Proposal (#370) to South American Classification Committee
Elevate subspecies insularis of Sporophila intermedia to species rank
Effect on South American CL: This proposal would split one species from within our
broad Sporophila intermedia.
Background (taken from Restall 2002): Sporophila intermedia insularis was described
by T. Gilliard in 1946 from Trinidad (and also occurs in Venezuela north of Orinoco),
and was subsequently considered a synonym of S. i. intermedia by Meyer de
Schauensee (1952). It has been largely ignored ever since. It was described as differing
from intermedia in having white neck patches, but this character evidently appears to
varying degrees within S. intermedia.
New information: Restall (2002) first noticed that insularis also differs from all other
intermedia populations in having a white bar across the rump, but his initial hypothesis
was that this just represented individual variation within intermedia. After studying about
100 male specimens of intermedia and about 35 of insularis (determined as such by the
white rump bar?), Restall found the following differences:
1. significantly larger bill
2. significantly larger body weight
3. significantly longer tarsus
4. qualitative differences in songs based on aviary birds
He also noted that the one known nest of insularis differed in color from those of
intermedia (N=?). Restall also noted some other potential differences (e.g., vocal
mimicry) that need to be investigated.
The most important point, however, is that insularis and intermedia are broadly
sympatric, from Trinidad across northern Venezuela. One could attribute this to some
sort of polymorphism or age difference in male plumage of the eastern populations of
intermedia; however, that specimens identified as insularis by rump pattern also have
statistically bigger bills and longer tarsi would be unusual for a plumage variant.
Analysis: South American Sporophila represent a drastically understudied group in
terms of male plumage variation (notorious in this genus) and species limits. In the case
above, ideally we would have breeding season data that show that both forms breed
sympatrically with the vocal differences described by Restall quantified in detail, as well
as genetic data. What we have is a study that should provoke such an investigation. But
is what we have sufficient for elevating insularis to species rank and placing burden-ofproof on the idea that insularis represents only within-species plumage variation? My
main concern is the possibility of seasonal movements (well known in other species in
this genus) creating sympatry only outside the breeding season.
Recommendation: I recommend, tentatively, a YES on this one for two reasons: (1) the
morphological characters indicate to me that this is more than just a plumage variant,
and (2) Restall's extensive experience with Sporophila and other small seed-eating
birds, including from an avicultural perspective, leads me to suspect strongly that he's
got it right.
English name: Restall recommended "Ring-necked Seedeater" for insularis in
recognition of a plumage difference between it and Gray Seedeater, and in recognition
of the local name "Ring-neck" in Trinidad. I would have gone for "Band-rumped
Seedeater" myself to emphasize the overlooked but diagnostic character, and because
the white in the neck doesn't really form a ring. Discussion?
Lit Cit:
MEYER DE SCHAUENSEE, R. 1952. A review of the genus Sporophila. Proc.
Academy Natural Sciences Philadelphia 104: 153-196.
RESTALL, R. l. 2002. Is the Ring-necked Seedeater (Sporophila insularis) from Trinidad
extinct, or is it a cryptic species widespread in Venezuela? Pp. 37-44 in "Studies in
Trinidad and Tobago ornithology honouring Richard ffrench" (Hayes, F. E., and S. A.
Temple, eds.). Occasional Paper No. 11, Department of Life Sciences, University of
West Indies, Trinidad.
Van Remsen, September 2008
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Additional comments from Steve Hilty and Robin Restall (an exchange between them):
Hilty to Restall:
"I read, recently, your article on Sporophila insularis. You make an interesting case in support of
Sporophila insularis; however, I am not sure I am fully convinced. The measurement differences
were ever so slight (even if they did apparently show statistical significant) and what you have
shown looks a bit like some of the Grant's work (popularized in "Beak of the Finch") with
Galapagos finches, albeit on a tiny scale, with these measurement averages of theirs shifting a bit
from decade to decade with environmental changes on islands. Am left wondering what these
tiny measurement differences mean."
Restall response to Hilty:
"One of the ornithologists at UCV here did her PhD thesis in Kansas and
worked at a distance with Jorge Perez. At one point in time, they took
tissue from a good sample of insularis and one of intermedia. There
was a distance between the two, although admittedly they were close.
The same study showed that schistacea was the same distance from
intermedia/insularis as was Oryzoborus angolensis."
Further thoughts from Hilty:
"First: Sporophila is notable for polymorphism in plumages.
"Second: Regarding S. insularis, little is known about seasonal movements, breeding overlap, or
interspecific territoriality (assuming they are valid species) with allied S. intermedia. Nor is their
much information on habitat usage (I have none)? The question of how the two taxa might
achieve reproductive isolation remains puzzling?
"Third: Vocal data might be helpful. Most males of S. intermedia seem to mimic, in the wild. It
could be helpful to determine if S. insularis also is or is not a mimic, or if its songs are different
than those of S. intermedia.
"[Restall tells me that he does have song cuts of S. insularis and will have them digitized for
further analysis so this could be useful]
"To follow up on Restall's comments, perhaps some additional genetic work would be helpful. I
suppose my conclusion is that Restall just might be on to something interesting here, but perhaps
a proposal to validate or refute S. insularis as a valid taxon is premature at this point. Could be
worthwhile letting the story unfold."
Comments from Cadena: "NO. I am afraid all the necessary data are not quite there yet.
The data do seem suggestive (particularly the fact that birds with a particular plumage
phenotype are also different in morphometrics), but I would like to see a detailed study
that allows rejecting the possibility of seasonal movements that Van mentioned. Also,
note that the differences in means of morphological measurements between insularis
and intermedia need not imply diagnosability, as there is some overlap in at least some
of them; because sample sizes are rather large, I am actually not very impressed to see
that t-tests find significant differences between insularis and intermedia. All this, in
addition to Hilty's comments, suggests it would be best to wait for more detailed
analyses to unfold."
Comments from Nores: "NO. Aunque Restall puede tener razón, los elementos
aportados no son del todo convincente y hay un poco de razonamiento circular. Aunque
él menciona que la banda blanca de la rabadilla está presente en todos los ejemplares
de insularis (por él atribuidos), no significa que algunos de ellos no sea intermedia.
Además, las medidas en que él basa la separación de los ejemplares con banda blanca
no son tan diferentes y hay bastante superposición. Las medidas del pico difieren en
alrededor de 0.5 mm y la medida del tarso, aunque alcanza a 1 mm, es siempre más
relativa. En síntesis: el considera que todos los ejemplares con banda blanca en la
rabadilla son insularis porque son más grandes, lo que en la realidad no es así. El
promedio es mínimamente más grande, pero no los ejemplares en particular. Si todos
los individuos con banda blanca en la rabadilla fueran más grandes, si habría que
admitir que son dos especies diferentes. Como el análisis molecular de un ejemplar
sugiere que puede ser distinta, yo esperaría a tener otros ejemplares para hacer el
análisis, antes de elevarla a especie."
Comments from Zimmer: "NO, for reasons stated by Daniel and Steve."
Comments from Robbins: "NO, for the time being. The relatively minor morphological
differences coupled with the uncertainty about breeding sympatry and quantified song
differences beg for further study before making a taxonomic change."
Comments from Stiles: "NO, for the moment. Robin may well be right, but I feel that
more data, especially from the field and genetics, are required. Variation in plumage of
the magnitude of that described by Robin occurs in related species and notably, in the
bogotensis race of intermedia itself (see Stiles 1996, Ornitología Neotropical); because
song is learned in these birds, its use in taxonomy, while not to be ignored, should be
done with great care; and while mean differences in several dimensions exist, overlap is
also great such that many individuals will not be distinguishable by this means. I find it
odd that the distributions of two species so similar could overlap so widely without any
indication of ecological separation. Especially for such cryptic species, detailed genetic
and vocal data have proven critical in confirming their distinctness and it seems prudent
to wait for such data here before going ahead with this split."
Comments from Stotz: “NO. There is some evidence to support this change, but like
others I am concerned by possibilities of seasonal movements inflating observed
sympatry and the relative weakness of both morphological and ecological differences.”
Comments from Jaramillo: YES. This does indeed seem similar to Darwin’s Finches as
Hilty mentions, and that is precisely why I buy the argument. Differences in plumage
and morphology in a sympatric populations of seed eating finches suggests to me that
we are not talking about morphs, hybrids or anything other than two very similar but
different populations. It seems like Sporophila are the Neotropical version of northern
hemisphere Larus – lots of grey areas and a very quick and massive radiation that went
on. Some may still be working themselves out (capuchinos), while others are
polymorphic, and others are over-lumped etc. I think that Restall’s logic is sound here, it
would be nice to have more data, but what is there seems fine to me.”
Comments from Pacheco: "NO. Ainda que concorde que há alguma possibilidade de
acerto neste tratamento, as evidências presentes são especulativas e não foram
devidamente imunizadas.”