A detailed summary of knowledge regarding reproductive ecology of the Great Black Hawk is provided in Gerhardt et al. (2012).
Breeding is reported December to May in southern Central America; June to November in n Venezuela and Suriname; October onwards in northern Argentina (Ferguson-Lees and Christie 2001). In southeastern Brazil, nest building begins in August and September; incubation takes place in September and October; and young fledge in November and December (Carvalho Filho et al. 2006).
Copulation and nest-building observed in March in Guatemala (Seavy and Gerhardt 1998).
Nest site microhabitat/site characteristics
In a nest study in Tikal, Guatemala, nests (n = 7) were constructed in Bajo or Scrub Swamp Forest of low canopy, usually less than 15 m tall, broken by large emergent trees, in which Great Black Hawks nested. These trees included Honduras Mahogany (Swietenia macrophylla: 2 trees), Black Olive (Bucida buceras), Hormigo (Platymiscium yucatanum), Kapok (Ceiba pentandra), and Black Cabbage-bark (Lonchocarpus castilloi). Average tree height was 29 ± 4 m (range = 22–35 m) and 120 ± 81 cm in diameter (Gerhardt et al. 2012). In Argentina, Great Black Hawk has been reported to construct nests on man-made structures such as telephone and high-tension poles (Olrog 1985).
In Tikal, Guatemala, nests are built of dry sticks and lined with green leafy twigs, which the adults replenish occasionally throughout the incubation and nestling periods (Gerhardt et al. 2012).
Structure, Composition Matter and Dimensions
In Tikal, Guatemala, nests are built 21–30 m above the forest floor (mean 25 ± 5 m, n = 7) in a variety of trees of 22–35 m high (mean 29 m ± 4 m; Seavy and Gerhardt 1998). Nest typically platform-shaped (Carvalho Filho et al. 2006, Grossman and Hamlet 1964), but sometimes described as deeply cupped (Smithe 1966, Brown and Amadon 1968, Ferguson-Lees and Christie 2001). Six of seven nests in Tikal, Guatemala, were platform-shaped (Seavy and Gerhardt 1998). A nest in the eastern Chaco of Argentina, located at 13 m from the ground, had an external diameter of 80–130 cm and an internal diameter of 35–45 cm, height of 30 cm and a depth of 15 cm (Di Giacomo 2000).
Clutch size typically one, rarely two eggs. All 27 egg sets collected in Venezuela (n = 7), Argentina (n = 18) and Trinidad (n = 2) were single-egg clutches, indicating that this is the norm (Gerhardt et al. 2012), although Martin et al. (1966) report an observation of a family group of four from Tamaulipas, Mexico.
Eggs white with some brown spotting, on average 67.8 x 51.9 mm (n = 5) for urubitinga (Carvalho Filho et al. 2006). Egg of ridgwayi from western Panama described as slightly ovate in shape, dull white with scattered, tiny, irregular, brownish specks; size 59 x 47.5 mm (n = 1) (Hartman 1966). In Tikal, Guatemala, laying dates ranged from late March to early May (Gerhardt et al. 2012).
Seavy and Gerhardt (1998) report an incubation period of 40 ± 2 d. Both adults incubate, although females much more than males (Gerhardt et al. 2012). During 57 hr of observation over a five day period during incubation, no prey transfers at the nest were observed, suggesting that both adults met their foraging needs while off the nest (Gerhardt et al. 2012).
In the early stages of chick development after hatching, the female remains on the nest to protect the chick from sun and predators, while the male brings food directly to the nest or to a nearby tree (Gerhardt et al. 2012).
Nestling phase was observed June and July in Tikal, Guatemala (Gerhardt et al. 1993). One young in Tikal, Guatemala, made its first flight at 56–61 days after hatching, and they estimate that it fledged when it was 65–70 days old (Gerhardt et al. 2012). In Argentina, one young fledged close to 60 days, and another young from another nest reached the "branching" stage (on branches close to the nest, ready to fledge) at 60–66 days of age (Di Giacomo 2000).
Gerhardt et al. (2012) report a lengthy post-fledging dependency period for Great Black Hawk in Tikal, Guatemala. One juvenile was fed nearly eight months after fledging, and another remained within 500 m of its nest and dependent on parental care up to 12 months after fledging, when observations ended. Di Giacomo (2000) reports a similar lengthy dependency for juveniles in Argentina, where a juvenile of 7.5 months of age remained close to the nest and its parents.