Australian Field Ornithology 2020, 37, 129–131 http://dx.doi.org/10.20938/afo37129131

On the dark morph of the Pygmy Eagle Hieraaetus weiskei

S.J.S. Debus

Zoology, University of New England, Armidale NSW 2351, Australia Email: [email protected]

Abstract. The juvenile dark morph of the Pygmy Eagle Hieraaetus weiskei remains essentially undescribed, as here I re- identify a published photograph of one such alleged individual cited in an early paper on the morphs of the allospecific Little Eagle H. morphnoides. The problem photograph illustrates the potential for confusion between the dark-morph Pygmy Eagle (or indeed Little Eagle) and the juvenile Brahminy Kite Haliastur indus (Australasian subspecies H. i. girrenera).

The Pygmy Eagle Hieraaetus weiskei, endemic to New Attempts to source a photograph of an in-flight, genuine Guinea and the Moluccas, is now given specific rank dark-morph Pygmy Eagle proved unsuccessful. Google separate from the Little Eagle H. morphnoides. Like the images of an alleged [uniformly dark] adult Pygmy Eagle four other species in the revised genus, validly separate from Wapenamanda, central PNG, in June 2019 by Neil from Aquila, the former is plumage-polymorphic with light Bowman/Alamy Stock Images, and being sold online as and dark morphs (e.g. Ferguson-Lees & Christie 2005; such, were actually of a dark-plumaged Papuan Gjershaug et al. 2009; Clark 2012; Lerner et al. 2017). Circus spilothorax (either a juvenile or possibly a dark The Pygmy Eagle is very poorly known in all aspects of morph). This diagnosis was readily apparent from the ‘five- its biology (e.g. Bishop et al. 2016; Debus 2017). Here fingered’ primaries (rather than six), short owl-like head and I correct an error in Debus (1989) on the identity of a facial ruff, unbarred wings and tail, and bare yellow tarsi. supposed juvenile dark-morph Pygmy Eagle. Several other Google images/eBird gallery photographs mislabelled (at the time of writing) as a Pygmy Eagle Debus (1989) interpreted the photograph in Pruett-Jones were of a juvenile Brahminy Kite, distinguishable on the & Pruett-Jones (1981), captioned ‘Whistling Kite’ [Haliastur sphenurus], as a juvenile dark morph of the Pygmy Eagle. above-mentioned characters as well as the small feet and The small-format, slightly ‘soft’ colour image, as printed bare tarsi. These image labels are in the process of being from a slide, created (along with the angle and the sunlit corrected (J. Eaton pers. comm.). head) the illusion of a yellow gape, tawny crown and yellow An image of a dark Little Eagle in similar pose to feet, and seemed to show the proportions and characteristic Figure 1 is substituted here (Figure 4) for a dark Pygmy hunting posture of a Little Eagle. The printing process also Eagle, as the dark morphs of the two eagle species are created ‘warmer’ tones than in the original slide. very similar ventrally (cf. Figure 2 of Gjershaug et al. 2009). A study of the morphs of the Little Eagle (Larkin & Debus Figure 4 herein emphasises the overall shape, barred 2020) prompted a review of Debus (1989), and research into underwings and tail, feathered tarsi and larger feet of the the Pygmy Eagle (Debus 2017) prompted an examination Eagle, compared with the Brahminy Kite. of the original photograph that was reproduced in Pruett- This episode illustrates the difficulty of identifying the Jones & Pruett-Jones (1981). That slide (Figure 1) and Pygmy Eagle from the Haliastur kites, arising largely from three others taken at the time (Figure 2, Figure 3), courtesy the incomplete knowledge of the Pygmy Eagle and its of the photographer, when enlarged on-screen revealed plumages. The morph ratios of the Pygmy Eagle are almost the to be a juvenile Brahminy Kite Haliastur indus [the undocumented (5 light: 1 dark in museum specimens, forested ‘canyon’ background in the published photograph, and 11 light: 1 dark in field sightings: Gjershaug et al. inferred to be from Wau in the eastern uplands of Papua 2009), although the dark morph is readily observable in New Guinea (PNG), notwithstanding]. The features the Moluccas (J. Eaton pers. comm.) and the species is that distinguish the bird as a juvenile Brahminy Kite (of now known to occur on the Bird’s Head in West Papua Australasian subspecies H. i. girrenera), as shown in the (Gjershaug et al. 2009). There are no detailed descriptions digitised photographs (Figures 1–3), include wing shape of the juvenile plumage of either morph. These aspects, (more S-curved trailing edge), tail shape (rather short), along with the biology and ecology of the species, warrant and lack of barring in the wings and tail, compared with further study. the Pygmy Eagle (e.g. see photographs of the light-morph Pygmy Eagle in Debus 2017). Other, more subtle plumage features include the two-toned tail (paler basal half), pale Acknowledgements belly demarcated from the dark breast, and unbarred I thank Steve Pruett-Jones for lending me the original slide primary ‘fingers’ of the Kite. Thus, the juvenile dark morph photographs of the problematic New Guinea bird, and Lucy of the Pygmy Eagle remains to be described, although a Farrow and Chris Pavey for comments on a draft. I thank Bill dark-morph female specimen shown in Gjershaug et al. Oates (University of New England Heritage Centre) for scanning (2009) was said to be ‘immature’ (but may not be a first- the slides, and David Whelan for the Little Eagle photograph. I year bird on the features visible in the photographs of also thank David Bishop, James Eaton, Markus Lagerqvist, dorsal and ventral views). Markus Lilje and Lars Petersson for responding to requests for 130 Australian Field Ornithology S.J.S Debus

Figure 1. The original photograph in Pruett-Jones & Pruett- Figure 2. The same bird as in Figure 1 in a different pose, Jones (1981), misidentified by Debus (1989) as a juvenile same site and occasion, Madang Province, Papua New dark-morph Pygmy Eagle. Photo: Steve & Melinda Pruett- Guinea, 1980. Photo: Steve & Melinda Pruett-Jones Jones

Figure 3. Additional photographs of the same bird as in Figures 1 and 2 taken at the same time against the sky, showing it unequivocally to be a juvenile Brahminy Kite. Photos: Steve & Melinda Pruett-Jones

photographs, and I acknowledge the late Jon Hornbuckle for his photographic contributions to relevant publications (Bishop et al. 2016; Debus 2017). I owe the origin of this pursuit to the late Graham Debus, who facilitated my trip to PNG in 1984 and thus the finding of said photograph (Figure 1) in the in-flight magazine.

References Bishop, D., Diamond, J., Hornbuckle, J. & Debus, S. (2016). New breeding, distribution and prey records for the Pygmy Eagle Hieraeetus weiskei. Australian Field Ornithology 33, 224–226. Clark, W.S. (2012). The eagle genus Hieraaetus is distinct from Aquila, with comments on the name Ayres’ Eagle. Bulletin of the British Ornithologists’ Club 132, 295–298. Debus, S. (2017). Australasian Eagles and Eagle-like . CSIRO Publishing, Melbourne. Debus, S.J.S. (1989). Plumages and moult of the Little Eagle. Australian Bird Watcher 13, 103–113. Figure 4. Adult dark-morph Little Eagle, substituted for Ferguson-Lees, J. & Christie, D.A. (2005). Raptors of the World, an image of the very similar dark-morph Pygmy Eagle, A Field Guide. Helm, London. contrasting the overall shape, barred wings and tail and Gjershaug, J.O., Lerner, H.R.L. & Diserud, O.H. (2009). larger feet of the Eagle (cf. juvenile Brahminy Kite in and distribution of the Pygmy Eagle Aquila (Hieraaetus) weiskei Figures 1–3). Photo: David Whelan (: ). Zootaxa 2326, 24–38. Pygmy Eagle dark morph 131

Larkin, C. & Debus, S.J.S. (2020). Inheritance of plumage morphs Pruett-Jones, S. & Pruett-Jones, M. (1981). Hunters by day, in Little Eagles Hieraaetus morphnoides in northern New South hunters by night. Paradise (Air Niugini magazine) 30, 21–23. Wales. Australian Field Ornithology 37, 124–128. Lerner, H., Christidis, L., Gamauf, A., Griffiths, C., Haring, E., Huddleston, C.J., Kabra, S., Kocum, A., Krosby, M, Kvaløy, K., Mindell, D., Rasmussen, P., Røv, N., Wadleigh, R., Wink, Received 2 October 2019, accepted 2 July 2020, M. & Gjershaug, J.O. (2017). Phylogeny and new taxonomy of published online 4 September 2020 the booted eagles (Accipitriformes: Aquilinae). Zootaxa 4216, 301–320.