Species-specific interactions in avian–bryophyte dispersal networks

Studies from seed plants have shown that animal dispersal fundamentally alters the success of plant dispersal, shaping community composition through time. Our understanding of this phenomenon in spore plants is comparatively limited. Though little is known about species-specific dispersal relationships between passerine birds and bryophytes, birds are particularly attractive as a potential bryophyte dispersal vector given their highly vagile nature as well as their association with bryophytes when foraging and building nests. We captured birds in Gifford Pinchot National Forest to sample their legs and tails for bryophyte propagules. We found 24 bryophyte species across 34 bird species. We examined the level of interaction specificity: (i) within the overall network to assess community level patterns; and (ii) at the plant species level to determine the effect of bird behaviour on network structure. We found that avian–bryophyte associations are constrained within the network, with species-specific and foraging guild effects on the variety of bryophytes found on bird species. Our findings suggest that diffuse bird–bryophyte dispersal networks are likely to be common in habitats where birds readily encounter bryophytes and that further work aimed at understanding individual bird–bryophyte species relationships may prove valuable in determining nuance within this newly described dispersal mechanism.

Overall the manuscript is well-written and fits well to the standards of the journal. I have only a few comments to the authors. Please see them below.

Methods:
With the cotton swabs, I assume you collected not just the spores, but some fragments of the bryophytes. If this is the case please correct. How did you categorize the birds feeding guilds? What literature where used? For example, the hummingbird could be easily categorized by several guilds. Please add the literature, which was used.
It would be great to have a supplementary table with the birds and their traits (feeding behaviour).
page 6, line5 to 10: they can even survive the gut passage of waterbirds. See: Wilkinson et al. 2017(Wilkinson, D. M., Lovas-Kiss, A., Callaghan, D. A., & Green, A. J. (2017. Endozoochory of large bryophyte fragments by waterbirds. Cryptogamie, Bryologie, 38(2), 223-228.) page 7 line 53: "sampling" do you mean sampled? page 9 line 8: "phylogenetic" something missing here? distance? page 14 line3: So if fragments easily, in the methods you only mention spores, but you could easily swab the fragments (which can be very viable) from the legs and feathers of the birds and not just spores right?
Decision letter (RSOS-201193.R0) We hope you are keeping well at this difficult and unusual time. We continue to value your support of the journal in these challenging circumstances. If Royal Society Open Science can assist you at all, please don't hesitate to let us know at the email address below.

Dear Dr Chmielewski
The Editors assigned to your paper RSOS-201193 "Species-specific interactions in an avianbryophyte dispersal network" have made a decision based on their reading of the paper and any comments received from reviewers.
Regrettably, in view of the reports received, the manuscript has been rejected in its current form. However, a new manuscript may be submitted which takes into consideration these comments.
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Kind regards, Andrew Dunn Royal Society Open Science Editorial Office Royal Society Open Science openscience@royalsociety.org on behalf of Dr Sean Rands (Associate Editor) and Pete Smith (Subject Editor) openscience@royalsociety.org Associate Editor Comments to Author (Dr Sean Rands): Associate Editor: 1 Comments to the Author: Firstly, please accept my apologies for the extreme delay in getting a decision to you -I have been somewhat compromised by other duties associated with the ongoing pandemic, and the delay lies with me. I hope that you are all well and coping with the current conditions. Thankyou for your submission, which I think presents some interesting biology -taking an editorial view as a generalist reader, I was intrigued by the natural history element of your manuscript, and think that conceptually it's a nice interesting piece. Your manuscript was independently read by two specialist reviewers, whose comments should be reproduced below. Based on their comments, which directed my own reading, I think that the manuscript would need some more analysis and some restructuring before it could be considered as suitable for publication, and it's not clear at this stage whether the changes would render the manuscript acceptable. I'm therefore suggesting this version is rejected, but that you have the opportunity to resubmit a new version if you wish.
This decision is based mostly on the criticisms of reviewer #1, who raises some concerns about the logic and methodology behind the network analyses. The following observations were also passed on, which I think are very relevant to what you would need to do in a revision. "The authors use two metrics (H2 and d') to describe network structure. In the manuscript these metrics are misinterpreted as measures of specialization when in fact they are measures of selectivity. While these apply well to animals, such as frugivores or pollinators, foraging on plants, their meaning when used to describe bird-bryophyte interactions is obscure." "In addition, the departure from randomness of network structure was assessed using an unspecified null model (not available in github either). It is important that the authors describe the model in detail because there are many possible null models and results are heavily contingent on the assumptions made. Finally, the influence of the relative abundances of species seems to have been entirely overlooked when analyzing network patterns. In this context, claims such as "Our study system reflects a network structure in which certain bryophyte-bird associations are more common than others, and this demonstrates that bipartite species relationships show significant specialization" (line 55, page 12) lack a solid underpinning because some interactions may be more common than others simply because they involve two abundant species. A proper null model should include this neutral effect. In relation to this, the authors "measured the cover of bryophytes on both tree trunks and the ground by quadrat sampling every 10 meters along multiple transects". Such abundance data could be used to gauge bryophyte occurrence on birds' bodies." Reviewer comments to Author: Reviewer: 1 Comments to the Author(s) This is a study that follows up on a previous analysis of the same data set that was published in Proceeding B last year. I have three concerns regarding this manuscript: -originality: objectives largely overlap with the 2019 paper. Although this new manuscript is focused on networks I found it too similar to the previous one and revolting around the same ideas. A symptom of this is that there is an entire paragraph in the Discussion that is an almost verbatim copy of one in the previous paper (page 14, line 49).
-hypotheses are too general. Network ecology has moved from merely describing networks to assessing the causes behind the patterns. In this sense, I suggest you think of more concise hypotheses regarding the association between bird traits and their role/degree of specialization in the network. -specialization indices: H2 and d' measure selectivity, not specialization. I suggest you have a look at the help file of networklevel function in the bipartite R package, where this issue is discussed (not extensively though). Relative abundances: the relative abundances of bird and bryophyte species may be constraining network structure. Perhaps compare the observed values against a null model that estimates the expected frequency of interaction based on the crossproduct of abundance vectors could deal with this issue (I suggest you have a look at Diego Vázquez and Carsten Dormann papers on this issue).
Reviewer: 2 Comments to the Author(s) This excellent and original manuscript falls within the scope of Royal Society Open Science and presents well-designed field study and analyses. This manuscript's focus is the bryophyte and bird species dispersal network, which could attract great interest in the field of dispersal ecology. Overall the manuscript is well-written and fits well to the standards of the journal. I have only a few comments to the authors. Please see them below. Methods: With the cotton swabs, I assume you collected not just the spores, but some fragments of the bryophytes. If this is the case please correct. How did you categorize the birds feeding guilds? What literature where used? For example, the hummingbird could be easily categorized by several guilds. Please add the literature, which was used.
It would be great to have a supplementary table with the birds and their traits (feeding behaviour). page 6, line5 to 10: they can even survive the gut passage of waterbirds. See: Wilkinson et al. 2017(Wilkinson, D. M., Lovas-Kiss, A., Callaghan, D. A., & Green, A. J. (2017. Endozoochory of large bryophyte fragments by waterbirds. Cryptogamie, Bryologie, 38(2), 223-228.) page 7 line 53: "sampling" do you mean sampled? page 9 line 8: "phylogenetic" something missing here? distance? page 14 line3: So if fragments easily, in the methods you only mention spores, but you could easily swab the fragments (which can be very viable) from the legs and feathers of the birds and not just spores right? ===PREPARING YOUR MANUSCRIPT=== Your revised paper should include the changes requested by the referees and Editors of your manuscript. You should provide two versions of this manuscript and both versions must be provided in an editable format: one version identifying all the changes that have been made (for instance, in coloured highlight, in bold text, or tracked changes); a 'clean' version of the new manuscript that incorporates the changes made, but does not highlight them. This version will be used for typesetting if your manuscript is accepted.
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Author's Response to Decision Letter for (RSOS-201193.R0)
See Appendix A.

RSOS-211230.R0
Review form: Reviewer 2 Is the manuscript scientifically sound in its present form? Yes

Recommendation?
Accept as is

Comments to the Author(s)
The authors have revised the manuscript taking into account almost all suggestions and comments. I have no further major issues regarding this manuscript. Regarding the first reviewer's comments on the statistics and use of terms, the authors tackled them and I suggest accepting the paper.

Recommendation?
Major revision is needed (please make suggestions in comments)

Comments to the Author(s)
My main concern with this ms is overinterpretation of the results with exaggerated claims of the importance of the results (examplified below). I suggest that the authors should focus on the natural history, which gives a story that is interesting enough.
Abstract. The first two sentences of abstract give the impression that there are very few studies on dispersal and community structure in spore plants. Yet several cases are cited, and the authors seem to have good knowledge of the literature. This is probably intended as a selling point but is not convincing. The same can be said about the statement that dispersal relationships between birds an bryophytes have never been examined. 4:24-36. This is one example where the text promises results that go beyond this study! 16:24. Here the importance for long-distance dispersal is suggested. Did you find diaspores of bryophytes that don't grow at the site or in the region. Otherwise this passage is too speculative.
17:15. The interpretations are stretched much too far. That these bird dispersal events are of importance for atmosphere-biosphere interactions and soil-atmosphere interface is not credible. Focus on the natural history and the relevance for the bird and moss communities (as later in the paragraph). This is interesting enough, and the conclusions would be within the scope of the results.
The final paragraph (17:33) is somewhat disappointing. It can make sense to mention potential future studies, but it would be nice to focus the final paragraphs on the main conclusions of the study.
Other comments 11:45. That the network is nonrandom is not surprising, but you could help the reader by picking out noteworthy observations from Fig. 1. What is is that makes the pattern non-random? For example the common mosses AUAN and ISMY seem are strongly linked to the common bird SWTH, which seems as expected by random. In contrast, the most common moss (Ceratodon) is more linked to AMRO, than to SWTH, which seems non-random. 11:52 (text to Fig. 2). This was difficult to evaluate, because I did not fully understand Fig. 2 as the boxplot and brown vertical bar was not explained in legend. Conversely, the sentence "Specificity of the full network,..." should be in text, not in legend.
A technically that I did not understand in Fig. 2: Is deltaH2´ the difference between the observed and the mean of the null distribution? Or the median (since the plot does not show mean)?. Or perhaps I just misunderstood. 12:3. In the legend to Fig. 3 there are also some observations that should rather be in the text (eg. "While ground foraging tended to decrease specificity, specificity of associations for Polytrichum juniperinum increased. Ground foraging associations strongly drive overall network patterns", and others).
13:5, Fig. 4. Clarify here that it is phylogenetic distance of bryophytes. Again, the text should extract the interesting observations in the graphs. To just note that it was lower than expected seems trivial. What do you want the reader to see (which should then be dealt with in the disussion)?
13:18. The statement that this is the "first species-specific interaction network between birds and topically resident bryophyte propagules" seems to have overlooked the paper by Fonturbel (Functional Ecology, 35 (2021), 226-238).

Decision letter (RSOS-211230.R0)
We hope you are keeping well at this difficult and unusual time. We continue to value your support of the journal in these challenging circumstances. If Royal Society Open Science can assist you at all, please don't hesitate to let us know at the email address below.

Dear Dr Chmielewski
The Editors assigned to your paper RSOS-211230 "Species-specific interactions in an avianbryophyte dispersal network" have now received comments from reviewers and would like you to revise the paper in accordance with the reviewer comments and any comments from the Editors. Please note this decision does not guarantee eventual acceptance.
We invite you to respond to the comments supplied below and revise your manuscript. Below the referees' and Editors' comments (where applicable) we provide additional requirements. Final acceptance of your manuscript is dependent on these requirements being met. We provide guidance below to help you prepare your revision.
We do not generally allow multiple rounds of revision so we urge you to make every effort to fully address all of the comments at this stage. If deemed necessary by the Editors, your manuscript will be sent back to one or more of the original reviewers for assessment. If the original reviewers are not available, we may invite new reviewers.
Please submit your revised manuscript and required files (see below) no later than 21 days from today's (ie 30-Sep-2021) date. Note: the ScholarOne system will 'lock' if submission of the revision is attempted 21 or more days after the deadline. If you do not think you will be able to meet this deadline please contact the editorial office immediately.
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Thank you for submitting your manuscript to Royal Society Open Science and we look forward to receiving your revision. If you have any questions at all, please do not hesitate to get in touch.
Kind regards, Royal Society Open Science Editorial Office Royal Society Open Science openscience@royalsociety.org on behalf of Dr Sean Rands (Associate Editor) and Pete Smith (Subject Editor) openscience@royalsociety.org Reviewer comments to Author: Reviewer: 3 Comments to the Author(s) My main concern with this ms is overinterpretation of the results with exaggerated claims of the importance of the results (examplified below). I suggest that the authors should focus on the natural history, which gives a story that is interesting enough.
Abstract. The first two sentences of abstract give the impression that there are very few studies on dispersal and community structure in spore plants. Yet several cases are cited, and the authors seem to have good knowledge of the literature. This is probably intended as a selling point but is not convincing. The same can be said about the statement that dispersal relationships between birds an bryophytes have never been examined. 4:24-36. This is one example where the text promises results that go beyond this study! 16:24. Here the importance for long-distance dispersal is suggested. Did you find diaspores of bryophytes that don't grow at the site or in the region. Otherwise this passage is too speculative.
17:15. The interpretations are stretched much too far. That these bird dispersal events are of importance for atmosphere-biosphere interactions and soil-atmosphere interface is not credible. Focus on the natural history and the relevance for the bird and moss communities (as later in the paragraph). This is interesting enough, and the conclusions would be within the scope of the results.
The final paragraph (17:33) is somewhat disappointing. It can make sense to mention potential future studies, but it would be nice to focus the final paragraphs on the main conclusions of the study.
Other comments 11:45. That the network is nonrandom is not surprising, but you could help the reader by picking out noteworthy observations from Fig. 1. What is is that makes the pattern non-random? For example the common mosses AUAN and ISMY seem are strongly linked to the common bird SWTH, which seems as expected by random. In contrast, the most common moss (Ceratodon) is more linked to AMRO, than to SWTH, which seems non-random. 11:52 (text to Fig. 2). This was difficult to evaluate, because I did not fully understand Fig. 2 as the boxplot and brown vertical bar was not explained in legend. Conversely, the sentence "Specificity of the full network,..." should be in text, not in legend.
A technically that I did not understand in Fig. 2: Is deltaH2´ the difference between the observed and the mean of the null distribution? Or the median (since the plot does not show mean)?. Or perhaps I just misunderstood. 12:3. In the legend to Fig. 3 there are also some observations that should rather be in the text (eg. "While ground foraging tended to decrease specificity, specificity of associations for Polytrichum juniperinum increased. Ground foraging associations strongly drive overall network patterns", and others).
13:5, Fig. 4. Clarify here that it is phylogenetic distance of bryophytes. Again, the text should extract the interesting observations in the graphs. To just note that it was lower than expected seems trivial. What do you want the reader to see (which should then be dealt with in the disussion)? 13:18. The statement that this is the "first species-specific interaction network between birds and topically resident bryophyte propagules" seems to have overlooked the paper by Fonturbel (Functional Ecology, 35 (2021), 226-238).
Reviewer: 2 Comments to the Author(s) The authors have revised the manuscript taking into account almost all suggestions and comments. I have no further major issues regarding this manuscript. Regarding the first reviewer's comments on the statistics and use of terms, the authors tackled them and I suggest accepting the paper.

===PREPARING YOUR MANUSCRIPT===
Your revised paper should include the changes requested by the referees and Editors of your manuscript. You should provide two versions of this manuscript and both versions must be provided in an editable format: one version identifying all the changes that have been made (for instance, in coloured highlight, in bold text, or tracked changes); a 'clean' version of the new manuscript that incorporates the changes made, but does not highlight them. This version will be used for typesetting if your manuscript is accepted.
Please ensure that any equations included in the paper are editable text and not embedded images.
Please ensure that you include an acknowledgements' section before your reference list/bibliography. This should acknowledge anyone who assisted with your work, but does not qualify as an author per the guidelines at https://royalsociety.org/journals/ethicspolicies/openness/.
While not essential, it will speed up the preparation of your manuscript proof if accepted if you format your references/bibliography in Vancouver style (please see https://royalsociety.org/journals/authors/author-guidelines/#formatting). You should include DOIs for as many of the references as possible.
If you have been asked to revise the written English in your submission as a condition of publication, you must do so, and you are expected to provide evidence that you have received language editing support. The journal would prefer that you use a professional language editing service and provide a certificate of editing, but a signed letter from a colleague who is a native speaker of English is acceptable. Note the journal has arranged a number of discounts for authors using professional language editing services (https://royalsociety.org/journals/authors/benefits/language-editing/).

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Comments to the Author(s)
Much improved, and I am pleased with the better focus in this version.

Decision letter (RSOS-211230.R1)
We hope you are keeping well at this difficult and unusual time. We continue to value your support of the journal in these challenging circumstances. If Royal Society Open Science can assist you at all, please don't hesitate to let us know at the email address below.

Dear Dr Chmielewski,
It is a pleasure to accept your manuscript entitled "Species-specific interactions in an avianbryophyte dispersal network" in its current form for publication in Royal Society Open Science. The comments of the reviewer(s) who reviewed your manuscript are included at the foot of this letter.
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Thank you for your fine contribution. On behalf of the Editors of Royal Society Open Science, we look forward to your continued contributions to the Journal. We have taken the great suggestions by the AE and reviewers below, and think it has marked improved our manuscript. In order to address the specific comments, we provide a point-bypoint response to the original comments below.
Thank you for your time and patience, Matthew Chmielewski, Ph.D.

Below, we provide line-by-line responses to the reviewer commentary along with editorial concerns. We think that the manuscript, having integrated these suggestions, has been markedly improved.
Associate Editor Comments to Author (Dr Sean Rands): Associate Editor: 1 Comments to the Author: Firstly, please accept my apologies for the extreme delay in getting a decision to you -I have been somewhat compromised by other duties associated with the ongoing pandemic, and the delay lies with me. I hope that you are all well and coping with the current conditions. Thank you for your submission, which I think presents some interesting biology -taking an editorial view as a generalist reader, I was intrigued by the natural history element of your manuscript, and think that conceptually it's a nice interesting piece. Your manuscript was independently read by two specialist reviewers, whose comments should be reproduced below. Based on their comments, which directed my own reading, I think that the manuscript would need some more analysis and some restructuring before it could be considered as suitable for publication, and it's not clear at this stage whether the changes would render the manuscript acceptable. I'm therefore suggesting this version is rejected, but that you have the opportunity to resubmit a new version if you wish.
This decision is based mostly on the criticisms of reviewer #1, who raises some concerns about the logic and methodology behind the network analyses. The following observations were also passed on, which I think are very relevant to what you would need to do in a revision. "The authors use two metrics (H2 and d') to describe network structure. In the manuscript these metrics are misinterpreted as measures of specialization when in fact they are measures of selectivity. While these apply well to animals, such as frugivores or pollinators, foraging on plants, their meaning when used to describe bird-bryophyte interactions is obscure."

We discuss the concerns regarding network metric choice below in response to the comments provided by reviewer 1.
"In addition, the departure from randomness of network structure was assessed using an unspecified null model (not available in github either). It is important that the authors describe the model in detail because there are many possible null models and results are heavily contingent on the assumptions made.

We agree that the null model specifications are important in interpreting our approach and that we overlooked making this clear and available via github. We now both explicitly address the null model specifications in the text, and have made the code available on github.
Finally, the influence of the relative abundances of species seems to have been entirely overlooked when analyzing network patterns. In this context, claims such as "Our study system reflects a network structure in which certain bryophyte-bird associations are more common than others, and this demonstrates that bipartite species relationships show significant specialization" (line 55, page 12) lack a solid underpinning because some interactions may be more common than others simply because they involve two abundant species. A proper null model should include this neutral effect.
This concern is related to the null model approach and is articulated as a concern by reviewer 1 below. We address the null model specifications relative to reviewer 1's concerns below.
In relation to this, the authors "measured the cover of bryophytes on both tree trunks and the ground by quadrat sampling every 10 meters along multiple transects". Such abundance data could be used to gauge bryophyte occurrence on birds' bodies." Reviewer comments to Author: Reviewer: 1 Comments to the Author(s) This is a study that follows up on a previous analysis of the same data set that was published in Proceeding B last year. I have three concerns regarding this manuscript: -originality: objectives largely overlap with the 2019 paper. Although this new manuscript is focused on networks I found it too similar to the previous one and revolting around the same ideas. A symptom of this is that there is an entire paragraph in the Discussion that is an almost verbatim copy of one in the previous paper (page 14, line 49).

We have edited the text to reflect an emphasis on how this particular manuscript is novel compared to the previous work. We maintain that describing species associations within the network is an entirely unique product from these data than previously studied topical spore loads, and thus merits publication.
-hypotheses are too general. Network ecology has moved from merely describing networks to assessing the causes behind the patterns. In this sense, I suggest you think of more concise hypotheses regarding the association between bird traits and their role/degree of specialization in the network.
We address this concern by providing more explicit predictions within the paper linked to out analyses, with new interpretations.
-specialization indices: H2 and d' measure selectivity, not specialization. I suggest you have a look at the help file of networklevel function in the bipartite R package, where this issue is discussed (not extensively though). We therefore used the term "specialization" in its original context as described by Bluthgen et al. rather than selectivity.

Bluthen, Menzel, and Bluthgen introduce the derivation of d' and H2' in Bluthgen
We additionally examined the networklevel function of the bipartite package documentation, in which Dormann refers to these metrics with the term "specialization".
We agree with Reviewer 2 that the use of these various specific terms can lead to a textual interpretation of the underlying meaning of these indices that can vary depending on the term used.
The dominant application of these methods to describe plant-pollinator and plantfrugivore networks may have lead to a dominant use of "selectivity", with the interpretation being that animals are making choices based on tightly co-evolved interactions. Despite this, these indices are derived ultimately from matrix mathematics in which the topology of nodes and edges of a network are being described. The emphasis on animal choice of resources is therefore an interpretation of the network structure, rather than being inherent to any interpretation of these indices.
Indeed, these indices have gone on to be used by Bluthgen and others to describe various networks in which co-evolved "specialization" or behavioral choice of resources ("selectivity") may not be the most appropriate ecological description of the studied relationship.
Following these examples, we interpret the patterns of bird-bryophyte interaction in our system as a product of avian use of particular niche space throughout the habitat which differentially exposes them to particular bryophytes.
We agree again with Reviewer 2 that the terms "specialization" and "selectivity" can be interpreted to imply the coevolution of a dispersal syndrome in which particular birds are choosing particular mosses. While this has been shown to be true for avian choice of nesting material (and likely a factor in our system), and may be true for avian use of foraging substrates, we don't make the claim that we can interpret this to be true within our study system. We therefore have chosen to change out language to move away from "specialization" and instead to "specificity" of interaction.
While we feel that this helps disambiguate our meaning, we add additional text to the methods to clarify the specific meaning of our use of these indices by discussing the derivation as well as providing examples that align with our use of these terms.
Relative abundances: the relative abundances of bird and bryophyte species may be constraining network structure. Perhaps compare the observed values against a null model that estimates the expected frequency of interaction based on the crossproduct of abundance vectors could deal with this issue (I suggest you have a look at Diego Vázquez and Carsten Dormann papers on this issue).
We agree that both asymmetric sampling and null model selection can have profound impacts on the outcome of bipartite network indices. Nico Bluthgen, indeed, argues that generally measures of partner interactions increase with sampling effort, but that d' and H'2 are specifically built to account for asymmetric sampling:

"In interaction datasets that are limited by sampling, however, partner diversity simply increases with the number of observations, whereas selectivity (e.g. H'2, d′) can be determined independently of the completeness of interactions observed." Kaiser-Bunbury and Bluthgen (2015)
Regardless, Reviewer 1 is correct in criticizing an approach employing an undisclosed null model. This was an oversight that we have now corrected, including the null model in both the text and the available code.
As suggested by Reviewer 1, we employ Dormann's null.dist function which fits a distribution to the observed data, then generates null webs based on the crossproduct of abundance vectors from these distributions. We discuss this explicitly in the methods, improving the clarify of our approach.

Reviewer: 2
Comments to the Author(s) This excellent and original manuscript falls within the scope of Royal Society Open Science and presents well-designed field study and analyses. This manuscript's focus is the bryophyte and bird species dispersal network, which could attract great interest in the field of dispersal ecology. Overall the manuscript is well-written and fits well to the standards of the journal. I have only a few comments to the authors. Please see them below. Methods: With the cotton swabs, I assume you collected not just the spores, but some fragments of the bryophytes. If this is the case please correct.
We have gone back and made it apparent that we are discussing bryophyte propagules rather than spores per se. We find the distinction between seed dispersal and dispersal of spore-bearing plants to be important to our introduction, so have kept our focus on spore-bearing plants in place. We think that with the additional language we have made it clear that we are not sampling only spores for this study.
How did you categorize the birds feeding guilds? What literature where used? For example, the hummingbird could be easily categorized by several guilds. Please add the literature, which was used.
The previous approach used the Cornell Lab of Ornithology's Birds of North America resource in order to classify feeding guilds.
When considering a response to this review, we decided to move beyond simply citing those resources and have changed to a more quantitative approach of classification based on the Elton Traits database.
We believe that this approach is a) more explicitly repeatable, b) classifies species based on a quantitative threshold, and c) allows species to belong to multiple guilds, better reflecting the complexity of resource us by various birds.
We explain this approach in the revised text.
It would be great to have a supplementary table with the birds and their traits (feeding behaviour).
We have generated our new traits from a published database, clarifying this point. Indeed! We are specifically focused on epizoochory but mentioned synzoochory via hummingbirds and think it is appropriate to also mentioned endozoochory so have added a reference here. Thanks! page 7 line 53: "sampling" do you mean sampled? Corrected page 9 line 8: "phylogenetic" something missing here? distance? Corrected page 14 line3: So if fragments easily, in the methods you only mention spores, but you could easily swab the fragments (which can be very viable) from the legs and feathers of the birds and not just spores right? We have gone back and changed the methods relate to swab sampling to use the general term "propagules"

===PREPARING YOUR MANUSCRIPT===
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Dear Royal Society Open Science editorial staff, Below we provide a point-by-point response to the editorial and reviewer comments on manuscript RSOS-211230.
Response to comments from the editor: This review came without additional editorial comments, which we took to mean that the editorial concerns were sufficiently outlined by the reviewers during this round.
Response to comments from reviewers: Reviewer comments to Author: Reviewer: 3 Comments to the Author(s) My main concern with this ms is overinterpretation of the results with exaggerated claims of the importance of the results (examplified below). I suggest that the authors should focus on the natural history, which gives a story that is interesting enough.