An Adaptation of Wintering Water Birds to Man-Made Weirs in Relation to the Freeze–Thaw Process in Tancheon Stream, Korea

Round 1

Reviewer 1 Report (Previous Reviewer 4)

Comments and Suggestions for Authors

The authors addressed well with my concerns and I have no further comment.

 

Author Response

Many thanks for your comments and suggestion.

Reviewer 2 Report (Previous Reviewer 2)

Comments and Suggestions for Authors

Lines 39–43 I do not understand why this paragraph appears here. If it is related to the research topic, please indicate this clearly. In its current form, this section of the introduction seems to be taken out of context. There is no connecting sentence or clear link to the rest of the text.

In the “Materials and Methods” section, it would be useful to include an introductory sentence describing what data was collected and what parameters were measured. Only then should detailed information about the measurements be provided (i.e., what is already in this section).

The authors have moved the text fragment containing the table !from the “Materials and Methods” section to the “Results” section, following my earlier comment, which stated: “Shouldn't the bird abundance be presented in the ‘Results’ section instead of the ‘Material and Methods’ section?” However, this comment referred only to bird numbers. It is important to distinguish between two elements: information such as the type of binoculars used, the time of observation, etc. should be included in the “Materials and Methods” section, while the results of these observations, i.e., data on bird numbers, should be presented in the “Results” section.

The caption for “Figure 5” has been corrected, and this figure is now Figure 6. Figure 5 appears later in the text.

Lines 184-185 Severe cold days have already been defined earlier and there is no need to repeat the thawed ratio and mean air temperature. The same applies to cold days and warm days.

I have serious objections to the unnecessary duplication of results (test values given in the table and text or in the figure and text). The results presented in Figure 6 are described in detail in the text. Fig. 6 is unnecessary if all results are presented in the text. The same applies to Table 2. The results presented therein are also described in detail in the text.

Lines 261-269 This part of the text is more relevant to the discussion.

Line 244 Please correct to “abundance of water birds.”

Author Response

Q1. Lines 39–43 I do not understand why this paragraph appears here. If it is related to the research topic, please indicate this clearly. In its current form, this section of the introduction seems to be taken out of context. There is no connecting sentence or clear link to the rest of the text.

Response> Thank you for your suggestion regarding the connection of this sentence to the rest of the text. We inserted this sentence to show the recent change of precipitation trends in a city of Korea, however, as you suggested it looks unnecessary addition. So we deleted this sentence.

Meanwhile, over the past 20 years (2001–2020), annual precipitation averaged 1,318 mm, approximately 0.8% higher than the 1981–2010 period, while the number of precipi-tation days decreased by 1.4% in Korea. Conversely, the frequency of heavy rainfall events exceeding 80 mm/day increased by approximately 16.7% [11], with most precipitation concentrated during the flood season from June to September [12, 13].

Q2. In the “Materials and Methods” section, it would be useful to include an introductory sentence describing what data was collected and what parameters were measured. Only then should detailed information about the measurements be provided (i.e., what is already in this section).

Response> I deeply appreciate your suggestion. In the “Materials and Methods”, we composed the subsection as, 2.1. Study area, 2.2. Collected data and measured parameters, 2.3. Statistical analysis. And, in the subsection of 2.2., we added the collected data and measured parameters as following sentences.

2.2. Collected data and measured parameters.

We collected number of water birds, and we measured the parameters of water depths, thawed ratio, temperature, distance from weirs, area of sandbars. 

Q3. The authors have moved the text fragment containing the table !from the “Materials and Methods” section to the “Results” section, following my earlier comment, which stated: “Shouldn't the bird abundance be presented in the ‘Results’ section instead of the ‘Material and Methods’ section?” However, this comment referred only to bird numbers. It is important to distinguish between two elements: information such as the type of binoculars used, the time of observation, etc. should be included in the “Materials and Methods” section, while the results of these observations, i.e., data on bird numbers, should be presented in the “Results” section.

Response> I deeply appreciate your detailed explanations and suggestions. So, we moved the sentence following parts to the methods parts, and we added the abundance results of Table 1 as below.

## Moving to the methods parts ##

We recorded water bird numbers in the stream channel during the first two hours after sunrise on the survey days. Binoculars (8 x 30 magnification) were used to identify birds, with reference to a field guide [18]. Also, we divided the observed birds into diving ducks and dabbling ducks to comprehend the habitat use of water depth at the study areas (Table 1).

## Added sentence ##

Among the observed water birds, the abundance was highest in the order of Spot-billed duck, Little Grebe, and Common Merganser (Table 1).

Q4. The caption for “Figure 5” has been corrected, and this figure is now Figure 6. Figure 5 appears later in the text.

Response> Many thanks for your comments. We corrected the location of Figure 5. It was a mistake in editing the clean version and the editing version of the manuscripts.

 

Q5. Lines 184-185 Severe cold days have already been defined earlier and there is no need to repeat the thawed ratio and mean air temperature. The same applies to cold days and warm days.

Response> I deeply appreciate your precious comments. And we corrected them as follows.

During the severe cold weather conditions, with a mean thawed ratio of less than 20% and mean air temperatures below -9°C, the highest mean thawed ratios were observed at the front of the weirs (0-100 m), ranging from 36 to 39% (Fig. 5(a1 ~ a3), Table S2). In the subsequent sections (100–200 m, 200–300 m), thawed ratios decreased to 20–23% and 13–18%, respectively. Other sections (300-700 m) exhibited lower thawed ratios of less than 8%. The correlation with distance was statistically significant (r = - 0.90, p < 0.001, Fig. 6). Under the cold weather conditions (mean thawed ratios: 50–70%, mean air temperatures: -2 to 4°C), the front section of the weirs (0-100 m) exhibited higher thawed ratios (73-93%) compared to the severe cold conditions (Fig. 5(b1 ~ b3)). The mean thawed ratios gradually decreased with distance from the weirs, and the correlation with distance remained statistically significant (r = - 0.85, p < 0.001, Fig. 6). However, during the warmer conditions (mean thawed ratios: > 90%, mean air temperatures: 0 to 5°C),

Q6. I have serious objections to the unnecessary duplication of results (test values given in the table and text or in the figure and text). The results presented in Figure 6 are described in detail in the text. Fig. 6 is unnecessary if all results are presented in the text. The same applies to Table 2. The results presented therein are also described in detail in the text.

Response> I deeply appreciate your precious comments and double-checking. We corrected the duplicated expression of test values as follows. And, we showed the values in text and removed Figure 6, and we showed Table 2, and removed the test P-values from the text. To understand the correlation status, we retained the r-values in the text.

The mean water depths (ranging from 21 to 69 cm) increased gradually with distance from the weirs (Fig. 4(a), Table S1), showing a statistically significant correlation with the distance (r = 0.61, p < 0.01, Fig. 6). In contrast, the mean areas of sandbars were primarily concentrated in the 0–300 m and 400–500 m sections, while the 300–400 m and 500–700 m sections showed relatively smaller sandbar areas (Fig. 4(b)). The correlation with the distance was statistically significant (r = - 0.61, p < 0.01, Fig. 6).

 

To further examine the relationships between the abundance of water birds and environmental variables, we calculated correlation coefficients (Table 2).

During the severe cold weather, the abundance of both dabbling ducks and diving water birds showed strong positive correlations with the thawed water surface ratios (dabbling ducks: r = 0.85; diving water birds: r = 0.87). However, as the weather warmed, these correlations gradually weakened (cold days: dabbling ducks (r = 0.68), diving water birds (r = 0.60); warm days: dabbling ducks (r = 0.29), diving water birds (r = -0.27). The abundance of dabbling ducks was also positively and significantly correlated with the area of sandbars across all periods (severe cold days: r = 0.58; cold days: r = 0.62; warm days: r = 0.44). In contrast, the abundance of diving water birds showed a significant positive correlation with sandbar areas only during the severe cold days (r = 0.64). Water depth had a negative and significant correlation with the abundance of dabbling ducks during all periods (severe cold days: r = - 0.59; cold days: r = - 0.55; warm days: r = - 0.55). For diving water birds, a significant negative correlation with water depth was observed only during the severe cold days (r = -0.65).

 

Q7. Lines 261-269 This part of the text is more relevant to the discussion.

Response> I deeply appreciate your suggestions. We moved this part to the first paragraph of the discussion part.

 

Q8. Line 244 Please correct to “abundance of water birds.”

Response> I deeply appreciate your suggestions. We corrected it as follows:

distribution of water birds à abundance of water birds

Round 2

Reviewer 2 Report (Previous Reviewer 2)

Comments and Suggestions for Authors

Thank you for taking my comments and suggestions into account. I have one more, more technical comment, but it affects the overall reception of the text. In my opinion, the discussion should not begin with the fragment that previously appeared in the Results section (lines 236–244). I suggested moving this fragment to the Discussion section, but it would be better to include it somewhere later in the text rather than at the very beginning. The ideal beginning of the Discussion section is the fragment that previously started it (i.e., the current lines 247–251).

Author Response

Many thanks for your quick and proper suggestion on the location of paragraphs.

I followed your suggestion, and moved that paragraph.

During the reviewing process, I deeply appreciate your precious contribution and development of manuscripts.

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Dear authors,

 

Could you write an independent paragraph to describe the statistics that you used in your research?

Reviewer 2 Report

Comments and Suggestions for Authors

The topic of the work is very interesting and, in my opinion, the manuscript will contribute to the knowledge of the impact of human activities on biodiversity and the distribution of organisms in the habitat. However, the paper needs some improvements, especially in the presentation of the results.

 

Introduction

 

The Introduction is too short, insufficiently showing the background and introducing the research topic.

It might be useful to provide some examples of the effects of dams, weirs and other similar structures, freezing bodies of water on the distribution of birds

Lines 50-51 – “Little attention was given to the weirs in the viewpoint of biodiversity and habitats for the water birds” Are the authors aware of any publications on the impact of dams or weirs on biodiversity, especially birds? It would be worth mentioning something about them here

Methods

Line 124 - Please write down what is meant by ‘waterbird distribution’. The authors correlated not the distribution of waterbirds, but simply the number of waterbirds (from the two groups separately) with various variables.

Results

General comments: The results are unnecessarily duplicated (test values given in the table or in the graph and text). It seems to me that the authors focused too much on correlations between environmental factors and not enough on the distribution of birds and its relation to environmental factors. It would have been better to use e.g. GLM instead of multiple individual correlations.

Detailed comments:

Shouldn't the bird abundance be presented in the ‘Results’ section instead of the ‘Material and methods’ section.

Lines 128-178 All correlation results are given in the text and at the same time presented in Fig. 5. In my opinion, Fig. 5 is unnecessary if all results are presented in the text. However, it would be better to leave Fig. 5 and describe the results in less detail without including the correlation results.

The caption for Figure 5 only gives a general indication that these are correlation results. There is no indication of what the numbers and asterisks mean (which was done for Table 2).

Lines 148-149 Severe cold days have already been defined earlier and there is no need to repeat what the mean thawed ratio and mean air temperature are.

Lines 154-155 As above

Lines 158-159 As above

Lines 148-161 In the case of severe cold days and thawed ratio, the text describes in great detail what is visible on the chart (unnecessarily duplicating information). In the case of cold days and warm days, there is no such detailed description (which is good).

Line 153 – I think you mean Fig. 5, not Fig. 6

Lines 181-182 Severe cold days have already been defined earlier and there is no need to repeat what the mean thawed ratio and mean air temperature are.

Lines 184-185 As above

Line 187 As above

Line 190 The reason for missing observations of diving water birds should be given in the discussion section, not in the results.

Lines 203-204. This sentence fits into the ‘Methods’ section, not the ‘Results’ section..

Lines 209-222. Again, the correlation results are presented in detail in the text and in Table 2. The general rule in scientific publications is that we do not present (duplicate) the same results in the text and in a table or graph.

Lines 223-232 This fragment is more relevant to the discussion than to the results.

Reviewer 3 Report

Comments and Suggestions for Authors

the manuscript focussed on the impact of thawed stream on avian diversity, which could help conserving the wintered birds under the climate change.

several comments need to be addressed before publication.

1.  the terms Fws and Tws are just mentioned in the caption, not shown in the figure 2.

2.  the air temperature of cold day on 12th Jan was somehow higher than that of warm day on 13th Feb. the authors should define the cold day and warm day in detail. I suggest defining the warm day as the days that cumulative air temperature in former days not below a threshhold value. 

Reviewer 4 Report

Comments and Suggestions for Authors

Please see attached comments.

Comments for author File: Comments.pdf