Species recognition between geographically isolated populations (2 Viewers)

BenFreeman said:

Dan -- you are an active tour leader so are in a good position for me to ask the following question: Is it feasible to conduct occasional playback experiments while guiding tours? It's easy for me to get excited and imagine that it would indeed be feasible -- that you are often already using playback to lure in an interesting bird for the group to admire, and you are probably already telling your clients/friends about geographic variation in song that might be pertinent to species limits, perhaps even briefly playing allopatric song so everyone can hear how different songs are. But it may well be that my imagination is too rosy as I sit here at my desk -- in the field with a big group things may be way too busy and you have your hands full.

The broader idea is that I think it would be great if guides, ornithologists and birders could team up on playback experiments (each person doing a couple as they are able to) to compile data relevant to assessing species limits. Not sure if this would work in practice, but I do think it is a good idea. Playback experiments are easier to conduct then ever before (wireless speakers, lots of good quality recordings publicly available). One of the main goals of publishing this paper was simply to motivate others to try doing playback experiments themselves.

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Ben, what would be the protocols for doing useful playback experiments in this way? If a bird has already been ‘taped in’ by a tour leader playing its call, I’d suggest it may not respond in the same way to a tape of an allopatric species as it would before it was provoked. So how useful would a playback experiment be in those circumstances? Just curious. Also I imagine there's a lot of room for different people to reach different conclusions on whether an individual bird has responded to a call. The idea sounds very interesting but my inner skeptic wonders whether the data produced would be robust enough to be useful?

Murray Lord said:

Ben, what would be the protocols for doing useful playback experiments in this way? If a bird has already been ‘taped in’ by a tour leader playing its call, I’d suggest it may not respond in the same way to a tape of an allopatric species as it would before it was provoked. So how useful would a playback experiment be in those circumstances? Just curious. Also I imagine there's a lot of room for different people to reach different conclusions on whether an individual bird has responded to a call. The idea sounds very interesting but my inner skeptic wonders whether the data produced would be robust enough to be useful?

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Hello Ben,
I have to agree with Murray here. Between the goals of tours (to show birds to clients in a timely fashion, where the guide's most important concern is the clients' experience) and the protocols necessary to conduct scientifically viable playback experiments, I fear that the two would not mesh well. There are many tours where I hardly get to look at a bird because I can only look long enough to confirm it is our target, then must spend the next 20 minutes trying to get the clients on it (by which time, it usually loses interest and melts back into the habitat). It is a rare instance that I am able to study a bird in any detail while on tour, much less try to perform playback experiments on it (and again, as Murray points out, usually the bird is hyped up because of playback to begin with, so the time necessary for it to "cool off" to play alternative sounds using some experimental protocol would be prohibitive in a tour scenario). In addition, I foresee the concept of "citizen science" playback databases would provide in such uneven results that they couldn't be used for any sort of scientific purpose. It's a fine idea in theory, but the realities of the issues working against it would probably be insurmountable. To assure that a standardized protocol is followed and the proper source sounds and target birds are used, I think it best if the experiments be carried out by one or a small group of investigators who are thoroughly familiar with the project.

BenFreeman said:

what we are trying to do is figure out which populations are reproductively isolated from one another and which are not.

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Sorry, but you are not checking reproductive isolation. You are checking response of a male to a playback of another male. Two males will not make an egg.

Territorial defense from males and attractiveness to females are two distinct functions. In some birds and other animals, even different parts of the song are responsible for either. Response to playback is not equal to 'species recognition' either. Males can respond aggressively to other species, even dissimilar, which compete for resources. Males can also not respond to the song of its own species, for example because they are in a different time of breeding cycle, perceive playback as too dominant male, or respond by observation without approaching or calling back. Actually, I think your concept of 'species recognition' is rather artificial, because you lump different responses: mating and territory, with different signals.

To be sure, you are doing valuable and interesting study on bird communication. But it is not exactly reproductive isolation.

Thanks for the messages -- what Dan (and Murray) wrote makes sense. It won't be guides leading tours, but I do hope that more people (whether academics or not; such projects are often appropriate for sharp students as well) will conduct playback experiments along these lines.

Jurek -- you bring up a crucial point. What we really want to know is whether populations are reproductively isolated or not. Again the basic problem is that allopatric populations don't actually have the ability to interbreed (they don't interact in nature), so we can't directly measure the strength of barriers to reproduction. But clearly mate choice is what we really want to measure. The trick is that measuring mate choice (both female choice of males and also male choice of females) is really very difficult, while measuring territorial response is much easier. The assumption is that selection should be much stronger on mate choice (make a wrong mating decision and that is very bad for your fitness) vs. territorial response (respond when you didn't have to and that is more or less inconsequential in the scheme of things). So, in response to a given set of variable signals, birds should generally have broader territorial responses and narrower mating responses. Such that if a bird ignores a signal in a territorial context, we can infer that it would also ignore the signal in a mating context (but we can't confidently make the opposite assumption that a bird that responds to a signal in a territorial context also would respond to that signal in a mating context). That is the logic behind using territorial responses to infer reproductive barriers.

Also worth noting is that females defend territories in many/most tropical birds. So playback experiments often elicit an aggressive territorial response from females (and also males; often the pair respond together). This is why it is not in fact true that playback experiments in the tropics measure male responses alone -- they measure female responses too in many/most cases. It remains true that such experiments measure territorial responses (and not mate choice) in both sexes.

Kratter said:

Nope. Reproductive isolation could arise by theoretically a single base pair (e.g., changing the color of the throat from red to violet). Lack of assortative mating could occur between populations much greater than 5% different. For example, Common Ravens in California vs the rest of North America show no phenotypic/behavioral/vocal differences but are quite different in DNA (I think around 5%). The populations were isolated for a very long time, but never accrued differences that would lead to reproductive isolation.

Andy

Andy

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Andy. Actually "California" Common Ravens sound more like Chihuahuan Ravens, and they seem to rarely if ever give the complex clicks, pops, etc. that Holarctic Ravens give. As well, I think the extent of nasal bristles is different in the California birds. I think the real situation may be more complex than the papers on the ravens have made out. In fact, I wonder if the two are sympatric but separate. Very difficult to ascertain when specimens look so much alike, and no vocalizations are taken of the birds in the field before collection. But when I hear holarctic ravens, they sound noticeably different to my ear than the locals in CA. Confusingly, in SE Arizona when trying to separate ravens by call, everyone finds it difficult. Part of the reason is that over there, it is the CA Raven that appears to be present, not the Holarctic. Cheers! Alvaro.

DLane said:

Hello Ben,
I have to agree with Murray here. Between the goals of tours (to show birds to clients in a timely fashion, where the guide's most important concern is the clients' experience) and the protocols necessary to conduct scientifically viable playback experiments, I fear that the two would not mesh well. There are many tours where I hardly get to look at a bird because I can only look long enough to confirm it is our target, then must spend the next 20 minutes trying to get the clients on it (by which time, it usually loses interest and melts back into the habitat). It is a rare instance that I am able to study a bird in any detail while on tour, much less try to perform playback experiments on it (and again, as Murray points out, usually the bird is hyped up because of playback to begin with, so the time necessary for it to "cool off" to play alternative sounds using some experimental protocol would be prohibitive in a tour scenario). In addition, I foresee the concept of "citizen science" playback databases would provide in such uneven results that they couldn't be used for any sort of scientific purpose. It's a fine idea in theory, but the realities of the issues working against it would probably be insurmountable. To assure that a standardized protocol is followed and the proper source sounds and target birds are used, I think it best if the experiments be carried out by one or a small group of investigators who are thoroughly familiar with the project.

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Could the tour companies consider sponsoring researchers in any way (do they already?) Flights, permits, accommodation? It must be in the interests of a tour company to increase the number of species and to say that "this bird was 'discovered' because we made it possible" should have some attractions?

Having been a poor scientist in another life, I know the trials and tribulations of that career path!

Cheers, MCM

DLane said:

I might point out that, beyond not being peer-reviewed, the vast majority of these reports themselves don't cite previous publications. Furthermore, most do not provide the actual analyses or data other than a representative sonogram and the author's conclusion. Thus, as "gray literature," one mustn't be too upset if they are not cited by others.

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Dan's comment is partially correct, but:
* I can cite quite a few SACC cases where the vocal evidence on top of other data/paper(s) was less well documented than in the above notes but seemingly allowed SACC to take a positive decision
* The few peer-reviewed papers that have been published since these ornithological notes and which tackled voice for the same species have fully or to a large extent confirmed the conclusions (and I am not aware of any contradictory cases)
* The reason for these brief ornithological notes lacking some of the criteria mentioned by Dan has been explained elsewhere (and I welcome anyone to find an author who single-handedly has published 400 papers meeting these standards in a single year...).

It thus boils down to the question whether the SACC members use their expertise to work with conclusions which have been published in a brief format (as they seemingly have done in the past) or not...

DLane said:

I might point out that, beyond not being peer-reviewed, the vast majority of these reports themselves don't cite previous publications..... Thus, as "gray literature," one mustn't be too upset if they are not cited by others.

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As a further comment, Dan seems to imply that "gray literature" should not be cited. In this case, I assume that the comment " the vast majority of these reports themselves don't cite previous publications" refers to "white publications"...

In this case I strongly disagree with his critic insinuating that in the vast majority of the notes existing in depth vocal analysis was not mentioned. On the contrary...

Peter Boesman said:

As a further comment, Dan seems to imply that "gray literature" should not be cited. In this case, I assume that the comment " the vast majority of these reports themselves don't cite previous publications" refers to "white publications"...

In this case I strongly disagree with his critic insinuating that in the vast majority of the notes existing in depth vocal analysis was not mentioned. On the contrary...

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Peter, I think you misunderstood my intent. "Gray literature" is that which has content, but is not published using "formal pathways" (i.e., peer-reviewed journals). Typically gray literature is not easily located unless the author already knows of its existence (environmental assement reports prepared for government agencies, for example), or is in field guides, or other published sources that have not passed through review and other processes to ensure the quality of the content. In this case, these reports do not present the recording numbers that were analyzed so that they can be reviewed by the reader, and therefore one has to take it on faith that the author's conclusions are well-based. I know that many recordings in XC and Macaulay are misidentified to taxon (species or subspecies), or the taxonomy used was flawed (our discussion on Herpsilochmus marginatus scapularis on the XC forum is one such situation), or vocalization type was misrepresented in the library (were homologous vocalizations compared?). If the reader can't know what recordings were used, then there is no way to know how the analyses were affected by these variables. If these data and analyses are not available to the reader (in some cases in these reports, results are available, but not what measurements were taken or how), then how is the reader to determine if the conclusions may be compromised?

I'm not saying that your reports are not valuable and should not be cited at all. However, I am saying that you should not consider it a personal slight if they are not. Viewed strictly from the point of view of the scientific process, they are not a standard publication and cannot be replicated by a third party if their samples and analyses are not provided; their citation would be anecdotal at best, the same way a field guide might be cited. Thus, if another author chooses not to cite them, or isn't aware of them, I don't think they can or should be blamed. Whether or not similar material has been cited previously in SACC proposals is immaterial.

McMadd said:

Could the tour companies consider sponsoring researchers in any way (do they already?) Flights, permits, accommodation? It must be in the interests of a tour company to increase the number of species and to say that "this bird was 'discovered' because we made it possible" should have some attractions?

Having been a poor scientist in another life, I know the trials and tribulations of that career path!

Cheers, MCM

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Some do. Several companies have guides who actively publish such work, and they credit the company for helping to fund the fieldwork necessary. I don't know if it is reasonable to ask a tour company to fund extensive fieldwork by researchers with whom they have no relationship, however. Similarly, some tour companies also send funds to conservation organizations, both local and international, to help pay for conservation projects, as well as provide optics and other support for local guides who lack it. If you are curious, I encourage you to ask your favorite tour companies if they fund such work.

DLane said:

I might point out that, beyond not being peer-reviewed, the vast majority of these reports themselves don't cite previous publications. Furthermore, most do not provide the actual analyses or data other than a representative sonogram and the author's conclusion. Thus, as "gray literature," one mustn't be too upset if they are not cited by others.

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Hmmm.... It's worth bearing in mind here that:
(I) these reports are part of HBW Alive, which is quite a widely consulted resource
(II) the HBW Alive accounts themselves generally include a discussion of previous published literature and these notes accompany those
(III) the accounts provide additional useful information justifying the positions taken in Del Hoyo & Collar's new taxonomy
(IV) over the past 15 years SACC and over the past 10 years IOC have failed to do anything much more than lazily sit about waiting for other people to publish research and either ignoring it, grumbling about it or getting round to thinking about it quite slowly.

Well done Peter, I found your pieces to be a valuable, informative and much needed contribution, peer reviewed, grey or not.

thomasdonegan said:

Hmmm.... It's worth bearing in mind here that:
(I) these reports are part of HBW Alive, which is quite a widely consulted resource
(II) the HBW Alive accounts themselves generally include a discussion of previous published literature and these notes accompany those
(III) the accounts provide additional useful information justifying the positions taken in Del Hoyo & Collar's new taxonomy

Well done Peter, I found your pieces to be a valuable, informative and much needed contribution, peer reviewed, grey or not.

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I'm not quite sure how you could peer review a sonogram and factual descriptions of the the notes - they are what they are and where linked to sound archives can be re-tested by any who are so inclined. I don't see any substantially greater analysis of songs and calls (esp ref sample size) in recent papers describing new species or recommending splits, compared to the HBW analyses by PB.

I can't help feeling that the huge amount of analysis on vocals undertaken for HBW Volume 2(and the related splits) has annoyed some museum workers, who might have suspected (or known) of the differences - and their implications - but have not had the time or inclination to publish in the traditional manner.

cheers, alan

Automolus exsertus

Peter Kovalik said:

Benjamin G. Freeman and Graham A. Montgomery (2017) Using song playback experiments to measure species recognition between geographically isolated populations: A comparison with acoustic trait analyses. The Auk: October 2017, Vol. 134, No. 4, pp. 857-870.

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IOC Updates Diary July 2

Accept split of Chiriqui Foliage-gleaner

Ramphocelus passerinii, R. costaricensis

Peter Kovalik said:

Benjamin G. Freeman and Graham A. Montgomery (2017) Using song playback experiments to measure species recognition between geographically isolated populations: A comparison with acoustic trait analyses. The Auk: October 2017, Vol. 134, No. 4, pp. 857-870.

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IOC Updates Diary July 2

Lump Passerini’s and Cherrie’s tanagers as Scarlet-rumped Tanager