Lynx Edicions and BirdLife International are planning to publish a taxonomic checklist of the birds of the world, building off the Handbook of the Birds of the World series, and BirdLife’s annually updated taxonomic checklist. On top of a comprehensive review of the taxonomic literature, the new Lynx-BirdLife list will also be based on application of the criteria for recognising species limits described by Tobias et al. (2010). The new list will form the taxonomic basis of BirdLife’s assessments of the status of the world’s birds for the IUCN Red List.
Information and comment is now sought on a subset of potential ‘splits’ and ‘lumps’, particularly those for which acoustic and/or behavioural information may be critical in determining the appropriate taxonomic status. These are listed below. In some cases, details are provided of apparent morphological differences (with numbers in parentheses referring to provisional scores following Tobias et al. 2010), and specific requests for additional information sought.
Note that this is NOT a comprehensive list of all potential taxonomic revisions being considered, simply those for which input is particularly sought to determine whether changes to the status quo are appropriate.
Please provide any feedback and information by posting comments below. Unfortunately, owing to a tight publication schedule, we cannot undertake to provide responses to contributions at this stage.
Subsequent to publication, an open and transparent process will be established by which anyone can provide information or comments to inform regular updates to the list.
Please see the attached spreadsheet if you wish to search for species in the consultation by their countries of occurrence: Taxa for forum consultation, searchable by country
Potential taxonomic changes
Crypturellus (atrocapillus) garleppi
In museum specimens of females (males not seen), the form garleppi is less dark grey and slightly browner on the crown, nape and mantle, with the upper breast also more shot with brown so that the dark grey coloration is far less intense. Its barring on the wing-coverts is not so contrastingly black and pale buff, more brownish-black and pale tan. However, the pattern is identical. Is there any reason these should be split?
Crypturellus (cinnamomeus) occidentalis
The sample in BMNH does not cover all populations or taxa but we find that the greyer, less heavily barred birds from Nicaragua (presumably allied to occidentalis) are matched by some birds from Mexico, and it seems there is variation with age and perhaps sex that renders a split in this species improbable. Does anyone disagree?
Bubulcus (ibis) coromandus
‘Consistent differences between Bubulcus ibis and B. coromandus in breeding plumage, proportions and vocalisations indicate they are better treated as two species’ (Rasmussen & Anderton 2005: 58). These differences are
- longer bill, neck and legs;
- puffy, bright golden-orange head, neck and breast when breeding vs white on these parts except peachy-buffy crest and central breast plumes;
- lower, less nasal and more gravelly calls.
However, the morphometric data in Ahmed (2011: 301) yield an effect size of 1.492 for longer tarsus (score 1) and of ‒0.935 for shorter tail (score 1), these being the highest values, and Ahmed (2011: 294) also reports that ‘No differences in vocalisations could be found by George Sangster…; the sounds compared in Rasmussen & Anderton (2005) were possibly not homologous… Note that up to 11 different call types have been described…’, thus no score can be allowed. This leaves the clear difference in plumage coloration, for which a score of 3 is appropriate (LDCF & NJC). A survey of photographs on the internet reveals no distinctions in the colour of bare parts at any time in the annual cycle. Thus a total of 5 leaves coromandus at this stage as a well-marked subspecies. Have we missed anything?
Cochlearius (cochlearius) zeledoni
Wetmore (1965: 117) says of nominotypical cochlearius in Panama that it is ‘so markedly different from the race of the rest of Panama in its much lighter color—light gray on the back, and pure white on the foreneck and side of the head, in the adult—as almost to suggest a separate species’. He mentions that it ‘ranges along the Pacific cost only to the Rio Jaqué, since C. c. panamensis is found in the Tuira drainage a short distance to the north’. He (p.118) distinguishes panamensis as ‘darker throughout that C. c. cochlearius, with the side of the head and neck and the back and wings dark gray; lower foreneck and breast light grayish brown’. From measurements in this and Blake (1977: 172-3) it appears nominotypical birds have longer tails, but not by much and only on average.
Some birds in Mexico are almost as pale above as nominotypical ones. A score of 3 is appropriate for the buff-grey vs white breast and lower face, but only perhaps 1 is allowable for the darker upperparts. Are there any vocal differences between taxa in Central and South America?
Dendrocygna (autumnalis) discolor
Although HBW says the subspecies it calls fulgens starts in s Panama, neither the Ridgely nor the Angehr guides mention it. According to Blake (1977: 218) it intergrades with nominotypical in E Panama; he gives its range in N S Am as Colombia, from the Cauca Valley e to Arauca and Meta, and the Pacific lowlands S to El Oro, Ecuador… The only diagnostic feature he gives is ‘breast and upper mantle grayish, in strong contrast to the chestnut back and lower neck’. His measurements show slight differentiation in dimensions (longer wing and shorter bill in autumnalis but with so much overlap it is hard to consider this important). This might score 3 for major plumage difference, 1 for shorter wing, and 1 for longer bill (2 for intergradation is disallowed here)… We need strong supporting evidence on vocalisations or else photographic evidence that shows difference in eye colour or in shade of leg colour, etc.
Sarkidiornis (melanotos) sylvicola
The South American form sylvicola differs from nominotypical melanotos by its
- blackish-grey vs white flanks (3)
- blackish-grey vs greyish-white back (a continuation of the flanks, so no score; but this character not widely noted)
- purer white wherever this occurs on plumage vs slightly yellowish-tinged (1)
- possibly (n=2 in NHM) more heavily black-flecked head- and neck-sides (about twice as much in NHM sample) on males (no score as this seems correlated with dark flanks and back)
- slightly smaller size (Madge & Burn, HBW)
The characters involved in the differentiation of these two taxa present a problem associated with the Tobias criteria, in that the dark coloration appears three times in different parts of the plumage of sylvicola, and could be scored independently for each occasion, which could perhaps carry the form to species level (3 for flanks, 2 for back, 1 for head and neck [if this is correct; larger sample needed], 1 for supposedly smaller size). However, as this pattern seems certain to be correlated, it seems as unreasonable to make such a score as it is to score larger forms more than once for size characters.
Unless there are good behavioural or vocal differences between the two taxa, at least for the moment Comb Duck remains a single species.
Anas (platyrhynchos) diazi & A. fulvigula
AOU (in 1998) and the South American Checklist Committee (in 2005) rejected the split of diazi, the former on the grounds that it hybridises extensively with platyrhynchos; yet AOU (1998) recognises fulvigula even though diazi and fulvigula are extremely similar. Given that diazi and fulvigula both lie to the south of the range of platyrhynchos and approach each other fairly closely at the respective eastern and western edges of their ranges, it seems plausible to consider them conspecific. Kear (2005) fails to illustrate diazi or give any indication how it differs from fulvigula. Sibley (2000: 82-3) shows diazi with a dark crown, fulvigula with a black gape-spot and warmer, buffier, unmarked throat, but none of these characters is apparent in a sample at BMNH, and in any case these are not strong differences; the single obvious difference is in the upper white edge to the speculum, present in diazi, absent in fulvigula (score 1 or 2).
If the two are lumped, fulvigula becomes a subspecies of diazi and the question arises whether the degree of the hybridisation in nominotypical diazi continues to obstruct specific status for the newly enlarged form. AOU (1998) is not clear why hybridisation represents a stumbling block to specific status for diazi when it continues to accept species status for the widely hybridising American Black Duck Anas rubripes, and we conclude that hybridisation need not be a reason to discount diazi sensu latu as a species.
Anas diazi with race fulvigula differs from A. platyrhynchos on account of
- male appearing like female (4);
- white line on lower edge of speculum narrower or non-existent (1);
- upperwing-coverts dark-mottled brown, continuous with back vs plain grey in male and dark-mottled brownish-grey in female platyrhynchos (ns);
- speculum green-blue vs purple-blue (2).
What are the obstacles to this treatment?
Ortalis (ruficauda) ruficrissa
Fide HBW2: 343 the form ruficrissa differs from ruficauda ‘in size, tone of general coloration and colour of tail-tip’, this last character being white vs chestnut (3); but the other two characters are not supported in the limited material in BMNH, and HBW mentions ‘intergradation with ruficauda’ in two separate areas. This therefore seems an improbable split unless other evidence is forthcoming.
Francolinus (coqui) hubbardi
The form hubbardi is distinct from most other taxa in coqui on account of
- blackish vs dull chestnut cap and nape (2);
- underparts below breast plain tan-buff vs all barred (3);
- no rufous staining to pattern on mantle and breast-sides in either sex (ns);
- female with almost plain pale grey-brown vs rufous breast (2).
There is a hybrid in BMNH from 100 miles SE Tabora, Tanzania. A further problem is the form spinetorum, in which the male is like the male hubbardi, although this is not mentioned or illustrated in HBW. BMNH possesses no females of this form, so a judgement cannot yet be made on hubbardi. However, technically the existence of spinetorum significantly weakens the prima facie case for hubbardi as a species.
Francolinus (albogularis) dewittei
Although significantly disjunct such that one might expect progress to speciation, the form dewittei is not particularly strongly differentiated from buckleyi in Cameroon. It differs in
- rufous breast-patch in male much more complete, but chestnut on mantle somewhat reduced (these colours related; 2);
- lores, supercilium and subocular area in male blackish-tinged buff vs plain rufous-buff (2);
- crown in both sexes rather more blackish and lower underparts a shade darker and duller (ns);
- female with denser, darker barring below (ns);
- female tail clearly barred dark and buff vs vaguely barred to plain (2).
A score of 6 scores these differences rather too highly, basically because the last four bullet points above reflect a single general trait of the taxon to be darker. These differences in skins look decidedly subspecific. Mensurally there appear to be no distinctions. It would be valuable to have acoustic evidence. BMNH lacks ‘dewittei’ from DRC but has three specimens (1m,2f) from Angola, treated as race meinertzhageni.
Fulica americana & F. caribaea (HBW3: 207)
These two taxa are sympatric in Cuba (caribaea not seen for 50 years fide Kirkconnell guide) and Hispaniola (where they interbreed quite widely fide Latta et al. 2006). It is not at all clear that two species are involved. A greater review of the literature and evidence is needed.
Haematopus (ostralegus) osculans
Livezey (2010) treated this form as a separate species, but did not provide any supporting evidence. Material in BMNH appears very similar to other forms.
Himantopus (himantopus) leucocephalus
Himantopus (himantopus) knudseni
Himantopus (himantopus) mexicanus
Himantopus (himantopus) melanurus
Livezey (2010) treated all the above except, puzzlingly, melanurus, as separate species, but did not provide any supporting evidence. Patterns of differentiation on the head are notable but thematically recurrent (e.g. between knudseni and mexicanus, and between leucocephalus and melanurus), and unless vocal evidence indicating strong differences between taxa is forthcoming the case for treating this complex as anything but a single species with variations in the amount and distribution of black on the head and neck is rather weak.
Haematopus ater & H. bachmani (HBW3: 321)
It is very difficult on specimen evidence to see any distinction between these two taxa except for the deeper bill of ater (HBW says ‘rather deeper’ but it looks significantly deeper in skins). All other differences are evidently slight (HBW says the two are ‘almost identical’). The voice of the two taxa might prove distinct, but even this might not be enough to prevent these two from being united as one species under the Tobias criteria.
Vanellus (senegallus) lateralis
The form lateralis differs from senegallus in its
- blackish belly-band, variable in extent and intensity (2)
- black tip to the entire terminal third of the bill rather than on the top (2).
No other characters appear to exist, unless there is something vocal or ecological?
Vanellus (indicus) atronuchalis
Livezey (2010) treated this form as a separate species, but did not provide any supporting evidence. Notably, given their tendency to split species whenever the evidence allowed them to, Rasmussen & Anderton (2005) retained atronuchalis as a subspecies and made no comment about another potential status, remarking ‘some Assam and Khasi Hills specimens are intergrades’.
The form atronuchalis differs from indicus in its
- continuous black collar, isolating the white ear-coverts (3)
- narrow white line between black on nape and brown of mantle, not always clearly visible or developed on specimens (1)
Are there other differences?
Charadrius (mongolus) atrifrons
Livezey (2010) splits this form. It would be very helpful to have a full assessment of the characters that distinguish it, particularly behavioural, acoustic and ecological.
Gallinago (undulata) gigantea
There is a very significant size difference in these two disjunct taxa (probably producing a score of 3), but no other characters appear to exist. Is there information on the vocalisations of the two taxa?
Limosa (limosa) melanuroides
The size difference between this form and nominotypical is fairly extreme, and probably would produce a score of 3. Apart from this, the face of breeding birds appears to be paler, sometimes almost whitish, but this is an inconstant character, and in many cases the rufous on the belly extends further down, with rather denser, darker barring (see Rasmussen & Anderton 2005). Hayman et al. (1986) depict a rather narrower wing-bar. However, none of these characters is particularly strong or stable. What more evidence of difference is there?
Numenius (phaeopus) hudsonicus
Sangster et al. (2011) recommend species status for this American representative of the Whimbrel on the basis of ‘diagnostic differences in plumage and mean morphometric differences’ plus mtDNA divergence of 3.6% (see also Condor 97: 639). However, this major and perhaps exceptional difference in hudsonicus, its all-dark back, rump and uppertail-coverts (score 3), with perhaps a buffier colour overall (1), need to be matched by a clear set of differences in vocalisations. These are not apparent from Skeel & Mallory (1996). What other evidence can be adduced?
Larus novaehollandiae & L. scopulinus (HBW3: 614)
HANZAB 3: 542 remarks that there was no justification for this split in Sibley & Monroe. HBW admits that scopulinus is ‘usually considered a race’. This then appears to be an unjustified split. Material in BMNH shows characters so slight in their difference that subspecific status for scopulinus appears appropriate.
Sterna albifrons & S. antillarum
The latter differs from the former ‘marginally in greyer rump and tail, and more clearly inflected disyllabic contact call’. This does not seem strong enough to warrant specific separation. On the other hand, lookalike terns with different voices exist, and this may be a further case.
Columba (janthina) nitens
The illustration in Gibbs et al. (2001: 35) exaggerates and distorts the differences between nitens and janthina. In reality they are fairly close to one another in plumage, although it appears that nitens has forecrown, cheek and throat mid-brownish-pink vs purplish-grey-green (3) and is somewhat smaller (considerable variation in BMNH specimens (not measured; Gibbs indicates no overlap in male wing-length) (perhaps 1). Vocal differences need checking in this case; do they exist?
Columba (vitiensis) metallica, anthracina and castaneiceps
The two outlying taxa in the C. vitiensis complex, metallica of the Lesser Sundas and castaneiceps of Samoa, appear close to specific separation, especially castaneiceps. The forms griseigularis (Philippines), halmaheira (Sulawesi islands to Solomons), hypoenochroa (New Caledonia), leopoldi (Vanuatu) and vitiensis (Fiji) vary within the limits of subspecific differentiation, on the basis of BMNH specimen material. However, one form not represented in BMNH is anthracina from Palawan, which Gibbs et al. (2001: 209) report as ‘very like griseigularis but a little smaller and without a purple tinge to the underparts, mantle and wings. The throat lacks any shade of white or pale grey and thus appears more like metallica’. This renders the separation of the dark-throated metallica highly problematic, but it also suggests that anthracina cannot be very like griseigularis. Comparison of the plumages of metallica and anthracina is evidently required, along with vocal evidence, because in any case metallica differs from other taxa in the vitiensis group by
- dull mid-grey not white or pale grey throat (2);
- dull darkish-grey belly to vent (3).
The form castaneiceps is distinct from its nearest neighbour vitiensis in its
- distinctly brownish vs grey-green crown (3);
- slaty-grey vs vinous-russet underparts (3);
(the crown and belly are more-or-less reversed in colour in these two taxa) and therefore depends on a vocal difference to be established. Even so, it should be noted that vitiensis is clearly a stepping-stone from the western Pacific taxa, being duller russet below and losing the strong pink to breast, crown and mantle that mark out the other taxa (halmaheira to leopoldi). If vocal evidence also indicates its distinctiveness, this form too might achieve species status, but clearly a great deal of recorded evidence, from across the range of the taxa, is needed before a solid decision can be made.
From the labels of the BMNH material, it appears that bare part colours (red eye-ring, yellow to deep orange eye, horn bill with red base, red legs) are stable throughout the complex.
Comments are welcome.
Macropygia (emiliana) cinnamomea
The Enggano form cinnamomea is treated in HBW4: 145 and Gibbs et al. (2001: 268) as a well-marked subspecies of Ruddy Cuckoo-dove M. emiliana. However, the preamble to the genus Macropygia in Gibbs et al. (2001: 264) points out that M. emiliana has itself been treated as a component of a single species embracing M. tenuirostris (Philippines), M. amboinensis (Halmahera to New Britain) and M. phasianella (Australia). The differences between all these taxa would probably not score sufficiently highly under the BirdLife criteria to form four species. Among them, cinnamomea is certainly rather distinctive on account of its larger size (wing 200 in Gibbs vs 181 next largest) and cinnamon coloration giving a scaly effect. Gibbs and HBW mention its ‘noticeably larger bill’ but in this the single (poor) BMNH specimen is matched by one of modiglianii from Nias.
Only if the voice of cinnamomea can be confirmed as distinct from other forms, and if a larger sample can demonstrate its considerably larger size, is it likely that this form can be elevated to species level.
Leptotila (cassini) rufinucha
The form rufinucha differs from cassini in its
- cinnamon-rufous vs dull grey-brown mid-crown to nape (3)
- and rather paler upperparts (1)
However, there are no mensural or vocal differences between this and cassini (as indicated in Wetmore, Stiles & Skutch, Ridgely & Gwynne, Gibbs). Wetmore refers to a more open habitat usage but this is not striking. The form is apparently now very rare (Ridgely). Are there any vocal differences?
Geotrygon (caniceps) leucometopius
The form leucometopius of Hispaniola differs from the Cuban nominotypical on account of
- a much clearer white forehead shading sharply to a dull darkish grey rest of crown and head-sides, vs a greyish-white forehead shading gently to a pale and then mid-grey rest of crown and head-sides (3);
- the glossy purple of the mantle extending much further onto the breast-sides in most specimens (variable character; 1);
- rather richer rufous in the wings (1).
Mensural and structural evidence still needs to be assessed. With such evidence to hand, the form leucometopius has already been split in Bird Conserv. Internatn. 12 (2002): 269, but the authors admit that their vocal evidence was incomplete, and this still seems to be important.
Gallicolumba (crinigera) leytensis
The form leytensis differs from crinigera in
- white confined to throat, not extending down either side of rusty breast-spot (2);
- grey of neck-sides (bordering white throat and replacing white either side of breast-spot) extends lower on breast so as to join up below breast-spot (2);
- shorter tail (needs adequate sample; score probably only 1).
Some vocal differences will be needed to establish this fairly distinctive form as a separate species.
Phapitreron (leucotis) nigrorum
Differs from nominotypical in
- Buffy (not vinous-russet) throat (2)
- Buffy (not white subcilial) streak (2)
- Brownish-grey (not pale grey) forecrown shading to greenish (not bronzy-russet) hindcrown and greener, less pinkish mantle and neck-sides (2)
- Smaller (1)
Differs from P. (l.) brevirostris in
- Buffy (not whitish) throat (1)
- Buffy (not white subcilial) streak (2)
- Brownish-grey (not strong buffy-white) forecrown shading to greenish (not pinkish) hindcrown and greener, much less pinkish mantle and neck-sides, weaker metallic blue centre to mantle (3)
- Larger (1)
These initial differences were considered less marked in Collar (2011), where vocal evidence considered necessary to clinch the split. Is there vocal evidence?
Phapitreron (leucotis) brevirostris
Differs from nominotypical in
- Buffy-whitish (not vinous-russet) throat (2)
- Strong buffy-white (not pale grey) forecrown (2)
- Strong pink (not bronzy-russet) on hindneck, pinker tinge on neck-sides and breast, with stronger metallic blue centre to mantle (2)
- Shorter bill (1)
Differs from P. (l.) nigrorum as indicated above. These initial differences were considered less marked in Collar (2011), where vocal evidence considered necessary to clinch the split. Is there vocal evidence?
Phapitreron (amethystinus) maculipectus
Differences outlined in Collar (2011) were not quite enough to establish species status for this form, which will require vocal evidence. Does it exist?
Treron (apicauda) lowei
The form lowei differs from apicauda and laotinus on account of
- reduced or absent dull orange breast-patch (1) ;
- brighter yellow rump (2) ;
- feathered lores (1) ;
- slightly different structure to two primaries (conceivably 2, but difference not obvious and function unknown).
Are there vocal, behavioural or ecological differences shown by lowei ?
Ducula (badia) cuprea
The form cuprea achieves species status on account of
- dark vs pale iris (3);
- pinker-grey underparts shading to slightly rusty lower belly (2);
- greyer-pink mantle and head, with no grey crown, more as in insignis (1);
- slightly shorter wing yet mean bill length slightly longer (vs insignis, closest geographical representative of badia), effect size ‒0.91 for wing (score 1), 0.6 for bill (score 1) (score 2)
- moreover, the terminal tail-band in cuprea is not as broad as in badia insignis (mean 38.5 vs 45.5 mm, effect size ‒1.7, [score 1]).
Rasmussen & Anderton (2005) mention that its voice is unknown: it would clearly be valuable to obtain and compare recordings.
Ducula (lacernulata) williami
Ducula (lacernulata) sasakensis
The form williami (eastern Java and Bali) differs from nominotypical (West Java) in having the entire head and neck pale vinous-tinged grey, virtually continuous with pale grey of rest of mantle and breast, rather than clear-cut pale grey on crown and face (score 3), but no other differences are apparent in the BMNH sample. The form sasakensis (Lombok to Flores) differs from nominotypical in having the grey restricted to the crown, not covering the sometimes slightly vinous-tinged cheeks (2), cinnamon vs chestnut untertail-coverts (2), and slightly blacker wings and back (1). It differs from williami in pattern of the crown (3), cinnamon vs chestnut untertail-coverts (2), and slightly blacker wings and back (1). These three taxa seem destined to remain conspecific unless vocal evidence demonstrates exceptional differences in lacernulata and medium differences in sasakensis.
Gymnophaps (mada) stalkeri
The form stalkeri (Seram) differs from mada (Buru) in its
- pinkish-white vs white chin and throat shading to
- vinous-tinged pink-grey vs pinkish-white breast shading to
- chestnut-pink vs pale pinky-grey belly shading to
- rich chestnut vs dark cinnamon undertail-coverts (3).
Rheindt & Hutchinson (2007) expressed the view that this difference in underpart coloration is strong enough to warrant the specific separation of the taxa. However, it is not apparent that any other differences exist. Mensurally the two taxa appear the same. Vocal evidence and more careful evaluation of morphology seem necessary to support a split, although the photographs in Rheindt & Hutchinson (2007: 22) do appear to show a much stronger reddish-pink bare eye-ring in stalkeri. So—are there differences in calls or behaviour?
Cyanoramphus (novaezelandiae) saisseti
The form saisseti is distinct from nominotypical and other taxa in novaezelandiae on account of
- yellower face and underparts (the yellow making the red of the crown slightly fierier) (1),
- larger size (obvious from cyanurus, hochstetteri and nominotypical but less so from cookii and erythrotis) (1).
Despite its apparent genetic distinctiveness, this form does not meet the Tobias criteria and therefore, against general trends, is unlikely to be split by BirdLife. What additional evidence are we missing?
Alisterus (amboinensis) hypophonius
This form differs from all others in amboinensis by its blackish-blue vs green wings and scapulars (3-4), but in no other known way. Are there any other characters that separate the two taxa?
Poicephalus (robustus) fuscicollis
The forms suahelicus and fuscicollis differ from nominotypical robustus only in being pale grey mottled dull brown vs pale olive-green mottled dull brown on the head and breast, a distinction which in skins is less apparent than in illustrations and perhaps only warrants a Tobias score of 2. There is a degree of variability in this complex that suggests approach in coloration between robustus and suahelicus even in this character. Are there other insights that establish a greater degree of difference?
Diopsittaca (nobilis) cumanensis
The forms cumanensis and longipennis differ from nominotypical nobilis in their
- whitish vs black upper mandible (2, possibly 3)
- larger bill (data needed to establish degree of difference)
but in no other obvious way in specimens. Are there any other characters that separate the two groups ?
Aratinga (acuticaudata) haemorrhous
The northern forms koenigi, neoxena and haemorrhous are distinct from the southern forms acuticaudata and neumanni on account of
- whitish vs black lower mandible (2, possibly 3)
- greatly reduced blue on crown and face (2 in comparison to nominotypical but perhaps only 1 in comparison to neumanni)
- smaller size, not in bill (which may be bigger) but mainly in tail length, where Forshaw has 180.9 and 180.8 for males of the two southern forms vs 164.2 for haemorrhous (1).
This takes the northern forms close to species level. Are there other characters that separate the two groups ?
Amazona (farinosa) guatemalae
The northern forms guatemalae and virinticeps differ from nominotypical farinosa, chapmani and inornata in their yellow vs red lower carpal edge (score 3), blue-suffused (or blue) crown (2), and possibly slightly smaller size (0-1). Are there other characters (behavioural, vocal or even morphological) by which the two groups may be further distinguished?
Tauraco (macrorhynchus) verreauxii
The Upper Guinea form verreauxi (‘Red-tipped Crested Turaco’) has the elongate feathers of the hindcrown tipped dull red rather than white and black (score 3), but in every other way the two taxa appear identical. Is there evidence of vocal difference?
Tauraco (leucotis) donaldsoni
The donaldsoni has the elongate feathers of the hindcrown dull reddish-brown rather than dull blackish-blue in the nominotypical, in which this colour starts earlier on the mid-crown so most of the crown looks indigo rather than green then maroon, though the contrast is not as strong as illustrated in HBW4: 502 (score 3), but in every other way the two taxa appear identical. However, donaldsoni is said by Ash & Atkins (2009) to be ‘found east of the Rift Valley in the Din Din forest… and Bale mountains, where in the latter at least it is found alongside nominate leucotis supporting the view for its specific separation’. Nevertheless, a far clearer definition of ‘alongside’ is needed to substantiate the implication that pairs of both taxa coexist in the Bale mountains without interbreeding. Moreover, the evidence for the two taxa occurring ‘alongside’ each other needs to be clarified, in terms of observations past and future. A score of 3 for parapatry would seem possible in this case, so that any small vocal difference would be sufficient.
Caprimulgus (parvulus) heterurus
Cleere (2010) and SACC split the northern South American form heterurus; however, Cleere gave no solid reason for his decision (his plumage accounts are identical) and SACC depended entirely on vocal evidence, which some and seemingly most committee members could not directly access, although some of them voted in favour simply on the grounds that Peters’s original lumping was itself unfounded.
There are no specimens of heterurus in BMNH. There is only one unequivocally identified specimen in AMNH, by Dickerman, labelled female but with the bold white throat of male parvulus. It seems identical to parvulus. Without strong evidence of vocal differentiation, it is not easy to see how heterurus can be unlumped.
Collocalia (formerly Aerodramus) (fuciphagus) germani
The basis for the split of germani from fuciphagus is its ‘strikingly pale underparts and broad whitish rump’ (HBW5: 434), although this is not so clearly emphasised in Robson (2000: 287), who accepts the split, and indeed specimens in BMNH reveal that the underparts of germani are merely a shade paler than nominotypical fuciphagus from Java and that the rump is whitish-grey rather than ‘whitish’. Is germani really a separate species?
Chaetura (chapmani) viridipennis
On the basis of two specimens in AMNH and three in USNM, viridipennis compared to chapmani is
- darker on underparts and rump, scoring 2 in AMNH, but rump same colour in USNM material and belly only a shade darker (1);
- longer-winged (probably 2).
Marin (1997) compared viridipennis to meridionalis and accepted that chapmani is no different except in size (the colour of wing gloss changes with age of the feather and is taxonomically irrelevant); but his reason for accepting viridipennis as a species (p.440) is related to consistency in matching the accepted status of two other taxa, and this is not convincing.
Chaetura (brachyura) ocypetes
HBW5: 445 text diagnoses the form ocypetes on basis of ‘longer tail and wings than other races and paler grey chin and throat, brown forehead and pale-fringed superciliary line’. Ridgely & Greenfield (2001a: 331) elevate it to species status (Tumbes Swift) on account of ‘several distinctive morphological characters as well as its different voice and disjunct range’; they (2001b: 239) mention ‘uppertail-coverts… completely covering tail, which is longer than in Short-tailed… wings notably long and bowed, very different from Short-tailed…’ and while Short-tailed voice is given as ‘very fast, high-pitched, run-together twitters’ for Tumbes Swift ‘one flight call is a series of well-enunciated, somewhat descending notes, “chip-chip-chip-chip-chip-chip-chup”.’
Schulenberg et al. (2007) makes much less of these differences and actually contradicts the wing-length issue: ‘Ocypetes smaller with shorter wings; may show paler chin. Calls (both subspecies) single chip notes and rapid chippering phrases.’ However, Restall et al. (2006a: 221) split ocypetes and write of brachyura that it ‘flies differently from other Chaetura, like a bat and relatively slow’ (this contrast presumably including ocypetes, and may or not be based on Ridgely & Greenfield’s account of brachyura); Restall et al. (2006b: 195) indicate that the very short tail of ocypetes (essentially visible only as a strip round the tail-coverts) is ‘much darker’, the comparison evidently being with brachyura.
There are no specimens in BMNH but enough in AMNH. Without a rigorous search, the tray at AMNH (case 210a, tray 29) also produced a nominotypical brachyura (786052) from Trinidad which has a throat as pale as ocypetes, and a pale-fringed superciliary line. The crown is the same colour and the wings are the same length. Other material in the collection indicate the same overlap of features, and on this basis ocypetes is discounted as a species. However, comments and reactions are solicited.
Coeligena (iris) hesperus ‘Cuenca Rainbow [Starfrontlet]’
Coeligena (iris) aurora ‘Cutervo Rainbow [Starfrontlet]’
Coeligena (iris) fulgidiceps ‘Levanto Rainbow [Starfrontlet]’
Coeligena (iris) flagrans ‘Chugur Rainbow [Starfrontlet]’
Coeligena (iris) eva ‘Cajabamba Rainbow [Starfrontlet]’
Adopting a geographical system of comparison, hesperus is distinct from iris on account of
- brilliant gold-red crown (except central stripe and rear-crown) vs green-gold (3);
- central stripe and rear-crown brilliant purple vs green-gold (2);
- glittering green-yellow throat surrounded by less glittering green breast and breast-sides vs continuous glittering green throat to breast (ns);
- green vs chestnut mid-belly and back (3).
The form aurora is distinct from hesperus, iris and fulgidiceps on account of
- glittering (at some angles slightly bluish-) green vs multicoloured crown (3);
- mantle, back and wing-coverts all chestnut vs dull green (3);
- no violet-blue breast-spot (2);
- dull green of breast does not extend onto upper belly and is clearer-cut (at mid-breast) (ns[1+]).
The form fulgidiceps is distinct from hesperus on account of
- crown with same colours but differently arranged, thus all flame-gold except for violet-blue rear edge vs flame-gold with broadening violet-blue central line, but in addition, flame-gold of crown sheens in some light to brilliant green, quite unlike this colour in eva (4);
- blackish mantle and chestnut back and rump vs dark green mantle to rump (3);
- chestnut vs dark green belly (3).
However, fulgidiceps is not specifically distinct from iris on account of
- stronger flame-gold on crown (1);
- paler chestnut on belly and tail (1).
Nor is it specifically distinct from flagrans, differing in
- stronger flame-gold on crown (1).
It is different from eva in
- crown with same colours but differently arranged, thus all flame-gold except for violet-blue rear edge vs flame-gold with broadening violet-blue central line, but in addition, flame-gold of crown sheens in some light to brilliant green, quite unlike this colour in hesperus (4);
- black vs dull chestnut rear head-sides and nape (2);
- richer, more extensive chestnut belly (2).
The form flagrans is evidently conspecific with fulgidiceps. Meanwhile, the form eva is distinct from fulgidiceps and by extension flagrans and iris on the basis of the characters outlined above plus no violet-blue breast-spot, and differs from aurora on account of
- totally different crown colour and pattern (3 or 4);
- dull chestnut vs black rear head-sides and nape (2);
- more extensively green belly with paler chestnut (2).
However, eva is not specifically distinct from hesperus on account of
- steel-blue vs violet-blue central crown-stripe (2);
- no violet-blue breast-spot (2);
- dull chestnut vs chestnut-tinged blackish rear head-sides and nape (ns);
- buffy vs chestnut undertail-coverts (2).
Hence the only taxon which is clearly distinct from all other taxa in this complex is aurora from Cutervo. How much biogeographic sense this makes is not clear. Comments?
Chlorostilbon poortmani & C. alice
Alice has a shorter bill than poortmani, and is slightly smaller overall, but the taxa otherwise appear identical. HBW mentions a hybrid (found in Brazil!) but it is not clear how anyone could ever judge a hybrid between these two, since they are so similar. Pointed rectrices (reflected in its name) are visible in stenurus, and given that it is sympatric with alice (according to maps) the two must be separate species, but why should poortmani not simply be regarded as a subspecies of alice?
Aglaiocercus kingi, A. coelestis & A. berlepschi
Material in BMNH is not sufficient to make an assessment of these taxa (berlepschi absent altogether; also none in USNM), but they may relate to a single species. The white breast-patch of female coelestis, shown as a distinctive character in HBW5: 658, is not constant in that taxon (5 of 11 specimens in BMNH subtray spotmark 11 do not show it) and one specimen of smaragdina shows it. Fide Ridgely & Greenfield p.383 Paul Salaman has claimed species status for the green-throated green-tailed emmae, which seems as reasonable as these other splits, although Zimmer Am. Mus. Nov. “1595, 1952” argues otherwise. Also fide Ridgely & Greenfield p.383 coelestis has an elevation of 800-1950 m to kingi’s 1600-2600 m, and fide Hilty & Brown coelestis is solitary and forages usually low inside forest at small clumps of flowers whereas kingi occupies more open areas, feeds at almost any height, and gathers with other hummers in the canopy; Hilty adds (p.296) under kingi “in zone of overlap in W Andes tail brilliant emerald green or blue green (not violet to peacock blue with green tips on feathers)”. Yet HBW5: 659 states that coelestis forages “from near ground occasionally up to tree tops, along edges and trails and inside forest”, so the ecological difference is immediately in question. If indeed there is a zone of overlap, then coelestis may be considered a separate species. However, it is not clear that this is fully established in both space and time—could Hilty have encountered birds at different seasons? This whole complex needs a lot more work.
Trogon (surrucura) aurantius
The form aurantius (Northern Surucua Trogon) differs from surrucura (Southern Surucua Trogon) by
- the orange not pinkish-red underparts (3);
- yellow not pink eye-ring (1);
- slightly more green-shot (vs purplish) breast, notably breast-sides, in male (1);
- narrow zone of hybridisation near Rio de Janeiro (arguably score 2, assuming not wider than 200 km; fide P. F. Develey only at Itatiaia).
However, the suggestion that the female has a whitish mid-belly (vs grey in female surrucura) overstates this difference: in some aurantius females there is slightly more whitish feathering than in others and than in surrucura females.
However, are there vocal differences between these taxa?
Indicator conirostris & I. minor
These two have historically shifted back and forth between being considered as separate species or with conirostris as a subspecies of minor. The recent trend of treating the two as separate follows from the work of Friedmann (1971) who reported ‘precise sympatry’ in Bwamba, Uganda. However, in other parts of their respective ranges where they come into contact intermediates are reported. This led Snow (1978), who kept them separate, to comment that the decision was ‘to some extent arbitrary’, because of the conflicting evidence. Thus, they are ‘not distinguishable in central Nigeria where the 2 apparently interbreed’ (BoA III). In HBW this becomes ‘they may interbreed in Nigeria, but are so similar in appearance that hybrids are difficult to establish’.
From the many races of minor, nominate conirostris differs as follows:
- Slightly larger (=deeper) bill (not measured but insufficient to score more than 1);
- Darker grey below with heavier flank streaking (2);
- Darker olive green above, with heavier streaking (2).
Note however that conirostris ussheri of Upper Guinea is much paler above and below (where it is washed yellow) and compared to minor these scores both become 1. An additional score of 1 given since (unlike conirostris sensu stricto) ussheri has a green wash to the crown and hindneck vs the grey head of minor.
The habitat difference (conirostris in forest, minor in a variety of other habitats excluding forest) could be given a score of 1 but given what Friedmann says about sympatry in Bwamba—in light of which it is curious that Carswell et al. (2005) report that in Uganda in ‘areas of apparent sympatry they are separated by habitat preference’—and that Dowsett & Dowsett-Lemaire (1993) state that minor sensu stricto may be a forest bird in parts of its range, it is not clear how rigid such a difference actually is. Vocally they are identical, and very different from any other honeyguides (Dowsett & Dowsett-Lemaire 1993).
Veniliornis (formerly Picoides) lignarius & P. mixtus
According to HBW7: 489, Striped Woodpecker (lignarius) differs from extremely similar Chequered Woodpecker on account of its ‘marginally larger size, slightly darker appearance, narrower white markings above, heavier markings below’, plus a long-distance trill call that is ‘lower and less harsh than that of P. mixtus’. The two taxa are indeed very similar, differing on the former’s larger size (not just marginal) (effect size on tail 4.14, score 2) and in very subtle differences in plumage which tend to even out into generalisations rather than specific diagnosable traits with increasing sample size (e.g. hindcrown is seemingly always much less streaked and plain black than in mixtus; the tail-bars appear less dense because the same number distributed over a greater length; slightly more consistently streaked on the throat where most mixtus seem to show short broken streaks that have almost a spot-like effect; black of plumage a shade blacker; underparts a shade less tinged buffy). Comments?
Veniliornis chocoensis, V. cassini, V. affinis & V. maculifrons
AMNH and USNM lack chocoensis. The amount of variation in head coloration in these taxa is considerable (there is a maculifrons that has the entire crown streaked red, with no space for any blackish forecrown with tiny white streaks which presumably gives the form its name). These do indeed appear to be so similar that conspecificity may be appropriate, but further information is sought, particularly with respect to maculifrons, which appears south of affinis somewhere around the Rio de Janeiro/Espirito Santo border.
Colaptes (formerly Piculus) (rubiginosus) aeruginosus
The form aeruginosus, a northerly isolate (E Mexico) of Golden-olive Woodpecker, is distinct from all forms of the latter on account of
- in the male, lack of a full red supercilium (2);
- in both sexes, breast pattern formed by curved scales rather than irregularly arranged bars (not a striking feature in all specimens, however) (1);
- greyish not buffy ear-coverts (1);
- different voice (fide Howell & Webb 1995).
Inspection of specimens could not validate the view in Howell & Webb (1995) that aeruginosus has a back of a green different from rubiginosus (there is some variation). Moreover, the birds being not obviously larger than yucatanensis. Thus voice will have to be a major difference in order to elevate this taxon to species level. Is there recorded evidence of this?
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