Breeding

Pair Formation

No information.

Nest-Building

Kaua‘i ‘Ö‘ö. May have begun early Mar, but probably mostly in Apr and May (Munro 1944a Munro, G. C. (1944a). Birds of Hawai'i. Honolulu: Tong Publ. Co. Close , J. L. Sincock unpubl.; Figure 4).

Hawai‘i ‘Ö‘ö. Wilson (Wilson 1890a Wilson, S. (1890a). On some of the birds of the Sandwich Islands. Ibis 2:170-196. Close ) speculated breeding season to be May–Jun. Perkins (Perkins 1893b Perkins, R. C. L. (1893b). Notes on collecting in Kona, Hawaii. Ibis ser. 6 5 (1):101-112. Close ) described an observation by others who saw an ‘ö‘ö enter a hole 2 or 3 times that was high in an ‘öhi‘a tree about mid-Jun, at about same time he had collected a recently fledged bird. Henry W. Henshaw, between 1900 and 1902, collected 4 adults (males, BPBM 3600, AMNH 193378; females, AMNH 193379, 193380) in Feb and Mar and examined their gonads, noting breeding or nonbreeding condition on specimen labels. Eight fledged hatch-year birds collected in Jun–early Sep were also examined (PWS). Thus, nesting season appears to have been late Mar–late Jun.

Broods Per Year

No information.

Selection Process

No information.

Microhabitat

Kaua‘i ‘Ö‘ö. Three nest sites known, all from Alaka‘i Swamp, 1,300–1,340 m elevation, on steep slopes near small streams (J. L. Sincock unpubl., PWS). Cavity-nester in natural hollows of large ‘öhi‘a trees. Height of cavity entrance 8–12 m (n = 3); nest tree height 17–24 m (n = 3; J. L. Sincock unpubl., PWS). See also Habitat, above. Only 1 nest, from 1971, was examined and measured. Cavity, a triangular hole, was about 40 cm deep and 30 cm wide, and was flat at bottom, with small fern growing from lower lip of cavity entrance (J. L. Sincock unpubl.).

Hawai‘i ‘Ö‘ö. Possible cavity-nester. Perkins (Perkins 1893b Perkins, R. C. L. (1893b). Notes on collecting in Kona, Hawaii. Ibis ser. 6 5 (1):101-112. Close : 109) stated, “I strongly suspect it builds in holes in the trunks of the lehua -trees [‘öhi‘a] at a great elevation [height], as my native assistant and a white boy, who was with him at the time, assured me that they saw one of these birds enter such a hole two or three times, but that they could not possibly climb up, though they made the attempt. This was about the middle of June—at the same time I obtained the young, which certainly had not been long out of the nest.”

Construction Process

No information.

Structure And Composition Matter

Kaua‘i ‘Ö‘ö. On 7 Aug 1971, after young fledged, J. L. Sincock (unpubl.) collected an open-cup nest (now at BPBM) that was inside a natural tree cavity. Bottom of cavity was covered with 8 cm of fine dry litter, with nest cup on top against one wall. Nest elliptical, consisting of closely woven threadlike vegetation; mostly grasses (mainly leaf veins, but some stems) and liverworts (several species; mainly leafless stems, though some still bore fine, scalelike leaves) in approximate ratio 1:1. Other components totaling <10% consisted of a few small twigs (2 mm in diameter) of pükiawe, fine aerial rootlets of ‘öhi‘a, small chunks of scales and pubescent structures of tree ferns, and lichens (Usnea sp. and others; T. K. Pratt pers. comm., J. L. Sincock unpubl.). A few pieces of ‘öhi‘a bark were on underside of nest cup.

Dimensions

Kaua‘i ‘Ö‘ö. Outside diameter of 1 nest cup 170 × 130 mm; inside, 110 × 65 mm. Thickness of cup lip varied from 10 mm near cavity opening to 45 mm on far wall. Inside cup depth 35 mm (J. L. Sincock unpubl.).

Microclimate

Kaua‘i ‘Ö‘ö. All nest cavities (n = 3) had openings toward west, affording some protection from predominant northeast trade winds (Berger 1972b Berger, A. J. (1972). Hawaiian Birdlife. 2nd edition. University Press of Hawaii, Honolulu, HI, USA. Close , J. L. Sincock unpubl., PWS).

Maintenance Or Reuse Of Nests, Alternate Nests

Kaua‘i ‘Ö‘ö. Same nest cavity used in 1972 and 1973 (Berger 1972b Berger, A. J. (1972). Hawaiian Birdlife. 2nd edition. University Press of Hawaii, Honolulu, HI, USA. Close , J. L. Sincock unpubl.) on Halehaha Stream. Lone male was observed at nest site on Halepa‘akai Stream in 1980 and 1983 (PWS). Apparent strong site fidelity.

Nonbreeding Nests

No information.

Kaua‘i ‘Ö‘ö. The only nest examined contained 2 small young of undetermined age (J. L. Sincock unpubl.), so clutch size in this case was at least 2. No eggs of any ‘ö‘ö ever described.

No information.

Kaua‘i ‘Ö‘ö. No information. Sincock did not find eggshell fragments in nest collected in 1971 nor on ground around nest trees in 1971, 1972, or 1973.

Condition At Hatching

Kaua‘i ‘Ö‘ö. Sincock found 2 nestlings of unknown age on 11 Jun 1971 in a nest he had discovered on 31 May. He removed 1 nestling from nest, examined it briefly, and photographed it (see Figure 5); felt second nestling in nest cavity with hand, but did not see it (J. L. Sincock unpubl.). Mass unknown. Measurements taken from photographs: exposed culmen 23 mm, bill width at commissure 28 mm, nostril length 5 mm and width 2.5 mm, eye (front to rear) 4 mm, mean primary and secondary feather lengths 16 mm, claw of middle toe 6 mm, rear of head to tip of bill 44 mm, width of sternal apterium 20 mm, and total length 104 mm. Eyes open slightly. Basal two-thirds of primaries and secondaries in sheath. Very short gray pin-feathers on capital tract; much of remainder of head naked. Down on head and legs light to medium gray. Down on neck, breast, and sides light brown, approaching russet, but gray toward base. Pin-feathers of wings had light-gray sheaths; emergent part of feathers brownish black. Upper back feathers black, with maroon cast. Upper mandible dark gray, tending toward black, with yellow tip, operculum, and nasal groove, and buffy-yellow base; lower mandible and lining of mouth yellow. Base of upper and lower mandibles in rictal region fleshy and flattened, lateral extension greatly exaggerated. Base of lower mandible extends laterally and anteriorly much farther than in upper mandible. Outer lateral edge of upper mandible at base is concave for anterior two-thirds; lower mandible at base is convex throughout, forming smooth arc. Eye dark; tarsus, toes, and digital pads dull black; claws dark gray.

Growth And Development

No information.

Brooding

No information.

Feeding

Kaua‘i ‘Ö‘ö. Both members of pair fed insects, insect larvae, and other invertebrates to young at nest every few minutes throughout day. Often as one adult entered cavity, other adult emerged (Berger 1972b Berger, A. J. (1972). Hawaiian Birdlife. 2nd edition. University Press of Hawaii, Honolulu, HI, USA. Close , J. L. Sincock unpubl.). Short double-note whistle call was given by adults approaching and leaving vicinity of nest cavity (J. L. Sincock unpubl.). No other information.

Nest Sanitation

Kaua‘i ‘Ö‘ö. One nest collected shortly after young fledged contained 3 centipedes (Chilopoda) and trace of fecal material, indicating that adults must remove and carry away the fecal sacs (T. K. Pratt pers. comm., J. L. Sincock unpubl.).

Carrying Of Young

Not reported.

None reported.

None reported.

Kaua‘i ‘Ö‘ö. On 24 May 1973, J. L. Sincock (unpubl.) saw young, having just fledged, perched 6 m from nest, being fed moths and spiders by adults every 1–2 min.

No information.