Species-Specific Effects of a Sound Prototype to Reduce Bird Use of Powerline Poles

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This is a straight forward piece of work. It is well reported. What the authors did and why they did it is clear. Their conclusions are based upon suitably cautious interpretations of the results. However, this is a preliminary study and the authors acknowledge this in their Discussion where there is a good review of how the work should be extended and refined. The work provides a good indication that these technique, and equipment employed, could be a useful tool in reducing bird electrocution at power line poles, but it is not definitive. One short coming is the lack of calibration of the sounds produced by the device at the different poles used in the study. For example, the authors state that  sound levels up to 100dB could be produced but it is not stated what the actual sound levels were and crucially whether they varied with the different sounds produced ( for example where the church bells as loud as the dog barks?). Also, there seems to be no record of which sounds were most effective. Is it possible that dog barks cause more birds to leave the vicinity of the poles that church bells? That should certainly be considered  in the report here and in any future work. My overall view is that this is an intriguing preliminary study  and that more Discussion of how to refine the study should be included.

Author Response

Comments 1: This is a straight forward piece of work. It is well reported. What the authors did and why they did it is clear. Their conclusions are based upon suitably cautious interpretations of the results. However, this is a preliminary study and the authors acknowledge this in their Discussion where there is a good review of how the work should be extended and refined. The work provides a good indication that these technique, and equipment employed, could be a useful tool in reducing bird electrocution at power line poles, but it is not definitive.

Response 1: Thank you very much for your assistance in improving the manuscript.

Comments 2: One short coming is the lack of calibration of the sounds produced by the device at the different poles used in the study. For example, the authors state that sound levels up to 100dB could be produced but it is not stated what the actual sound levels were and crucially whether they varied with the different sounds produced ( for example where the church bells as loud as the dog barks?)

Response 2: The four sound elements were loud, peaking at 100 dB. This information has been included on page 2, paragraph 6, line 80. In addition,  the noises were random, and it was not possible to analyse them separately, as written on page 2, paragraph 5, line 78.

Comments 3: Also, there seems to be no record of which sounds were most effective. Is it possible that dog barks cause more birds to leave the vicinity of the poles that church bells? That should certainly be considered in the report here and in any future work.

Response 3: We appreciate this comment and agree with the observation. Unfortunately, we did not record which sound was playing during the flushing events. We have included this information on page 3, paragraph 2, line 109.

Comments 4: My overall view is that this is an intriguing preliminary study and that more Discussion of how to refine the study should be included.

Response 4: We have further elaborated the limitations of the study in the discussion, focusing on ways to refine both the device and the experimental design to enhance its effectiveness - page 10-11, paragraph 5-10, line 268-299.

Author Response File: Author Response.doc

Reviewer 2 Report

Comments and Suggestions for Authors

I like the idea of using sound to deter commonly electrocuted species, so this is a valuable research endeavour. As a first step to reduce electrocutions it is a good start, but as the authors say, it can be improved as the results were perhaps not as encouraging as they would have liked. They are good to suggest ways of improvement and that it should be tried with different species.

The presentation and clarity are very good. 

There are other studies using sound deterrents around wind turbine blades (via DT Bird and BioSeco) and i think it may worth the authors investigating results from those too, in order to compare effectiveness? 

It is encouraging that the GAM analysis showed no effect of habituation to the sounds used - typically the biggest problem with such mitigations.

In your abstract give the % that were flushed for each species. I think you have included all poles (0, 25 and 50m). I think the low proportion (10.6%) of flushed birds is because you've used all instances and the low flush rate at 50m? I think it would help to give the average for 0m separately?

Are you able to give some idea of the most frequently electrocuted species in Portugal. In other words, if the deterrent is effective for kites, but not for storks is this mitigation going to help save the more at-risk species? Do Storks suffer electrocution more than kites?  

Figure 2:  I think you must re-configure this figure. I cannot make out the small indistinct text within the figures. They are clearly important so please clarify. 

Table 1: If you use the number of birds approaching or perching with the device on and off then you must surely use the numbers per 10 days. Your "off" period was 10 days but the "on" period was 37 days. So, you would expect more birds in the "on" period. In other words, you need a rate of approaches or perches to account for these different observation periods.

And on reflection on this unwieldy table, I think it would be better as a figure. or figures (one for storks, one for corvids, one for kites). The same applies for  Table 2. I just cannot wrap my head around the trends here - so please try a figure?

The authors have provided a nice summary of the limitations and ways for improvement. I like the idea that it could be adapted to power lines themselves, They will know from the literature that bustards are often the most common power line impact victim partly because they do not detect the bird diverters or bird flappers. I've long thought that if these were audible rather than visual we wouldn't have so many fatalities. So either a system like the one promoted by the authors or a whistle-type device that uses the naturally higher winds at height to give an audible signal to alert bustards that there's danger ahead.... more research for the group :-)   

Comments for author File: Comments.pdf

Author Response

Comments 1: I like the idea of using sound to deter commonly electrocuted species, so this is a valuable research endeavour. As a first step to reduce electrocutions it is a good start, but as the authors say, it can be improved as the results were perhaps not as encouraging as they would have liked. They are good to suggest ways of improvement and that it should be tried with different species. The presentation and clarity are very good.

Response 1: Thank you very much for your words and for taking the time to review this manuscript.

 

Comments 2: There are other studies using sound deterrents around wind turbine blades (via DT Bird and BioSeco) and i think it may worth the authors investigating results from those too, in order to compare effectiveness?

Response 2: We have reviewed 7 recent publications testing the use of sound deterrents around wind turbines and have included their results in the discussion - page 10, paragraph 2, line 246.

 

Comments 3: In your abstract give the % that were flushed for each species. I think you have included all poles (0, 25 and 50m). I think the low proportion (10.6%) of flushed birds is because you've used all instances and the low flush rate at 50m? I think it would help to give the average for 0m separately?

Response 3: Thank you for your comment. We have added that information to the summary (page 1, paragraph 1, line 24), in the results (page 7, paragraph 3, lines 173 and 176) and discussion (page 9, paragraph 7, line 212).

 

Comments 4: Are you able to give some idea of the most frequently electrocuted species in Portugal. In other words, if the deterrent is effective for kites, but not for storks is this mitigation going to help save the more at-risk species? Do Storks suffer electrocution more than kites?  

Response 4: The white storks and corvids appear to have some of the highest electrocution mortality rates. Although Buteo buteo is the bird of prey most affected by electrocution (together with white storks and corvids), black kite has fewer recorded fatalities. We have added some references to support these observations. This information has been included on page 9, paragraph 9, line 230.

 

Comments 5: Figure 2:  I think you must re-configure this figure. I cannot make out the small indistinct text within the figures. They are clearly important so please clarify.

Response 5: We agree and have reconfigured Figure 2. We think it is now easier to read.

 

Comments 6: Table 1: If you use the number of birds approaching or perching with the device on and off then you must surely use the numbers per 10 days. Your "off" period was 10 days but the "on" period was 37 days. So, you would expect more birds in the "on" period. In other words, you need a rate of approaches or perches to account for these different observation periods. And on reflection on this unwieldy table, I think it would be better as a figure. or figures (one for storks, one for corvids, one for kites). The same applies for  Table 2. I just cannot wrap my head around the trends here - so please try a figure?

Response 6: Thank you for your recommendation. In both tables we used the average number of birds approaching or perching as a rate to account for differences in observation periods.  Also, we have moved both Table 1 and Table 2 to the supplementary materials and created Figures 3 (page 6, paragraph 1, line 153) and 4 (page 8, paragraph 1, line 178) to better illustrate the trends.  

 

Comments 7: The authors have provided a nice summary of the limitations and ways for improvement. I like the idea that it could be adapted to power lines themselves, They will know from the literature that bustards are often the most common power line impact victim partly because they do not detect the bird diverters or bird flappers. I've long thought that if these were audible rather than visual we wouldn't have so many fatalities. So either a system like the one promoted by the authors or a whistle-type device that uses the naturally higher winds at height to give an audible signal to alert bustards that there's danger ahead.... more research for the group :-)   

Response 7: Thank you so much for your comment. We also believe that these concerns may be better mitigated through audible signals rather than visual ones, and we aim to explore this further in future work.

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

none

Author Response

Reviewer 3 did not include any comments.

Author Response File: Author Response.docx

Reviewer 4 Report

Comments and Suggestions for Authors

see attached.

Comments for author File: Comments.pdf

Author Response

Comments 1: The tested sound prototype emitted sound effectively flushed 10.6% of the birds either perching or approaching the poles, suggested a low success for this sound prototype. Thus it is difficult to make such prototype for application.

Response 1: Our results still show a low number of successful cases. However, this is partly due to the study design, which included various distances from the pole where we installed the device, further reducing the likelihood of deterring the birds. We have also included in the summary (page 1, paragraph 1, line 24), results (page 7, paragraph 3, lines 173 and 176) and discussion (page 9, paragraph 7, line 212) the percentage of the deterred birds only at 0 meters (25%) to provide a clearer understanding of the effectiveness at close range.

 

Comments 2: This study lacked a control group, e.g., poles without the sound device, made it difficult for readers to access effect (whether and how) of such tested sound prototype.

Response 2:  We are aware of this limitation and acknowledge that. We have further elaborated the limitations of the study in the discussion, focusing on ways to refine both the device and the experimental design to enhance its effectiveness - page 10-11, paragraph 5-10, line 268-299.

Author Response File: Author Response.docx

Reviewer 5 Report

Comments and Suggestions for Authors

Major faults

The research was conducted on light poles that pose no threat to birds, while  birds risk collision and electrocution at low- or high-voltage power lines.

Data were collected at only one location with a few poles, and for a short time.

The device is still a prototype that needs to be improved. Some shortcomings of the tested prototype are highlighted, but not mentioned are some practical issues such as the maintenance cost of changing the battery of each device.

I found some contradictory statements in the Discussion  (see e.g. r. 209)

Minor faults

If the χ2 tests cited within the Results derive from chi-square tests, you should mention this test in chapter 2.4. Data analysis, where only ANOVA and GAM are cited

Some sentences are repetitious and should be deleted (see e.g. r. 201)

The extensive Tab. 1 and 2 better placed in Supplementary Material

On the enclosed pdf copy of you ms. you’ll find comments about additional points that you’re your attention

Comments for author File: Comments.pdf

Comments on the Quality of English Language

See the enclosed pdf copy of you ms.

Author Response

Comments 1: The research was conducted on light poles that pose no threat to birds, while  birds risk collision and electrocution at low- or high-voltage power lines.

Response 1: Thank you for pointing this out. Therefore, we initially conducted this test near the electrocution poles, but the number of birds approaching the poles was very low, and on some days, it was nonexistent. For this reason, we decided to move the test to an area with higher bird abundance, where different species typically perch, to ensure more meaningful results.

 

Comments 2: Data were collected at only one location with a few poles, and for a short time.

Response 2: We are aware of this limitations and acknowledge that. To emphasize these points we have further elaborated the limitations of the study in the discussion, focusing on ways to refine both the device and the experimental design to enhance its effectiveness. This information has been included on page 10-11, paragraph 5-10, line 268-299.

 

Comments 3: The device is still a prototype that needs to be improved. Some shortcomings of the tested prototype are highlighted, but not mentioned are some practical issues such as the maintenance cost of changing the battery of each device.

Response 3: We have added a comment on the Discussion about the maintenance cost of battery charging and the verification of absence of water inside the battery box - page 10, paragraph 3, line 304.

 

Comments 4: I found some contradictory statements in the Discussion  (see e.g. r. 209)

Response 4: You are right, it was a mistake. We have corrected the sentence - page 9, paragraph 8, line 225.

 

Comments 5: If the χ2 tests cited within the Results derive from chi-square tests, you should mention this test in chapter 2.4. Data analysis, where only ANOVA and GAM are cited

Response 5: Thank you for pointing this out. We have corrected the chapter 2.4 (Data analysis) and now mention the χ2 tests - page 3, paragraph 6, line 116.

 

Comments 6: Some sentences are repetitious and should be deleted (see e.g. r. 201)

Response 6: You are correct, and we have deleted it.

 

Comments 7: The extensive Tab. 1 and 2 better placed in Supplementary Material

Response 7:  We agree with this comment. Therefore, we have moved both Table 1 and Table 2 to the supplementary materials and developed  Figures 3 (page 6, paragraph 1, line 153) and 4 (page 8, paragraph 1, line 178) to better illustrate the trends.

 

Comments 8: On the enclosed pdf copy of you ms. you’ll find comments about additional points that you’re your attention

Response 8: Ok, thank you very much for your time in reviewing our manuscript.

Author Response File: Author Response.docx

Round 2

Reviewer 4 Report

Comments and Suggestions for Authors

The authors addressed well with my comments, and I have no further comments.

Reviewer 5 Report

Comments and Suggestions for Authors

No further comments.