Passive Acoustic Monitoring as a Tool to Investigate the Spatial Distribution of Invasive Alien Species

Round 1

Reviewer 1 Report

This manuscript addresses the use of passive acoustic monitoring as a tool to investigate the spatial distribution of invasive alien species.

The topic addressed is very interesting. The work is very well approached, with an adequate methodological design and an optimal statistical analysis, including the use of restricted spatial regression. The website developed as part of the results constitutes a valuable and significant contribution to the management of invasive species on the island of Puerto Rico. The discussion is well focused and well resolved.

Specific comments

For this manuscript I have no relevant comments to add.

Author Response

We appreciate the Reviewer’s comments and the positive feedback of our work. There is no question to be addressed.

Reviewer 2 Report

I reviewed the manuscript "Passive acoustic monitoring as a tool to investigate the spatial distribution of invasive alien species" by Ribeiro et al. Overall it looks quite an accomplishment, congratulations to the authors. I found the methods very well described, and the overall presentation is of very good quality. Only minus point: the discussion was Ok, but does not add much to what has been already said in the intro and results.

I have only very minor comments:

Abstract:

Lines 9-10: The phrase "Unfortunately, researchers, agencies and other management groups are not doing a good job of detecting and monitoring IAS at large spatial and temporal scales." is not objective, what is "a good job"?. I would suggest to use a more neutral but still meaningful phrase like: "Researchers, agencies and other management groups face the unsolved challenge of effectively detecting and monitoring IAS at large spatial and temporal scales." or something like that. 

Introduction:

Line 32: You could delete the "a myriad of" and it will still have the same meaning

Lines 54-56: Not sure if I understand correctly, but I don't think monitoring automatically leads to "improving the capacity to counter the biodiversity crisis in recent years". Could you please clarify?

Methods:

343-345: "The other bird species had low raw detections and were detected in few sites (less than 10 sites); thus it was not possible to run occupancy models and diel call pattern analysis for them." I understand this limitation for the analysis, but it is likely that many invasive alien species will have low number of detections before they become widespread and established. Thus, how can we use this limited information to inform management actions? Could you add a paragraph in the discussion about the challenge of analysis of species with few records?

Lines 351-356 and Figure 2:

Aren't these polar plots biased by the method applied?. In lines 199-200 the pattern matching analysis seems to be limited to 5am-6pm for diurnal and 6pm-5am for nocturnal, thus precluding the detection of "nocturnal species" after 5am or "diurnal species" after 6pm. If this indeed so, it seems likely that some calls remained undetected, please clarify if this is the case or if I am misunderstanding the methods.

Figure 3:

Would be informative to add sampling sites without detections to the map, or add a reference to map with the distribution of all sampling sites (in Appendix) to appreciate the spatial distribution of sampling effort.

Author Response

We thank the Reviewer for their positive comment and careful review. We have provided with care a point-by-point response to the Reviewer #2 in the attached file. 

Author Response File: Author Response.docx

Reviewer 3 Report

The manuscript presents the assumptions, the description of the research area, the methods used, and the results obtained from passive acoustic monitoring and models based on the distribution of invasive species of birds, amphibians and mammals on the islands of the Commonwealth of Puerto Rico.

I found the text interesting and recommendable to publish in Remote Sensing.

My reservations are only raised by fragments of two paragraphs in the "Introduction" section. In lines 50-52 it is written that: "Remote sensing has been successfully used to distinguish and monitor alien plant species [15-17]. However, remote sensing is still mostly overlooked for invasive fauna, ... ", and in the next paragraph returns to these issues again, "However, while remote sensing through satellite and airborne images has been successfully used to detect and monitor changes in forest cover, vegetation type, disturbance regimes, plant phenology, and ecosystems [21, 22], most animal species still require in situ sensing technologies [20]." (Lines 56-59). I suggest modifying these passages so as not to repeat quite similar information.

 

Moreover:

- in line 16 there is an unexplained abbreviation "ROI", the meaning of which should be given in "Abstract";

- in line 347 the citation of the drawing is written in capital letters ((FIGURE 2), and not as before (Figure 1) - see line 173;

- in line 551 one should write (similar to the section "Material and methods") – “AudioMoth devices”, not "audiomoth device";

- remove an unnecessary contour of an unexplored island from the map in Figure B3;

- add in the description of the table an explanation of the abbreviations used (eg: NC, LC, VU, DD, etc.);

- in Appendix D in the graphs for model of American bullfrog, model of chicken, model of domestic dog, clarify the scale on the x-axis, explain what the marked "chain," mean, and indicate (in a short description) what results from the presented charts, except that they exist and contain some data.

Author Response

We very appreciate Reviewer's constructive review. We have provided a care point-by-point response to the reviewer’s comments.

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 4 Report

The manuscript describes novel approach to research on IAS distribution. The methodology is adequately described and the results are clearly presented. My main concern is that the authors do not compare the number of species they detect using PAM with the overall number of vocally active vertebrate species known for the investigated region (i.e., each island) – and I think that this is an important aspect when drawing some of the conclusions related to the results. In addition, it would be interesting to test the automatic recognition with species that were not registered in the manual annotation, but are known to be present in some of the 841 sampling sites (for many species there are freely available sound files that could be used as templates). I recommend to include such analysis in order to better demonstrate the usefulness of their approach (i.e., if PAM only detects a small portion of the species present in a given region, then interaction models based on it would be questionable). This would be especially interesting for Mona Island, considering that the entire island is a protected area. Below are some more specific comments:

Lines 143-144: The provided web address could not be opened (Error 404 - Page Not Found)

Lines 188-197: Apart from the species from the manual annotation, it seems that you did not include other species, which were not detected by the manual annotation, but are expected/known to be present in the region. Why?

Lines 311-312: Provide a number of detected species for each island, including percent detected in relation to the overall species known from the island.

Lines 383-385: While this statement is generally true, it seems a bit forced, considering that you only have recordings from March-June. If it was March-October, for example, there could have been more variability.

Lines 492-496: This could be possible if you detect a large enough percentage of the native species. However, if there is a large number of species left undetected, results could be biased.

Line 721: I think it should be "When" instead of "Whether".

Author Response

We thank the Reviewer for their positive comment and careful review. We have provided a point-by-point reponse to the reviewer’s comments in the attached file.

 

Author Response File: Author Response.docx

Reviewer 5 Report

Title: Passive acoustic monitoring as a tool to investigate the spatial distribution of invasive alien species

 Abstract: Line 9 and 10, it is not a good sentence. Change for “IAS monitoring can be improved by using”... Soniferous species representing an small percentage of IAS. The abstract content is very poor. It is like a technical report. It is totally descriptive. There is no objective, there is no comparison with previous methodologies and there are no statistical analyses. These contents are not enough for a scientific paper.

Keywords: Not all the keywords are presented in the abstract. So, something is wrong, or the abstract or the keywords. Acronyms are not recommended.

Introduction: At the beginning of the draft you must clearly defined the (1) IAS components and proxies, due to in this paper you only will consider “an small percentages of the species”, and (2) describe the different remote sensing tools, and which tools you will explore here. It is necessary to reduce the draft topic... you will not analyse everything, and you will not compare your technique vs everything. In example eDNA effectiveness and costs. Any technique must be analysed considering at least three dimensions: (a) effectiveness, (b) feasibility of implementations, (c) costs. Otherwise, it is just a presentation of some incomparable results.

There is a lack of scientific objective. This is just like a technical report. The database is amazing, and the authors must reformulate the “history in behind” to present a new scientific knowledge, and not just a report with the obtained results (point 1 in Figure 1, we need this).

Methods: The single species occupancy models were not presented in the objectives, and it is no clear the relation with the remote sensing survey. All this section must be presented previously and linked with clear objectives.

Results: This is a mix of results, methods and discussion (e.g. lines 314-329). The results must be used to present what do you do. This section must be re-written. Besides, this section looks like you present what you can do with these tools... what without a clear scientific objective.

Discussion: The same for this section. There is no clear “history in behind”, and this is due to no clear objective was presented. I suggest to present a clear scientific objective and some questions to be solved with this research. You have a wonderful data base. Use it to solve some gaps in the knowledge. Besides, the IAS are just lack in the “sound” of the draft.

Conclusions: These sentences are not conclusions. The conclusions are the “new knowledge” for the Science. These new knowledges must be derived from your results, and this draft has no new knowledge due to it is like a technical report.  

Author Response

Please see the attachment

Author Response File: Author Response.docx

Round 2

Reviewer 5 Report

Thanks to improve the draft. I  think the paper is suitable as Communication un the present form.