggs, touching eggs with bill-tip and turning, gular-flapping with bill open during heat, bobbing head up and down, and closing eyes while apparently not asleep (Allen 1942, 1962). Time off eggs is not known in relation to weather or time of day. Frequency of behaviors and variation among individuals poorly documented. One individual incubating in full sunlight for 6 h changed position 19 times; other birds in shade appeared to stir very little (Allen 1942).

Hardiness Of Eggs Against Temperature Stress; Effect Of Egg Neglect

No information.

Preliminary Events And Vocalizations

Emits vocalization similar to Begging Call of young (see Sounds: vocalizations, above) before and after pipping (J. Lorenz pers. comm.). No other information.

Shell-Breaking And Emergence

No information on time of day, or on duration of hatching per egg. Eggs hatch in the order laid (n = 29 nests; White et al. 1982). Hatching interval 1 or 2 d; first and second eggs hatch on consecutive days; intervals between second, third, and fourth eggs are every other day. All parents in colony are extremely excitable during hatching period; Upflights (see Behavior: social and interspecific behavior, above) are more frequent as well (Allen 1942).

Parental Assistance And Disposal Of Eggs

No information. Parents do not remove addled eggs (White et al. 1982).

Condition At Hatching

Semialtricial. Body mass about 50 g at hatching (White et al. 1982). No other measurements available. Skin of body, bill, and legs bright salmon pink (Bent 1926, Allen 1942, White et al. 1982); not black, as reported in Palmer 1962 . Bill initially tubular, soft and leathery; see below. Egg tooth located at tip of upper mandible (J. Lorenz pers. comm.). At hatching, feather tracts contain short, thick white down that dries and fluffs at 12 h, so body appears to be covered with down but does not conceal bright-pink skin (Allen 1942, Bent 1926, White et al. 1982). Eyes closed. Unable to stand (Bent 1926); hatchlings mostly lie prone on nest floor (R. Bjork pers. comm.). Begin feeding at 1 d old (Allen 1962), suggesting that hatchlings are capable of (at least some) begging behavior.

Growth And Development

Eyes open at about 2 d old; iris black, not yellow as reported by Allen (1942) or Palmer (1962), and remains so until fledging; legs and feet darken, becoming dark gray-brown at fledging. At about 5 d, bill begins to darken from midpoint to base, but otherwise remains essentially flesh-colored until fledging (White et al. 1982). No information on when egg tooth is lost.

Following description of Prejuvenal molt is based on White et al. 1982 (n = 10). Sheaths of the wing-feathers (alar tract) are the first to emerge: Primary sheaths emerge at day 5, secondary and alula at day 7, and tertial and covert sheaths at day 9, along with sheaths in scapulohumeral tract; sheaths rupture at day 21. Most of body remains covered with down until about 21 d, becoming wool-like at 1 wk (Allen 1942). Around 21 d, sheaths in remaining feather tracts emerge and rupture, except upper regions of dorsal tract (cervical and interscapular) and capital tract are last to rupture, at day 35. Growth of feathers continues until completion at about 42 d after hatching; young now capable of sustained flight (see Fledgling stage, below). Juvenal plumage chiefly white, with suffusion of pink (Allen 1942). Head entirely feathered, except for large loral area and broad ring around eye; both blue-grey in color (Florida Bay, JVD), but loral area reported as light yellow (Palmer 1962). Body-feathers white (dorsal, femoral, ventral, capital tracts); wing, tail, and tibiotarsal feathers light pink (alar, scapulohumeral, crural, caudal tracts; White et al. 1982). Primary tips blackish (White et al. 1982); primary and greater wing-coverts tipped dusky (Bent 1926, Allen 1942). Iris black; legs and feet dark gray-brown; bill flesh-colored, but darker toward base (White et al. 1982, but see Allen 1942). Recently fledged juveniles at a Florida Bay colony had similar leg coloration, some flesh coloration observed on upper most tibiotarsus. In older juveniles (already dispersed from a colony site), flesh coloration extended down to ankle, but color still dark below ankle (Sanibel Is., FL, JVD); suggests individual variation or a color change shortly after dispersing from natal colony. See also Appearance: molts and plumages, below.

No information on growth of body parts except for bill. Bill initially tubular, as in all other spoonbills (White et al. 1982, Hancock et al. 1992); chicks do not hatch with bills already spatulate (Palmer 1962). At day 1, mean bill length 20 mm, mean breadth at widest point 8.8 mm (n = 2; White et al. 1982). Bill-tip starts broadening and flattening 9 d after hatching (mean length 38.5 mm ± 1.9 SE, mean breadth 11.8 mm ± 0.8 SE, n = 4); becomes spatulate at 16 d (mean length 61.6 mm ± 1.2 SE, mean breadth 19.5 mm ± 0.5, n = 6). Both dimensions continue to grow at similar rates (39% and 42% of adult dimension at 19 d). By 39 d, bill has widened more than elongated; breadth 85% that of adults (44.7 mm ± 0.9 SE), length only 67% (114.3 mm ± 1.3 SE, n = 3). Growth differences apparently continue; 1 specimen found dead at about 8 wk old had length 73% that of adult (124 mm), breadth 95% (50 mm).

Chick gains average of 9 g altogether for first 3 d after hatching (White et al. 1982). Mass increases rapidly after that; by 16 d, chicks almost half of known adult weight (about 800–900 g, n = 7 nestlings; see Measurements: mass, below; see also Fledgling stage, below). Differences in weight gain among broodmates are minor up to 19 d; unrelated to actual age differences from asynchronous hatching (White et al. 1982).

No information on regulation of body temperature. Little information on physical abilities and behavior at this stage, or on progression (see Parental care: feeding, below). At about 14 d old, young are mobile and leave nest for nearby branches, gathering together so that individuals cannot be assigned to a nest (group size not reported; Bjork and Powell 1994).

Brooding

Little information. Probably initiated immediately after hatching, since chicks are semialtricial. Both parents brood (Palmer 1962). No information on duration, rhythm, or specific roles and behavior of parents. Once chicks are capable of thermoregulation (age unknown), no information on guarding by parents; young ≥1 mo old are left alone at nest while parents away feeding (Bent 1926).

Feeding

Figure 5 . Both parents feed chicks directly by regurgitation; young insert bill into side of adult’s open bill at base and down into throat; feed without assistance after about 1 wk old (Allen 1942, 1962). Parents help new hatchlings feed by grasping chick’s bill, placing chick’s head and bill inside parent’s bill as chick’s head is raised toward parent’s throat (Allen 1962). Feeding bouts last about 10 s each (Chapman 1914 in Bent 1926). Begging Display includes bobbing head and neck up and down; probably similar to head-bobbing of Australian species (Kahl 1983). Young return to nest for feeding after they become mobile (about 2 wk), probably until fledging (see Allen 1962, Palmer 1962). For duration of parental feeding, see Fledgling stage, below. For food of young, see Food habits: diet, above.

Mean number of trips per day by 29 parents with small nestlings in Florida Bay: 2.1 ± 0.7 SD (n = 102) in 1990–1991; 1.4 ± 0.9 SD (n = 72) in 1991–1992 (represents number of feedings by 1 parent; Bjork and Powell 1994). Average time away: 4.6 h ± 1.93 SD (n = 139 trips) in 1990–1991; 4.9 h ± 1.96 SD (n = 24 trips) in 1991–1992. Flight activity at colony is much reduced in afternoon (Ogden 1976). Amount of food delivered/feeding: mean 8.75 g (range 1.90–15.64, n = 6 nestlings, Florida Bay; Powell and Bjork 1989). No information on apportionment of food among young. Negligible differences in weight gain among chicks of different ages may reflect simply good feeding conditions (White et al. 1982, R. Bjork pers. comm.).

Nest Sanitation

No information on defecation; no fecal sacs (i.e., nonpasserine). No information on invertebrate associates of nest.

Carrying Of Young

Not recorded.

Not reported.

Departure From Nest

Fledging estimated at 6 wk of age; feather development complete then, and nestlings are capable of sustained flight (White et al. 1982). No information on manner of departure or time of day. Young remain in colony until about 2 mo of age and are fed by parents during this time (mean age at colony departure = 67 d ± 6.6, n = 7 radio-tagged young, Florida Bay; Powell and Bjork 1990). Similarly, in Galveston Bay, TX, young leave nest at about 5–6 wk but remain in vicinity and are fed by parents for several more weeks (Chaney et al. 1978). Postbreeding dispersal occurs at about 2 mo of age (see Demography and populations: range, below).

Growth

Body mass at fledging estimated to be similar to known adult mass; according to Gompertz growth equation, asymptote is about 1,700 g (White et al. 1982). Fledging body mass is similar among broodmates. For bill, see above. No other measurements reported.

Association With Parents Or Other Young; Ability To Get Around, Feed, And Care For Self

Young congregate and feed in shallows around colony site for a few weeks after fledging until dispersal; continue to beg and be fed by parents (Allen 1942, 1962). Adults returning with food may be pursued by many youngsters, indicating that nest site no longer serves as exclusive rendezvous for feeding. Allen (1962) noted young birds near independence following adults (possibly parents) heading in direction of more distant feeding grounds. Little information on abilities. Young feed by Head Sweeping like adults (Allen 1962); no data on capture rates or handling. No evidence for close association of parents and young after dispersal from colony; flocks of juveniles observed during dispersal period (Robertson et al. 1983). No information on association between broodmates.

Very little information from independence to first breeding; see Demography and populations: measures of breeding activity; life span and survivorship; and range, below. Immatures are present at colony sites during breeding season (Allen 1942).