Tests of the Oddity Effect Hypothesis in mixed-species parid flocks

Zaharia A. Selman; Eric K. Frazier; Colton B. Adams; Todd M. Freeberg

doi:10.1371/journal.pone.0341779

Peer Review History

Original SubmissionApril 23, 2025
17 Jul 2025 Decision Letter - Valeria Mazza, Editor Dear Dr. Selman, Thank you for submitting your manuscript “Tests of the Oddity Effect Hypothesis in mixed-species parid flocks” to PLOS One. I regret that I am unable to accept your paper for publication in Plos One in its present form. However, I would be prepared to consider for publication a substantially revised version that takes into account the suggestions of the reviewers. Such a revised paper would be reviewed and there would be no guarantee of acceptance. As you can see, both reviewers agree that the study could, in principle, be a meaningful contribution to our understanding of the behaviour of animals in mixed-species groups, but also raise important issue regarding the soundness of the analyses, the clarity of the rationale for the study in general and specific approaches in particular, and identify a weakness in terms of power that needs to be acknowledged and incorporated in a substantial revision of the discussion and interpretation of the findings. In particular, R1 highlighted how the small sample size is not sufficient to draw robust conclusions, and since this aspect cannot be fixed post-hoc, the interpretation of the findings need to be consequently toned town to acknowledge this aspect. Additionally, R2 raised important concerns on the statistical approach used, and recommends the used of mixed models as a more suitable way to take into consideration multiple potential factors that could affect your analysis. I urge you therefore to revise the analyses and the discussion in light of the new findings. Finally, both reviewers have a number of other comments (detailed below), which you should address in your revision. With best regards, Valeria Mazza Acedemic Editor PLOS ONE ============================== Please submit your revised manuscript by Aug 31 2025 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org . When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file. Please include the following items when submitting your revised manuscript: A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'. 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Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols . We look forward to receiving your revised manuscript. Journal requirements: When submitting your revision, we need you to address these additional requirements. 1. Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at https://journals.plos.org/plosone/s/file?id=wjVg/PLOSOne_formatting_sample_main_body.pdf and https://journals.plos.org/plosone/s/file?id=ba62/PLOSOne_formatting_sample_title_authors_affiliations.pdf 2. Please include captions for your Supporting Information files at the end of your manuscript, and update any in-text citations to match accordingly. Please see our Supporting Information guidelines for more information: http://journals.plos.org/plosone/s/supporting-information . [Note: HTML markup is below. Please do not edit.] Reviewers' comments: Reviewer's Responses to Questions Comments to the Author 1. Is the manuscript technically sound, and do the data support the conclusions? Reviewer #1: Partly Reviewer #2: Partly ******** 2. Has the statistical analysis been performed appropriately and rigorously? -->?> Reviewer #1: No Reviewer #2: No ****** 3. Have the authors made all data underlying the findings in their manuscript fully available??> The PLOS Data policy Reviewer #1: Yes Reviewer #2: Yes ****** 4. Is the manuscript presented in an intelligible fashion and written in standard English??> Reviewer #1: Yes Reviewer #2: No ****** Reviewer #1: Manuscript ID: PONE-D-25-21798 Title: Tests of the Oddity Effect Hypothesis in mixed-species Parid flocks General comments This is a manuscript regarding a very interesting topic, not very investigated. However, I found some weaknesses about clarity of methods and results. In particular, you tested the oddity effect hypothesis with very small sizes (i.e. N = 2) for sole birds and although you used non parametric tests, you should be very cautious to draw conclusions. Specific comments Methods 1. Line 150-157 and 178-182: if I understand correctly, in both experiments, you had to wait 10-15 minutes before showing the predator model mount, in which you count birds in the flock. Then you walked to the feeder, placed the model, and returned to the observation place. Don’t you think that the operator could have affected in some way the birds behavior? Do birds remained there, at the feeder, or flew away when you walked to place the predator models? I think that it is important to write something about it, either if operator was disturbing or not. 2. Line 157: how far was the observation place in the screech owl experiment? Was the observer hidden or in plain sight? Please, add these details. Results 3. Lines 205-208: so, to test both the “probability of calling” and the “recruitment” hypotheses, you correlated the same things, i.e. number of conspecifics in the flock vs the latency for the first individual to call. What differed was the prediction, right? Aren’t these hypotheses in contrast? When a bird is rare in a mixed flock either could be silent to doesn’t draw attention (probability of calling hypothesis) or be loud to recruit conspecifics (recruitment hypothesis). I suggest to say something about this, also in discussion, if there is some threshold that lead to one or the other hypothesis, and why a rare bird choose to be quite or loud. 4. Lines 223-225 and 235-242: as I understand, you compared latencies of 2 vs 34 chickadees flocks in the screech owl experiment, latencies of 2 vs 28 chickadees flocks in the hawk experiment, and latencies of 2 vs 28 titmice flocks in the hawk experiment. Therefore, even if you used non-parametric tests, I suggest to be very cautious to draw some conclusions with these results for the oddity effect hypothesis. Discussion and Conclusions 5. As I said in the previous comment, because of the small sample size you should be very careful to draw conclusions about the oddity effect hypothesis, as you said as well in conclusions. However, you seemed very convinced of these results (see lines 263-265, 277-279, 282, 299), but I suggest to rephrase using a more cautious tone. Reviewer #2: General comments: I think this is a nice study, and a good addition to the growing body of literature that is trying to dig into individual behavioral changes in flocking contexts. I do, however, think that the abstract, introduction, and methods could all use some restructuring to make both the question, statistics and field methods clearer. In particular, it is hard to understand exactly what data were taken, whether the data between the two experiments is different, and what the purpose of the two experiments was. I also would strongly consider the authors changing their statistical analysis to take advantage of GLMs and the fact that they can incorporate multiple factors and interactions. I think this reframing in a way that unifies the data and the variability present in the mixed-species flocks may significantly impact the discussion as well. Abstract: Line 15 - This first sentence is confusing and, as it stands, could be interpreted multiple ways. I would advise reframing this and maybe swapping the major points of the first two sentences in the abstract. First, describe rarity, then describe its role in predation. Line 25 - The description of the experiment here is also a bit confusing. Given this is the abstract, there isn't much space to explain further, but the details added here don't clarify your findings and instead pose several questions. Why two experiments? How did they differ? Were they analyzed together or separately? Given that (after going through the rest of the paper) the data for the two experiments are different yet are addressing the same question in very similar ways I would just simplify this and state that you had evidence that at least two species (chickadees and titmice) were less likely to call (alarm call?) in response to predators when alone as compared to with conspecifics. I would then maybe use that tiny bit of extra space to explain further the comment below. Line 27-28 - I also had trouble following this explanation of ruling out alternative hypotheses. Are these your alternatives, or is this what you found? Maybe stating that you tested both the oddity effect and these two alternative hypotheses in one sentence earlier in the abstract would help clarify. Introduction: Line 65 - Somewhere here I think it is important to state that mixed-species groups are often signaling to each other - transmitting information about food or predators etc. This will set up the reasoning below that it isn't always good for specific (rare) individuals to call. Line 67 - might be better here to emphasize that signaling can increase predation by making individuals more conspicuous, prior to describing how a reduction in signaling can mitigate this. Line 75 - 76 - sentence here about attracting mates and deterring competitors feels out of place. somewhere here, it might be better to lean into the mixed-species group stuff and talk about how there may be benefits to signaling in flocks, but that rarity may interact with appearance /vocal distinctiveness to make it not always beneficial and thus a contributing factor to flock formation, function, and individual behavior Line 86 - mixed species should have a dash in it Line 105 - single conspecifics within heterospecific flocks? And multiple conspecifics within heterospecific flocks? Assuming yes, but this should be clear. Line 117 - 121 - describing the hypothetical probabilities here seems unnecessary. I would in stead use this space to describe your second alternative hypothesis, perhaps describing the recruitment of birds to mobbing flocks more explicitly. May also expect that birds would call to recruit in order to avoid the oddity effect. Methods: General comment - I'd recommend putting a sentence in near the front of the methods here clearly stating you conducted two experiments using two different predator stimuli. The first you mention that there were two is "Our two experiments involved..." Also would be helpful to clarify why you used these two different experiments. Is it because these two predators represent different threat levels? Line 146 - It is implied, but not clear, that you also used this same plastic screech owl that was used in the other study. Also might be good to state that in the previous work birds responded to it like a predator, as many birds get habituated to plastic stimuli. Line 152 - are you assuming all the individuals remained in the area following the placement of the stimuli? Did you account for any individual departures driven by the presence of the observer with the stimulus? Line 157 - Was the call type recorded? Also, assuming you recorded what species was producing each call. Line 184 - What do you mean by "coded"? Identified? Did you record the time to the first call as well as the number of each call type? General method question: Were each of the experiments only conducted once at each of the 36 feeder sites? Line 195 - explain how the data were non-normal Line 194 - This paragraph could use a bit more structure. For example, consider telling us how many analyses you ran to answer what questions. Even having a list of 1, 2, 3 might help. It is also not clear what was analyzed for which data set. Were they all compiled? General methods question - given that there is likely a variable number of both heterospecifics and conspecifics in each of these experimental flocks, I'd recommend using GLMs or a similar analysis that would allow you to incorporate both the number of conspecifics and heterospecifics and the potential interaction between them into your analysis. You could also include species and put all the species into the same analysis. Line 212 - The word ethically here isn't informative. Maybe instead say "Experiments were observational and did not involve the handling of any individuals. While predator stimuli can be temporarily stress-inducing, predator encounters are a normal occurrence, and thus these experiments are considered benign." Line 216 - consider rephrasing this: "In the screech owl experiment, flocks consisted of..." Can you also include the mean flock size over all for each experiment? Line 249 - you say there was no significance, but report a p value of 0. 015 for nuthatches. is this a typo? ****** what does this mean? ). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review? 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Revision 1
3 Nov 2025 Author Response Response to Reviewers – Plos ONE (PONE-D-25-21798) Tests of the Oddity Effect Hypothesis in mixed-species parid flocks Dear Dr. Mazza: Thank you for giving us the opportunity to revise and resubmit our manuscript to address the helpful criticisms and questions of the reviewers. We have copied and pasted the entire set of comments of the reviewers, which we include below. For each comment, we briefly describe in red text how it was addressed and, if relevant, where the changes can be found (by line number) in the clean, non-track-changes manuscript. +++++++++++++++++++++++++ Thank you for submitting your manuscript “Tests of the Oddity Effect Hypothesis in mixed-species parid flocks” to PLOS One. I regret that I am unable to accept your paper for publication in Plos One in its present form. However, I would be prepared to consider for publication a substantially revised version that takes into account the suggestions of the reviewers. Such a revised paper would be reviewed and there would be no guarantee of acceptance. We thank you and the reviewers for the opportunity to resubmit our manuscript, regardless of the end decision! When submitting your revision, we need you to address these additional requirements. 1. Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at https://journals.plos.org/plosone/s/file?id=wjVg/PLOSOne_formatting_sample_main_body.pdf and https://journals.plos.org/plosone/s/file?id=ba62/PLOSOne_formatting_sample_title_authors_affiliations.pdf 2. Please include captions for your Supporting Information files at the end of your manuscript, and update any in-text citations to match accordingly. Please see our Supporting Information guidelines for more information: http://journals.plos.org/plosone/s/supporting-information. Thank you for these comments, they have been addressed in the updated manuscript! *Reviewer 1:* Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented. Reviewer #1: Partly - We thank the reviewer for the comment and hope we have expanded our manuscript to fully meet the requirements for this specification. Has the statistical analysis been performed appropriately and rigorously? Reviewer #1: No - Thank you for this comment, it has been addressed in the updated manuscript in Lines 194-212. We opted to keep the non-parametric approach given its simplicity and conservative nature for studies with small Ns. We note below and in the text, however, that GLM analyses resulted in similar outcomes. Have the authors made all data underlying the findings in their manuscript fully available? The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified. Reviewer #1: Yes - We thank the reviewer for the supportive comments! Is the manuscript presented in an intelligible fashion and written in standard English? PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here. Reviewer #1: Yes - We thank the reviewer for the supportive comments! Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters) General comments This is a manuscript regarding a very interesting topic, not very investigated. However, I found some weaknesses about clarity of methods and results. In particular, you tested the oddity effect hypothesis with very small sizes (i.e. N = 2) for sole birds and although you used non parametric tests, you should be very cautious to draw conclusions. - We thank the reviewer for the supportive comments and hope we have addressed all concerns adequately below! Specific comments Methods 1. Line 150-157 and 178-182: if I understand correctly, in both experiments, you had to wait 10-15 minutes before showing the predator model mount, in which you count birds in the flock. Then you walked to the feeder, placed the model, and returned to the observation place. Don’t you think that the operator could have affected in some way the birds behavior? Do birds remained there, at the feeder, or flew away when you walked to place the predator models? I think that it is important to write something about it, either if operator was disturbing or not. - We agree and have added a few sentences to reflect this in Lines 142-152, 160-163, and 170-182. We conducted the same movements during the pre-stimulus and stimulus periods to avoid affecting the birds’ behaviors as much as possible. For the pre-stimulus period, we walked to the feeding platform (screech owl experiment) or model mount (Cooper’s hawk experiment) and touched it, and for the stimulus period, we walked to the feeding platform/model mount and placed the model on top. Also, the birds in our observation areas are used to observers so although they usually avoid the feeding platform when observers get too close (during both the pre-stimulus and stimulus periods) they rarely leave the area. The birds are typically back to foraging at normal rates from the feeders within seconds of our leaving the immediate area of the feeders. 2. Line 157: how far was the observation place in the screech owl experiment? Was the observer hidden or in plain sight? Please, add these details. - Thank you for catching this, we have addressed the observation distance and visibility in Lines 142-146 and 161-163. Results 3. Lines 205-208: so, to test both the “probability of calling” and the “recruitment” hypotheses, you correlated the same things, i.e. number of conspecifics in the flock vs the latency for the first individual to call. What differed was the prediction, right? Aren’t these hypotheses in contrast? When a bird is rare in a mixed flock either could be silent to doesn’t draw attention (probability of calling hypothesis) or be loud to recruit conspecifics (recruitment hypothesis). I suggest to say something about this, also in discussion, if there is some threshold that lead to one or the other hypothesis, and why a rare bird choose to be quite or loud. - Thank you for this suggestion! Yes, these hypotheses have contrasting predictions. The recruitment hypothesis is more about call rate than volume, but we have added text to the Introduction (Lines 101-113), Methods (Lines 208-212) and Discussion (Lines 362-378) sections to address these comments. 4. Lines 223-225 and 235-242: as I understand, you compared latencies of 2 vs 34 chickadees flocks in the screech owl experiment, latencies of 2 vs 28 chickadees flocks in the hawk experiment, and latencies of 2 vs 28 titmice flocks in the hawk experiment. Therefore, even if you used non-parametric tests, I suggest to be very cautious to draw some conclusions with these results for the oddity effect hypothesis. - We have adjusted the language to reflect consideration of our small sample size (Lines 275-276, 286, 349-352, and 379-381). Discussion and Conclusions 5. As I said in the previous comment, because of the small sample size you should be very careful to draw conclusions about the oddity effect hypothesis, as you said as well in conclusions. However, you seemed very convinced of these results (see lines 263-265, 277-279, 282, 299), but I suggest to rephrase using a more cautious tone. - We have adjusted the language to reflect consideration of our small sample size (Lines 275-276, 286, 349-352, and 379-381), as mentioned earlier. *Reviewer #2:* Is the manuscript technically sound, and do the data support the conclusions? Reviewer #2: Partly - We thank the reviewer for the comment and hope we have expanded our manuscript to fully meet the requirements for this specification. Has the statistical analysis been performed appropriately and rigorously? Reviewer #2: No - Thank you for this comment, it has been addressed in the updated manuscript in Lines 194-212. Have the authors made all data underlying the findings in their manuscript fully available? Reviewer #2: Yes - We thank the reviewer for the supportive comments! Is the manuscript presented in an intelligible fashion and written in standard English? Reviewer #2: No - We are not sure what the reviewer means by this comment, but would be happy to address any unclear or confusing text in our manuscript. Review Comments to the Author General comments: I think this is a nice study, and a good addition to the growing body of literature that is trying to dig into individual behavioral changes in flocking contexts. I do, however, think that the abstract, introduction, and methods could all use some restructuring to make both the question, statistics and field methods clearer. In particular, it is hard to understand exactly what data were taken, whether the data between the two experiments is different, and what the purpose of the two experiments was. I also would strongly consider the authors changing their statistical analysis to take advantage of GLMs and the fact that they can incorporate multiple factors and interactions. I think this reframing in a way that unifies the data and the variability present in the mixed-species flocks may significantly impact the discussion as well. - We thank the reviewer for the supportive comments on our study and hope that we have adjusted our manuscript to address these concerns! Abstract: Line 15 - This first sentence is confusing and, as it stands, could be interpreted multiple ways. I would advise reframing this and maybe swapping the major points of the first two sentences in the abstract. First, describe rarity, then describe its role in predation. - We have changed the wording to reflect this in Lines 16-19. Line 25 - The description of the experiment here is also a bit confusing. Given this is the abstract, there isn't much space to explain further, but the details added here don't clarify your findings and instead pose several questions. Why two experiments? How did they differ? Were they analyzed together or separately? Given that (after going through the rest of the paper) the data for the two experiments are different yet are addressing the same question in very similar ways I would just simplify this and state that you had evidence that at least two species (chickadees and titmice) were less likely to call (alarm call?) in response to predators when alone as compared to with conspecifics. I would then maybe use that tiny bit of extra space to explain further the comment below. - Thank you for the suggestions, we have added clarification in Line 22-23. Line 27-28 - I also had trouble following this explanation of ruling out alternative hypotheses. Are these your alternatives, or is this what you found? Maybe stating that you tested both the oddity effect and these two alternative hypotheses in one sentence earlier in the abstract would help clarify. - Thank you for the suggestions, we have added clarification in Lines 26-27 and 30-33. Introduction: Line 65 - Somewhere here I think it is important to state that mixed-species groups are often signaling to each other - transmitting information about food or predators etc. This will set up the reasoning below that it isn't always good for specific (rare) individuals to call. - Thank you for this – we have added some clarification to Lines 50-52. Line 67 - might be better here to emphasize that signaling can increase predation by making individuals more conspicuous, prior to describing how a reduction in signaling can mitigate this. - Yes, we have added some clarification to Lines 52-56. Line 75 - 76 - sentence here about attracting mates and deterring competitors feels out of place. somewhere here, it might be better to lean into the mixed-species group stuff and talk about how there may be benefits to signaling in flocks, but that rarity may interact with appearance/vocal distinctiveness to make it not always beneficial and thus a contributing factor to flock formation, function, and individual behavior - We have included this suggestion to Lines 66-67. Line 86 - mixed species should have a dash in it - Yes, thank you for catching this! This has been added to Line 71. Line 105 - single conspecifics within heterospecific flocks? And multiple conspecifics within heterospecific flocks? Assuming yes, but this should be clear. - We have added some clarification to Lines 90-93. Line 117 - 121 - describing the hypothetical probabilities here seems unnecessary. I would in stead use this space to describe your second alternative hypothesis, perhaps describing the recruitment of birds to mobbing flocks more explicitly. May also expect that birds would call to recruit in order to avoid the oddity effect. - We have included these suggestions in Lines 105-113. Methods: General comment - I'd recommend putting a sentence in near the front of the methods here clearly stating you conducted two experiments using two different predator stimuli. The first you mention that there were two is "Our two experiments involved..." - We have added some clarification to Line 118. Also would be helpful to clarify why you used these two different experiments. Is it because these two predators represent different threat levels? - Yes, this has been added to Lines 130-131. Line 146 - It is implied, but not clear, that you also used this same plastic screech owl that was used in the other study. Also might be good to state that in the previous work birds responded to it like a predator, as many birds get habituated to plastic stimuli. - We mention the reactivity of our study species to the screech owl model in Lines 140-141. Line 152 - are you assuming all the individuals remained in the area following the placement of the stimuli? Did you account for any individual departures driven by the presence of the observer with the stimulus? - As addressed from Reviewer 1’s suggestions, clarification has been added to Lines 142-152, 160-163, and 170-182, and 180-183 to address pre-stimulus and stimulus bird behavior. Line 157 - Was the call type recorded? Also, assuming you recorded what species was producing each call. - Thank you for catching this! The species that called during the 10-minute stimulus period was voice-recorded and this has been clarified in Lines 153-155 and 160-163. Line 184 - What do you mean by "coded"? Identified? Did you record the time to the first call as well as the number of each call type? - Yes, we added clarification to Line 184-188. As mentioned in Line 194-195, we recorded the time (latency) to call first, not including the number of each call type. General method question: Were each of the experiments only conducted once at each of the 36 feeder sites? - Yes, each experiment was only conducted once at each of the sites. This has also been added to Line 120. Line 195 - explain how the data were non-normal - We added some text to address this – Lines 195-199. In s Attachments Attachment Submitted filename: Response to Reviewers.docx https://doi.org/10.1371/journal.pone.0341779.r002
23 Dec 2025 Decision Letter - Valeria Mazza, Editor Thank you for your revisions. Both previous reviewers kindly agreed to read the new version, and both agree that the manuscript is substantially improved. One reviewer noted the somewhat inconsistent way in which the oddity effect hypothesis is formulated, and I agree this aspect should be addressed according to the reviewers' recommendations. Both reviewers also noted a couple of minor formal point to straighten up. I am sure these aspects will take very little time to address, and I look forward to your revised submission. Please submit your revised manuscript by Feb 06 2026 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org . When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file. A letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'. A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'. An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'. If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols . Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols . We look forward to receiving your revised manuscript. Kind regards, Valeria Mazza Academic Editor PLOS One Journal Requirements: If the reviewer comments include a recommendation to cite specific previously published works, please review and evaluate these publications to determine whether they are relevant and should be cited. There is no requirement to cite these works unless the editor has indicated otherwise. Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice. [Note: HTML markup is below. Please do not edit.] Reviewers' comments: Reviewer's Responses to Questions Comments to the Author Reviewer #1: All comments have been addressed Reviewer #2: (No Response) ******** 2. Is the manuscript technically sound, and do the data support the conclusions??> Reviewer #1: Yes Reviewer #2: Yes ****** 3. Has the statistical analysis been performed appropriately and rigorously? -->?> Reviewer #1: Yes Reviewer #2: Yes ****** 4. Have the authors made all data underlying the findings in their manuscript fully available??> The PLOS Data policy Reviewer #1: Yes Reviewer #2: Yes ****** 5. Is the manuscript presented in an intelligible fashion and written in standard English??> Reviewer #1: Yes Reviewer #2: Yes ****** Reviewer #1: This version of the manuscript is greatly improved by following reviewers' suggestions. I found only some minor issues that need to be addressed before acceptance: Line 17: “one” what? Maybe “one individual” or “one bird” or similar is better. Line 142: “Similar movements” of what/who? Please, replace with something like “Observers moved in the same way” or “We moved in the same way” to be more clear Line 362: remove the p-value from the conclusion Nice work! Reviewer #2: Thank you for addressing my previous recommendations, I think the manuscript is now much stronger and clearer. I do want to apologize for the comment that said the manuscript wasn't presented in an intelligible fashion, that was me clicking incorrectly in the dropdown menu and not realizing I had hit no when I had meant yes. I only have three minor wording suggestions that you can take or leave and one bigger comment that I strongly recomend you consider (the first comment below). Otherwise I think the manuscript is sound! Line 53—be careful about defining the oddity effect, it is typically defined by predators being attracted to odd, distinctive prey items within a group, but here you are making it sound like it is about prey behavior. While I don’t fully disagree with the definition, I think it might be better to define the oddity hypothesis in the context of the predator at the start of this paragraph then reframe how you are referring to the prey behavior throughout as a response to oddity or a reduction of risk. For instance, on line 284 you give the example from pigeon predation choice by goshawks and also call it the oddity effect, but this is a very different definition that you present at the start and is more in line with the general literature. I would recommend laying out your terms more clearly and to more appropriately reflect how this phrase is typically used, and make that change in framing throughout the manuscript. Line 43—Large here is a bit subjective, I’d recommend saying “Groups can often…” Line 68—Common might be better as “well-known” Line 257—Thank you for clarifying my confusion about your p-value in the last revision, I should have noticed the effect size. I do however think it might be important to point out that while you didn’t find a significant positive relationship, you instead found a significant negative relationship. It will help to emphasize the finding and also jog the reader to recognize what that finding means, like I needed! ****** what does this mean? ). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy Reviewer #1: No Reviewer #2: No ******** [NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.] To ensure your figures meet our technical requirements, please review our figure guidelines: https://journals.plos.org/plosone/s/figures You may also use PLOS’s free figure tool, NAAS, to help you prepare publication quality figures: https://journals.plos.org/plosone/s/figures#loc-tools-for-figure-preparation. NAAS will assess whether your figures meet our technical requirements by comparing each figure against our figure specifications. https://doi.org/10.1371/journal.pone.0341779.r003
Revision 2
9 Jan 2026 Author Response Response to Reviewers – Plos ONE (PONE-D-25-21798R1) Tests of the Oddity Effect Hypothesis in mixed-species parid flocks Dear Dr. Mazza: Thank you for giving us the opportunity to revise and resubmit our manuscript again. We have copied and pasted the entire set of comments of the reviewers, which we include below. For each comment, we briefly describe in red text how it was addressed and, if relevant, where the changes can be found (by line number) in the clean, non-track-changes manuscript. +++++++++++++++++++++++++ Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process We thank you and the reviewers for the opportunity to resubmit our manuscript, regardless of the end decision! Thank you for your revisions. Both previous reviewers kindly agreed to read the new version, and both agree that the manuscript is substantially improved. One reviewer noted the somewhat inconsistent way in which the oddity effect hypothesis is formulated, and I agree this aspect should be addressed according to the reviewers' recommendations. Both reviewers also noted a couple of minor formal point to straighten up. I am sure these aspects will take very little time to address, and I look forward to your revised submission. If the reviewer comments include a recommendation to cite specific previously published works, please review and evaluate these publications to determine whether they are relevant and should be cited. There is no requirement to cite these works unless the editor has indicated otherwise. Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice. Thank you for these comments, they have been addressed in the updated manuscript! Our references have also remained the same. Comments to the Author: If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation. Reviewer #1: All comments have been addressed Reviewer #2: (No Response) We thank the reviewers for their comments and hope we have expanded our manuscript to fully meet their suggestions. Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented. Reviewer #1: Yes Reviewer #2: Yes We thank the reviewers for their comments. Has the statistical analysis been performed appropriately and rigorously? Reviewer #1: Yes Reviewer #2: Yes We thank the reviewers for their comments. Have the authors made all data underlying the findings in their manuscript fully available? The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified. Reviewer #1: Yes Reviewer #2: Yes We thank the reviewers for their supportive comments! Is the manuscript presented in an intelligible fashion and written in standard English? PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here. Reviewer #1: Yes Reviewer #2: Yes We thank the reviewers for their comments. Review Comments to the Author Reviewer #1: This version of the manuscript is greatly improved by following reviewers' suggestions. I found only some minor issues that need to be addressed before acceptance: Line 17: “one” what? Maybe “one individual” or “one bird” or similar is better. Line 142: “Similar movements” of what/who? Please, replace with something like “Observers moved in the same way” or “We moved in the same way” to be more clear Line 362: remove the p-value from the conclusion Nice work! We thank the reviewer for the supportive comments and have addressed these comments in Lines 17, 145-146, and 372. Reviewer #2: Thank you for addressing my previous recommendations, I think the manuscript is now much stronger and clearer. I do want to apologize for the comment that said the manuscript wasn't presented in an intelligible fashion, that was me clicking incorrectly in the dropdown menu and not realizing I had hit no when I had meant yes. I only have three minor wording suggestions that you can take or leave and one bigger comment that I strongly recomend you consider (the first comment below). Otherwise I think the manuscript is sound! We thank the reviewer for the supportive comments and completely understand the mishap, thank you for your clarification! Line 53—be careful about defining the oddity effect, it is typically defined by predators being attracted to odd, distinctive prey items within a group, but here you are making it sound like it is about prey behavior. While I don’t fully disagree with the definition, I think it might be better to define the oddity hypothesis in the context of the predator at the start of this paragraph then reframe how you are referring to the prey behavior throughout as a response to oddity or a reduction of risk. For instance, on line 284 you give the example from pigeon predation choice by goshawks and also call it the oddity effect, but this is a very different definition that you present at the start and is more in line with the general literature. I would recommend laying out your terms more clearly and to more appropriately reflect how this phrase is typically used, and make that change in framing throughout the manuscript. We thank the reviewer for this suggestion and have addressed it in Lines 21-23, 53-57, 99-100, 115-116, 120, 202, 297-298, 314-315. Line 43—Large here is a bit subjective, I’d recommend saying “Groups can often…” We agree and have changed the wording in Line 43. Line 68—Common might be better as “well-known” We have changed the wording in Line 69. Line 257—Thank you for clarifying my confusion about your p-value in the last revision, I should have noticed the effect size. I do however think it might be important to point out that while you didn’t find a significant positive relationship, you instead found a significant negative relationship. It will help to emphasize the finding and also jog the reader to recognize what that finding means, like I needed! We agree and have added this suggestion to Lines 260-263. Attachments Attachment Submitted filename: Response_to_Reviewers_auresp_2.docx https://doi.org/10.1371/journal.pone.0341779.r004
12 Jan 2026 Decision Letter - Valeria Mazza, Editor Tests of the Oddity Effect Hypothesis in mixed-species parid flocks PONE-D-25-21798R2 Dear Dr. Selman, thank you for making those changes to your manuscript, which I am now pleased to recommend for publication. I will look forward to seeing your fine contribution in print in due course. Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication. An invoice will be generated when your article is formally accepted. Please note, if your institution has a publishing partnership with PLOS and your article meets the relevant criteria, all or part of your publication costs will be covered. Please make sure your user information is up-to-date by logging into Editorial Manager at Editorial Manager® and clicking the ‘Update My Information' link at the top of the page. For questions related to billing, please contact billing support . If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org. Kind regards, Valeria Mazza Academic Editor PLOS One https://doi.org/10.1371/journal.pone.0341779.r005
Formally Accepted
Acceptance Letter - Valeria Mazza, Editor PONE-D-25-21798R2 PLOS One Dear Dr. Selman, I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS One. Congratulations! Your manuscript is now being handed over to our production team. At this stage, our production department will prepare your paper for publication. This includes ensuring the following: * All references, tables, and figures are properly cited * All relevant supporting information is included in the manuscript submission, * There are no issues that prevent the paper from being properly typeset You will receive further instructions from the production team, including instructions on how to review your proof when it is ready. Please keep in mind that we are working through a large volume of accepted articles, so please give us a few days to review your paper and let you know the next and final steps. Lastly, if your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org. You will receive an invoice from PLOS for your publication fee after your manuscript has reached the completed accept phase. If you receive an email requesting payment before acceptance or for any other service, this may be a phishing scheme. Learn how to identify phishing emails and protect your accounts at https://explore.plos.org/phishing. If we can help with anything else, please email us at customercare@plos.org. Thank you for submitting your work to PLOS ONE and supporting open access. Kind regards, PLOS ONE Editorial Office Staff on behalf of Dr. Valeria Mazza Academic Editor PLOS One https://doi.org/10.1371/journal.pone.0341779.r006

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