Breeding

Pair Formation

Breeding chronology for C. c. rufa poorly known. Other races typically arrive unpaired in breeding areas in late May–early Jun; arrival dates vary with snowmelt conditions (Tomkovich and Soloviev 1996). Simultaneous arrival of male and female C. c. islandica noted on Ellesmere I. coast during late May–early Jun, followed by movement into inland nesting habitats within 1–2 d (Parmelee and MacDonald 1960, Portenko 1981). Males arrive on territory before females (Whitfield and Brade 1991). Individuals scatter over the tundra on day of their arrival (Whitfield and Brade 1991). Pairing occurs within 1–2 d (sometimes 1–2 h; Whitfield and Brade 1991) of female arrival. No quantitative information on mate fidelity between years or duration of courtship between reunited mates versus new mates (but see Tomkovich and Soloviev 1994, Whitfield and Brade 1991).

Nest-Building

See Behavior: sexual behavior, above.

First/Only Brood Per Season

Figure 5 . On Ellesmere I., laying by islandica begins mid-Jun, about 2 wk after arrival; mostly completed before 1 Jul (Nettleship 1974). In 4 study nests in n. Ellesmere I., hatching between 12 and 20 Jul; dates of 4 nests on w.-central Ellesmere were 3–13 Jul (Parmelee and MacDonald 1960); on the basis of similar hatching dates, laying dates evidently are similar in Russia (A. Birula in Pleske 1928), but slightly earlier (first week of Jun) on Wrangel I. (Portenko 1981).

Second Brood Per Season

Not known to lay >1 clutch.

Testes evidently are close to maximum size (13 × 8.5 mm) at time of arrival on breeding grounds (Parmelee and MacDonald 1960) or soon thereafter, with recrudescence beginning before or early in egg-laying period of females and continuing through incubation and hatching periods (Nettleship 1974). Cloacae of females also are in enlarged condition during arrival period, and they remain distinctly larger than those of males until after eggs are laid (Tomkovich and Soloviev 1996). Ova of arrival females are somewhat enlarged (largest in 8 collected females was 6 mm in diameter; Parmelee and MacDonald 1960). Other ova measurements (range 3.5–6.5 mm) come from 3 females of unknown breeding status collected during and after principal laying period on Ellesmere I. (Nettleship 1974). A Siberian female collected early in laying period (5 Jun) had an ovary 25 mm long and an egg follicle with 24-mm diameter. This female, like other knots at same season, had appreciable accumulations of subcutaneous fat (Portenko 1981).

Selection Process

In Russia, male (and less so, female) knots are site-faithful with probably most surviving birds returning to the same breeding locality every year (Tomkovich and Soloviev 1994). Nest locations apparently are strongly influenced by snow cover at time of return.

Microhabitat

Seven nests at Camp Hazen, Ellesmere I., were scraped into main body or edges of dryas patches (Nettleship 1974); nests on Fosheim Peninsula, w. Ellesmere I., were similar but tended to be in low, spreading vegetation on hummocky ground, and contained more twigs and moss (Parmelee and MacDonald 1960).

Site Characteristics

During recent studies on Southampton Island (Niles 2000), 7 knot nests were found in barren tundra with rocky ridges in close proximity to wetlands. All nests were on rocky substrates with low lichen patch density, on the east or north side of ridges (which are snow-free on earlier dates than the south and west slopes).

Construction Process

Males prepare 3–5 nest scrapes in their territory before females arrive. Remove vegetation by pulling with bill, and by sitting in nest depression and pivoting on breast while kicking backward with feet.

Structure And Composition

At Camp Hazen, Ellesmere I., nests were cup-shaped depressions, often with well-defined rims, lined with dried leaves, grasses, and sometimes lichens (Nettleship 1974). Red Knot nests were distinctive from the more shallow nests of turnstones nesting in same area. A. Birula (in Pleske 1928) noted that the lichens used for nest-lining were of a species forming hollow tubes, thus providing an excellent insulating layer above the cold ground.

Dimensions

Average 11.9 cm across, 11.1 cm wide, and 4.4 cm deep (n = 7; Nettleship 1974).

Microclimate

No data. On Fosheim Peninsula, w. Ellesmere I., nests principally at elevations below 200 m, often in damp habitats (Parmelee and MacDonald 1960). At Hazen Camp, knots nested in drier sites, but not far from damp habitats. Pleske (1928) noted that nest sites often were in higher relief where little winter snow accumulated and/or where spring melt was earliest.

Nonbreeding Nests

Unknown, except as described above.

Shape

Subpyriform or ovate (Nettleship 1974).

Size

Forty-two eggs (location not given) averaged 43.1 × 29.6 mm (Bent 1929), virtually the same as Nettleship (1974) found for 23 eggs (43.2 [range 41.5–45.0] × 29.6 mm [range 28.9–30.7]) from Ellesmere I.

Mass

Estimated 19.0–19.5 g (Schönwetter 1963), roughly 15% of female body mass.

Color

Colors highly variable within and between clutches. Ground color from a light, faint olive to olive-buff or deep olive-buff; markings include spots (blotches where spots overlap) of dark olive-brown, sepia, or almost black, denser at larger end (Bent 1929).

Surface Texture

Slight gloss (Bent 1929).

Eggshell Thickness

No data.

Clutch Size

Mean clutch size for 8 nests on w. Ellesmere I. was 4 eggs ± 0 SD (Parmelee and MacDonald 1960); at Camp Hazen, ne. Ellesmere, 3.71 eggs ± 0.49 SD (n = 7; Nettleship 1974).

Egg-Laying

Few nests found before completion of clutch. In 2 instances in which nests were found between laying of third and fourth eggs, interval between the two was 2 d (Nettleship 1974). Other shorebirds are known to have longer interval between third and fourth eggs (Paulson 1996) than between earlier eggs of a clutch. Nettleship (1974) estimated that the entire 4-egg clutch of Red Knots required 6 d to complete.

Onset Of Broodiness And Incubation In Relation To Laying

No data. Individuals readily leave nests during early incubation stage but are very tenacious incubators in later stages (A. Birula in Pleske 1928).

Incubation Patches

No brood patches on 5 males and 8 females collected on 1 Jun on w. Ellesmere I., but a female on 19 Jun had bare brood patches; both males and females collected during incubation had bare brood patches (Parmelee and MacDonald 1960).

Five adults (sex unknown) captured in Massa-chusetts during mid-Aug 1972 showed clearly discernible, refeathering brood patches; one of 2 examined in mid-Sep had recognizable vestiges of brood patches (BAH). Red Knots in Waddenzee in Aug also showed refeathering brood patches (n = about 80; T. Piersma pers. comm.).

Incubation Period

Lasts 21.5–22.4 d from last egg laid to last egg hatched (n = 1; Nettleship 1968).

Parental Behavior

Both sexes incubate eggs (Pleske 1928, Parmelee and MacDonald 1960, Nettleship 1968), with each sex participating about equally (T. Piersma pers. comm.). “Off-duty” par-ents join in flocks with other adults to forage in nearby wetlands (Niles 2000). During early incubation, no active defense of nesting areas against humans; adults simply fly long distances away from nest when flushed, sometimes taking several hours to return (Parmelee and MacDonald 1960). During late incubation, adults sit tight when approached by humans; sometimes can be touched or gently lifted up from clutch (Parmelee and MacDonald 1960).

Hardiness Of Eggs Against Temperature Stress; Effect Of Egg Neglect

Adults stay away from nests for long periods when disturbed during early incubation (Parmelee and MacDonald 1960); 3 of 4 pipped eggs hatched after being unattended for several hours in near-freezing weather (Parmelee and MacDonald 1960).

Accounts from Ellesmere I. in Canada (Parmelee and MacDonald 1960, Nettleship 1974), Greenland (Salomonsen 1950), central arctic Siberia (A. Burila in Pleske 1928), and Wrangel I. (Portenko 1981) all report generally synchronized hatching. Blunt end of all 4 eggs cracked 3 d before a clutch hatched (Nettleship 1968). In one clutch, all 4 eggs hatched within 14 h (Nettleship 1974).

Whitfield and Brade (1991) observed eggshell removal once when a male carried shell from a newly hatched egg 60 m away from nest. Of 6 nests studied, fragments of a single egg remained in 1 nest.

Young leave vicinity of nests almost immediately after hatching and begin to move to new locations; broods can move several meters within 14 h of hatching (Nettleship 1974). Their extremely cryptic plumage and “freezing” response to vocalized parental alerts make following of development and behavior difficult.

Condition At Hatching

Downy plumage well developed at hatching (see Appearance: molts and plumages, below). A. Burila (in Pleske 1928) noted that newly hatched young recognize and respond to parental alarm calls.

Growth And Development

No published measures of growth and development, in part because broods are extremely cryptic and difficult to follow. First hatching of eggs on Southampton I. was 13 Jul (Niles 2000) and on w.-central Ellesmere I. was during first week of Jul (Parmelee and MacDonald 1960). By middle of Jul, some young weighed 50 g; by 22 Jul, nearly able to fly; and most fledged by end of month. Fledging period estimated at 18 d (Parmelee and MacDonald 1960).

After hatching, families quickly move away from higher nesting terrain to lower, wetland habitats. Although there is conflicting information (e.g., Parmelee and MacDonald 1960), typically only male parent stays with brood once it leaves nest (Whitfield and Brade 1991). Often families of knots and turnstones group together as mixed flocks in favored locations.

Brooding

Male parents gather young to be brooded by adopting low, crouched posture and fluffing breast-feathers while uttering characteristic calls (see Sounds: vocalizations, above; Whitfield and Brade 1991). No information on how long young are brooded.

Feeding

No information. Feeding by parents not observed; probably similar to that of other sandpipers—i.e., young almost certainly feed themselves.

Defense Of Broods

Male leads brood by walking or flying ahead and then standing on raised ground in alert posture while calling softly (Whitfield and Brade 1991).

A. Burila (in Pleske 1928) noted that adults defend older young differently than they do eggs and small chicks (in which case they vigorously feign injury; see Behavior: predation, above). After vocal alarms, adults approach human intruder and then fly directly away, barely skimming just above ground.

Male parents fly up at jaegers and give chase while uttering both alarm calls and Chatter Yodels (see Sounds: vocalizations, above), with chase ending when jaeger is 50–100 m away from chicks (Whitfield and Brade 1991). If a jaeger lands close to chicks, male may flutter at jaeger’s head.

Duration Of Parental Care

Parental care by females typically ends at hatching (Whitfield and Brade 1991). However, A. Burila (in Pleske 1928) describes what was believed to be a family of 4 flying juveniles and 2 parental adults in Siberia; in contrast, all late-season adults collected on Ellesmere I. while attending broods were males (Parmelee and MacDonald 1960). Seventeen broods <10 d old were attended only by male, and 3 of 4 broods >14 d old were not attended by an adult (Whitfield and Brade 1991).

Unreported.

Unreported.

See Young birds, above.

See Young birds, above.