Least and Little terns (2 Viewers)

[rwkno1]

Does anyone know if Least and Little terns are classified as two seperate species or sub species?

Any help much appreciated

 

[wintibird]

Hi

The Handbook of the Birds of the World (Volume 3) regards them as separate species. Little Tern Sterna albifrons occuring in Europe, Asia, Africa and Australia and Least Tern Sterna antillarum from the Americas. They do form a superspecies (including Saunder's Tern, Yellow-billed Tern and Peruvian Tern). It is also noted that the separation is based mainly on basis of voice and that some works threat them conspecific, so Little Tern woud be the species and Least Tern a subspecies of it.
You see, the answer to your question is, as always with taxonomy, not so easy and depends on the authorities you are following.

Greetings
André

 

[rwkno1]

Hi

The Handbook of the Birds of the World (Volume 3) regards them as separate species. Little Tern Sterna albifrons occuring in Europe, Asia, Africa and Australia and Least Tern Sterna antillarum from the Americas. They do form a superspecies (including Saunder's Tern, Yellow-billed Tern and Peruvian Tern). It is also noted that the separation is based mainly on basis of voice and that some works threat them conspecific, so Little Tern woud be the species and Least Tern a subspecies of it.
You see, the answer to your question is, as always with taxonomy, not so easy and depends on the authorities you are following.

Greetings
André

Thanks, great informative reply, much appreciated

Rob

 

[Docmartin]

The American Ornithologists' Union treat them as two species, British Ornithologists's Union as one.

 

[Edward woodwood]

can't improve on Doc Collinson's post

other than to mention that 'two species' are, by definition, separate

sorry

Tim

 

[pemburung]

Just being picky, if they are one species, both Little and Least would be subspecies; there should be another name - say, eg, Allwood's Tern - for the species, Sterna albifrons; this species comprises two subspecies, albifrons albifrons and albifrons antillarum.

Ok, it's late; cheers all.

 

[Docmartin]

other than to mention that 'two species' are, by definition, separate

Don't start me on that. Or on 'full' species either.

 

[Richard Klim]

Least Tern

Draheim, Miller, Baird & Haig 2010. Subspecific status and population genetic structure of Least Terns (Sternula antillarum) inferred by mitochondrial DNA control region sequences and microsatellite DNA. Auk: in press.
http://caliber.ucpress.net/doi/abs/10.1525/auk.2010.09222

Incidentally, S antillarum is now recognised as a species by AOU/ABA, IOC, BLI, H&M3, Cornell/Clements, HBW, Dutch Birding, Svensson et al 2009.
BOU is in a distinct minority in continuing to treat the antillarum group as subspecies of S albifrons.​

Richard

 

[Farnboro John]

BOU is in a distinct minority in continuing to treat the antillarum group as subspecies of S albifrons.[/INDENT]

Richard

They certainly don't get my vote over this matter.

John

 

[gropperwinch]

if they could make them separate species, Sussex might actually retain the pride of having the only british record of a species within our boundaries, since Lesser and Greater Sand Plovers have suddenly started turning up all over the place

 

[Docmartin]

if they could make them separate species, Sussex might actually retain the pride of having the only british record of a species within our boundaries, since Lesser and Greater Sand Plovers have suddenly started turning up all over the place

Frustratingly for Sussex, as i remember, 'Squeaker' also had a trip over to Colne Point, Essex.

 

[Richard Klim]

Least Tern

Incidentally, S antillarum is now recognised as a species by AOU/ABA, IOC, BLI, H&M3, Cornell/Clements, HBW, Dutch Birding, Svensson et al 2009.
BOU is in a distinct minority in continuing to treat the antillarum group as subspecies of S albifrons.

Gauntlett 2010. Letters: The taxonomic status of Least Tern. British Birds 103(12): 728-730.

Throws down the gauntlet to BOU over non-recognition of the widely-accepted split of Sternula antillarum Least Tern from S albifrons Little Tern. A response from BOURC (TSC) comments:

...The Little Tern group represents a wide-ranging polytypic complex and it is perhaps unwise to make new taxonomic decisions on the basis of study of birds from only a small part of the world range...
...A mtDNA genetic study (Bridge et al. 2005) showed that American antillarum and Little Terns from Australia (S. albifrons sinensis) were genetically distinct and suggested that S. albifrons was sister to Fairy Tern S. nereis. No European individuals were included in the study, and there was no indication whether or not nominate Little Terns were likely to be genetically similar to S. a. sinensis. Some samples from Norfolk were subsequently sourced and Allan Baker, senior author on Bridge et al. (2005), has uploaded a preliminary gene tree (see http://barcoding.si.edu/presentations/Argentina Presentations/Baker-Presentation.ppt). Albeit with small sample sizes, the new data show that English Little Terns are genetically similar to Australian Little Terns, and together they form a clade that is sister to Fairy Tern, to the exclusion of Least Terns. Of course, mtDNA alone does not always accurately represent the relationships between taxa, but nevertheless this represents strong evidence that Least Tern should be split from the rest of the complex as a single polytypic species S. antillarum. There is a continuing possibility that there may be other cryptic species of Little Tern that are yet to be recognised. The TSC understands that these data are being prepared for publication...

...While the sum of evidence points strongly towards a split of these taxa, TSC feels it is important that, if at all possible, the available molecular evidence for relationships among Least Terns and various populations of Little Terns is formally analysed and published in full, especially because these terns may not represent a simple two-way split...

[The linked presentation (Baker, Tavares & Elbourne. Success of DNA barcoding in distinguishing sister species of diverse clades of birds) includes other interesting stuff.]

Richard

 

[GMK]

Hats off to the BOURC TSC for having the "temerity" to not be bulldozed into accepting "taxonomy by field guide". I thought their response was spot on. Most of the authors of the references listed by Martin Gauntlett had clearly just played "copy cat" without truly investigating the issue for themselves.

Some might grumble at the length of time take to reach conclusions in respect of the British list, but in this case do we really want the advisory committee to our national list keepers to merely rubber stamp whatever other "authorities" think, or hold out for evidence? I, for one, will stand up and say, the latter, please. Gauntlett finds the BOURC's TSC stance to be "isolated and precarious", but to me there seems nothing precarious about playing a long game and getting it right, hopefully, in the end.

 

[Farnboro John]

I don't entirely agree. I see no obstacle to basing taxonomy on latest valid information i.e. the certain knowledge that Little Tern should be split into a minimum of two species should be acted on immediately and does not preclude revision later as further work defines splits within the two revealed species.

To phrase the question differently, how long is too long for "playing the long game"? When does that attitude actually harm forward movement in understanding relationships? Once Little and Least Tern are split, future research can be more focused (and probably less expensive and therefore more do-able).

BOU hung about for decades over Herring Gull to eventually come up with nothing that was excitingly different from what even birders gut feelings (I am not recommending these as a basis for taxonomy) had concluded.

Their attitude suggests a belief that they can wait to achieve the definitive answer to questions like this: history suggests otherwise and that all they are doing is missing the bus.

John

 

[Steve Babbs]

Hats off to the BOURC TSC for having the "temerity" to not be bulldozed into accepting "taxonomy by field guide". I thought their response was spot on. Most of the authors of the references listed by Martin Gauntlett had clearly just played "copy cat" without truly investigating the issue for themselves.

Some might grumble at the length of time take to reach conclusions in respect of the British list, but in this case do we really want the advisory committee to our national list keepers to merely rubber stamp whatever other "authorities" think, or hold out for evidence? I, for one, will stand up and say, the latter, please. Gauntlett finds the BOURC's TSC stance to be "isolated and precarious", but to me there seems nothing precarious about playing a long game and getting it right, hopefully, in the end.

Absolutely. I thought this was a fine example of a birder saying, 'Why don't you just split it, everyone else does?' and the BOU showing that it isn't just sitting on its arse, as many people seem to think, but actually looking into it properly. Just because they may well end up coming to the same decision, in the end, as the tick hungry listers, doesn't mean they weren't correct to actually do the research and take their time.

 

[Richard Klim]

BOURC-TSC has given a good justification of its position on Little/Least Terns (earlier uncertain affinities of nominate albifrons etc). But I don't necessarily agree with the implication that a species complex shouldn't be split until relationships throughout the world range are well understood. BOU seems to have done just that in other cases, eg the Larus argentatus complex: splitting L michahellis and L armenicus in 2005, then L cachinnans and L smithsonianus in 2007, with perhaps further splits (vegae, mongolicus, atlantis?) or lumps still possible; and the premature inappropriately-scoped split of Lanius meridionalis from L excubitor (where some fence-sitting might have been wise). The recognition of Loxia scotica arguably also conflicts with BOU's statement that it's unwise to make taxonomic decisions on the basis of studies of birds from only a small part of the world range.

To put it into perspective - given BOU's summary of the latest available evidence, S antillarum is probably now more deserving of recognition as a species than Carduelis cabaret, where even the leading author of the paper cited by BOU fully agrees with AERC TAC that BOU's split seems premature (but I don't think BOU does lumps ).

Richard

 

[Mysticete]

Also I would just like to say that the decision to split Least and Little is not merely "Field Guide Taxonomy"; it's a split fully endorsed by AOU and SACC committees, just off the top of my head.

 

[Richard Klim]

Also I would just like to say that the decision to split Least and Little is not merely "Field Guide Taxonomy"; it's a split fully endorsed by AOU and SACC committees, just off the top of my head.

And AOU-NACC is generally considered to be more conservative than BOU, eg not (yet) recognising BOU's splits of Anas carolinensis, Melanitta deglandi, Puffinus baroli, Larus smithsonianus, Turdus eunomus.

Richard

 

[GMK]

Also I would just like to say that the decision to split Least and Little is not merely "Field Guide Taxonomy"; it's a split fully endorsed by AOU and SACC committees, just off the top of my head.

This much is true, but the vast majority of references in support of splitting cited by Gauntlett in his letter, which is the issue at hand, were field guides or the like.

 

[jforb]

Also see Pyle, Hoffman, Casler, and Mckee. Little and Least Terns Breeding on Midway Atoll: Identification, Range Extensions, and Assortive Breeding Behavior. North American Birds 55(1): 3-6
available here