Background Mortality of Wildlife on Renewable Energy Projects
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsI think this is an excellent manuscript, given the way it was structured, considering all the possible variations and possibilities, and how it was carried out. It sheds new light on baseline mortality before and after the installation of renewable energy plants, and on how much this latter may then influence mortality during the plants' operation.
Author Response
Reviewer 1
I think this is an excellent manuscript, given the way it was structured, considering all the possible variations and possibilities, and how it was carried out. It sheds new light on baseline mortality before and after the installation of renewable energy plants, and on how much this latter may then influence mortality during the plants' operation.
Reply: Thank you!
Reviewer 2 Report
Comments and Suggestions for AuthorsThis paper addresses a long-proposed issue that background mortality is a positive bias related to fatality searches at wind turbine facilities and other renewable resource infrastructure. To address the issue of background mortalities of birds and bats, the author used past data that he collected while mapping burrow systems of fossorial mammals, as well as data collected by the author and others during preconstruction, during active operation, and after the removal of the turbines. Overall, I found that this article compiled an impressive mix of data sets, made reasonable adjustments in the data to maximize comparability, and derived the convincing conclusion that background mortalities have minimal effect on fatality searches at wind turbine facilities. One criticism of this study might be that the background fatality searches related to mapping burrow systems of fossorial mammals may not be comparable to those searches conducted at operational wind turbine facilities. However, I actually feel that the attention to detail required in mapping burrow systems could be a positive bias in terms of detecting a higher proportion of the carcasses actually present compared to a technician doing a search under a wind turbine. If anything, I suspect that the background mortality estimates that were performed by the author in 1999 – 2019 may be biased high. During fatality searches, most observers miss a substantial number of small carcasses that are present. In multiple detection assessments of carcasses related to a study of communication tower mortalities, we found that most observers only detected about 30-40% of the planted carcasses that were present. My suggestions for the author are relatively minimal and amount to mostly clarifications. My specific comments are as follows:
Throughout the ms. Diversity, I believe, uses the numbered references for in-text citations rather than the author-year in-text citation format. You will need to adjust your in-text citations accordingly and properly number and order the references in the sequence that they are cited in the Literature Cited section.
Page 1, lines 27 – 32. I feel the term “turbine addresses” could be confusing to some readers. For the abstract I suggest using “turbine site” or “turbine location.” Then, early on in the manuscript, clarify that you will be using “turbine address” to indicate the specific location of a wind turbine structure.
Page 2, lines 63 - 64. Maybe change to “the proportion of carcasses or remains included in a fatality estimate …”
Page 2 and 3, lines 85 – 96. I do not follow this argument related to Johnson et al. (2000), and Johnson (2007), which are unpublished reports that are not available to me. It sounds pretty sketchy to me to use Partner in Flight estimates based on BBS data (which are coarse and relative data at best) with selected published estimates of natural mortality (which also have lots of problems due to small sample sizes and speculative models) to somehow conclude that background mortality would exceed wind energy-caused mortality. Could this be condensed by stating something like ”It is noteworthy that Johnson (2007), based on using a combination of BBS, selected published natural mortality estimates, and unpublished data concluded that background mortality may exceed wind energy mortality. However, this approach in estimating background mortality has not been critically evaluated and may be flawed due a number of different biases incorporated by using multiple unrelated data sets.” I also find the last sentence confusing as the author stated above that confounding anthropogenic caused mortality should not be included in estimates of background mortality. I agree with the author on this point. Perhaps, clarify that you consider background mortality equivalent to natural mortality excluding all anthropogonic factors. At any rate, please revise and clarify your point here.
Page 3, lines 124 – 125. Please add an example citation for this point.
Page 10, line 341. Change to “… red-tailed hawk carcass …”
Page 10, line 350. Change to “… 1 Swainson’s hawk ….”
Page 10, lines 354 - 355. Were these small birds all passerines? If so, change to “4 unidentified small passerines.”
Page 12, lines 402 – 404. Redundant and wordy. I suggest changing to: “Frist searches of 1998-2014 averaged 20.1 turbine addresses …”
Page 13, line 433. The notation D sort of comes out of nowhere. Perhaps, put in parentheses something like “(see 2.3 Bias Identification and Adjustment)”
Page 14, Tables 5 and 6. Clarify titles, if I am following correctly, to: “Table 5. Adjusted estimated fatalities/ha related to body mass before and after ….”
Page 15, lines 458 – 459. I find the use of “between” here a bit awkward and confusing. Change to: “The 95% confidence intervals based on these two data sets were nearly equal, …”
Page 16. Line 465. Approximately what is “insufficiently distant” from wind turbines? Maybe put in what distance you believe is insufficiently distant to measure an accurate background mortality. E.g., “(<10 km)”
Page 17, lines 516 – 530. Very important points!
Author Response
Reviewer 2
This paper addresses a long-proposed issue that background mortality is a positive bias related to fatality searches at wind turbine facilities and other renewable resource infrastructure. To address the issue of background mortalities of birds and bats, the author used past data that he collected while mapping burrow systems of fossorial mammals, as well as data collected by the author and others during preconstruction, during active operation, and after the removal of the turbines. Overall, I found that this article compiled an impressive mix of data sets, made reasonable adjustments in the data to maximize comparability, and derived the convincing conclusion that background mortalities have minimal effect on fatality searches at wind turbine facilities. One criticism of this study might be that the background fatality searches related to mapping burrow systems of fossorial mammals may not be comparable to those searches conducted at operational wind turbine facilities. However, I actually feel that the attention to detail required in mapping burrow systems could be a positive bias in terms of detecting a higher proportion of the carcasses actually present compared to a technician doing a search under a wind turbine. If anything, I suspect that the background mortality estimates that were performed by the author in 1999 – 2019 may be biased high. During fatality searches, most observers miss a substantial number of small carcasses that are present. In multiple detection assessments of carcasses related to a study of communication tower mortalities, we found that most observers only detected about 30-40% of the planted carcasses that were present. My suggestions for the author are relatively minimal and amount to mostly clarifications. My specific comments are as follows:
Throughout the ms. Diversity, I believe, uses the numbered references for in-text citations rather than the author-year in-text citation format. You will need to adjust your in-text citations accordingly and properly number and order the references in the sequence that they are cited in the Literature Cited section.
Reply: I understand. Diversity and I agreed that I would submit the manuscript without first adhering to the citation standard, because I was headed out on an extended research expedition, and I didn’t have time to finish the formatting.
Page 1, lines 27 – 32. I feel the term “turbine addresses” could be confusing to some readers. For the abstract I suggest using “turbine site” or “turbine location.” Then, early on in the manuscript, clarify that you will be using “turbine address” to indicate the specific location of a wind turbine structure.
Reply: I revised as suggested.
Page 2, lines 63 - 64. Maybe change to “the proportion of carcasses or remains included in a fatality estimate …”
Reply: I revised, but not exactly as suggested. Carcass remains represent the study unit, which is a fatality. Carcass remains can vary from one to many pieces whereas the fatality is only but one entity that is interpreted from the carcass remains. A fatality estimate is based on fatalities, which themselves are determined from carcass remains.
Page 2 and 3, lines 85 – 96. I do not follow this argument related to Johnson et al. (2000), and Johnson (2007), which are unpublished reports that are not available to me. It sounds pretty sketchy to me to use Partner in Flight estimates based on BBS data (which are coarse and relative data at best) with selected published estimates of natural mortality (which also have lots of problems due to small sample sizes and speculative models) to somehow conclude that background mortality would exceed wind energy-caused mortality. Could this be condensed by stating something like ”It is noteworthy that Johnson (2007), based on using a combination of BBS, selected published natural mortality estimates, and unpublished data concluded that background mortality may exceed wind energy mortality. However, this approach in estimating background mortality has not been critically evaluated and may be flawed due a number of different biases incorporated by using multiple unrelated data sets.” I also find the last sentence confusing as the author stated above that confounding anthropogenic caused mortality should not be included in estimates of background mortality. I agree with the author on this point. Perhaps, clarify that you consider background mortality equivalent to natural mortality excluding all anthropogonic factors. At any rate, please revise and clarify your point here.
Reply: Agreed on all points. I adopted the recommended sentence replacement (Thanks!), and I revised the last sentence of the paragraph. I think I was trying to do too much with the paragraph, and the last sentence ended up stating the opposite of what I intended.
Page 3, lines 124 – 125. Please add an example citation for this point.
Reply: I added two citations.
Page 10, line 341. Change to “… red-tailed hawk carcass …”
Reply: Thanks for catching this. I repaired it.
Page 10, line 350. Change to “… 1 Swainson’s hawk ….”
Reply: Done.
Page 10, lines 354 - 355. Were these small birds all passerines? If so, change to “4 unidentified small passerines.”
Reply: These 4 birds could not be identified to species, so it is unknown whether they were passerines.
Page 12, lines 402 – 404. Redundant and wordy. I suggest changing to: “Frist searches of 1998-2014 averaged 20.1 turbine addresses …”
Reply: Good point. I revised as suggested.
Page 13, line 433. The notation D sort of comes out of nowhere. Perhaps, put in parentheses something like “(see 2.3 Bias Identification and Adjustment)”
Reply: I revised as suggested.
Page 14, Tables 5 and 6. Clarify titles, if I am following correctly, to: “Table 5. Adjusted estimated fatalities/ha related to body mass before and after ….”
Reply: I revised the Table headings.
Page 15, lines 458 – 459. I find the use of “between” here a bit awkward and confusing. Change to: “The 95% confidence intervals based on these two data sets were nearly equal, …”
Reply: Great suggestion! I revised accordingly.
Page 16. Line 465. Approximately what is “insufficiently distant” from wind turbines? Maybe put in what distance you believe is insufficiently distant to measure an accurate background mortality. E.g., “(<10 km)”
Reply: I revised as suggested.
Page 17, lines 516 – 530. Very important points!
Reply: Agreed! And thanks!
Reviewer 3 Report
Comments and Suggestions for AuthorsThe study has been well planned and executed. Rusults are under robust statistical analysis. In 'Discussion' the reults are well interpreted and confronted with literature.
It is advisable, for higher clarity for readers, to show on a map all the sites/places in California and Nevada listed in Table 1, 2 and 3. Some nomenclatorial changes to be considered: Bubulcus ibis is now split into two separate species and transferred to the genus Ardea. So, now we have Ardea ibis, which is the Western Cattle Egret from Africa and Americas, and Ardea coromanda, the Eastern Cattle Egret, from the Oriental and Australian Regions. The Barn Owl is also split into few species. So, the American Barn Owl is now Tyto furcata (English name: American Barn Owl), while the one from the Western Pelearctic and Afrotropical remains Tyto alba.
Author Response
Reviewer 3
The study has been well planned and executed. Rusults are under robust statistical analysis. In 'Discussion' the reults are well interpreted and confronted with literature.
Reply: Thank you!
It is advisable, for higher clarity for readers, to show on a map all the sites/places in California and Nevada listed in Table 1, 2 and 3.
Reply: I added the recommended map.
Some nomenclatorial changes to be considered: Bubulcus ibis is now split into two separate species and transferred to the genus Ardea. So, now we have Ardea ibis, which is the Western Cattle Egret from Africa and Americas, and Ardea coromanda, the Eastern Cattle Egret, from the Oriental and Australian Regions. The Barn Owl is also split into few species. So, the American Barn Owl is now Tyto furcata (English name: American Barn Owl), while the one from the Western Pelearctic and Afrotropical remains Tyto alba.
Reply: Thanks! I revised accordingly.
