Breeding: Nesting appears to coincide with the onset of the rainy season and extends from October through December, while no nests have been discovered between January and September to date (Cahill et al. 2008). Both parents take turn incubating the eggs in an open-cup shaped nest, and one parent oftentimes acts as a sentinel while the other forages.
Nest Construction: Nests are supported by branches and are secured by twigs and grasses, which are interwoven with supporting branches. Three collected nests had a mean (± SD) mass of 201 ± 44 g, an external height of 9.5 ± 0.7 cm, and a width of 20 ± 1 cm (Cahill et al. 2008). The external portion of nests is composed of twigs and sticks interwoven with soft plant material, while the interior lining contains moss, thin strips of Polylepis bark, feathers and sheep wool (Cahill et al. 2008). Nest material consisted mostly of Polylepis parts, again underlining the integral tie between these two species. However, Cahill (2008) also notes that 21 additional species of plants were used in smaller quantities, the majority of which were mosses.
Nesting site: All observed nests have occurred in the interior of Polylepis woodlands, while Giant Conebills seem to prefer substrate trees with an average (± SD) height of 3.16 ± 0.56 m. The average height of nests is 2.43 ± 0.25 m, and nests were well camouflaged inside dense foliage (Cahill et al. 2008).
Eggs and Incubation: Two eggs were found in the same nest and described as white with tiny brown specks, with a mean (± SD) weight of 3.0 ± 0.2 g. The incubation period is unknown, but both parents have been observed taking turns incubating (Cahill et al. 2008). Clutch size is generally two, although nests have been observed with one and three hatchlings as well.
Hatchlings: Both parents feed hatchlings, while hatchlings fledge 14-16 days post hatching (n=11) (Cahill et al. 2008). O. fraseri appears to forage in groups that are presumed to be family based, although the relatedness of these monospecific flocks has not been studied. Cahill et al. (2008) observed juveniles with both adults 5 weeks after hatching, but juveniles from the same study had been observed in non-familial monospecific flocks within the same period.