Downloaded from http://rsos.royalsocietypublishing.org/ on June 18, 2017
Group cohesion in foraging meerkats: follow the moving
‘vocal hot spot’
Gabriella E. C. Gall and Marta B. Manser
Article citation details
R. Soc. open sci. 4: 170004.
http://dx.doi.org/10.1098/rsos.170004
Review timeline
Original submission:
1st revised submission:
2nd revised submission:
Final acceptance:
2 January 2017
27 February 2017
28 March 2017
28 March 2017
Note: Reports are unedited and appear as
submitted by the referee. The review history
appears in chronological order.
Review History
RSOS-170004.R0 (Original submission)
Review form: Reviewer 1 (Christina Wolf)
Is the manuscript scientifically sound in its present form?
Yes
Are the interpretations and conclusions justified by the results?
Yes
Is the language acceptable?
No
Is it clear how to access all supporting data?
Not Applicable
Do you have any ethical concerns with this paper?
No
Have you any concerns about statistical analyses in this paper?
I do not feel qualified to assess the statistics
© 2017 The Authors. Published by the Royal Society under the terms of the Creative Commons
Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use,
provided the original author and source are credited
Downloaded from http://rsos.royalsocietypublishing.org/ on June 18, 2017
2
Recommendation?
Major revision is needed (please make suggestions in comments)
Comments to the Author(s)
Dear Gabriella,
Some recommendations from my side to make some things more clear to the reader.
Introduction
The introduction is almost clear to me. Please think of defining what "front of the group" exactly
means in terms of group formation. Is the front associated with specific group members of
hierarchy or age? If not and it is only spatial shortly say that (p3, row37).
May be it needs to be a little more clear if you playback the calls from opposite sides of the group
or always from the front and the back (p3, row40).
If there is information/reference about group dispersion during foraging behavior it would be
helpful to create a picture of the behavior for the reader (introduction).
Methods
General information about weather condition in the Kalahari during your data collection would
be nice to know may be in the context of foraging behavior in that time of the year that might be
different from winter?!
For number of individuals per group you don't need decimal, please change to full numbers.
If you want to avoid confusion for readers please use the same term/wording for anything callspecific, e.g. call pattern/ call density/ call rate (p3) if! you mean the same.
Did you playback close calls from one speaker and control / close calls from the other speaker?
You wrote playback order was randomized which implies this procedure but I was not sure.
Results
I didn't understand the last sentence of your Results. Is "the time within each playback" and
"Time step" the same? If they are, time step did influence the length of the group p = 0.002 (Table
1). Please check this or write it more clearly.
I am missing a sentence about whether or not you found an interaction effect (as seen in Table 1,
no).
May be the "intercept" in your model could be shortly explained, what it is (may be in the
statistics part).
Discussion
You mention "structured habitat" here but didn't explain in the methods, you referred to ref14.
May be in the discussion you can name what structured means, just very shortly.
Close call behavior in the context of spacial location is clear but social environment could mean
different things, should be described (p5, row 105) on the basis of references. Is there a reference
for the last part of the sentence row 105,106?
Please explain/describe the findings for the wild mangabeys otherwise the reader cannot follow
you well. May be in the last part of discussion also mention the foraging context while writing
about other examples.
Please check your references for completeness.
For data accessibility may be use the direct link where to find your data.
This was a very interesting manuscript to read, thank you both.
Downloaded from http://rsos.royalsocietypublishing.org/ on June 18, 2017
3
Review form: Reviewer 2
Is the manuscript scientifically sound in its present form?
Yes
Are the interpretations and conclusions justified by the results?
Yes
Is the language acceptable?
Yes
Is it clear how to access all supporting data?
Yes
Do you have any ethical concerns with this paper?
No
Have you any concerns about statistical analyses in this paper?
No
Recommendation?
Major revision is needed (please make suggestions in comments)
Comments to the Author(s)
Although it has been shown in many species that individuals emit vocal signals to maintain
group cohesion only few studies showed that also receiver use acoustic information to make
movement decisions. In this study the authors investigated whether meerkats use close-calls
given by other individuals to make movement decisions and maintain group cohesion. By
presenting simultaneously playbacks of close-calls from four adult subordinates each at the front
and the rear of the group and environmental background noise as a control to 8 different groups
of meerkats, the authors investigated whether foraging meerkats use this acoustic information to
make movement decisions. They could show that after presenting playbacks with close calls, the
group spatially elongated and were more likely to split up into subgroups than after presenting
the control. This study nicely illustrates that meerkats use moving vocal hotspots as a
coordination mechanism.
The manuscript is well written and the methods are in principle flawless and of broad interest for
readers of Royal Society Open Science. I have a few comments that should be addressed in a
revision.
L 38: wording: “dense part of the group” – might be better to say where most group members are
L 61: How did you randomize call rate between individuals?
L 64: Please explain why you presented both playback stimuli on the same but not on different
days?
How much time were between the playback stimuli and the control?
Did you present the two conditions in a counter balanced order across the 8 groups?
L 83: What are time steps? How are they measured?
L 83: Please explain why you included the interaction between playback condition and time
steps. The interactions are in all models not significant and should, thus, to my knowledge be
excluded.
L 89: Did the two playback stimuli differ in call rate? If so explain it in the Methods.
L 92: Time? Do you mean the time steps?
L 104 – 109: explain in more detail in how far meerkats adjust their calling rate to the spatial
position they are in.
L 119: Why do you assume that leaders can influence travel directions by increasing their call
rate? From the presented results it is not really clear that the two stimuli differed in call rate and
Downloaded from http://rsos.royalsocietypublishing.org/ on June 18, 2017
4
that meerkats were more likely to follow a simulated hotspot with a higher call rate – see
comment above.
Decision letter (RSOS-170004)
07-Feb-2017
Dear Ms Gall,
The editors assigned to your paper ("Group cohesion in foraging meerkats: follow the moving
‘vocal hot spot’") have now received comments from reviewers. We would like you to revise
your paper in accordance with the referee and Associate Editor suggestions which can be found
below (not including confidential reports to the Editor). Please note this decision does not
guarantee eventual acceptance.
Please submit a copy of your revised paper within three weeks (i.e. by the 02-Mar-2017). If we do
not hear from you within this time then it will be assumed that the paper has been withdrawn. In
exceptional circumstances, extensions may be possible if agreed with the Editorial Office in
advance.We do not 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.
To revise your manuscript, log into http://mc.manuscriptcentral.com/rsos and enter your
Author Centre, where you will find your manuscript title listed under "Manuscripts with
Decisions." Under "Actions," click on "Create a Revision." Your manuscript number has been
appended to denote a revision. Revise your manuscript and upload a new version through your
Author Centre.
When submitting your revised manuscript, you must respond to the comments made by the
referees and upload a file "Response to Referees" in "Section 6 - File Upload". Please use this to
document how you have responded to the comments, and the adjustments you have made. In
order to expedite the processing of the revised manuscript, please be as specific as possible in
your response.
In addition to addressing all of the reviewers' and editor's comments please also ensure that your
revised manuscript contains the following sections as appropriate before the reference list:
• Ethics statement (if applicable)
If your study uses humans or animals please include details of the ethical approval received,
including the name of the committee that granted approval. For human studies please also detail
whether informed consent was obtained. For field studies on animals please include details of all
permissions, licences and/or approvals granted to carry out the fieldwork.
• Data accessibility
It is a condition of publication that all supporting data are made available either as
supplementary information or preferably in a suitable permanent repository. The data
accessibility section should state where the article's supporting data can be accessed. This section
should also include details, where possible of where to access other relevant research materials
such as statistical tools, protocols, software etc can be accessed. If the data have been deposited in
an external repository this section should list the database, accession number and link to the DOI
for all data from the article that have been made publicly available. Data sets that have been
Downloaded from http://rsos.royalsocietypublishing.org/ on June 18, 2017
5
deposited in an external repository and have a DOI should also be appropriately cited in the
manuscript and included in the reference list.
If you wish to submit your supporting data or code to Dryad (http://datadryad.org/), or modify
your current submission to dryad, please use the following link:
http://datadryad.org/submit?journalID=RSOS&manu=RSOS-170004
• Competing interests
Please declare any financial or non-financial competing interests, or state that you have no
competing interests.
• Authors’ contributions
All submissions, other than those with a single author, must include an Authors’ Contributions
section which individually lists the specific contribution of each author. The list of Authors
should meet all of the following criteria; 1) substantial contributions to conception and design, or
acquisition of data, or analysis and interpretation of data; 2) drafting the article or revising it
critically for important intellectual content; and 3) final approval of the version to be published.
All contributors who do not meet all of these criteria should be included in the
acknowledgements.
We suggest the following format:
AB carried out the molecular lab work, participated in data analysis, carried out sequence
alignments, participated in the design of the study and drafted the manuscript; CD carried out
the statistical analyses; EF collected field data; GH conceived of the study, designed the study,
coordinated the study and helped draft the manuscript. All authors gave final approval for
publication.
• Acknowledgements
Please acknowledge anyone who contributed to the study but did not meet the authorship
criteria.
• Funding statement
Please list the source of funding for each author.
Once again, thank you for submitting your manuscript to Royal Society Open Science and I look
forward to receiving your revision. If you have any questions at all, please do not hesitate to get
in touch.
Yours sincerely,
Alice Power
Editorial Coordinator
Royal Society Open Science
on behalf of Kevin Padian
Subject Editor, Royal Society Open Science
[email protected]
Comments to Author:
Reviewers' Comments to Author:
Reviewer: 1
Comments to the Author(s)
Dear Gabriella,
Some recommendations from my side to make some things more clear to the reader.
Downloaded from http://rsos.royalsocietypublishing.org/ on June 18, 2017
6
Introduction
The introduction is almost clear to me. Please think of defining what "front of the group" exactly
means in terms of group formation. Is the front associated with specific group members of
hierarchy or age? If not and it is only spatial shortly say that (p3, row37).
May be it needs to be a little more clear if you playback the calls from opposite sides of the group
or always from the front and the back (p3, row40).
If there is information/reference about group dispersion during foraging behavior it would be
helpful to create a picture of the behavior for the reader (introduction).
Methods
General information about weather condition in the Kalahari during your data collection would
be nice to know may be in the context of foraging behavior in that time of the year that might be
different from winter?!
For number of individuals per group you don't need decimal, please change to full numbers.
If you want to avoid confusion for readers please use the same term/wording for anything callspecific, e.g. call pattern/ call density/ call rate (p3) if! you mean the same.
Did you playback close calls from one speaker and control / close calls from the other speaker?
You wrote playback order was randomized which implies this procedure but I was not sure.
Results
I didn't understand the last sentence of your Results. Is "the time within each playback" and
"Time step" the same? If they are, time step did influence the length of the group p = 0.002 (Table
1). Please check this or write it more clearly.
I am missing a sentence about whether or not you found an interaction effect (as seen in Table 1,
no).
May be the "intercept" in your model could be shortly explained, what it is (may be in the
statistics part).
Discussion
You mention "structured habitat" here but didn't explain in the methods, you referred to ref14.
May be in the discussion you can name what structured means, just very shortly.
Close call behavior in the context of spacial location is clear but social environment could mean
different things, should be described (p5, row 105) on the basis of references. Is there a reference
for the last part of the sentence row 105,106?
Please explain/describe the findings for the wild mangabeys otherwise the reader cannot follow
you well. May be in the last part of discussion also mention the foraging context while writing
about other examples.
Please check your references for completeness.
For data accessibility may be use the direct link where to find your data.
This was a very interesting manuscript to read, thank you both.
Reviewer: 2
Comments to the Author(s)
Although it has been shown in many species that individuals emit vocal signals to maintain
group cohesion only few studies showed that also receiver use acoustic information to make
movement decisions. In this study the authors investigated whether meerkats use close-calls
given by other individuals to make movement decisions and maintain group cohesion. By
Downloaded from http://rsos.royalsocietypublishing.org/ on June 18, 2017
7
presenting simultaneously playbacks of close-calls from four adult subordinates each at the front
and the rear of the group and environmental background noise as a control to 8 different groups
of meerkats, the authors investigated whether foraging meerkats use this acoustic information to
make movement decisions. They could show that after presenting playbacks with close calls, the
group spatially elongated and were more likely to split up into subgroups than after presenting
the control. This study nicely illustrates that meerkats use moving vocal hotspots as a
coordination mechanism.
The manuscript is well written and the methods are in principle flawless and of broad interest for
readers of Royal Society Open Science. I have a few comments that should be addressed in a
revision.
L 38: wording: “dense part of the group” – might be better to say where most group members are
L 61: How did you randomize call rate between individuals?
L 64: Please explain why you presented both playback stimuli on the same but not on different
days?
How much time were between the playback stimuli and the control?
Did you present the two conditions in a counter balanced order across the 8 groups?
L 83: What are time steps? How are they measured?
L 83: Please explain why you included the interaction between playback condition and time
steps. The interactions are in all models not significant and should, thus, to my knowledge be
excluded.
L 89: Did the two playback stimuli differ in call rate? If so explain it in the Methods.
L 92: Time? Do you mean the time steps?
L 104 – 109: explain in more detail in how far meerkats adjust their calling rate to the spatial
position they are in.
L 119: Why do you assume that leaders can influence travel directions by increasing their call
rate? From the presented results it is not really clear that the two stimuli differed in call rate and
that meerkats were more likely to follow a simulated hotspot with a higher call rate – see
comment above.
Author's Response to Decision Letter for (RSOS-170004)
See Appendix A
RSOS-170004.R1 (Revision)
Review form: Reviewer 1 (Christina Wolf)
Is the manuscript scientifically sound in its present form?
Yes
Are the interpretations and conclusions justified by the results?
Yes
Is the language acceptable?
Yes
Is it clear how to access all supporting data?
Yes
Downloaded from http://rsos.royalsocietypublishing.org/ on June 18, 2017
8
Do you have any ethical concerns with this paper?
No
Have you any concerns about statistical analyses in this paper?
No
Recommendation?
Major revision is needed (please make suggestions in comments)
Comments to the Author(s)
Dear author,
Comments from first revision were satisfyingly implemented.
The results are interesting and therefore, need more differentiation.
Basic feedback:
Results:
Figure 1: Use units for length and width.
Figure 2: There is a mistake in the description --> gap size should be c and width should be b;
color for playback condition is black not grey?
Table 1: The alpha-level: is that the significance level? If yes, significance level is more clear, but
this is just a suggestion. Why was it reduced to exactly 0.017. Please, shortly explain the number,
where does it come from? You wrote the units of parameters in figure 2, please add them in the
description of table1. --> Check in the text as well.
It would be easier to follow if results are described in an order, e.g. all factors that affected length
parameter, then width, then gap size or effect of testing condition on length, width and gap size,
then effect of time step on all parameters, then interaction effects or stating that there was none.
Use more information from your table and describe the differences of estimates for the three
parameters, e.g. the weight of the variables in relation to the intercept, to explain/describe the
significant effects. I needed time and advice of colleagues to relate effects to the data given. You
could also mention, what it means, if the estimate values are negative.
Length and gap size expand during playback and shrink to the end of playback. Why? -->
Discussion.
Discussion:
You described and explained the significant effects well. Please discuss your results more deeply
and comprehensively.
What if you would have placed the speakers at the two sides of group width? Would "width" be
affected too? Or is this an unlikely consequence and why? Please discuss also the limits of your
experiment.
General feedback
Try to shorten the sentences. If you use "however" within a sentence, you could end the sentence
"." and start with "However, ...". (e.g. L 93, 109)
Put the information that the tracks had the highest or a higher call rate than the observed
individuals into the method section. It is a very important aspect and was not clearly said, you
could easily copy the first part of the sentence from L 105.
Downloaded from http://rsos.royalsocietypublishing.org/ on June 18, 2017
9
L 17: Do not start the sentence with "To achieve...", put first part of the sentence as second part.
L 41: Brackets are not as the others.
L 41 -43: Mark as your hypothesis.
L 71: ... the order of calls of -recorded- individuals ...
L 72: what do you mean with time of a call within each track? - Do you mean: "we randomized
the order of calls from individuals and within the playback track? If so, last part of sentence
would be unnecessary.
L 84: Every two minutes -(time steps)- ...
L 95: no need for "respectively"
L 105: Explain more precisely the second part of the first sentence of results. "closest location"
means speaker? "highest call rate" coming from the speaker?
L 128: Sentence too long.
L 133: another word for provide as you didn't provide results for the production of a vocal
hotspot, you did for the receiver side.
L 138: second part of sentence not needed, not important for the reader.
Data: I couldn't access you data via dryad. Please try as well again. I know it was working for the
first review.
References:
13, Germany is missing.
Thank you again very much. Your work is progressing well.
Review form: Reviewer 2
Is the manuscript scientifically sound in its present form?
Yes
Are the interpretations and conclusions justified by the results?
Yes
Is the language acceptable?
Yes
Is it clear how to access all supporting data?
Yes
Do you have any ethical concerns with this paper?
No
Downloaded from http://rsos.royalsocietypublishing.org/ on June 18, 2017
10
Have you any concerns about statistical analyses in this paper?
No
Recommendation?
Accept as is
Comments to the Author(s)
I am happy with the revised version of the MS and recommend it for publication.
Decision letter (RSOS-170004.R1)
14-Mar-2017
Dear Ms Gall:
On behalf of the Editors, I am pleased to inform you that your Manuscript RSOS-170004.R1
entitled "Group cohesion in foraging meerkats: follow the moving ‘vocal hot spot’" has been
accepted for publication in Royal Society Open Science subject to minor revision in accordance
with the referee suggestions. Please find the referees' comments at the end of this email.
The reviewers and Subject Editor have recommended publication, but also suggest some minor
revisions to your manuscript. Therefore, I invite you to respond to the comments and revise your
manuscript.
• Ethics statement
If your study uses humans or animals please include details of the ethical approval received,
including the name of the committee that granted approval. For human studies please also detail
whether informed consent was obtained. For field studies on animals please include details of all
permissions, licences and/or approvals granted to carry out the fieldwork.
• Data accessibility
It is a condition of publication that all supporting data are made available either as
supplementary information or preferably in a suitable permanent repository. The data
accessibility section should state where the article's supporting data can be accessed. This section
should also include details, where possible of where to access other relevant research materials
such as statistical tools, protocols, software etc can be accessed. If the data has been deposited in
an external repository this section should list the database, accession number and link to the DOI
for all data from the article that has been made publicly available. Data sets that have been
deposited in an external repository and have a DOI should also be appropriately cited in the
manuscript and included in the reference list.
If you wish to submit your supporting data or code to Dryad (http://datadryad.org/), or modify
your current submission to dryad, please use the following link:
http://datadryad.org/submit?journalID=RSOS&manu=RSOS-170004.R1
• Competing interests
Please declare any financial or non-financial competing interests, or state that you have no
competing interests.
• Authors’ contributions
All submissions, other than those with a single author, must include an Authors’ Contributions
section which individually lists the specific contribution of each author. The list of Authors
Downloaded from http://rsos.royalsocietypublishing.org/ on June 18, 2017
11
should meet all of the following criteria; 1) substantial contributions to conception and design, or
acquisition of data, or analysis and interpretation of data; 2) drafting the article or revising it
critically for important intellectual content; and 3) final approval of the version to be published.
All contributors who do not meet all of these criteria should be included in the
acknowledgements.
We suggest the following format:
AB carried out the molecular lab work, participated in data analysis, carried out sequence
alignments, participated in the design of the study and drafted the manuscript; CD carried out
the statistical analyses; EF collected field data; GH conceived of the study, designed the study,
coordinated the study and helped draft the manuscript. All authors gave final approval for
publication.
• Acknowledgements
Please acknowledge anyone who contributed to the study but did not meet the authorship
criteria.
• Funding statement
Please list the source of funding for each author.
Please note that we cannot publish your manuscript without these end statements included. We
have included a screenshot example of the end statements for reference. If you feel that a given
heading is not relevant to your paper, please nevertheless include the heading and explicitly state
that it is not relevant to your work.
Because the schedule for publication is very tight, it is a condition of publication that you submit
the revised version of your manuscript within 7 days (i.e. by the 23-Mar-2017). If you do not think
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To revise your manuscript, log into https://mc.manuscriptcentral.com/rsos and enter your
Author Centre, where you will find your manuscript title listed under "Manuscripts with
Decisions". Under "Actions," click on "Create a Revision." You will be unable to make your
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Downloaded from http://rsos.royalsocietypublishing.org/ on June 18, 2017
12
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Once again, thank you for submitting your manuscript to Royal Society Open Science and I look
forward to receiving your revision. If you have any questions at all, please do not hesitate to get
in touch.
Best wishes
Alice Power
Editorial Coordinator
Royal Society Open Science
[email protected]
on behalf of Kevin Padian
Subject Editor, Royal Society Open Science
[email protected]
Comments to Author:
Reviewer: 2
Comments to the Author(s)
I am happy with the revised version of the MS and recommend it for publication.
Reviewer: 1
Comments to the Author(s)
Dear author,
Comments from first revision were satisfyingly implemented.
The results are interesting and therefore, need more differentiation.
Basic feedback:
Results:
Figure 1: Use units for length and width.
Figure 2: There is a mistake in the description --> gap size should be c and width should be b;
color for playback condition is black not grey?
Table 1: The alpha-level: is that the significance level? If yes, significance level is more clear, but
this is just a suggestion. Why was it reduced to exactly 0.017. Please, shortly explain the number,
where does it come from? You wrote the units of parameters in figure 2, please add them in the
description of table1. --> Check in the text as well.
It would be easier to follow if results are described in an order, e.g. all factors that affected length
parameter, then width, then gap size or effect of testing condition on length, width and gap size,
then effect of time step on all parameters, then interaction effects or stating that there was none.
Downloaded from http://rsos.royalsocietypublishing.org/ on June 18, 2017
13
Use more information from your table and describe the differences of estimates for the three
parameters, e.g. the weight of the variables in relation to the intercept, to explain/describe the
significant effects. I needed time and advice of colleagues to relate effects to the data given. You
could also mention, what it means, if the estimate values are negative.
Length and gap size expand during playback and shrink to the end of playback. Why? -->
Discussion.
Discussion:
You described and explained the significant effects well. Please discuss your results more deeply
and comprehensively.
What if you would have placed the speakers at the two sides of group width? Would "width" be
affected too? Or is this an unlikely consequence and why? Please discuss also the limits of your
experiment.
General feedback
Try to shorten the sentences. If you use "however" within a sentence, you could end the sentence
"." and start with "However, ...". (e.g. L 93, 109)
Put the information that the tracks had the highest or a higher call rate than the observed
individuals into the method section. It is a very important aspect and was not clearly said, you
could easily copy the first part of the sentence from L 105.
L 17: Do not start the sentence with "To achieve...", put first part of the sentence as second part.
L 41: Brackets are not as the others.
L 41 -43: Mark as your hypothesis.
L 71: ... the order of calls of -recorded- individuals ...
L 72: what do you mean with time of a call within each track? - Do you mean: "we randomized
the order of calls from individuals and within the playback track? If so, last part of sentence
would be unnecessary.
L 84: Every two minutes -(time steps)- ...
L 95: no need for "respectively"
L 105: Explain more precisely the second part of the first sentence of results. "closest location"
means speaker? "highest call rate" coming from the speaker?
L 128: Sentence too long.
L 133: another word for provide as you didn't provide results for the production of a vocal
hotspot, you did for the receiver side.
L 138: second part of sentence not needed, not important for the reader.
Data: I couldn't access you data via dryad. Please try as well again. I know it was working for the
first review.
Downloaded from http://rsos.royalsocietypublishing.org/ on June 18, 2017
14
References:
13, Germany is missing.
Thank you again very much. Your work is progressing well.
Author's Response to Decision Letter for (RSOS-170004.R1)
See Appendix B.
Decision letter (RSOS-170004.R2)
28-Mar-2017
Dear Ms Gall,
I am pleased to inform you that your manuscript entitled "Group cohesion in foraging meerkats:
follow the moving ‘vocal hot spot’" is now accepted for publication in Royal Society Open
Science.
You can expect to receive a proof of your article in the near future. Please contact the editorial
office ([email protected] and [email protected]) to let us know if
you are likely to be away from e-mail contact. Due to rapid publication and an extremely tight
schedule, if comments are not received, your paper may experience a delay in publication.
Royal Society Open Science operates under a continuous publication model
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Appendix A
Zurich, 27 February 2017
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Dear Ms. Power,
Thank you bery much for considering our manuscript entitled “
Please find enclosed our paper entitled “Group cohesion in foraging meerkats: follow the moving ‘vocal
hot spot” for publication in Royal Society Open Science.
We have addressed all the specific points raised by the reviewers in order to improve the quality of the
manuscript. Below you can find the point-by-point responses with their respective page and line
numbers. We hope our responses are satisfactory, but we would be happy to make further changes to
clarify or improve specific points of needed.
We would like to thank you and the two reviewers for your time and comments on our manuscript. We
feel the manuscript has greatly benefited from your input.
Many thanks for the opportunity to resubmit our revised manuscript
Kind regards,
Gabriella Gall
Response to Referees
MS Reference Number: RSOS-170004
Group cohesion in foraging meerkats: follow the moving ‘vocal hot spot’
27 February 2017
In the following we provide a detailed response to each reviewer.
Comments to Author – Reviewer 1
Introduction
The introduction is almost clear to me. Please think of defining what "front of the group" exactly means
in terms of group formation. Is the front associated with specific group members of hierarchy or age? If
not and it is only spatial shortly say that (p3, row37).
We clarified in the text. The front means the area of the group at the front in relation to the movement
direction of the group. (P3, L38)
May be it needs to be a little more clear if you playback the calls from opposite sides of the group or
always from the front and the back (p3, row40).
We added the information where calls were played back from, namely from the front edge and the back
edge of the group (P3 L43). We also changed Figure 1 to indicate the location of the speakers in relation
to the group.
If there is information/reference about group dispersion during foraging behavior it would be helpful to
create a picture of the behavior for the reader (introduction).
We added a short section in the description of meerkat foraging behaviour, the sentence now reads as
follows: “Meerkats, cooperatively breeding mammals, live in social groups of up to 50 individuals [11]
which forage cohesively, typically 1 to 10 m next to each other [10].” (P3 L33)
Methods
General information about weather condition in the Kalahari during your data collection would be nice to
know may be in the context of foraging behavior in that time of the year that might be different from
winter?!
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We now included more detailed information about rainfall/temperatures during the period of data
collection as well as how foraging times of meerkats change between winter and summer. The section
now reads: “. Data were collected from January - March 2015 on eight groups, ranging from 9 to 22
individuals (mean ± SD = 16 ± 4) during the morning foraging session. During the period of data
collection, daily temperatures ranged from 10 to 42 °C and daily rainfall from 0.0 to 30.0 mm/m^2
(with rain on a total of 26 days during the 3 month of data collection). A more detailed description of the
climate and habitat are provided by Clutton-Brock et al 1998 [15]. In contrast to winter when meerkats
mostly forage continuously for the whole day, in summer meerkats forage for a couple of hours, starting
just after dawn and in the evening before sunset, and rest during the hottest part of the day.” (P3 L51L57)
For number of individuals per group you don't need decimal, please change to full numbers.
Corrected.
If you want to avoid confusion for readers please use the same term/wording for anything call-specific,
e.g. call pattern/ call density/ call rate (p3) if! you mean the same.
Instead of call pattern, we now use “distribution of calls” which we define when we first mention the
term: “Here we investigated whether foraging meerkats (Suricata suricatta) use the distribution of close
call in the group (given by number of individuals and their call rate at a specific location) and follow in
the direction of ‘vocal hotspots’, areas with many closely aggregated individuals calling at high rates
[10], to maintain cohesion during movement.” (P2 L29). We don’t use call density anymore in the text
and Instead refer to the number of callers at a given location.
Did you playback close calls from one speaker and control / close calls from the other speaker? You
wrote playback order was randomized which implies this procedure but I was not sure.
We tried to state the procedure more clearly and the section now reads: “The call rate of each individual
on the track reflected its ‘natural’ call rate, observed during previous foraging sessions and was the
same for both playback tracks. However, to avoid playing exactly the same sound files back
simultaneously from both loud speakers, we randomized the order of the calls of each individual as well
as the time of a call within each track, by assigning two random numbers to each call, one for the time
within the playback and one for the call itself.”” (P4 L68-72)
Results
I didn't understand the last sentence of your Results. Is "the time within each playback" and "Time step"
the same? If they are, time step did influence the length of the group p = 0.002 (Table 1). Please check
this or write it more clearly.
I am missing a sentence about whether or not you found an interaction effect (as seen in Table 1, no).
We changed the sentence accordingly to “Groups elongated with the time step in the playback,
independent of the playback condition, however the time steps within each playback did not influence
the width of the group, nor the gap size and we found no interaction between the time step within each
playback and the playback condition (Table 1, Figure 2).” (P5 L107-110)
May be the "intercept" in your model could be shortly explained, what it is (may be in the statistics
part).
We added an explanatory sentence to describe the meaning of intercept in the statistical analysis section
of the methods and the legend of Table 1. “The intercept of the model represents the predicted values
for the control playback of background noise at time step zero.” (P5, L97)
Discussion
You mention "structured habitat" here but didn't explain in the methods, you referred to ref14. May be
in the discussion you can name what structured means, just very shortly.
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We changed “structured habitat” to “vegetation and topographical barriers.” The sentence now reads:
“Following a moving vocal hot spot allows each individual to constantly direct towards the part of the
moving group where a certain number of members aggregates, and ensures group cohesion even if
visual contact is restricted due to vegetation and topographical barriers.” (P5 L116-L118)
Close call behavior in the context of spacial location is clear but social environment could mean different
things, should be described (p5, row 105) on the basis of references. Is there a reference for the last
part of the sentence row 105,106?
We added a more detailed description of the calling behaviour and as the very last part is an inference
from our results, we added “presumably” to make this clearer the sentence now states “Meerkats adjust
their close call rate based on their own relative spatial location within the group as well as their social
environment, calling less with increasing distance to the closest neighbour, and at higher rates toward
the front of the group as well as when in close proximity to dominant individuals [10,14]. By following
the emergent vocal hotspot, meerkats thus adjust their movement direction presumably to avoid losing
contact with their group.” (P5 L121-L125)
Please explain/describe the findings for the wild mangabeys otherwise the reader cannot follow you
well.
We added a more detailed description of the findings for mangabeys, the sentence now reads as follows
“While sooty mangabeys change their movement speed and potentially their direction depending on the
call rate of their own subgroup and call rates of other primate species frequently associating with
mangabeys, it is unclear how individual mangabeys adjust their own call rate to their surroundings and
contribute to the movement of others through their own vocal behaviour.” (P5 L126- P6 L130)
May be in the last part of discussion also mention the foraging context while writing about other
examples.
We added that this coordination mechanism is used in the foraging context. The section now reads “This
suggests that signal hotspots, consisting of vocalisations or signals of other modalities, provide a robust
and flexible way for individuals to track the core of the group and maintain cohesion during foraging,
allowing the collective use of environmental resources” (P6 L136-L138)
Please check your references for completeness.
We asserted that all references mentioned in the text appear in the list of references at the end of the
manuscript
For data accessibility may be use the direct link where to find your data.
We added the dryad DOI for more easy accessibility
Comments to the Author(s) – Reviewer 2
L 38: wording: “dense part of the group” – might be better to say where most group members are
We changed the sentence accordingly and it now reads: “This might allow meerkats to determine where
most group members are located relative to their own spatial location, thus guiding each individual’s
future movement toward them.” (P3 L40-41)
L 61: How did you randomize call rate between individuals?
We randomized the order of calls within a playback track and not the call rate. To make the sentence
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clearer for the reader, we now added how the randomization was achieved: “The call rate of each
individual on the track reflected its ‘natural’ call rate, observed during previous foraging sessions and
was the same for both playback tracks. However, to avoid playing exactly the same sound files back
simultaneously from both loud speakers, we randomized the order of the calls of each individual as well
as the time of a call within each track, by assigning two random numbers to each call, one for the time
within the playback and one for the call itself.” (P 4 L68-72)
L 64: Please explain why you presented both playback stimuli on the same but not on different days?
How much time were between the playback stimuli and the control?
Did you present the two conditions in a counter balanced order across the 8 groups?
We added the reason why both conditions were played back during the same session and changed the
section where we explain the randomization of the playback during each session. The section now reads
“We played both conditions to a group during the same morning session (starting 30 minutes after the
onset of foraging to midday), to avoid confounding time effects due to possible changes in habitat and
climate between sessions. The sound files were played from a Marantz Recorder connected to a speaker
(X-Mini Uno XAM14) attached to the leg of the observers at about 15 cm above ground. The order in
which we played the close calls (test condition) and the background noise (control condition) was
counter balanced, with at least 15 min between conditions.” (P4 L74-L79)
L 83: What are time steps? How are they measured?
We added the following sentence: “The time steps refer to the 2 min intervals at which we documented
the length and width of the group and the gap size between subgroups” (P4 L95-96)
L 83: Please explain why you included the interaction between playback condition and time steps. The
interactions are in all models not significant and should, thus, to my knowledge be excluded.
We think the interaction between time-step and playback condition is a reasonable interaction to be
found, and therefore we included them in the models. Even though the results are not significant, there
might still be an effect that we simply cannot detect with our sample size. Leaving the interaction term
between the condition and the time steps within the playback away (as suggested also by the plots in
figure 1) might lead to the reader overlooking this possible interaction. In addition, as we actually tested
the interaction, it would give false/missing information not reporting it in our results.
L 89: Did the two playback stimuli differ in call rate? If so explain it in the Methods.
The two playback stimuli did not differ in their call rate, we clarified this in the methods and the section
reads: “The call rate of each individual on the track reflected its ‘natural’ call rate, observed during
previous foraging sessions and was the same for both playback tracks.” (P4 L68-L69)
L 92: Time? Do you mean the time steps?
We changed the sentence accordingly, it now reads: “Groups elongated with the time step in the
playback, independent of the playback condition, however the time steps within each playback did not
influence the width of the group, nor the gap size and we found no interaction between the time step
within each playback and the playback condition (Table 1, Figure 2).” (P5 L107-110)
L 104 – 109: explain in more detail in how far meerkats adjust their calling rate to the spatial position
they are in.
We added the following section “, calling less with increasing distance to the closest neighbour, and at
higher rates toward the front of the group as well as when in close proximity to dominant individuals”
and the complete sentence now reads “Meerkats adjust their close call rate based on their own relative
spatial location within the group as well as their social environment, calling less with increasing distance
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to the closest neighbour, and at higher rates toward the front of the group as well as when in close
proximity to dominant individuals [10,14]. By following the emergent vocal hotspot, meerkats thus
adjust their movement direction presumably to avoid losing contact with their group.” (P5 L121- P6
L125)
L 119: Why do you assume that leaders can influence travel directions by increasing their call rate?
From the presented results it is not really clear that the two stimuli differed in call rate and that
meerkats were more likely to follow a simulated hotspot with a higher call rate – see comment above.
We added an additional sentence and changed the last sentence of the discussion. This section now
reads “Previous studies show, that close call rate increases toward the front of the groups progression
[10], suggesting that individuals located at the front might actively increase their call rate. Furthermore,
meerkats are able to distinguish between close calls of different individuals [14] and might therefore
take the identity of the callers into account when following a signal hotspot. Whether these potentially
more informed individuals can ‘lead’ the group [19, 20] by affecting the location of the signal hotspot
with an increase of their own call rate, thereby influencing the movement of others, is yet to be
explored.” (P6 L139-L144)
Appendix B
Response to Referees
MS Reference Number: RSOS-170004
Downloaded from http://rsos.royalsocietypublishing.org/ on June 18, 2017
Group cohesion in foraging meerkats: follow the moving ‘vocal hot spot’
24 March 2017
Thank you very much for giving us the opportunity to improve our manuscript RSOS-170004 entitled
“Group cohesion in foraging meerkats: follow the moving ‘vocal hot spot’”. In the following we provide a
detailed response to each reviewer. The reviewer’s comments are pasted below with our response given
directly below each comment.
Comments to Author – Reviewer 1
Basic feedback
Results:
Figure 1: Use units for length and width.
 Figure one is a schematic diagram and therefore units do not really make sense. We clarified the fact
in the Figure legend by adding “Diagram of the experimental setup:” at the beginning of the
description.
Figure 2: There is a mistake in the description --> gap size should be c and width should be b; color for
playback condition is black not grey?
 We corrected the order of the results in the figure as well as the legend.
Table 1: The alpha-level: is that the significance level? If yes, significance level is more clear, but this is
just a suggestion. Why was it reduced to exactly 0.017. Please, shortly explain the number, where does
it come from? You wrote the units of parameters in figure 2, please add them in the description of
table1. --> Check in the text as well.
 We added the units of the width, length and gap-size in the table and explained in the Table legend
that the new alpha level comes from the Bonferroni correction.
It would be easier to follow if results are described in an order, e.g. all factors that affected length
parameter, then width, then gap size or effect of testing condition on length, width and gap size, then
effect of time step on all parameters, then interaction effects or stating that there was none.
 P5 L107-114: We adjusted the order of the presented results to the reviewers second suggestion.
Use more information from your table and describe the differences of estimates for the three
parameters, e.g. the weight of the variables in relation to the intercept, to explain/describe the
significant effects. I needed time and advice of colleagues to relate effects to the data given. You could
also mention, what it means, if the estimate values are negative.
 P5 L100: We added an explanation for the interpretation of the model estimates in the methods
section on Statistical Analysis as well as in the legend of Table 1. The section reads: “The coefficients of
the model (‘Estimate’ in Table 1) gives the difference in the mean of the levels of a categorical
explanatory variable and the slope for continuous variables. It also indicates the direction of the effect of
a factor (positive or negative) on the response variable.”
Length and gap size expand during playback and shrink to the end of playback. Why? --> Discussion.
 P5 L111: We added this observation in the results section and also gave an explanation in the
discussion of why this happened (P5 L120). The section reads: “(…). This effect decreased after some
time into the playback, likely due to individual meerkats of most groups realized that they were getting
separated and started to produce alert calls, causing the whole group coming back together (pers. obs.
GG).”
Discussion:
You described and explained the significant effects well. Please discuss your results more deeply and
comprehensively.
What if you would have placed the speakers at the two sides of group width? Would "width" be affected
too? Or is this an unlikely consequence and why? Please discuss also the limits of your experiment.
 P6 L123-135: We added the following paragraph to the discussion: “Two different mechanisms might
lead to groups splitting: individuals might orientate and follow toward the closest speaker, as the closest
vocal hotspot, or individuals at the back of the group might move more slowly due to hearing many calls
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around them, but follow a general movement direction given by individuals in the front or being
determined as commonly used foraging route. Given that not only the observer at the front of the group,
but both observers slowly moved apart from each other and away from the closest meerkats, the first
option is more likely. Meerkats followed the speakers carried by the observers, who decided on the
movement direction (pers. obs. GG). Whether the movement direction of animals at the front of the
group might have coincided with the direction chosen by the group is impossible to tell. However, the
individuals in the back turned around to follow the speaker in the opposite direction. Thus if we had
played the calls from both sides instead of the front and back of a group, we would expect the same
results. Following a moving vocal hot spot allows each individual to constantly direct towards the part of
the moving group where likely several members aggregate, and ensures group cohesion even if visual
contact is restricted due to vegetation and topographical barriers, and no general foraging direction or
route governs a group’s movement.”
General feedback
Try to shorten the sentences. If you use "however" within a sentence, you could end the sentence "."
and start with "However, ...". (e.g. L 93, 109)
 We tried to shorten sentences throughout the manuscript.
Put the information that the tracks had the highest or a higher call rate than the observed individuals
into the method section. It is a very important aspect and was not clearly said, you could easily copy the
first part of the sentence from L 105.
 We write in the methods section (P4 L63) that we induced two artificial vocal hotspots. However, we
now included the explanation for vocal hotspots, i.e. areas with the highest calling rate.
L 17: Do not start the sentence with "To achieve...", put first part of the sentence as second part.
 Corrected.
L 41: Brackets are not as the others.
 Corrected.
L 41 -43: Mark as your hypothesis.
 P3 L41-43: We marked the sentence as our hypothesis, it now reads: “Here we hypothesise that,
meerkats use the vocal hotspot to determine where most group members are located relative to their
own spatial location, thus guiding each individual’s future movement toward them.”
L 71: ... the order of calls of -recorded- individuals ...
 Corrected.
L 72: what do you mean with time of a call within each track? - Do you mean: "we randomized the order
of calls from individuals and within the playback track? If so, last part of sentence would be
unnecessary.
 We removed the second part of the sentence.
L 84: Every two minutes - (time steps)- ...
 P4 L84: Added “(time steps)” accordingly.
L 95: no need for "respectively"
 Deleted.
L 105: Explain more precisely the second part of the first sentence of results. "closest location" means
speaker? "highest call rate" coming from the speaker?
 P5 L107: We added the speaker, the section now reads: “When artificially inducing two vocal hot spots
by playbacks of close calls at the front and back edge in meerkat groups, individuals followed the nearby
speaker, i.e. the closest location with the highest calling rate.”
L 128: Sentence too long.
 P6 L143: We split the sentence into two parts and the section now reads: “Sooty mangabeys change
their movement speed and potentially their direction depending on the call rate of their own subgroup
and call rates of other primate species frequently associating with them. Nevertheless, it is unclear how
individual mangabeys adjust their own call rate to their surroundings and contribute to the movement of
others through their own vocal behaviour.”
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L 133: another word for provide as you didn't provide results for the production of a vocal hotspot, you
did for the receiver side.
 P6 L 148: We changed the wording and the sentence now reads as follows: “Based on prior knowledge
and the results of this experimental study we can integrate our understanding on both the production
[10] and the receiver side of a moving vocal hotspot, defined as the location of the highest call rate
within a group, and suggest it as a highly flexible coordination mechanism enabling to adjust to fast
changing movement decisions.”
L 138: second part of sentence not needed, not important for the reader.
 We removed it.
Data: I couldn't access your data via dryad. Please try as well again. I know it was working for the first
review.
 We checked whether the data was accessible: It was for us and a collaborator, so we hope think it is
working properly. We think the problem might be that the DOI for Dryad in the article itself is not yet
accessible as the article is in review. The DOI for the reviewers is slightly different: DOI:
http://dx.doi.org/10.5061/dryad.qp562 and is therefore not the same as in the article.
References:
13, Germany is missing.
 Corrected.
Comments to Author – Reviewer 2
I am happy with the revised version of the MS and recommend it for publication.