PONE-D-24-45551Characteristics of Vitelline Warbler songs and calls: Novel acoustic descriptions of a range-restricted Caribbean songbird (Setophaga vitellina )PLOS ONE

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Additional Editor Comments:

We have received two very helpful reviews for your manuscript. They both see merit in the paper but they have important suggestions for improvement.

My main concerns are related to the distributional surveys and habitat characterizations. I recognize that these components were not the focus of the paper, but they are critical for conservation.

Title and abstract

Are you sure that the title is appropriate? The acoustics are clearly the focus, but you also collected useful data on distribution and habitat requirements. I think it would probably be better to include something about abundance and habitat in the title. These parts of the paper are important.

Similarly, you include the abundance and habitat methods prominently in the abstract, but you don’t say anything about these results in the abstract. Please revise. Finally, please make the first part of the last sentence of the abstract more specific. What needs to happen to help conserve this species?

Methods and results

More details are required to make the methods replicable.

I agree with reviewer 2 that a clearer statement on data availability is needed. Even if the data will be archived in a public location it would probably be best to have the abundance data and metadata presented, possibly in a summarized form, in the supplementary material. Please specify what time of day you did the surveys by bike, including the earliest time surveys started and the latest time surveys ended. Please also give the length of each transect and the number of times it was surveyed. Was your survey period peak breeding season (so that your detection probability was high)? Under what weather conditions did you do the surveys?

Please specify how you evaluated the habitat and assigned the sampled habitat to a category. Was this done in the field or by satellite images? Did you divide up the transects by habitat? If so, please show this in the data file in the supplementary material and include the GPS tracks or GPS coordinates of the habitat divisions so that future researchers can repeat your surveys and monitor broad changes in vegetation.

I see that the habitat categories are discussed in another reference but please give more details on them. What are the couple most common plant species in each, how tall is the vegetation on average, etc.?

Discussion

Again, please include an interpretation of your habitat and abundance results. Remind us which habitats are most important for the species and give your appraisal of the current status of the species on the island. Also, you list the main threats but what is your opinion about the most urgent threats? And what feasible actions are needed to help the species? Of course more research is needed but please give us your opinion.

Lines 265-266: We need more information on distribution and abundance? Of course it’s always nice to collect more data but you’ve just done pretty thorough surveys of this island. I’m hoping that my requested revisions will clarify how much you learned and make this statement unnecessary.

Delete line 266-267. Instead, give us a clear appraisal of the current status and the necessary actions to help the species.

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

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3. Have the authors made all data underlying the findings in their manuscript fully available?

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Reviewer #1: Yes

Reviewer #2: Yes

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Reviewer #1: Yes

Reviewer #2: Yes

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Strengths:

Good writing. Clear and concise.

I like that this study is on a tropical warbler and how the authors compare it to the closely related Setophaga discolor.

The data analysis is simple and easy to understand.

I like the literature review on what is known and what is lacking.

I like the description of density in different habitats.

Good summary of song structure.

Concerns:

The introduction about sub-species in Cayman and Swan Islands gives the impression that this study was conducted in both islands. I would recommend specifying that this study focuses on one of the islands.

There are many tables linked to figures (see below for examples).

We need more information on recording equipment. Were these recorded with phones without external microphones? Recordings with omnidirectional microphones, such as those found in smart phones, do not meet the typical standard for bioacoustics research. Nevertheless, the recording quality is adequate for the purpose of this study.

What time of day did you record birds?

What were the spectrogram setttings?

There seems to be some variation in the tone of the down notes. E.g., the DN’s in Figs. 4f and j appear skinnier on the spectrogram, than those in b, d, can h. I don’t think this difference is an artifact of the spectrogram settings, because the other notes don’t seem to be affected. It would be helpful to interpret this difference.

Chip structure is also quite variable, but that variability is not acknowledged in the text.

Tables 1 and 2: How did you choose these 10 types to highlight? Are they the 10 most common types? The only 10 types? If they are just 10 examples of song types, I would point out that it’s not typical to present representative data like this. While I like how they provide some insight into how songs were scored, they should probably be dropped for concision. Perhaps you could put them in electronic supplementary material. If these are just examples, how many total song types were there?

Did any individuals sing more than one song type?

Details by line number:

Line 50 – 62: I suggest excluding this information since do not interpret songs with respect to bill length or explore differences between males and females.

Line 62: Are they also sexually dimorphic in their vocalizations? Were all songs from adult males?

Lines 72 – 76: I suggest adding that this study intends to compare this species’ vocalizations to those of S. discolor

96. “biked” is colloquial.

Lines 94 - 100: At what times did the authors do the surveys?

Lines 99, 106, 112, 122: Add citations of the programs used?

Line 123: I recommend talking about song types in this species before this sentence.

Line 125: By “shape varieties” you mean the shape of the notes within a song?

Line 221: It would be nice to have spectrograms for the calls as well (after this paragraph).

Line 221 – 228: Any possibility these vocalizations were from females or juveniles? Is the end of February and beginning of March part of their breeding season?

234. Can you cite a description of S. discolor song here?

Lines 263 – 269: I would recommend adding how understanding their song structure is related to conservation implications.

Line 263 – 269: The authors could add future directions in the discussion

Figure 6: Add the bracket that indicates where the down note is in each spectrogram (like in figure 5).

Reviewer #2: This paper provides a report of variation in the songs of Vitelline Warblers on a single island within their range. The data collection and analysis are straightforward, and the study pertains to a poorly known species of some conservation interest. The song typology of the species is relevant to the study of evolution in warblers as the species is a resident, island-dwelling relative of the migratory Prairie Warbler, and has multiple subspecies with poorly defined (perhaps undocumented?) vocal differences. I also like the approach to quantitatively documenting different categories of note variations in the up- and down-notes.

I would like to suggest a few relatively minor additions, which I believe would help increase readership and citations of your paper with little additional effort. The below could be described in statements added to existing sections of the text, or added as their own short sections:

1. Describe how songs compare to those of birds on other islands. If there are no recordings available from other islands/other subspecies, I would note that. From a quick look on eBird, songs differ significantly between islands and subspecies, which may have bearing on taxonomy and conservation of unique populations, and should be included given that the title does not specify that the paper is specific to a certain subpopulation/subspecies.

2. It would be interesting to provide an account of within-individual variation in song type. Do individuals change what song type they use over the course of the 3-min sampling period?

3. Are any song types given at specific times of the day? Some other warbler species have a dawn song.

4. Are there any geographic differences in singing in different habitats/different parts of the island? Assuming not, state somewhere that there appeared to not be geographic or habitat determinants of song type.

Other minor suggestions for edits:

- L49: Paruline --> Parulid

- L69-70: Looks like all of the recordings on eBird are of songs, including those not tagged as “song” – 17 recordings in total prior to 2023

- Include a (brief) comparison with Prairie Warbler song in the paragraph at L69-76 in addition to Black-throated Blue

- L233: it would be more accurate to say, “… down-notes represents song components with no analog …” A discussion of complexity would require defining “complexity” in songs and perhaps making a more explicit comparison (because, for example, using a definition that more complex songs have more individual notes, Prairie Warbler songs would be classified as more complex as they can have 25+ notes). Similarly, the following paragraph at L235-245 should be edited for clarity about complexity and what the expectation should be for songs in island birds – more variability in note types? Note number? Frequency range? All of the above? Etc.

- Provide a spectrogram of the short call, as a figure or supplementary figure

- The Conservation Implications section in the Discussion should mention that there exist song differences between the subspecies/different islands

- Include a Data Availability statement in the main text

Overall, the study provides a detailed description of song variability in the Vitelline Warbler, including measures of variability within individual song components. This level of detail is often not documented, especially in species in the tropics. I think the paper would be more well-rounded and have better uptake (e.g., broader readership, more citations) with some changes, detailed above, after which it will be a solid contribution to the literature.

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Reviewer #1: Yes:  David Logue

Reviewer #2: No

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Vitelline Warbler songs, calls, and habitat preferences: novel acoustic descriptions of a range-restricted Caribbean songbird (Setophaga vitellina )

PONE-D-24-45551R1

Dear Dr. Cummings,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

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Additional Editor Comments (optional):

Thank you for your close attention to our comments. I only have the following small requests:

Title: move the scientific name immediately after the common name.

Line 63: remove period after “study”

Line 76 S. caerulescens and S. discolor should be italicized

Lines 191-192 Bursera simaruba should be italicized

Line 225 S. vitellina should be italicized

Line 370 ‘on Little Cayman’ should not be italicized

Line 386 Capitalized 'Vitelline Warblers'

Line 415 It would be better to not start your conservation implications section by saying ‘more studies are needed’. I would focus on your results and interpretations and then say this at the end if needed (I’m not sure it is).

Line 419 It’s Near Threatened, not Near Vulnerable

Reviewers' comments: