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Language of manuscript is clear and proper. I do not see any problems with English, however I am not a native speaker and I leave to editor decision whether it should be improved.
Article includes many relevant papers, however
Figures are clear, however I don't see point of most of them, but this is rather due to some of the shortcomings of research itself:
1) Fig. 1 - I really do not think it is necessary to show these phenotypes, it is only inflating length of the article
2) Fig. 2 - Here I would merge both in such matter that you have all three activity periods in different color in one bar for each 1) year and 2) month; and presented as proportion; there is no point of showing growing number of observations - it is obvious, that growing interest in INaturalist will inflate numbers of observations, but does not relate to this study that much (unless it is study about INaturalist itself)
3) Fig. 3 shows geographical extent of observation and I would leave it as it is, however without differentiating between grass snakes phenotypes
4) Fig. 4 is visually nice, however it is not needed at all, because of merit behind it - I wrote more about it in design
I see this study as rather exploratory than typical experiment, however authors made few analyses, and yet there is no prior statement about hypothesis in introduction. If they would like to leave these analyses, then it should be expected to include hypotheses regarding them in mansucript. Also I would suggest to put last paragraph of Introduction above stated aims of the study.
Basic point of this article is to broaden knowledge on grass snake nocturnal activity, which it does. However, for me analysis of difference of temperature during nocturnal activity between phenotypes. First, just by looking on map in Fig. 3 it is obvious that night activity of stripped individual will have higher mean temperatures than in unstripped individuals, as they are distributed in southern part of species range; even authors noted this;
Second, stripped morphology was at some point thought to be characteristic of different subspecies (N.n. persa, versus N.n.natrix), currently taxonomy of Nnatrix gets even more complicated, and subspecies/different lineages may exhibit different temperature preferences due to past selection, which is not connected with coloration;
Third, 24h temperature records are misleading in such analyses, as in continental climates higher temperatures during the day does not necessarily lead to the same during the night, actually most of the time in continental climate, especially Eastern Europe, hot and sunny weather leads to lower night time temperatures due to more efficient heat dissipation due to lack of cloud cover.
Fourth, there is really no biological background to this differentiation - while coloration may influence both avoiding predators by camouflage and thermal regulation by acquiring more heat with darker colors, both of these functions are lost during the night.
Another problematic part of manuscript is comparing numbers of day and nighttime observations, since number of nighttime observations is obviously lower due to simple fact that most people don't go into the field during night. To make this comparison sound, numbers should by standardized some way, eg. given as number of all observation available for both day and night in the area?
Manuscript deals with actually known phenomenon (eg. I have few observation of nocturnal activity in grass snake myself, as have few of my colleagues), however not very well studied and probably often ignored by researchers. That way it provides knew knowledge about common and supposedly known species, which is always very welcome.
However, as I said, the temperature part of the study is not adding anything to manuscript meaningfulness due to problems I described earlier.
If the authors really want to pursue temperature part of the study, I would suggest to include only individuals living in areas of sympatric occurence of both phenotypes.
I would also suggest to try do European-wide questionnaire among wildlife biologist, especially those working on amphibians, owl, carnivores and bats, as they may have plenty of unpublished observations of grass snake from their fieldwork during the night. I think it would bring much more data to this research.
The well-crafted article explores the activity patterns of the common grass snake (Natrix natrix) and delves into the traditionally perceived diurnal behavior of this European snake species. The authors employ a combination of citizen science data from platforms like iNaturalist and Observation.org, as well as personal field observations, to unveil previously undocumented aspects of the grass snake's behavior, specifically its crepuscular and nocturnal activities. The study is grounded in the understanding that activity patterns in animals are often species-specific, offering valuable insights into ecological adaptations and behaviors. The inclusion of citizen science data underscores the collaborative and expansive nature of the research. The authors effectively leverage the power of these platforms, emphasizing the importance of such initiatives in advancing biological and ecological research. The extensive spatial and temporal coverage provided by citizen science platforms is highlighted as a crucial element in understanding the behavioral nuances of widespread species like the grass snake.
Dear authors,
In general, I thoroughly enjoyed reading your ms on the activity patterns of the common grass snake (Natrix natrix). The research questions were well-defined, and the introduction section provided a comprehensive background, enhancing the overall clarity of the study. The integration of citizen science data from platforms like iNaturalist and Observation.org, alongside personal field observations, showcased a robust and collaborative methodology.
However, I would like to point out the use of ANOVA when exploring differences between body patterns. As you mentioned you had only 4 melanistic individuals in the first group. Having only four occurrences in one group may pose challenges in terms of statistical power and robustness of the analysis. It is generally recommended to have a sufficient number of observations within each group to obtain reliable and meaningful results. With a small sample size, the results may be less reliable, and the assumptions of ANOVA, such as homogeneity of variances, may be difficult to meet. So I recommend removing these individuals from your analysis and re-running it with just the other two groups (if your data follows normal distribution a t-test would be just fine).
Everything seems fine with the exception that I did not find in the results the response to your 2nd research question: "whether there are any geographical variations in the crepuscular and nocturnal activity". In Line 160 you wrote that: "The distribution map of nighttime behavior was created using ArcGIS Pro 3.1.3"....However I could not find this map in the ms or in the supplementary material that you provided....
The Discussion and the Conclusions are well-written!
The manuscript uses clear, unambiguous, professional English language throughout.
The intro & background information needs improvement to highlight the importance of this work (why is it essential to shed light on the nocturnal nature of this species?), and justify the methodology applied. Enriching the ecology behind the nocturnal activity is also essential if authors investigate the environmental conditions linked to the nocturnal activity.
Literature well referenced & relevant although in many cases outdated. More recent and relevant citation is needed in some areas (see general comments below).
The structure of the manuscript is in line with the PeerJ standards and the RAW data have been supplied
Although relevant and of high quality, figures could be improved and described further enchasing their clarity.
This is an original primary research within the Scope of the journal. The research can fill an identified knowledge gap providing insights into the nocturnal activity of this species.
Research question although well defined and relevant is not adequately addressed by the manuscript. Research results despite their value and importance are not strong enough to support the entire hypothesis and the research questions set (L110 – Q iii and iv).
The investigation, although rigorous, as comes to the iNaturalist database, is not taking into account other platforms (e.g. GBIF) that can provide a significant addition to the existing dataset.
The methodology applied is only partially described with sufficient detail. For the case of data acquired from observation.org, there is an absence of detail, as well as for the personal observation where a structural protocol is also absent.
The findings are valid although there is room for discussion on some subjective decisions (see General comments). Some results although derived from statistical analysis are debatable (e.g. L188-189) and (in my opinion) not statistically sound in the absence of additional information and more ecologically oriented comparison and analysis.
All underlying data have been provided, benefit to literature is clearly stated and methodology is encouraged to be replicated.
This is a very interesting work, but to my opinion, is not able to support the scientific questions set by the authors.
My main concerns are the following:
- Authors have not taken full advantage of the available citizen science databases (e.g. GBIF) and are not adequately explaining parts of their methodology (see comments below).
- The statistical analysis is mostly descriptive. Although valuable in presenting an activity not adequately observed, lacks the depth to provide solid findings and sound arguments for the “nightlife” of the species.
- Although the authors in their introduction explain and cite references related to the “nocturnal activity”, in the rest of their manuscript there is a tendency to confuse “activity” with “behaviours”. As I understand, the authors are discussing activity patterns and not behavioural patterns. It would be good (if not essential) to clarify.
- Several parts of the methodology are not adequately addressed, and questions remain. The authors need to elaborate more, proactively answering possible questions that might arise.
- The introduction could be improved by adding more relevant recent publications on the topic and providing a clear overview of what the authors are trying to do and why.
All of the above are developing a cumulative impression of a paper that needs both major revisions and additional final refinement before published.
Below are more detailed comments and suggestions on the manuscript. I hope the authors will find them helpful in their efforts to improve their research.
Title The title gives the false impression that the manuscript will deal with and explore the activity of the individuals during the night. This is not the case.
L21 Activity patterns vs Behaviours. It is extremely important to clarify your aims. Activity and behaviour are two different things.
L27 State the period covered by your data (iNaturalist, Observatioh.org and field observations).
L35 Based on Figure 2 you have less than 1% (86/9058) nocturnal behaviour... this is not extensive
L47 More recent and relevant references
L48 I would suggest first elaborating on nocturnal activities and the factors that influence it and then starting to discuss specific animal groups (e.g. Amphibians and reptiles).
L53-55 What kind of patterns, why on arid habitats and tropical species? Please elaborate using references. Is this nocturnal activity linked with ecological and environmental parameters?
L59 Please give examples from other European nocturnal species.
L62 More recent and relevant references
L84 Please refer to “common phase” with the more scientifically correct term... common morph. in addition, use this term to name the "unstriped" morph in the rest of the manuscript and figures.
L97 Too many citations. Please keep only 3 more relevant/recent
L109-112 Although the manuscript can answer questions (i) and partially (ii), I feel that the data at hand are not able to sufficiently answer the rest of the questions.
L124 Why did you choose to work with iNaturalist and not GBIF? GBIF includes data from iNaturalist and Observation.org. A simple search in GBIF indicates nearly 70.000 records on N.natrix in comparison to the c.15.000 of the iNaturalist.
L125 Add information on (a) the amount of data collected, (b) the cleaning procedure to remove not relevant or not valuable for your analysis data and (c) the amount of data used in the research.
L126 More scientifically correct to report that you followed definitions set by others, and provide appropriate references than to say, “We defined”.
L128 Since you have the data it would be interesting to see the actual time of those nocturnal activities. If the majority are close to the threshold (30 minutes), it might be necessary to change your approach.
L134 This is not clear. In case of timestamp or data entry errors, how were you able to confirm the day/time of the observation?
L136 In Figure 2 you are comparing all observations vs the nighttime activities. If using your personal data and data from observation.org you have only included nighttime activities, then you will have a bias in favour of nighttime activities. Regardless of how small this bias is, it would be good for methodological purposes to be consistent. It would also be very interesting to see the day/night percentage of your own observation.
L138 How did you extract data from observation.org? Was it with a similar procedure as with the data from iNaturalist? Please elaborate.
L140 Were you able to distinguish immature vs adults using the photographs... please elaborate. How appropriate is this procedure and what would be the replicability of your work in case a second team would like to follow your approach?
L141 Please elaborate. If the individual was photographed next to a river... this habitat is aquatic or terrestrial? How was this decided?
L145 What do you mean by "presence of the moon"? Do you mean the moon phase or the visual presence due to clouds? It is not clear what you have done.
L157-158 What type of nocturnal behaviour?
L163 Authors' observations are 17% of the data at hand. Although authors are highlighting the significance of citizen science, the high proportion of personal data reduces the value of citizen science.
L169 Was the percentage (all vs nocturnal) before and after 2019 the same?
L173-174 How do those numbers relate to the total number of morphs reported?
L175 How does the distribution map of the occurrence relates to the distribution of the three morphs?
L188-189 This relates to the distribution of the species. Based on Figure 3, unstripped individuals are found in the centre and northeastern parts of Europe vs stripped that are found in the southern parts near the Mediterranean coast where the climate is more milt with generally higher temperatures during the night.
L271-272 In your introduction you mention that this activity has been reported from other relative species such as the Natrix tessellate even in northeastern areas of its distribution. Although it is not adequately reported for N.natrix, we can debate that this type of activity is not something extraordinary and could be expected.
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