PHENOTYPIC DISCRIMINATION OF THE ANDEAN IBIS (THERISTICUS BRANICKII) NIGEL J. COLLAR 1,2,3 AND JEREMY P. BIRD 1 ABSTRACT.—Many authors do not recognize the highland Andean Ibis (Theristicus branickii) as a species distinct from lowland Black-faced Ibis (T. melanopis). We considered this problem using a new system of quantitative criteria for species recognition. Andean Ibis differs from Black-faced Ibis markedly in proportions (shorter bill: mean 118 vs. 140 mm; longer tail: mean 215 vs. 185 mm), structure (no wattle), and color pattern (rufous-chestnut crown, face and nape rather than rufous-chestnut crown only; larger white vs. smaller rusty-buff belly-patch). We propose elevation of Andean Ibis to full species. It is rare in Ecuador and Bolivia, vagrant in Chile and only likely to be moderately abundant in Peru. Received 28 September 2010. Accepted 19 January 2011. Opinion is unevenly divided over whether the Black-faced Ibis (Theristicus melanopis) of south- ern South America, itself only relatively recently split from Buff-necked Ibis (T. caudatus) (e.g., Steinbacher 1979), is one or two species. The majority view is that it is one with its high Andean representative, branickii, considered a subspecies (Hellmayr and Conover 1948, Meyer de Schauen- see 1966, Blake 1977, Steinbacher 1979, Parker et al. 1982, Fjeldsa˚ and Krabbe 1990, Hancock et al. 1992, Matheu and del Hoyo 1992, Stotz et al. 1996, Ridgely and Greenfield 2001, Dickinson 2003, Jaramillo 2003, Restall et al. 2006, Schulenberg et al. 2007). These two taxa are treated as two species by Sibley and Monroe (1990), Clements (1991, 2000, 2007), Wells (1998), Clements and Shany (2001), Walker and Fjeldsa˚ (2002), and Martı ´nez Pin˜a and Gonza´lez Cifuentes (2004). Diagnoses were provided only by Clements and Shany (2001), who indicated melanopis ‘‘has a larger black wattle on throat’’, Walker and Fjeldsa˚ (2002), who described and illustrated something closer to melanopis than to branickii, and Martı ´nez Pin˜a and Gonza´lez Cifuentes (2004: 82), who wrote (our translation): ‘‘like [melano- pis], but legs much shorter, neck thicker, gular wattle divided, and head and hindcollar brown’’. Those maintaining one species since publica- tion of Sibley and Monroe (1990) seem not to have looked afresh at the evidence. Hancock et al. (1992: 185) mentioned that branickii is ‘‘some- what smaller than the other subspecies [here including caudatus]… but has the longest wings’’ with rufous-tinged neck-base, palest breast and undersides, rather dark gray wing-coverts and more consistently gray dorsal coloration (nothing outside quotation marks is accurate). Matheu and del Hoyo (1992: 499) called it ‘‘paler, [with] less ochraceous foreneck and breast, and usually smaller area of bare skin on throat’’, and noted that it is sometimes given species status ‘‘on [the] basis mainly of ecological differences’’. Ridgely and Greenfield (2001) also noted branickii is at times given species status but, as only branickii occurs in Ecuador, they offered no diagnosis from nominotypical melanopis. Restall et al. (2006) offered no diagnosis either, and illustrated a nominotypical melanopis captioned as branickii. Schulenberg et al. (2007: 80) reported that melanopis differs from branickii ‘‘by often showing a black throat wattle…; paler (sometimes almost white) wing coverts, more extensive black on belly, and generally darker buff lower breast and belly’’. Two reviews pre-dating Sibley and Monroe (1990), namely Blake (1977) and Fjeldsa˚ and Krabbe (1990), offered similarly partial and even mistaken comparisons. Only Jaramillo (2003: 68), although not splitting the taxa, produced a reasonably close diagnosis: ‘‘Differs from melanopis in shorter bill, smaller wattle, more vivid and extensive cinnamon on cap and back of neck, paler breast and foreneck, and more restricted black belly’’. The fullest and (as evidence assembled below reveals) best description of branickii to date, however, is the French original. Von Berlepsch and Stolzmann (1894) reported that it differs from melanopis by the lack of a wattle (the mesial line being feathered), dirty white (not buffy-rufous) lower breast and belly, gray (not white) upper- wing-coverts, and longer wings and tail, although two features they used to distinguish branickii 1 BirdLife International, Wellbrook Court, Girton Road, Cambridge CB3 0NA, United Kingdom. 2 Bird Group, Department of Zoology, Natural History Museum, Tring, Herts HP23 6AP, United Kingdom. 3 Corresponding author; e-mail: nigel.collar@birdlife.org The Wilson Journal of Ornithology 123(3):459–463, 2011 459