Trophy hunters pay more to target larger-bodied carnivores

Hunters often target species that require resource investment disproportionate to associated nutritional rewards. Costly signalling theory provides a potential explanation, proposing that hunters target species that impose high costs (e.g. higher failure and injury risks, lower consumptive returns) because it signals an ability to absorb costly behaviour. If costly signalling is relevant to contemporary ‘big game’ hunters, we would expect hunters to pay higher prices to hunt taxa with higher perceived costs. Accordingly, we hypothesized that hunt prices would be higher for taxa that are larger-bodied, rarer, carnivorous, or described as dangerous or difficult to hunt. In a dataset on 721 guided hunts for 15 North American large mammals, prices listed online increased with body size in carnivores (from approximately $550 to $1800 USD/day across the observed range). This pattern suggests that elements of costly signals may persist among contemporary non-subsistence hunters. Persistence might simply relate to deception, given that signal honesty and fitness benefits are unlikely in such different conditions compared with ancestral environments in which hunting behaviour evolved. If larger-bodied carnivores are generally more desirable to hunters, then conservation and management strategies should consider not only the ecology of the hunted but also the motivations of hunters.

Associate Editor Comments to Author (Dr Claudia Wascher): Associate Editor: 1 Comments to the Author: The presented manuscript aims at testing whether predictions derived from costly signalling theory would apply to modern day big game hunting in humans and investigated whether the price to hunt a specific species would depend on the rarity, danger, or difficulty imposed by the species. The authors did find body size to positively affect hunting price. Both reviewers find the contribution potentially interesting, but raise concerns regarding the general framing of the manuscript within signalling theory. These concerns need to be addressed prior to potential publication of the manuscript.
Editor comments: I agree that the results of this manuscript will be of great interest to conservationists (and I think will raise awareness among the general public). However, there are concerns about framing this within the general theory of costly signaling, and reviewers and editors think that this needs some rethinking. If you choose to resubmit, please address these concerns fully in your response. Thanks for submitting.
Reviewers' Comments to Author: Reviewer: 1 Comments to the Author(s) The authors look at prices of trophy hunts in North America to test a signaling theory of hunters' motivations. While there is great potential benefit here to inform conservation policy, I have some issues with application of signaling theory to this dataset. First, there is no determination of what hunters are signaling by targeting game that is rare, dangerous, etc. Second, paying more to go on a hunt does not clearly signal any underlying quality on part of these hunters, such as physical condition or intelligence. It may be that those with more money can afford such hunts, but it's unlikely the hunts are primarily responsible for indicating affluence of the hunters to their peers. A reputation model and not a costly signaling model per se may be the better theoretical approach. These theoretical concerns don't aid the largely null results, which add to our inability to take much from the paper. I elaborate on these comments below.
Page 3, Line 28: the behavior you describe (paying large fees and traveling to unfamiliar areas) is clearly not the aspects of the behavior that evolved. Targeting large individuals and rare taxa may be (as you describe at the beginning of the paragraph) but your references are for modern trophy hunting not archaeological or ethnographic evidence from foragers. You should cite evidence here that such hunting behavior is characteristic of humans beyond modern trophy hunting. The Foraging Spectrum book by Kelly is a good overview. As well as studies you cite later, from Hawkes, Bliege Bird, etc. Page 3, Line 52: Costly signaling means signalers must pay an extra cost (the handicap) at equilibrium, and high quality signalers can better afford this marginal cost. So its not that only certain individuals can pay the cost-its that certain individuals can better afford the marginal cost. Page 4, Line 26: say what you mean by the theory not being universally accepted, per the article you cite. I think the gist is that signals need not be costly to be honest. Rather, the potential cost of cheating can keep signals honest, or some signals can be difficult if not impossible to fake (i.e. indices), or honest signalers may benefit more than fakers. Can these possibilities explain hunting behavior? Comment on this. Page 5, Line 5: in traditional societies, there is typically a substantial fraction of hunted game that is kept by hunters and given to their families (see work by Michael Gurven). Thus hunting is unlikely to be purely or even principally a costly signal, or one that is "wasteful". Indeed, much of the higher reproductive success attributable to better hunters may flow through family provisioning. See Gurven and von Rueden "Hunting social status and biological fitness". Also see paper by Wood and Marlowe "Household and kin provisioning by Hadza men" that shows Hadza hunters target both small and large game and game of all sizes is widely shared. Hunting motivations are multi-faceted. Page 5, Line 15: What is hunting actually signaling that begets higher reproductive success? There is no good evidence of this. The authors you cite only speculate, so be clear on this. An alternative to the costly signaling account of hunting is a reputation account. For details see "Costly signaling and the handicap principle in anthropology and zoology: a review" by Duncan Stibbard-Hawkes. It also makes points similar to comments above. Page 5, Line 45: In the context of modern trophy hunting, affluence is unlikely to be signaled principally by killing particular prey. Taking the hunting trip itself is an indication of affluence, and those spending a lot on hunting are also likely to spend a lot on other material goods, e.g. billionaires who trophy hunt the African Big Five. Also, physical competency and cognitive ability are not necessarily required when guides and vehicles and sophisticated weaponry are on hand-as you recognize. Page 6, Line 22: status among whom? Among Safari Club members, but normative disapproval of trophy hunting (e.g. Cecil the Lion) suggests status benefits are not likely to be widespread. Page 6, Line 29: Id suggest you set up an alternative prediction, that rarity associates with higher price because of supply/demand based on quotas to conserve the population. And this rarity need not be primarily a consequence of the Anthropogenic Allee Effect. But you wouldn't predict such quotas would track body size, danger, difficulty to hunt, or carnivory per se (independent of rarity). Page 17, Line 17: Investigating the motives of trophy hunters is important for conservation efforts, perhaps particularly so in North America, but in many parts of the world subsistence hunting has bigger consequences for endangered wildlife. To what extent does trophy hunting provide benefits for conservation, e.g. revenue is funneled into wildlife education or protected area management or lobbying.

Reviewer: 2
Comments to the Author(s) This is an interesting manuscript that makes a modest but solid contribution to the literatures on human signaling and commercial big game hunting.
My only problem with the manuscript is with the authors' presentation of costly signaling theory. They seem to equate costly signals with handicaps. That is not correct. One way to make a signal costly, and thus more likely to overcome a receiver's skepticism regarding the accuracy of the information it is trying to convey, is to make it a handicap. But that's not the only way to do it, and I don't think paying a lot of money to kill a bear or an elk qualifies as a handicap. I recommend the authors re-read the Grose article that they already cite. These two citations might also be useful: Regarding the Grose article, I think his problem is not so much with costly signaling theory in general, as implied by the way the authors of this manuscript cite it, but rather with how the handicap principle has been applied or misapplied.
Finally, I agree that the example of turtle hunting by the Meriam is a good one to use. The following article makes the same kind of point based on data from another island society, so the authors might want to cite it, as well:

Do you have any ethical concerns with this paper? No
Have you any concerns about statistical analyses in this paper? No

Recommendation?
Accept as is

Comments to the Author(s)
The changes addressed my concerns-looks good.

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

Do you have any ethical concerns with this paper? No
Have you any concerns about statistical analyses in this paper? No

Recommendation?
Accept as is

Comments to the Author(s)
The authors have taken the reviewers' comments to heart and greatly clarified their manuscript. The distinction between "cost" and "price" is especially helpful.
The only change I would recommend is the deletion of the subtitle. I does not seem necessary. The title alone summarizes the manuscript's main finding.

29-Jul-2019
Dear Ms Mihalik On behalf of the Editor, I am pleased to inform you that your Manuscript RSOS-191231 entitled "Big game hunters pay more to target larger-bodied carnivores: money, guns, and costly signals in non-subsistence systems" 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-191231 • 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.
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 before 07-Aug-2019. Please note that the revision deadline will expire at 00.00am on this date. If you do not think you will be able to meet this date please let me know immediately.
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 revisions on the originally submitted version of the manuscript. Instead, revise your manuscript and upload a new version through your Author Centre.
When submitting your revised manuscript, you will be able to respond to the comments made by the referees and upload a file "Response to Referees" in "Section 6 -File Upload". You can use this to document any changes you make to the original manuscript. In order to expedite the processing of the revised manuscript, please be as specific as possible in your response to the referees.
When uploading your revised files please make sure that you have: 1) A text file of the manuscript (tex, txt, rtf, docx or doc), references, tables (including captions) and figure captions. Do not upload a PDF as your "Main Document". 2) A separate electronic file of each figure (EPS or print-quality PDF preferred (either format should be produced directly from original creation package), or original software format) 3) Included a 100 word media summary of your paper when requested at submission. Please ensure you have entered correct contact details (email, institution and telephone) in your user account 4) Included the raw data to support the claims made in your paper. You can either include your data as electronic supplementary material or upload to a repository and include the relevant doi within your manuscript 5) All supplementary materials accompanying an accepted article will be treated as in their final form. Note that the Royal Society will neither edit nor typeset supplementary material and it will be hosted as provided. Please ensure that the supplementary material includes the paper details where possible (authors, article title, journal name).
Supplementary files will be published alongside the paper on the journal website and posted on the online figshare repository (https://figshare.com). The heading and legend provided for each supplementary file during the submission process will be used to create the figshare page, so please ensure these are accurate and informative so that your files can be found in searches. Files on figshare will be made available approximately one week before the accompanying article so that the supplementary material can be attributed a unique DOI.
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. The authors have significantly revised the manuscript alongside with previous comments by the reviewers. The reviewers recommend the manuscript to be accepted for publication, they only ask the subtitle to be deleted.
Reviewer comments to Author: Reviewer: 1 Comments to the Author(s) The changes addressed my concerns-looks good.

Reviewer: 2
Comments to the Author(s) The authors have taken the reviewers' comments to heart and greatly clarified their manuscript. The distinction between "cost" and "price" is especially helpful.
The only change I would recommend is the deletion of the subtitle. I does not seem necessary. The title alone summarizes the manuscript's main finding.

13-Aug-2019
Dear Ms Mihalik, I am pleased to inform you that your manuscript entitled "Trophy hunters pay more to target larger-bodied carnivores" 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 (openscience_proofs@royalsociety.org and openscience@royalsociety.org) to let us know if you are likely to be away from e-mail contact --if you are going to be away, please nominate a coauthor (if available) to manage the proofing process, and ensure they are copied into your email to the journal.
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 (http://bit.ly/cpFAQ). Your article will be published straight into the next open issue and this will be the final version of the paper. As such, it can be cited immediately by other researchers.
As the issue version of your paper will be the only version to be published I would advise you to check your proofs thoroughly as changes cannot be made once the paper is published.  humansuggests that subsistence and non-subsistence hunters evolved behaviour to target species 27 that impose high ecological costs (e.g. higher failure and injury risks, lower consumptive returns) 28 because it signals, thereby thus signalsling to potential mates or competitors antheir ability to 29 absorb such costly behaviour. If costly signalling is relevant to contemporary 'big game' 30 hunters, and if prices for guided hunts reflect desirability, we would expect non-subsistence 31 hunters to pay more higher prices to hunt taxa with higher associated perceived ecological costs. 32 (e.g. higher risks of failure risk, risk ofand injury). Accordingly, among guided hunters we 33 hypothesized that hunt prices would be higher for taxa with higher perceived ecological costs: 34 those that are that are larger-bodied, rarer, carnivorous, or described as dangerous or difficult to 35 hunt. In a data set on 721 guided hunts for fifteen North American big-game specieslarge 36 mammals, prices listed on the internet line did not vary with rarity or perceived danger or 37 difficulty but increased with body size in carnivores (from approximately $550 USD/day to 38 $1800 USD/day across the observed range). of body mass) in carnivores. This pattern suggests 39 that elements of costly signals maying persists among contemporary noncontemporarynon-40 subsistence hunters. Persistence might simply relate to deception, given that , despite, dDespite 41 unlikely signal honesty and any fitness benefits being are unlikely in such a radicallyin trophy 42 hunting systemsradically different social, and ecological and technological conditions compared 43

57
The behaviour of human human hunters and fishers diverges substantially from other predators 58 of vertebrate prey. Instead of targeting mainly juvenile or otherwise vulnerable individuals, 59 humans (and more often, males), typically seek large taxa, as well as large, and, reproductive-60 aged individuals within populations 1-5 , phenotypes targets,a behaviour also found iphenotypes 61 also targeted sought by early human groups 6 . This distinct pattern of hunting behaviour is likely 62 shaped by a suite ofmultiple of adaptive selective forces 7  sharing meat from large items prey beyond kin, and expecting the same in return,, maylikely 67 presents an example offollow (i.e. 'reciprocal altruism 12,13 . that honestyhHonesty is maintained through the differential costs and benefits of signal 99 production; individuals of higher quality are thought to be better affordable to payafford the 100 larger costs associated with more elaborate attractive signals; for lower-quality individuals,, 101 while the costs outweigh the benefits and signals are difficult to fake for lower-quality 102 individuals 12 individuals 12,132-24 .. Under this framework, evolutionary benefits flow to higher-103 qualitythe signallers (as well asand the signal recipients).the signaller. Individuals that can afford 104 costly signals attract mates orandand accrue social status, which can increase access to resources 105 (e.g., foods, material goods, approval from peers, knowledge) 11,14 . For example, in avian 106 courtship displays male birds subject themselves to predation risk by singing or dancing in the 107 open during sexual displays, signalling that they have underlying qualities that permit them to 108 absorb the energetic and predation-risk costs of the display 211 . Similarly, iInin human systems, 109 costly signalling has been used to explain behaviour associated with artistic elaboration, 110 ceremonial feasting, body modification, and monumental architecture 5,2515) . Individuals that can 111 afford costly signals can attract mates or accrue social status, which can increase access to 112 6 resources (e.g., foods, material goods, approval from peers, knowledge) 21,26 .. Using similar logic, 113 sociologists use the term 'conspicuous consumption' to describe the purchase and display of 114 luxury goods and activities 16 . Although costly signalling and associated theory is not universally 115 accepted 17 , it provides a useful framework with which to evaluate apparently inefficient 116 behaviour. 117 118 119 Whereas data are limited and debate common, cCostly , costly signalling has also been invoked 120 to explain hunting behaviour in some human subsistence -hunting systems, although relevant 121 data are limited and debate is common 10, 27-29 . .. According to the theory in this context, when 122 subsistence hunters target Hunting behaviour by humans is multifaceted and not mutually-123 exclusive, often motivated by provisioning oneself, kin, and/or through reciprocal altruism, while 124 certain behaviourHunting by humans has alsocan also been considered in a costly signalling 125 framework. Even in the case of subsistence hunting within traditional hunter-gather groups, male 126 hunters often target species with a highly variable caloric payoff over more reliably or safely 127 acquired alternatives 18 . In targeting items with high ecologic costsal costs, they (i.e. risk of 128 failure, injury, etc), such huntersthey would honestly signal their ability to absorb the 129 costs 149,3018 . Thus, according to this theory, hunting itself becomes serves as the signal, and s, 130 uccessfully and successfully hunting huntingor hunting a species with higher costs signals-131 produces a higher quality signal (akin to a more showy avian courtship display). Costly signalling may help to explain or not seemingly wasteful inefficient non-subsistence 158 8 hunting behaviour thatsamong non-subsistence hunters appear to conforms to predictions of 159 costly signalling theory might provide fresh new insight into the discussiondebate. In particular, 160 nNAs explained above, Nn, similar to behaviour observed in traditional hunter-gatherer groupsd. 161 Specifically, non-subsistencetrophy-hunters hunters would supposedly seeminglyappear to 162 would incur substantial costs --(in terms of high failure risk or risk of injury as well as low to nil 163 consumptive returns --) when they target large-bodied, carnivorous, rare, and/or dangerous or 164 difficult-to-hunt species. Specifically, wewWe would expect increased failure risk via lower 165 hunter encounter rates with larger and higher trophic-level animals, which tend to occur at lower 166 densities than small, low-trophic-level species 3522 . Similarly, hunters likely encounter other rare 167 species of high conservation concern (with populations reduced by human impacts) less 168 frequently than abundant species. of low conservation concern. In addition, species that are 169 dangerous or difficult to hunt are likely to increase failure and injury risk, posing another cost. 170 owing to injury or unsuccessful attempts. Moreover, hIn additionMoreover, human hunters often 171 kill seldom-eaten speciess (citation),species, such as carnivores, which includes the opportunity 172 cost of forgoing greater nutrition from hunting edible prey. Collectively, hunting inefficiently by 173 targetingtTargeting such preyinefficient preyharacteristics could signal a perceivedaperceivedn 174 ability to accept the costsobstaclecosts of higher failure and injury risk, as well as opportunity 175 costs, compared with targeting species that are more easily securedlocatsecured and offering 176 higher nutritional return. Throughout this paper, we use the term '"cost'" to refer to these 177 Though the signals shown-off by these opportunity costs (lower nutritional returns) andas well 178 asthese failure and hunters may no longer be honestly linked to cognitive/physical qualities (due 179 to expert guides and injury risks; in contrast costs ,efficient weaponry 8,36 ), and we use the term 180 '"price'" (see below) when referring to currencythe money hunters pay for perhaps not adaptive, 181 Although the targeting of some big -game (i.e., relatively large speciemammals hunted for sport) 197 by modern contemporary non-subsistence hunters appears to include many elements of costly 198 signalling behaviour, there have been no empirical evaluations of the theory in this context 199 .context.'s relevance. If such trophy-hunting behaviour is an example ofreflects elements of 200 costly signalling persistentthat persists amongin modernamong contemporary human hunters, we 201 would predict that species with high perceived costs should be more desirable to hunters because 202 they could signal a greater ability to absorbccept the accept costs. Accordingly, assuming that 203 market demand (which could also be influenced by lower supply in the case of rare species) 204

Commented [MOU4]:
In the context of modern trophy hunting, affluence is unlikely to be signaled principally by killing particular prey. Taking the hunting trip itself is an indication of affluence, and those spending a lot on hunting are also likely to spend a lot on other material goods, e.g. billionaires who trophy hunt the African Big Five. Also, physical competency and cognitive ability are not necessarily required when guides and vehicles and sophisticated weaponry are on hand-as you recognize.
causes influences price to reflect desirability --, (a common assumption 15-219-6 --) --, we 205 hypothesized that hunt prices would be higher, and accordingly hunters would be willing to pay, 206 for taxa with higher perceived ecological costs of hunting. We note that lower supply, through 207 rarity or hunting restrictions, could also drive up prices, but we would not expect to find an 208 association with prey body size, or hunt danger, or difficulty in this case.. We confronted this our 209 hypothesis using data fromin guided big-gametrophy -huntinger hunter systems, where . These 210 hunters hire specialist guides 368 . Prices for guided hunts can be substantial, ranging from several 211 hundred to many thousands of US dollars (USD) per day 152-174 . In addition, permits to hunt some 212 species can reach tens of thousands of USD 9 . Specifically, using price charged per day for 213 guided hunts as an index, we predicted that species that are 1) large-bodied, 2) rare, 3) 214 carnivorous, and 4) described by Safari Club International (SCI) 37 as dangerous or difficult-to-215 hunt would be priced higher. In other words, we predcitedpredicted that guided hunters would 216 pay higher prices for hunts that signal ecologically costlier behavior. 217 218

Species included 220
We collected prices advertised for guided hunts of 15 North American big game species (Table  221 1). We selected these species because they comprise the species requirements of SCI's Grand   Websites presented a variety of options to hunters, requiring a standardization approach. We 238 excluded websites that either did not include prices or stated to "call or email for prices". We 239 focused on free-range (i.e. not fenced) hunts targeting males during the rut (for ungulates) if 240 different seasons were available. Prices included guiding, meals, and accommodation. We did 241 not include baited hunts or 'combination' hunts that included more than one species for one 242 price. We chose rifle hunts when hunters were given options (usually among rifle, muzzleloader, 243 archery), and muzzleloader was chosen if rifle was not an option. If neither were available (n = 244 3), archery hunt prices were converted to firearm prices by using the average ratio (rifle 245 price/archery price; 1.20) calculated from those with a choice (n = 26). 246

247
We estimated the contribution of charter flights to total cost to remove that component from 248 prices that included it (n = 49). We subtracted the average flight cost if included, calculated from 12 hunts that stated the cost of a charter for the same species-jurisdiction. If no estimates were 250 available, the average flight cost was estimated from other species within the same jurisdiction, 251 or from the closest neighbouring jurisdiction. Similarly, trophy and license/tag fees (set by 252 governments in each province and state) were removed from prices if they were advertised to be 253 included. 254

255
We also estimated a price-per-day from hunts that did not advertise the length of hunt. We used 256 data from websites that offered a choice in the length (i.e. three days for $1000, five days for 257 $2000, seven days for $5000), and selected the most common hunt-length from other hunts 258 within the same jurisdiction. We used an imputed mean for prices that did not state the number 259 of days, calculated from the mean hunt-length for that species and jurisdiction. We used the provincial or state-level conservation status (the subnational rank or "S-Rank") for 273 each species as a measure of rarity. These were collected from the NatureServe Explorer 4127 . 274 Conservation statuses range from S1 (Critically Imperilled) to S5 (Stable) and are based on 275 species abundance, distribution, population trends, and threats 4127 . Some ranks denote 276 uncertainty within a range and fall in-between two ranks (e.g., S1S2; S2S3 etc.). Accordingly, 277 we converted ranks to 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5. 278 279 Classification: ungulate vs carnivore 280 We categorized species as either "carnivore" or "ungulate". Carnivore includes species of the 281 order Carnivora and ungulate includes species with hooves ( Our candidate set included models with various combinations of our potential predictor variables 306 as main effects. We did not include all possible combinations of main effects and their 307 interactions, and instead evaluated only those that expressed our hypotheses. We did not include 308 models with (ungulate vs carnivore) classification as a term on its own. Given that some 309 carnivore species are commonly perceived as pests (e.g. wolves) and some ungulate species are 310 highly prized (e.g. mountain sheep), we did not expect a stand-alone effect of classification. We 311 did consider the possibility that mass could influence the response differently for different 312 classifications, allowing for an interaction between classification and mass. Following similar 313 logic, we considered an interaction between SCI descriptions and mass. We did not include 314 models containing interactions with conservation status as we predicted rare species to be 315 expensive regardless of other characteristics. Similarly, we did not include models containing 316 interactions between SCI descriptions and classification; we assumed that species described as 317 15 difficult or dangerous would be more expensive regardless of their classification as carnivore or 318 ungulate. 319 320 We fit generalized linear mixed effects models, assuming a gamma distribution with a log link 321 function. All models included jurisdiction and species as crossed random effects on the intercept. 322 We standardized each continuous predictor (mass and conservation status) by subtracting its 323 mean and dividing by its standard deviation. We fit models with the lme4 package version 1.

330
We compared models including combinations of our four predictor variables to determine if prey 331 with higher perceived costs were more desirable to hunt, using price as an indication of 332 desirability. Our results suggest that hunters pay higher prices to hunt species with certain 333 'costly' characteristics, but do not provide support for all our hypotheses. Our highest ranking 334 model (Table 2)

359
At a North American continental scale, we analysed guided trophy hunting in the context of 360 costly signalling theory. We examined, exploring hunting as a signal, and the risks of failure and 361 injury, as well as opportunity costs related to low consumptive returns, as the potential associated 362 ecological costs. We asked if characteristics of prey associated with higher perceived costs were 363 correlated with higher prices charged to hunters (which we assume to represent a market-364 mediated index of desirability). We argue that costly signalling theory might could provide an 365 evolutionary explanation for why big -game hunters target specific species 78 . We found some 366 support for our prediction, showing that hunters pay more to kill larger-bodied carnivores, which 367 likely carry higher perceived risk of failure risk and injury, as well as and low consumptive 368 returns, and are therefore perceived as more costly, as we argue below. 369 370 Some patterns we observed differed from previously published findings. For one, the 371 jurisdiction-level conservation status (state or provincial-level within North America) of a 372 species (i.e.our proxy for rarity) did not affect price in our analysis. In contrast, larger-scale 373 conservation rankings (such as IUCN and/or CITES) have previously been found to correlate 374 with hunting price in Caprinae species 152 , Bovidae taxa 163,174 , ungulates 185 , and African felids 196 . 375 Two explanations for why we did not detect a relationship might be relevant. First, the 376 jurisdiction-level rankings showed little variation across species in our data set; only 18% (n = 377 27) of the species-jurisdiction combinations ranged from 'Vulnerable'/'Apparently Secure' 378 (S3/S4S3S4) to 'Critically Imperiled' (S1). The remainder were not classified as at risk. Second, 379 hunters (especially when they commonly originate from afar) might not know or consider the 380 jurisdiction-level conservation status (that wewhich were included in our models) of their targets, 381 whereas a species' IUCN ranking is typically well-known and often included in their SCI record 382 book descriptions. However, only two species used in our study were ranked by the IUCN as 383 "Vulnerable", while the remaining thirteen ranked as "Least Concern".  Thank you for the opportunity to submit our revised manuscript "Trophy hunters pay more to target larger-bodied carnivores" RSOS-191231.R1, following your request for minor revisions.