The Effect of Floods on Nest Survival Probability of Common Sandpiper Actitis hypoleucos Breeding in the Riverbed of a Large Lowland European River
Round 1
Reviewer 1 Report
Manustript entitled affects „The effect of floods on nest survival probability of Common Sandpiper Actitis hypoleucos breeding in the riverbed of a large lowland European river” presents the results of very interesting research and analysis based on very valuable sources of data. There is lack of such publications. Furthermore, it show how to use data from different sources. And maybe the biggest value of this manuscript is its conservation value. This paper shows how important it is to maintain character of semi-natural and natural rivers.
Line 22
Should be: of the date of first degg laying…
Line 50
Double space after „species”.
Line 54-55
How about trend in Poland?
Line 57
Lack of „dot” and double space.
Line 127
Was this model (from 2011) suitable for research done a few years later?, considering the high hydromorphological dynamics of the valley.
Line 145
Very valuable source of data, but I would like to see these data at least on a figure.
Line 221
Clarify, the lowest the difference, the better the model.
Line 236
Double space.
Figure 6
2010 (flood year) should be discussed in details. What about 1997? (also severe flood) and nest survical was relatively high (?)
Results
The effect of FED ad RNH were analyzed separately. It would be highly appreciated to perform multimodelling procedures that investigates the simultaneous effect of both variables (FED and RNH) and interaction between them. You wrote about the importance of these two variables in the last sentence of Discussion.
Results
What about other factors that can influence nest survival, like predation. I wonder if RNH affects the probability of predation.
Line 378
Double space.
Author Response
Please see the attachment
Author Response File: 
Author Response.docx
Reviewer 2 Report
This study evaluated the effects of water-level changes on the probability of nest flooding across the breeding season. The questions being tested in this study will likely be of high interest to readers and the simulation across 36 years adds an interesting component. The introduction is nicely written, but it would be beneficial to add specific hypotheses about nesting sites and dates relative to water levels. I have two major issues with the paper. First, the 36-year simulation study is assuming nest locations from two years of field data collection. That is a major assumption and one that needs to be discussed in detail, I am not sure that the authors can justify an assumption that the nest locations would not be dynamic with changing river conditions across such a long time. My second issue is the phrasing ‘nest survival probabilities’, when really the authors are testing ‘nest flooding probabilities’. Nest survival is a well-defined demographic parameter in the bird science literature and the current usage of this term in the manuscript is misleading. Lastly, a minor suggestion is to change present tense wording to past tense wording when describing results of the study throughout the paper. Minor comments are listed below.
Abstract
I am unfamiliar with the writing style preferred by this journal, but the present tense wording is awkward. I suggest changing to past tense.
Introduction
Last sentence of second paragraph (lines 44 – 48): This sentence is long and unclear. I suggest breaking it into two so you can clarify what you mean by “where breeds eq. up to 50% of Polish population”. You may want to rewrite that last part to something like: “Approximately 50% of the Polish populations of Little Tern Sternula albifrons (VU in Polish red list) and Common Ringed Plover Charadrius hiaticula (EN in Polish red list) breed on these sandy bars and islands”.
Line 49: It is important to note that Common Sandpipers nest on shorelines of other water bodies than just rivers. Also, important to note that this species is migratory and very wide-ranging, spending their nonbreeding seasons further south.
Line 61: Is there a link in these previous studies between breeding failures and population declines of Common Sandpipers?
Line 69: Do repeated disturbances increase or decrease mean breeding dates? Or is it a variable change? It is not clear why this occurs (are birds waiting to breed later when water levels are high?).
Line 76: Again, more details needed about how behaviors change relative to water levels.
Line 78: It would be nice if you could set up some predictions/hypotheses about patterns and trends you expected based on behavioral shifts from previous research.
Line 80: Be specific about the ‘tactics’ you are evaluating.
Methods
Line 110: I’m wondering if ‘controlled’ is meant to mean ‘monitored’?
Line 112: Same question as previous, change ‘control’ to ‘monitor’?
Line 124: This sentence needs clarification, I’m not sure what is meant that clutches were not repeated more than once. If birds were not individually marked, how can you be certain in distinguishing between first and repeated clutches? How many nests were categorized as a second clutch when they were found late in the season (not after a known flood)?
Figure 2: It looks like there are 3 white dots along the dotted line so the nest isn’t immediately clear, could you make the nest dot a different shape from the other two dots?
Line 180: What data were simulated specifically, whether a nest may have survived on each day based on water levels?
Line 182: That is a huge leap to assume nest locations from two years of data collection would be similar across 36 years, as water levels are dynamic, so are nest locations. Do you have justification for assuming that nest locations would be similar from 1980 – 2015? You need to make this assumption clearer.
Line 188: This is a unique way of assessing nest survival. It wasn’t clear at first in the methods that you didn’t observe nests throughout their incubation periods to determine their nest fates (i.e., search for evidence of successful hatching), you only assumed a nest’s fate based on water levels, if I’m understanding correctly. This also means that you have no estimate of the number of nests that may have failed due to causes other than flooding, such as predation or nest abandonment. Really what you are testing is the probability of a nest being flooded or under water, not nest survival. I would change the wording throughout the paper to ‘probability of not being flooded’ or use 1-nest survival probability and change the wording to ‘probability of flooding’. As it currently is, the use of ‘nest survival probability’ is misleading. Nest survival is a well-defined demographic parameter and there is a wealth of literature describing how it should be estimated (e.g., using logistic exposure models; Shaffer 2004; see also Dinsmore et al. 2002).
Shaffer, T.L., 2004. A unified approach to analyzing nest success. The Auk, 121(2), pp.526-540.
Dinsmore, S.J., White, G.C. and Knopf, F.L., 2002. Advanced techniques for modeling avian nest survival. Ecology, 83(12), pp.3476-3488.
Results
Section 3.2: Again, I would consider this to be the probability that a nest isn’t flooded, not nest survival.
Line 271-315: These sections are in present tense wording rather than past tense like the previous section, change to past tense.
Figure 6: What happened in 2010?
Figure 7: Does this average mean across all relative nest heights?
Figure 8: Are the white dots from simulated data?
Discussion
Line 325: Unclear what you mean by ‘more than one million dams on rivers of all sizes have been estimated’. Do you mean constructed?
Line 350: Change ‘it is’ to ‘nests were’.
Line 352: Probabilities of nest inundation rather than nest success.
Line 354: Your study did not find a linear trend, suggesting that flooding isn’t responsible for the population declines in Common Sandpipers.
Line 370: Change to “Significantly lower probability of flooding”.
Line 378: Costs of flooding are not hypothetical, but they are unpredictable.
Line 381: Change to past tense: “was not random”.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Reviewer 3 Report
Overall, this is an interesting paper that addresses an important topic of anthropogenic changes to river flow and the effects on avian nest success. However, the paper could use some improvement. I have attached the manuscript pdf with comments added. My primary comments are:
1. Minor edits for English grammar are needed throughout the paper.
2. The methods need more description and clarification.
3. Clarify if all failed nests were due to flooding or if there were other causes of failure (e.g., from predation, abandonment, or other causes). If there were other causes, clarify that nest survival probability is actually the probability that a nest at a given elevation surviving flooding (not the probability of surviving all potential causes of failure).
4. The estimates of nest survival probability are based on apparent rates of failure from flooding. This likely overestimates survival probability because it does not account for variation in survival over the nest period. This needs to be addressed by: 1) preferably, by reanalysis using a method that accounts for variation over time and estimates a daily survival probability, or 2) less preferably, by adding discussion of potential overestimation in nest survival probability and how that would affect interpretation of results.
5. Discuss whether the two years of the study are representative of the 36-year period in terms of water levels, flooding, etc. If they were not representative years, discuss how this might affect interpretation of the results.
Comments for author File: 
Comments.pdf
Author Response
Dear Reviewer,
First of all I would like to to thank for taking the necessary time and effort to review the manuscript. Unfortunately today morning I have uploaded wrong file in response to your comments. Please accept my sincere apologies. I hereby send my answers to the comments on the manuscript.
With best regards
Marek Elas
Author Response File: Author Response.docx
Reviewer 4 Report
This study assesses the effects of water fluctuations on Common Sandpipers’ nest survival on a semi-natural section of the Vistula River and evaluates the tactics that Common Sandpipers can adopt to minimize the effects. Overall, this is a well-presented paper and I appreciate the efforts that the authors made to achieve their goal. However, I am not convinced by the way the authors did the analyses. In particular, the authors had only 43 nests from two years (2014 and 2015) and they used the locations of these few nests in a simulation to evaluate the effect of water level on nest survival. I think the two years’ nest locations can not represent the whole situation as nest locations (heights) may vary by years and each year’s nest locations may respond to the water level when nesting was initiated. Furthermore, the authors proposed two tactics that Common Sandpipers may take to avoid nest loss caused by flooding and concluded the second tactic, which is placing nests in safer (higher) locations, is a direct response to periodic high-water levels. I don’t think this is a reliable conclusion because again they only had two-year empirical data of the nest locations.
Other minor points:
Line 12: It’s said that the work assesses the effects of water fluctuations on sandpipers nest survival over a 36-year period (line 12). This is quite misleading. Looks like the authors’ nesting data of Common Sandpipers spanned over years, which actually they only had two years’ data.
Line 22: no need to put FED behind first egg laying, as it was not mentioned in other parts of the abstract.
Line 45: m3 should be m3 and “effects” should be “affects”?
Line 110 and 112: I don’t understand the meaning of “control”. Do you mean “monitor”?
Line 111: Considering the study spanning for 36 years, 43 nests is not a big number.
Line 16 and 385: The threat of flooding seems to be one of the important determinants of Common Sandpipers’ nest placement. This conclusion appears to be meaningless because one can easily make this conjecture without conducting a study.
Author Response
Please see the attachment
Author Response File: Author Response.docx
Round 2
Reviewer 4 Report
The authors have had their manuscript significantly improved. I have no other comments, except that the grammar of the English still needs to be revised, better with the help of a native English speaker.
