Proposal (32) to South American Classification Committee
Recognize Glaucidium mooreorum
Effect on South American CL: This proposal would add a newly described species to the list
Background: Silva et al. (Ararajuba 10:123-130, 2002) presented evidence for recognizing a new pygmy-owl (Glaucidium mooreorum) that is restricted to the Pernambuco region of the northern Atlantic Forest of Brazil.
Although the evidence presented consisted of only two specimens and a single sound recording, I believe they have convincingly established, based on the very distinct song, that the Pernambuco Pygmy-owl is indeed different from the morphologically very similar Amazonian Pygmy-owl (G. hardyi) and Least Pygmy-Owl (G. minutissimum).
Plumage color and pattern is extremely similar among the presumed Least Pygmy-Owl (G. minutissimum) species complex (sensu Howell and Robbins 1995). Because of this extreme interspecific similarity coupled with variability in plumage within each taxon (varying in brown and dull red pigmentation and wear), I don't put any weight in the described color differences that they present. Because there were only two specimens available (no surprise given how difficult these subcanopy-dwelling owls are to obtain) the relevance of the tail/ring ratio in separating these taxa is hard to determine, especially given that one could argue that the two Pernambuco specimen ratios fall within the range of minutissimum.
However, the primary vocalization that they present is very distinct from that of minutissimum and hardyi. They accurately describe this in paragraph 2, left hand column of page 127. Although this is based on only a single recording (under natural conditions), my experience with this complex suggests that there is little intraspecific variation in natural song. Thus, I suspect that the vocal material that they present is an accurate representation of this taxon. Because this is truly the key (until we have genetic data) for separating these cryptically plumaged owls, I believe, despite the very limited material, that the authors have demonstrated that mooreorum deserves species rank.
Mark Robbins, June 2003
Comments from Zimmer: "I vote "yes" to add Glaucidium mooreorum as a new species to the list. I would like to see a bigger sample size here, but I agree with Mark that there doesn't seem to be much individual variation in this group (other than perhaps slight variation in number of notes, e.g. 2 versus 3 or 4, within an individual), so that the one tape recording is likely to reflect a very real distinction. It also fits a biogeographical pattern. I'm not very impressed with slight morphological distinctions (particularly color saturation) in this genus -- I think voice is the key."
Comments from Silva: "Voice is different as well as plumage colouration. Based on the specimens that I examined of minutissimum and hardyi I did not see a so large intraspecific variation in plumage colour that seems to be common in other species of the genus."
Comments from Jaramillo: "YES I am a bit concerned regarding the small sample sizes looked at, both skins and vocalizations. But I know a lot less than Mark about variation in natural songs, thus the fact that he is comfortable with the small number of voice samples is enough to make me comfortable with it."
Comments from Nores: "Si estoy de acuerdo, aunque uno esperaría una mayor cantidad de ejemplares y de registros vocales para dar una opinión definitiva."