Seasonal Variation in First Territory Settlement of Dispersing Golden Eagles: An Innate Behaviour?

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The article examines an interesting and poorly studied point in the ecology of top predators, namely: seasonal variation in first territory settlement. Overall, it is well written and an important contribution to the study of this little-known period in the life history of birds of prey. However, there are several issues that are worth clarifying before the article is published. They are mostly related to the methodology and the interpretation/presentation of the results.

-          Firstly Paragraph 163-166… Please provide more details as to the number of eagles identified by biometrics alone as well as the number of eagle subsequently confirmed based on their roles in the pairs (sexual behavior) or molecular studies?! This is an important point in terms of the subsequent interpretation of the results and the conclusions drawn. If a significant number of the birds were identified by biometrics alone (considering the fact that this indicator can vary widely among large eagles), this would be uncertain and would affect the results obtained and the conclusions drawn. If this is the case, I recommend that the eagles sexed by biometric data only be excluded and the analysis repeated including only those determined by molecular methods and/or their sexual role in the pair.

-          Line 230-231… For simplicity, we assigned ranges probabilistically to one of two occupancy classes but recognise that there may be a small number of cases in which that assignment was possibly incorrect. Be more specific?! How much? And if you're not sure why not just exclude them from the analysis?!

-          About the results: The finding that there was no significant difference between the seasonal timing of settlement according to whether the settled territory was occupied or vacant is a bit odd. If a territory has been occupied, then intruders such as marked birds should be chased away by the holders of the territory, i.e. the occupied territories should be less populated during the breeding period of the eagles (roughly February-August), while in the vacant territories this factor will not matter. Perhaps the status of the territory holders is relevant here. If they breed in a given year then they should be less likely to allow intruders, and vice versa if they don't breed in a given year regardless of having occupied the territory then they are likely to show greater tolerance to intruders?! This question deserves comment and clarification. Perhaps include the predictor "status of territory holders" in the analysis as breeders or non-breeders…

-          However, it is also interesting who in general settled earlier in a given territory, regardless of whether it was vacant or occupied?! Male or female eagles occupy territory earlier for the first time?! This result would be good to add.

-          I also think that the GLM mixed model results should also be presented and commented on. The lack of significant differences is also a result that has its explanations.

I also have some minor comments below:

 - In many places the authors cite too many sources (7-8 each). This is not necessary everywhere. Please refine it and give only the most important sources, usually 3-5 are enough. Such are the citations of lines 138-139; 147-148; 150-151; 172-173; 213-214; 220.

- Paragraph 2.2. GPS satellite tagging is described in detail. Contains unnecessary information such as what thread the transmitters are sewn with, etc. To be shorten by 1/3.

- Line 190 a settled bird will have constrained movements which can be measured by a threshold distance moved since the last location using median locations (what is the threshold?) This sentence is not very clear. Please rephrase it.

 - Line 192-193 The paragraph is not clear! How exactly is the averaging of the distances traveled over a period of days?! Please explain it more clearly!

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The authors present a study of the seasonal nature of territory establishment in Golden Eagles in Scotland based on individuals fitted with GPS transmitters. I found the paper well thought out, rigorously analyzed, and well written. The flow of the paper is good and requires very little correction.

I have two comments:

1. Please italicize all Latin names when first mentioned in the text

2. Self-citations - an accepted norm is ca. 10%. I counted much more than that. Recommend the authors to restrict to their most relevant papers.

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

the Authors have to fix two methodological steps:

1) the Rayleigh’s Test of Uniformity  assumes
evenly or unimodally (von Mises) distributed data, i.e. the test
is not appropriate for e.g. bimodal data.

I ask the Autors to repeat this test of uniformity using the
Rao’s spacing test (Batschelet 1981) for uniform distribution of circular data,
that is nonparametric, and does not assume e.g. von Mises distribution.
Probably results will be same as before but the most correct test must be applied to data.


2) the Rao's Tests for Homogeneity used by the Authors is not the proper test
to compare prior occupied vs. prior vacant territories, and males vs. females.
The proper test here is the Watson-Williams test (Batschelet 1981) that compares two or more samples to determine if their mean angles differ significantly. 
The Watson-Williams test for equal mean angle is a parametric test, assuming von Mises distribution, but is fairly robust.
Alternatively, the Authors can use the Mardia-Watson-Wheeler test (Batschelet 1981) that is non-parametric test for equal distribution of circular data.

I ask the Authors to repeat these comparisons (prior occupied vs. prior vacant territories, and males vs. females)
using the Watson-Williams test or, even better, the Mardia-Watson-Wheeler test. In fact I look at Figure 2 and I am not convinced
at all that there are no significant differences between prior occupied vs. prior vacant territories, and males vs. females.
Plausibly significant differences can emerge if the Authors will use the correct test.


Reference:

Batschelet, E. 1981. Circular statistics in biology. Academic Press.

Author Response

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Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

Dear Authors,

I read your manuscript entitled "Seasonal Variation in First Territory Settlement of Dispersing Golden Eagles: an Innate Behaviour?", and found it interesting for readers. However, there some point to clarify.

First, in many cases, I did not understand what you were trying to say. The text is full of unnecessary quotation marks, which completely break the continuity of the text. There were cases where the first and second parts of the sentence contradicted each other. I suggest that the wording of the text should be much simpler.

Another problem is that the Material and Methods contains paragraphs that fit into the Introduction. Therefore, both section should be re-written. In addition, there are some sentences that fits into the Discusion.

I feel that you also missed some relevant literature regarding to the Eastern Imperial Eagle.

Please see some specific comments below.

L35-37: This is true not only for birds of prey, but for most bird species.

L43-44: „while novel and valuable, have often involved few individuals”

The first and second half of the sentence contradict each other.

L63: should therefore enhance understanding large raptor populations

I don’t undestand what do we need to understand about populations?

L71: Aquila adalberti

Please use Italics.

L78-87: Please check the literature for the Eastern Imperial Eagle (Aquila heliaca) as this is one of the best known Aquila species, especially in the Carpathian Basin.

L134-148: This fits into the Introduction.

L211-236: Some part of this paragraphs fits into the Introduction.

L274: "thereby supporting our first hypothesis"

discussion

L292: perhaps not surprising given sample sizes

discussion

 

Comments on the Quality of English Language

Please see my previous comments.

Author Response

Please see attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

good work with revisions