Solorzano et al. (2000) found that the primary reproductive activities occur when fruits are most abundant. Similarly Wheelwright (1983) noted that breeding in Costa Rica corresponded with the peak of fruiting of Lauraceae trees. Thus, the breeding season falls between March and June, depending on location (Johnsgard 2000). Nesting is delayed in poor fruit years (Wheelwright 1983).
Nests are cavities, excavated in dead trees or stumps by the male and female. They appear like that of a large woodpecker (Skutch 1944). Wheelwright (1983) found the average height in Costa Rica to be 8.8 m in a limb or trunk of a tree. Bowes and Allen (1969) found the average nest height in Guatemala to be 9.5 m. If the same snag was used in a successive year the height of the cavity was lowered to accommodate decay (Wheelwright 1983). Nest cavities generally measure 10 cm at the entrance, with the nest 20 cm back, and a total depth of 30 cm (Bowes and Allen 1969). One pair began excavating five sites in a month before finally selecting one (Wheelwright 1983). Wheelwright (1983) found 43 nest sites in Costa Rica: 74% in forest, 12% in forest or pasture edge, and 14% in snags in the open.
The clutch size of the Resplendent Quetzal is two eggs (Skutch 1944, LaBastille et al. 1972). The few reported single clutch nests may represent incomplete clutches (Johnsgard 2000). Eggs are light blue and subelliptical with a mean of 38.9 mm x 32.4 mm (LaBastille et al. 1972). Nests are not lined, and eggs rest on loose fragments at the bottom of the cavity (Skutch 1944).
In addition to nest building, the male and female share in incubation. Skutch (1944) observed one nest that was incubated for 17-18 days, while Wheelwright (1983) observed two nests that were incubated for 18-19 days. Skutch (1944) and LaBastille et al. (1972) both observed double shifts with the female incubating over the night and the middle of the day and the male incubating in the morning and evening. In total the male sits six to seven hours each day (Skutch 1944). No nest exchange ritual is employed (LaBastille et al. 1972).
Like other young trogons, Resplendent Quetzal young are born with no down and tightly closed eyes (Skutch 1944). At two days they begin to have pin feathers, and at seven days the contour feathers are breaking from their sheaths. At eight days their eyes open. At ten days the flight feathers (remiges and rectrices) pushed out from the sheaths. On their fourteenth day the young quetzals were well-covered in feathers. At eighteen days green feathers are apparent.
Both parents are involved in provisioning of the young. Initially they spent long periods brooding with infrequent provision of food; later they alternated bringing food every hour (LaBastille et al. 1972). Among the trogons, the Resplendent Quetzal has the best studied nestling diet (Collar 2001). Wheelwright (1983) observed that the male brought more food items than the female and more were insects. The female brought more fruits. Wheelwright also observed shorter return times for parents providing fruits than animal items. Yet, even late in the nestling period, over half of the items give to the nestling were insects or lizards. At one nest, Skutch (1944) found that at sixteen days the mother stopped brooding her chicks in the night and began feeding them less. In the last 5-6 days, the entire duty of feeding the young was left to the male. Chicks fledged at one disturbed nest at 23 days and at 29 days at two others (Skutch 1944).
Resplendent Quetzals raise two clutches each year (Skutch 1944, Bowes and Allen 1969, Wheelwright 1983). Wheelwright (1983) indicated nest failure to be high (67-78%), but there is no information about brood parasitism. All three nests studied by LaBastille et al. (1972) and the two studied by Bowes and Allen (1969) failed. For more information on nest predation, see Predation.