The manuscript describes a straightforward study on the relationship between an exaggerated secondary sexual trait in male wētās, their mandibles, and foraging efficiency. The manuscript is well written, the data is important and relevant to the readers of Biology Letters, and the conclusions are mostly well supported by the data. I only have a couple of major comments on the interpretation and analyses of the data, and a number of less important minor suggestions.

Major comment 1: The authors use the words ‘experiments’ and ‘experimental chambers’, but their study is technically not experimental. There was no manipulation intervention, such as manipulating mandible size (which would be very difficult), for example. This is not a problem of the study though, and I still believe the authors have good evidence for the conclusions they derive. However, there is a limitation from the fact that their observations are correlational, and they could have acknowledged that a bit more in the manuscript. The title and the discussion (end of first paragraph) state that the large mandibles enhance foraging efficiency, but their data only allow them to conclude that these two things are correlated, given that a direct cause-consequence relationship would require an actual experiment. The study is nonetheless an important step towards understanding the evolution of exaggerated mandibles in wētās, and the evolution of male weapons and sexual dimorphism in general. However, given the above, I suggest the authors use the word ‘trial’ instead of ‘experiment’, and perhaps include a sentence or two in the discussion clearly addressing the limitations or implications of their study. For example, the relationship between mandible size and foraging feeding rate might not be direct, but these two traits could be genetically correlated. If the authors take up this suggestion, it will also affect the title of the paper.

Major comment 2: the analytical approach in the study is very good, but I would recommend a few important changes. (1) I feel like bite rate should have been analysed with Poisson errors, rather than Gaussian ones, unless the average number of chews was high enough for the data to behave as continuous, rather than count data. (2) I think the model selection and model averaging are good approaches here, but I would recommend not mixing it with inferences based on p-values of coefficients in the models (like I the caption to table 1). (3) I would also suggest presenting the full candidate sets, with their AICs and delta AICs, in table 1. (4) I would suggest using AICc (bias corrected version for small sample sizes), rather than AIC.

Minor suggestions

Line 17: add “in other contexts” after “who bear them” or somewhere else in this sentence, otherwise the sentence is telling the readers that weapons give males a disadvantage for fighting.

Line 27: Close the bracket after reference [1].

Line 29: this is a bit hard to follow.

Line 41: Should ‘functional activities’ be ‘naturally selected’ traits?

Line 43: At the end of the sentence, I suggest saying “…trade-offs between sexually selected and naturally selected functions”.

Line 45: “, which” should be “that” (note no comma). Also remove the comma before “is unclear”.

Line 47: perhaps replace “tension” with “conflict”? If so, then I would suggest deleting everything after “sexual selection” in the following line.

Line 56: should “closer” be “closing”?

Line 75: What was the reason to set up 3 arenas?

Line 76: What is the meaning of the “H”?

Line 116: Add a “(“ or remove the extra “)”.

Discussion line 1 (no line numbering here): “diverge” or “increase”?

Discussion, paragraph 2, line 7: I suggest removing the underscore for “and”.

Discussion, paragraph 3, line 3: Add a “(“ at the end of the sentence.

Discussion: Is it possible that males with larger mandibles have higher energy requirements than females and males with smaller mandibles (precisely because they spent more resources making large mandibles for fighting), and therefore eating at a faster rate is an adaptive compensatory response by these males? This would mean that there is a mechanism connecting mandible size and foraging rate that is slightly different to the mechanisms proposed in the discussion.

I am really pleased with the revised version, and I think the analytical part of the manuscript and interpretaion of the results are much improved. A small part of this came from addressing my comments, where the authors rephrased a few sentences (including the title) to make them less suggestive of causal relationships (due to the correlational nature of the findings), made it explicit that AICc was used (rather than AIC) and provided full candidate sets in the supplementary files. The authors also pointed out that they had actually already used Poisson errors for bite rate, so I apologise for this mistaken suggestion in my first review.

Moreover, an even more important part of the improvement came from addressing the comments of reviewer 3 regarding standardizing body morphometrics for the analyses. I congratulate the authors for having done a great job incorporating these comments and improving their manuscript.

I still tend to think that mixing up p-values of coefficients with model selection/averaging (as done in table 1) is not an ideal approach, but the rational given by the authors for this seems good, and given that the coefficients were estimated with model averaging, I think the authors' decision is a very good one. I probably need to reconsider my position on this in the future!