From the Reise der österreichischen Fregatte Novara [...] Zoologischer Theil, 1. Band: Wirbelthiere, A. Pelzeln, "Vögel": "An egg which the expedition brought back from Chile and which was labelled as coming from this species corresponds in all respects to Thienemann's illustration of the egg of H. niger (Fortpflanzungsgesch. t. 57 , Fig. 5 a), but is shorter and less pointed. Length 2'' 1 1/2''', width 17'''" (p. 117).