SHORT COMMUNICATIONS ORNITOLOGIA NEOTROPICAL 20: 147–151, 2009 © The Neotropical Ornithological Society FIRST NESTING RECORD OF THE WHITE-BROWED HAWK (LEUCOPTERNIS KUHLI) FROM THE MADEIRA-PURUS INTERFLUVIUM, BRAZILIAN AMAZONIA, WITH SOME REMARKS ON PLUMAGE VARIATION Guy M. Kirwan 74 Waddington Street, Norwich NR2 4JS, UK. E-mail: [email protected] Primer registro de nidificación de Gavilán de Ceja Blanca (Leucopternis kuhli), del interfluvio Madeira-Purus de la Amazonia brasileña y algunas notas sobre la variación del plumaje. Key words: White-browed Hawk, Leucopternis kuhli, nesting, Brazilian Amazonia, plumage variation. The exclusively Neotropical genus Leucopternis and most widespread of these, the White Kaup, 1847, comprises ten species of Accipi- Hawk (Leucopternis albicollis), are comparatively tridae principally distributed over Middle few compared to any raptor breeding in tem- America and the northern half of South perate regions. The only detailed observations America, although two species are restricted on any member of the genus are those by to the Atlantic Forest region of southeast Draheim & Aguirre (1992) and Draheim South America (Bierregaard 1994, Ferguson- (1993), who reported on six nests of L. albi- Lees & Christie 2001). It is a generally poorly collis that they discovered in Guatemala, and known and apparently polyphyletic collection Gelis & Greeney (2007), who described a of raptors (Amaral et al. 2006); three of the nesting record of Barred Hawk (L. princeps) in genus were deemed to be high research prior- northeast Ecuador. To date, nothing is known ity by Parker et al. (1996), and, of the rest, five concerning the breeding of the Slate-colored were stated to be of medium priority by the Hawk (Leucopternis schistaceus) of Amazonia, same authors. BirdLife International (2008) the Plumbeous Hawk (L. plumbeus) of eastern currently treats one species as Endangered, Panama to northwest Peru, the Black-faced another as Vulnerable, and two as Near Hawk (L. melanops) of the Guianan Shield and Threatened. Furthermore, breeding data for eastern Amazonia, the White-browed Hawk the entire genus are notoriously few. In their (L. kuhli) of Amazonia, the White-necked general surveys, Bierregaard (1994) and Fer- Hawk (L. lacernulatus) of eastern Brazil, and guson-Lees & Christie (2001) were able to list the Mantled Hawk (L. polionotus) of the Atlan- nesting information for just four species, and tic Forest region. Here I present the first even the available data for the best known breeding data for L. kuhli, which species is 147 KIRWAN generally considered to range from lowland Nest. In the late afternoon of 18 December I eastern Peru south of the Amazon and discovered an inconspicuous nest just 75 m extreme northern Bolivia through north- from the lodge (and c. 50 m from the central Brazil south of the Amazon to eastern favoured tree), and directly above a narrow Pará (Ferguson-Lees & Christie 2001). foot trail. In fact I had walked the same trail without observing the nest on the previous STUDY AREA afternoon. Indeed, the nest was only discov- ered through the chance discovery of an adult During 17 to 23 December 2007, I conducted L. kuhli perched c. 10 m up on the near-verti- ornithological fieldwork at Tupana Lodge, in cal trunk, in the upper midstory, of a canopy the Madeira–Purus interfluvium, Amazonas height tree. After I had watched the bird for state, Brazil (04°04’S, 50°40’W). Tupana lies c. over 10 minutes the bird flew 5 m to, and 150 km south of Manaus on the BR-319 high- landed on, the previously unseen nest, where- way to Porto Velho, the capital of Rondônia upon it settled as if incubating, or less likely state. Particularly to the east of the road, the brooding (no young was audible or visible in lodge clearing is surrounded by relatively low, the nest), at which point the adult was only closed-canopy, terra firme forest on rather just visible above the nest’s rim. sandy soils with some low-lying and poorly The nest was sited at approximately 15 m drained areas that are seasonally flooded, and above ground, i.e. within the subcanopy of a a canopy height of c. 20 m, though taller canopy height tree, in an area of the forest emergents reach c. 30 m. Large, natural tree- with a particularly dense understory and some fall gaps, some of them > 0.5 ha, are com- palms. Two branches within a major horizon- mon. The understory is dominated by large tal fork of the tree supported the hawk’s nest, areas of dense c. 2 m-tall palms and in places which was an untidy, near-hexagonal structure there are small, less than 2 m-wide, streams. constructed of sticks and some smaller twigs, and ‘adorned’ with a handful of dead leaves RESULTS AND DISCUSSION on its outer walls. From ground level it was impossible to evaluate whether the nest con- The White-browed Hawk was seen on most tained any lining, as has been described for L. days, usually from the lodge itself, where an albicollis (Draheim & Aguirre 1992, Ferguson- ‘upper observation’ deck that is almost at the Lees & Christie 2001). Some sticks were up to same height as the surrounding canopy per- 0.5 m long, protruding from the main walls, mits privileged views of the surrounding area. and c. 6 cm in circumference, and the main One bird, apparently always the same based mass of the nest (i.e. not including parts of on bare-parts coloration (see below), was reg- those twigs that protruded significantly from ularly seen perched, sometimes for quite long the whole) was estimated to have a width of periods of up to 45 minutes, in a particularly 40 cm at the widest point, and a depth of c. 20 tall emergent during the first two hours of cm. These estimated dimensions are smaller daylight. Such behaviour is typical of most than the measured sizes of L. albicollis nests in Leucopternis, including L. kuhli (pers. observ. at Guatemala (Draheim & Aguirre 1992, Dra- Alta Floresta, Mato Grosso, Brazil). The bird heim 1993), which is unsurprising given that was never heard to vocalise, although both the latter is a somewhat larger species (wing this species and L. melanops frequently do so length of female L. albicollis ghiesbreghti 362– when apparently advertising their territories 388 mm vs. female L. kuhli 214–237 mm: Fer- (A. Whittaker pers. com. 2008). guson-Lees & Christie 2001), but larger than 148 KIRWAN those of L. princeps in Ecuador (Gelis & that the species can be quite catholic in its Greeney 2007). The nest was lower off the choice of nesting sites, including on a rock ground than any of the six nests of L. albicollis ledge beside a waterfall. Draheim (1993) con- found by Draheim & Aguirre (1992), which sidered that the young at a nest of L. albicollis might reflect the different hunting strategy in Guatemala would have fledged at the start postulated for L. kuhli (Ferguson-Lees & of the wet season, and young were being fed Christie 2001) but could equally be reflective at a nest in northeast Ecuador during the wet of the overall stature of the different forests. season (Gelis & Greeney 2007). It is impossi- In late August 2008, A. Whittaker (pers. com. ble to know the state and development of the 2008) found an Ornate Hawk-Eagle’s (Spizae- L. kuhli nest I observed, but December is tus ornatus) nest with a fully-grown young in already about two months into the wet season the same general area. The presence of this in central Amazonia, and there were regular, species, and the sympatric and larger White heavy and prolonged rain showers every day, Hawk, might have forced the L. kuhli to be usually in the early afternoon, during my stay more secretive than usual in choosing its nest at Tupana. The globally threatened Grey- site. I deliberately refrained from visiting the backed Hawk (L. occidentalis), of western vicinity of the nest again in order to minimize Ecuador and extreme northwest Peru, is also any disturbance, especially as there were no assumed to breed in the wet season, although other visitors at the lodge. there have been no published observations of a nest to date (Ferguson-Lees & Christie Comparison with previous data. Unlike those 2001), except in the grey literature (Vargas nests of L. albicollis reported from Costa Rica 1995). and Trinidad (Stiles and Skutch 1989, ffrench 1991), the nest of L. kuhli was not con- Plumage variation. Amaral et al. (2007) discussed structed on or close to any bromeliads or and clarified the immature plumage of L. other epiphytes, but it was nonetheless dis- kuhli, but my observations at Tupana of two tinctly inconspicuous, even after it had been birds suggest either more complex age-related located. Stiles & Skutch (1989) considered the or, previously unidentified, sex-related varia- same to be true of nests of L. albicollis. A. tion. The bird attending the nest had very Whittaker (pers. com. 2008) mentioned a nest bright bare-parts colorations, with the orange (stage unknown) found north of Manaus, cere and tarsi having an almost pinkish cast, Brazil, on 21 February 1987, sited c. 35 m up and a single centrally positioned white tail in an emergent tree’s fork, 5 m from the top, band, whilst the other bird had three paler, at the edge of a 100-ha reserve. At least one less bright white, and narrower tail bands, and nest of L. princeps had been ‘concealed’ by epi- much paler, plain yellow bare-parts colora- phytes (Stiles & Skutch 1989). Greeney & tion, as well as apparently overall browner, Nunnery (2006) observed an adult L.