Proposal (10) to South American
Classification Committee
Continue
to retain usta as a subspecies of Otus watsonii
Otus watsonii. I'm not convinced by the published
data that usta should be recognized at the species level. Birds that
I've recorded in Guyana (LNS # 42754) sound very similar to birds from along
the Rio Napo, Ecuador (Hardy et al. 1999). However, my recordings of birds at
the base of the Ecuadorian Andes (prov. Morona-Santiago, Santiago, 3o 03'S,
78o03'W; LNS # 49232, 49255, 49401) sound intermediate to birds from the above
localities and those south of the Amazon (Hardy et al. 1999). Clearly, study is
needed in western Amazonia where the two forms might come together, i.e.,
southeastern Ecuador and northeastern Peru.
Mark Robbins, Dec. 2001
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Comments rom Schulenberg: "YES. I am not even certain of what the characters
are that separate usta from watsonii.
“Chapman (1928, American Museum Novitates)
diagnosed them as follows:
"In watsoni watsoni, the more northern
form, the ground color of the underparts is ochraceous tawny, the white markings
absent or comparatively restricted, and the black bars average fewer and
broader. In the form from south of the Amazon the ground color of the underparts
averages paler, the white markings are more extensive (present in all of our
six specimens) extending from breast to, or even on, lower tail-coverts, and
the black markings are finer and more numerous giving a vermiculated appearance
wholly absent, or less highly developed in watsonii watsonii. For this southern form it is probable that we may use the
name Otus watsoni usta (Sclater)
described from Ega, Brazil, in the south shore of the Amazon. While it is true that I have seen no specimens
from Ega, the comparative stability of the species warrants this proceeding
pending the receipt of topotypical specimens. It should be said, however, that
Sclater's plate suggests watsoni watsoni rather than the bird for which
I accept the name usta."
“A reasonably clear diagnosis, although he
manages to throw our use of the name usta
into some doubt.
“Compare this to the account in Handbook of the
birds of the world (where usta is regarded as a subspecies of watsonii):
‘Race usta similar in
pattern, but slightly smaller, rufous overall, broader streaks below.’
“which seems to contradict, at least in part,
Chapman's characterization.
“König et al. (1999) regarded usta as a
separate species. With regard to morphology, their description is equally
skimpy:
‘Very similar to [watsonii],
but slightly larger ... with a rufous wash above, a darker crown, and more
broadly streaked underparts.’
“This contradicts HBW with regard to size,
contradicts Chapman with regard to streaking on the underparts. Who to believe?
“Granted, "all" differences between watsonii
and usta could be in voice (and in genes), but since Chapman was the
only author to specifically tie his description to specimens that we can trace
(albeit a small sample) he still is the place to start. I can't take seriously
either of the other characterizations.
“König maps geographic overlap of the watsonii
and usta in northern Peru, but does not tell us how (or if) this apparent
sympatry was documented.
“With regard to voice, there is variation
within the "complex". I don't know whether this variation is
individual or sexual or contextual, clinal or stepped. What I am not inclined
to do is to listen to a song from here and a song from there, or even a song
from here, a song from there, and a song from somewhere in between, and make
decisions based on that. I also am not likely to get excited about changes in
species level taxonomy for small Otus until someone examines *all* vocal
material available, instead of listening to (or making sonagrams of) one or two
examples only. Harrumph.
Comments from Jaramillo: "YES, although with some reservations.
From my limited experience with this owl there do appear to be two song types,
one in the south and one in the north. The southern song type (I know it from
Bolivia) is very slow, strikingly slower than songs of watsonii from
Ecuador or Venezuela. I think that birds in the Napo of Ecuador give the
northern song, so it is not surprising that they sound like birds from Guyana.
Just listening to the two song types back to back I can see why the southern
bird has been proposed as a split. However, there are several questions to be
resolved before I can be comfortable with a split. First, are these song types
stable over large geographic expanses and meet up abruptly, or are they clinal?
Second, where is this zone of contact, or song change? I would like to see the
song types mapped, to make sense of this, rather than looking at subspecific
(i.e. morphological) distributions. Third, do birds from the type locality of usta
sing the southern song, or are they in fact part of the northern group? In
another words, if there is a different taxon with a separate song in the south,
is usta part of that taxon or is a new name needed (or elevation of an
old name)? With regards to visual differences between northern birds and
southern birds two features have attracted my attention. The birds in Ecuador
show a contrasting and very clean (largely unmarked) tawny belly, while the
ones in Bolivia are more heavily marked on the belly so it does not stand out as
contrasting from the heavily patterned breast. Furthermore the birds in Bolivia
have brown eyes, yet the ones in Ecuador have dark amber eyes."