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Insights on the effect of mega-carcass abundance on the population dynamics of a facultative scavenger predator and its preyuse asterix (*) to get italics
Mellina Sidous; Sarah Cubaynes; Olivier Gimenez; Nolwenn Drouet-Hoguet; Stephane Dray; Loic Bollache; Daphine Madhlamoto; Nobesuthu Adelaide Ngwenya; Herve Fritz; Marion ValeixPlease use the format "First name initials family name" as in "Marie S. Curie, Niels H. D. Bohr, Albert Einstein, John R. R. Tolkien, Donna T. Strickland"
<p>The interplay between facultative scavenging and predation has gained interest in the last decade. The prevalence of scavenging induced by the availability of large carcasses may modify predator density or behaviour, potentially affecting prey. In contrast to behavioural mechanisms through which scavenging affects predation, the demographic effects of facultative scavenging on predator and prey populations remain poorly studied. We used the semi-natural experimental opportunity in Hwange National Park, Zimbabwe, where contrasted management measures (culling and artificial supply of water) have led to fluctuations in elephant carrion abundance, to identify the consequences of facultative scavenging on the population dynamics of a large mammalian carnivore, the spotted hyaena (Crocuta crocuta), and its prey. Using a 50-year dataset and Multivariate Autoregressive State Space models, we estimated hyaena and prey densities over four periods contrasted in elephant carrion availability due to management practices. Models that allow hyaena and their prey populations’ growth rate to vary depending on these four periods contributed significantly to explain variations in their density, which is consistent with an effect of management measures on the population dynamics of hyaena and its prey. &nbsp;Although our results support a predominant role of bottom-up mechanisms, whereby hyaena density is driven by herbivore density, itself driven by resources availability, some subtle patterns of densities could be interpreted as consequences of changes in predation pressure following changes in scavenging opportunities. We discuss why signals of prey and predator population dynamics decoupling are less likely to be observed in systems with a high diversity of prey, such as African savannas, and why inputs of mega-carcasses as pulsed resources hardly impacted top-down relationships in the long run. This study represents a first investigation of the long-term effects of carrion pulses, whose frequency may increase with climate changes, on the classical predator-prey coupling for large mammals.</p> should fill this box only if you chose 'All or part of the results presented in this preprint are based on data'. URL must start with http:// or https:// should fill this box only if you chose 'Scripts were used to obtain or analyze the results'. URL must start with http:// or https://
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scavenging, predator-prey interactions, african savannas
NonePlease indicate the methods that may require specialised expertise during the peer review process (use a comma to separate various required expertises).
Community ecology
Marcos Moleon, Gabriele Cozzi, Kay Holekamp, Ainara Cortés Avizanda /, Cristopher C Wilmers, Kay Holekamp [] suggested: I apologize, but I am in the bush in Kenya with only occasional internet access, so performing this review would be too difficult from here. I advise contacting Dr Eli Strauss or Dr Tracy Montgomery as reviewers of this paper. They are both highly knowledgeable about spotted hyenas and their population dynamics. Their emails are:, Kay Holekamp [] suggested:, Kay Holekamp [] suggested:, John Fryxell suggested: Sorry, but I have a conflict of interest with 3 of the authors of this ms. I recommend Mark Boyce at the University of Alberta, who has a great deal of experience with this topic., Calum Cunningham [] suggested: Matthew Fielding, Darcy Ogada [] suggested: Campbell Murn, Eli Strauss suggested: A major goal of wildlife conservation and management is to predict population changes of wild animals. This study investigates how pulses of large megaherbivore (elephant) carcasses modifies predator-prey population dynamics using a long-term study of spotted hyena and ungulate observations at waterholes. They find no evidence that hyena or ungulate population growth changes as a result of increases in elephant carcasses. , Eli Strauss suggested: The paper uses an impressive ecological dataset and aims for an ambitious question of broad relevance. Although some aspects of the writing throughout the paper sometimes reduced clarity, I found that overall the ideas of the paper were well thought-out and communicated. The statistical approach was clearly explained, justified, and appropriate to the data. I have a few small suggestions for improvement. , Eli Strauss suggested: Major comments, Eli Strauss suggested: I would have liked to have learned more about the water supplementation policy. Given that the observation of hyena and prey animals occurs at watering holes, and some periods have more water availability than others, I’m left wondering if the trends presented in the results have more to do with varying attraction to watering holes over time rather than variation in population size. When there was active water supplementation, did data collectors count prey/hyenas at these new water sources? , Eli Strauss suggested: Can the authors explain why the model with constant growth rate consistently predicted lower densities of both hyenas and prey than the other two models across the entire study period (Figure 3)? Does this make sense, or could this reflect an issue with one or more of these models? , Eli Strauss suggested: Lastly, I found the interpretation of the results to be overly strong. In the discussion, the authors state “we do not detect patterns supporting effects of high carcass availability on the population dynamics of hyena and its prey” and I think this nicely summarizes what they found. However, elsewhere—including the title—the authors interpret this absence of evidence as evidence of absence. Given the messiness of the data and the sampling regime (one brief yearly count), it seems quite possible that these huge carcasses are influencing hyena predation rates, and thus prey demography, but that this effect is small or subtle enough not to be detected. In fact, it’s hard to imagine how these carcasses could really have no effect on prey or predator demography. I recommend that the authors alter the title and amend parts of the discussion to soften the conclusions. , Eli Strauss suggested: Minor comments, Eli Strauss suggested: l. 49-51: These sentences are confusing. Don’t the authors conclude that there is NO evidence of an effect of management measures on prey and hyena population dynamics? I think there may be a typo here, or at the very least, this needs to be clarified., Eli Strauss suggested: l. 50-52: These sentences seem very wishy washy and vague for the abstract. Can the authors streamline this to a more straightforward point? , Eli Strauss suggested: l. 55 “on the long run” should be “in the long run” , Eli Strauss suggested: Introduction: In this first paragraph, it would be helpful to clarify whether the work cited on lines 75-78 comes to some conclusion about the conditions under which carrion availability would reduce or increase predation pressure. These potential effects are mentioned in the paragraph, but it isn’t clear how they relate to the work cited. , Eli Strauss suggested: l. 81 it would be clearer to just say what the consequences are instead of referring the reader back to the prior sentence, Eli Strauss suggested: l. 138-139 I would like the authors to say more here about what this study found. What is the evidence that they reliably reflect actual population changes? , Eli Strauss suggested: l. 250 - this parenthetical statement is confusing, so I recommend the authors spell out that this is not what they found. , Eli Strauss suggested: Figure 3: What are the faint fluctuating lines in panels A and B? In C and D there are only confidence intervals for the constant model, despite statements in the figure caption that ribbons exist for each model type. , Eli Strauss suggested: l.327-328 Could the authors explain what they mean by “mortality is likely to be compensatory?” , Eli Strauss suggested: l. 334: I think “as we focused here” should be “as we observed here” , Eli Strauss suggested: The authors have carefully addressed my concerns from the last round of review and I have no further suggestions. Congrats to the authors on this nice work. No need for them to be recommenders of PCIEcology. Please do not suggest reviewers for whom there might be a conflict of interest. Reviewers are not allowed to review preprints written by close colleagues (with whom they have published in the last four years, with whom they have received joint funding in the last four years, or with whom they are currently writing a manuscript, or submitting a grant proposal), or by family members, friends, or anyone for whom bias might affect the nature of the review - see the code of conduct
e.g. John Doe []
2023-11-14 15:27:16
Esther Sebastián González
Eli Strauss