Article

Influence of trophy hunting and horn size on mating behavior and survivorship of mountain sheep

August 2002
Journal of Mammalogy 83(3):682-698

DOI:10.1644/1545-1542(2002)083<0682:IOTHAH>2.0.CO;2

Authors:

We conducted a study of the effects of horn sizes and trophy hunting on mating behavior and survival of rams in hunted and unhunted populations of Dall sheep (Ovis dalli), Rocky Mountain bighorn (O. canadensis canadensis), and desert bighorn (O. c. nelsoni) sheep. Mating success was positively correlated with horn size in Dall sheep (P = 0.03) and Rocky Mountain bighorns (P = 0.05), but not in the desert bighorn (P > 0.05) taxa. Group sizes, rams per rut group, and competition between rams were lowest in desert bighorn sheep. There were indications of greater harassment of ewes by young rams in trophy-hunted populations. In hunted populations, compared with unhunted, ewes ran away more often from approaching rams, ewes moved farther away from courting young rams (P = 0.003), younger rams performed fewer courtship displays (P = 0.042) and more aggressive displays to ewes, and sheep interacted 27% more of the time. Ram-to-ewe interaction times per individual ewe did not differ for any of the taxa (P > 0.05), and, apparently as a consequence of this, we found no discernable effects of trophy hunting on survivorship of ewes, ewe fecundity, or recruitment of young (P > 0.05). There were greater energy expenditures by young rams in the heavily hunted Dall sheep population versus the paired Dall sheep unhunted population, but not in the lightly hunted Rocky Mountain and desert bighorn populations when compared with unhunted populations. This was consistent with evidence for depressed survivorship of rams too young or too small to be hunted (approximately ages 4–6) in the heavily hunted Dall sheep population (P = 0.0001), but not in the bighorn sheep populations (P > 0.05).

Young and mature males have similar energy expenditure during the rut in a trophy‑hunted population of Mediterranean mouflon https://rdcu.be/cbdzZ

Article

Jan 2021

In polygynous ungulates, males invest time and energy to reproductive activities during the rut and this involvement is expected to increase with age due to different mating tactics in young versus adult males. In contrast, mating period is expected to be less costly for females for which late gestation and lactation are the most energetically demanding periods. However, empirical supports of these hypotheses through direct measures of reproductive effort are still limited in ungulate species, particularly in males. In addition, this general pattern may be modified in populations facing selective harvesting on adult males, where young males may experience less competition to mate and invest more energy during the rut. We investigated these hypotheses by studying the age- and sex-specific variations of kidney fat reserves from pre- to post-rut periods in a trophy-hunted population of Mediterranean mouflon (Ovis gmelini musimon × Ovis sp.), a polygynous dimorphic mountain ungulate. Females were found to build up energy from the pre-rut to the post-rut periods, most likely to face with the subsequent costs of gestation/lactation that occur few months later. Conversely, kidney fat mass strongly decreased similarly in both young and mature males, and with the same magnitude, suggesting a strong investment of males of all ages in this population. This might be related to the selective hunting pressure on mature males this population is facing with. This result supports the need for more empirical and comparative studies to better grasp the influence of trophy hunting on reproductive effort in male ungulates.

Modification of the structure of wild boar populations by hunting and influence on reproductive processes

Thesis

Jul 2018

Thibault Gayet

The wild boar (Sus scrofa scrofa) is a peculiar species. It is an appreciated game species for hunters, a nightmare for farmers and a subject of debate for the society in general. The tenfold increase of the population over the last decades in France and all over Europe, despite increased hunting pressure, generated great human-wildlife conflict. The wild boar is responsible for great economic losses due to vehicle collision, diseases transmission and damaged crops and ecosystems. Improving management strategies becomes a prime interest to avoid such conflicts, or at least keep them under control. Obtaining information on the species is a first step toward good management strategies. The objective of my work is, in a first part, to characterize the mating system of the wild boar and to identify some parameters, especially hunting, influencing the reproductive processes. The second part focus on the investigation of the influence of the mating system on wild boar life history traits. My researches are based on the study of several populations contrasting in their hunting practices and on longitudinal data of a highly monitored population. The study is based on data collected on wild boars killed by hunting. Genotypes were obtained for pregnant females and their litter and paternity analyses were realized to measure the number of fathers in a litter and estimate multiple paternity rates (proportion of litter sired by more than one father). I was able to show that the mating system is mainly promiscuous (several males mate with several females) contrasting with the polygyny (a dominant male monopolizing a group of females) usually described in this species. Moreover, reproductive processes, estimated by the number of mates of a female and the multiple paternity rates, are influenced by hunting variations in a population. I also showed that number of fathers has positive effect on female fecundity. High rates of multiple paternity together with high genetic diversity were found in a heavily hunted population, suggesting multiple paternity may buffer yearly bottlenecks. However, the increase of number of fathers is not associated with increase of within-litter variation

Young Bighorn (Ovis canadensis) Males: can they Successfully Woo Females?

Article

Jan 2008
ETHOLOGY

Mating by young males or low male-to-female ratios can decrease pregnancy rates and postpone birthdates in ungulates, thereby hindering population growth. Young (2.5–3.5 yr old) male bighorn (Ovis canadensis) behave differently than older males, and age, horn size, mating behavior, and social rank help determine reproductive success. We estimated birthdates in two populations of bighorn sheep in Utah, USA, to determine if mating by young males or low male-to-female ratios resulted in fewer young born per female, a shift in mean timing of births, or asynchronous births. When reintroduced, the Rock Canyon population consisted of four males (two each of 2.5 yr old and 1.5 yr old) and a 1 to 7.5 ratio of males (>2 yr old) to adult females (≥3.5 yr old); the Mount Nebo population consisted of four males ≤1.5 yr old and a 0 to 12 ratio of males to adult females. For both populations, the number of young born per female did not differ between the first parturition period after reintroduction (where females were impregnated by males from their source populations) and the second period of parturition (where females were impregnated by young, reintroduced males). Mean birthdates and synchrony (SD) of births did not differ for Rock Canyon (May 12, 2001 ± 4.5 d, May 14, 2002 ± 3.2 d) or Mount Nebo (May 23, 2005 ± 8.1 d, May 22, 2006 ± 10.2 d) between the first and second years following reintroduction. Mating by young males or low male-to-female ratios had no demonstrable effect on the number of young born per female or timing and synchrony of births in these populations.

Patterns of reproductive effort in male ungulates

Article

Oct 2004
J ZOOL

In ungulates, males and females have contrasting life histories, as usually only the females raise the young. How reproductive effort in males varies with individual level and population level characteristics has received little attention in the literature. Using published information on direct (weight loss during the rut) and indirect (rut- related changes in activity budgets, fighting frequency, etc.) measures of reproductive effort, we tested whether effort in males increased with (H1) increasing age, (H2) increasing body size, (H3) decreasing population density, (H4) increasingly female-biased sex ratio and with a younger male age structure. Consistent with H1, reproductive effort was consistently higher in prime-aged than in younger males in a large number of studies. Among younger males, sub-adult males had an equal or higher effort than yearling males. Prime-aged males had more typical rutting behaviour (e.g. roaring, tending, fighting and chasing frequencies) and they often lowered their intake of forage during the rut. However, reproductive effort usually declined for very old age classes. Reproductive effort increased with size (H2) also after accounting for age. Data on effort vs (H3) density and (H4) sex ratio/male age structure were inconclusive. Clearly, far more studies relating effort to population characteristics are needed before the rutting ecology of male ungulates can be understood.

The tragedy of the commons: Unsustainable population structure of Iberian red deer in hunting estates

Article

Full-text available

Apr 2014

Hunting can influence population structure with consequences in ecological and evolutionary processes. Populations of Iberian red deer (Cervus elaphus hispanicus) in Spain occur under two different management regimes: fenced and unfenced (open) estates. We compared census data, hunting bags and data from hunted individuals between both types of estates. Harvest on stags was moderate in fenced estates but strong in open ones, probably due to the competition between neighbouring landowners over the same deer populations. On the contrary, female culling was low in open estates compared to fenced ones. As a result, populations in open estates have mostly young males and strongly female-biased sex ratios. Female-biased population structure in open estates did not result in higher number of males being harvested per year compared with fenced estates, probably due to negative effects on development, survival and reproduction, and harvested males were younger, and hence, with smaller antlers. There is published evidence for undesirable effects of biased population sex ratio and age structure in these red deer populations. Our results indicate that this type of management may be unsustainable and recommend that harvest on males in open estates should be reduced and that on females increased, in order to maintain a more balanced population structure that may allow sustainable population dynamics and the operation of natural evolutionary processes.

Effects of harvest, culture, and climate on trends in size of horn-like structures in trophy ungulates

Article

Full-text available

Feb 2013

Hunting remains the cornerstone of the North American model of wildlife conservation and management. Nevertheless, research has indicated the potential for hunting to adversely influence size of horn-like structures of some ungulates. In polygynous ungulates, mating success of males is strongly correlated with body size and size of horn-like structures; consequently, sexual selection has favored the development of large horns and antlers. Horn-like structures are biologically important and are of great cultural interest, both of which highlight the need to identify long-term trends in size of those structures, and understand the underlying mechanisms responsible for such trends. We evaluated trends in horn and antler size of trophy males (individuals exhibiting exceptionally large horns or antlers) recorded from 1900 to 2008 in Records of North American Big Game, which comprised >22,000 records among 25 trophy categories encompassing the geographic extent of species occupying North America. The long-term and broad-scale nature of those data neutralized localized effects of climate and population dynamics, making it possible to detect meaningful changes in size of horn-like structures among trophy males over the past century; however, ages of individual specimens were not available, which prevented us from evaluating age-class specific changes in size. Therefore, we used a weight-of-evidence approach based on differences among trophy categories in life-history characteristics, geographic distribution, morphological attributes, and harvest regimes to discriminate among competing hypotheses for explaining long-term trends in horn and antler size of trophy ungulates, and provide directions for future research. These hypotheses were young male age structure caused by intensive harvest of males (H1), genetic change as a result of selective male harvest (H2), a sociological effect (H3), effects of climate (H4), and habitat alteration (H5). Although the number of entries per decade has increased for most trophy categories, trends in size of horn-like structures were negative and significant for 11 of 17 antlered categories and 3 of 8 horned categories. Mean predicted declines during 1950–2008 were 1.87% and 0.68% for categories of trophy antlers and horns, respectively. Our results were not consistent with a sociological effect (H3), nutritional limitation imposed by climate (H4), or habitat alteration (H5) as potential explanations for long-term trends in size of trophies. In contrast, our results were consistent with a harvest-based explanation. Two of the 3 species that experienced the most conservative harvest regimes in North America (i.e., bighorn sheep [Ovis canadensis] and bison [Bison bison]) did not exhibit a significant, long-term trend in horn size. In addition, horn size of pronghorn (Antilocapra americana), which are capable of attaining peak horn size by 2–3 years of age, increased significantly over the past century. Both of those results provide support for the intensive-harvest hypothesis, which predicts that harvest of males has gradually shifted age structure towards younger, and thus smaller, males. The absence of a significant trend for mountain goats (Oreamnos americanus), which are difficult to accurately judge size of horns in the field, provided some support for the selective-harvest hypothesis. One other prediction that followed from the selective-harvest hypothesis was not supported; horned game were not more susceptible to reductions in size. A harvest-induced reduction in age structure can increase the number of males that are harvested prior to attaining peak horn or antler size, whereas genetic change imposed by selective harvest may be less likely to occur in free-ranging populations when other factors, such as age and nutrition, can override genetic potential for size. Long-term trends in the size of trophy horn-like structures provide the incentive to evaluate the appropriateness of the current harvest paradigm, wherein harvest is focused largely on males; although the lack of information on age of specimens prevented us from rigorously differentiating among causal mechanisms. Disentangling potential mechanisms underpinning long-term trends in horn and antler size is a daunting task, but one that is worthy of additional research focused on elucidating the relative influence of nutrition and effects (both demographic and genetic) of harvest.

Alpine ibex males grow large horns at no survival cost for most of their lifetime

Article

Jun 2013
OECOLOGIA

Large horns or antlers require a high energy allocation to produce and carry both physiological and social reproductive costs. Following the principle of energy allocation that implies trade-offs among fitness components, growing large weapons early in life should thus reduce future growth and survival. Evidence for such costs is ambiguous, however, partly because individual heterogeneity can counterbalance trade-offs. Individuals with larger horns or antlers may be of better quality and thus have a greater capacity to survive. We investigated trade-offs between male early horn growth and future horn growth, baseline mortality, onset of actuarial senescence, and rate of ageing in an Alpine ibex (Capra ibex ibex) population. Horn growth of males in early life was positively correlated to their horn length throughout their entire life. Cohort variation and individual heterogeneity both accounted for among-individual variation in horn length, suggesting both long-lasting effects of early life conditions and individual-specific horn growth trajectories. Early horn growth did not influence annual survival until 12 years of age, indicating that males do not invest in horn growth at survival costs over most of their lifetime. However, males with fast-growing horns early in life tended to have lower survival at very old ages. Individual heterogeneity, along with the particular life-history tactic of male ibex (weak participation to the rut until an old age after which they burn out in high mating investment), are likely to explain why the expected trade-off between horn growth and survival does not show up, at least until very old ages.

Female reproductive success and costs in an alpine capital breeder under contrasting environments

Article

Full-text available

Jan 2002

We studied female reproductive success in two contrasting populations of Alpine Ibex: one colonizing, experiencing no density-dependence, and for which environmental conditions are consequently not limiting, the other well established, experiencing density-dependence and thus living in a limiting environment. Female body condition was better in the colonizing population than in the well-established one. As a result, reproductive success was higher in the colonizing population (80% of females reproduced each year) than in the well-established one (only 45% of females reproduced each year). We did not detect any cost of reproduction on subsequent reproduction in either of the populations, suggesting that ibex females adopt an extremely conservative reproductive tactic by limiting their reproductive effort when resource availability is reduced. However, we found a higher variance of individual reproductive success in the well-established population than in the colonizing one

Ageing and reproductive effort in male moose under variable levels of intrasexual competition

Article

Jul 2005
J ANIM ECOL

Capital breeding is a resource use tactic common among polygynous mammals, such as many ungulates. Even though large, prime‐aged males stop eating during the rutting season, younger individuals often do not and may adopt alternative mating tactics that are less strenuous. The pattern of reproductive effort is therefore probably very variable among age classes, but has rarely been quantified in male mammals. Based on data of body weight of 9949 male moose ( Alces alces L.) aged up to 21 years from seven populations in Norway, we tested hypotheses regarding the pattern of reproductive effort (weight loss during rut) in this capital breeder, and how this may be affected by factors such as age, population sex ratio and density. Reproductive effort increased with age, even after prime‐age was reached around the age of 6 years. This provides the first evidence consistent with the terminal investment hypothesis in male mammals. For the very oldest males (> 12 years) data were limited, but the tendency was that effort stabilized or even decreased slightly. Effort did not depend on the population sex ratio or density for adult males. Yearling males also lost some weight during the rutting season, but this was not related to population sex ratio. Decreasing trends in yearling body weight as seen in many strongly harvested moose populations, therefore are due probably to other causes than earlier onset of rutting. Further, effort in yearlings decreased with increasing density. Despite the lack of a correlation between effort and population sex ratio, a significantly faster ageing after prime‐age was observed with an increasingly female‐biased population sex ratio. This is consistent with the hypothesis that strongly skewed sex ratios may affect the ageing process. Most ungulate populations in Europe and North America are heavily harvested or otherwise managed extensively, harvest being typically male‐biased to varying degrees. The resulting skews in sex ratio provide manipulations that give unique opportunities to study life‐history variation, in particular for large mammals that are otherwise difficult to manipulate. These opportunities are currently not fully utilized.

Variation in harem size of red deer (Cervus elaphus L.): The effects of adult sex ratio and age-structure

Article

Full-text available

Sep 2004
J ZOOL

The relationships among harem size, adult sex ratio (proportion of males > 5 years in the adult population, i.e. males > 5 years plus females > 2 years) and male age-structure of red deer Cervus elaphus were investigated in La Petite Pierre National Reserve (PPNR) in France. We tested whether: (1) increasing adult sex ratio leads to a decrease in harem size along with an increase in the number of harems within a given rut period; (2) whether participation of sub-adult males in mating activities increases with decreasing adult sex ratio, and as the proportion of adult males decreases. Harem size did not vary over the mating period, suggesting a high turnover of harem-holders leading to an increase in the costs of mating for males. Harem size averaged 1.43 ± 0.91 and was lower than harem sizes typically reported for red deer (e.g. > 2.5 in Scotland and Norway). In support of the first prediction, a decrease in harem size and an increase in the total number of harems seen with an increasing sex ratio was observed (harem size = 2.08 – 1.26 [±0.43] ± (sex ratio); r2= 0.25, F1,18= 6.19, P= 0.02). Both the uniform distribution of females among harem stags and the small harem sizes observed in PPNR might concur to a smaller variance in male reproductive success than previously reported in red deer. Lastly, in partial support of the second prediction, the proportion of sub-adult males observed during the mating season decreased with increasing adult sex ratio and with increasing proportions of adult males. Whether or not the lower proportion of sub-adults seen when competition among mature males increases means that fewer young males mate cannot be assessed from our study.

A Case Against Trophy Hunting Through Utilitarianism Lens: Evidence from Selous Game Reserve, Tanzania

Article

Jul 2024

The paper delves into the debate on trophy hunting as a conservation tool, examining it from a utilitarian perspective. It financially analyzes the costs and benefits of trophy hunting using a simplified cost-benefit analysis. The study employs a mixed methods design, incorporating both quantitative and qualitative methods by gathering data from Selous Game Reserve (SGR) and its adjacent villages through interviews with 108 respondents. The findings indicate that trophy hunting in SGR generates positive net benefits of 310,438 USD, making it financially viable. However, the study also reveals that conservation and local community development are not prioritized in its expenditures. Moreover, the negative social and ecological impacts of trophy hunting mean it does not provide the greatest benefit to the greatest number, as Utilitarian theory requires. Therefore, the study concludes that trophy hunting is unethical and recommends against it. Thus, sustainable wildlife conservation and income generation options such as ecotourism may be tested and considered in Tanzania.

Modelling reindeer rut activity using on‐animal acoustic recorders and machine learning

Article

Full-text available

Jun 2024

For decades, researchers have employed sound to study the biology of wildlife, with the aim to better understand their ecology and behaviour. By utilizing on‐animal recorders to capture audio from freely moving animals, scientists can decipher the vocalizations and glean insights into their behaviour and ecosystem dynamics through advanced signal processing. However, the laborious task of sorting through extensive audio recordings has been a major bottleneck. To expedite this process, researchers have turned to machine learning techniques, specifically neural networks, to streamline the analysis of data. Nevertheless, much of the existing research has focused predominantly on stationary recording devices, overlooking the potential benefits of employing on‐animal recorders in conjunction with machine learning. To showcase the synergy of on‐animal recorders and machine learning, we conducted a study at the Kutuharju research station in Kaamanen, Finland, where the vocalizations of rutting reindeer were recorded during their mating season. By attaching recorders to seven male reindeer during the rutting periods of 2019 and 2020, we trained convolutional neural networks to distinguish reindeer grunts with a 95% accuracy rate. This high level of accuracy allowed us to examine the reindeers' grunting behaviour, revealing patterns indicating that older, heavier males vocalized more compared to their younger, lighter counterparts. The success of this study underscores the potential of on‐animal acoustic recorders coupled with machine learning techniques as powerful tools for wildlife research, hinting at their broader applications with further advancement and optimization.

Effects of telemetry collars on two free-roaming feral equid species

Article

Full-text available

May 2024
PLOS ONE

There are two species of free-roaming feral equids in North America: horses (Equus caballus) and donkeys or “burros” (E. asinus). Both species were introduced as domestic animals to North America in the early 1500s and currently inhabit rangelands across the western United States, Canada, and all continents except Antarctica. Despite their global distribution, little is known about their fine scale spatial ecology. Contemporary research tools to assess space use include global positioning system (GPS) tracking collars, but older models were problematic due to stiff collar belting causing poor fit. We tested modern designs of GPS collars on n = 105 horses and n = 60 burros for 4 years in five populations (3 horse, 2 burro) across the western United States, to assess whether collars posed welfare risks to horses or burros. We found no difference in survival of collared versus uncollared mares and jennies, and no difference in survival of their foals. In 4036 of 4307 observations for horses (93.7%) and 2115 of 2258 observations for burros (93.6%), collars were observed symmetrical, maintaining proper fit on the neck. Fur effects from collars (sweaty neck, indented fur, broken fur) were seen in 3% of horse observations and 25% of burro observations. Superficial effects (chafes and marks on skin surface) were seen in 2% of horse observations and 11% of burro observations; no severe effects from collars were seen. Body condition was not affected by collars; mean body condition of collared horses was 4.70 ± 0.54 (mean ± s.d) and 4.71 ± 0.65 for collared burros. Behavior results indicated minimal effects; collared horses stood slightly more than uncollared, and collared burros stood and foraged more in one population, but not in the other. For 6.3% of observations of horses and 6.4% of observations of burros, we found an effect of time wearing a collar on the cumulative sum of fur effects which increased over time (burros: rs = 0.87, P = <0.0001; horses: rs = 0.31, P = 0.002). Burros also showed an increase over time in the number of superficial effects, but horses did not. Collars occasionally moved into the wrong position, shifting forward over the ears; we observed this on 19 horses and 1 burro. Of those, most collars went over the ears in summer (n = 12). All collars were equipped with a remote release mechanism as well as a timed-release mechanism for redundancy, thus removed when observed in wrong position to avoid rubbing or discomfort. Our finding of no consequential physical effects in 98% of horse observations, and 89% of burro observations suggests the consequences of collars on free-roaming equid welfare and survival is biologically insignificant, although collars should be monitored regularly and continue to be equipped with a remote release mechanism to remove a collar if needed. With frequent welfare-driven, visual monitoring, collaring of free-roaming equids can be a safe and useful tool to increase our understanding of their spatial ecology, demography, habitat use, behavior, and interactions with other wildlife.

Mountain ungulate mating systems: patterns and processes

Article

Full-text available

May 2023
MAMMAL REV

1. Mountain ungulates of the subfamily Caprinae, including wild sheep, goats and goat-antelopes, show remarkable interspecific diversity in habitat preferences, social organisation and morphological features. We review how this diversity relates to their mating behaviour. 2. After introducing the ecology of mating systems and the evolution of the Caprinae, we investigate the pairwise, sequential relationships between habitat preferences, social behaviour, level of polygyny, and morphological features, and discuss the ecological processes underlying the patterns of mate monopolisation and acquisition. 3. From forest-dwelling, solitary, monogamous and monomorphic goat-antelopes, to highly dimorphic, polygynous and social wild sheep and goats inhabiting open landscapes, mountain ungulates reveal a close relationship between habitat openness and sexual dimorphism, through the level of sociality and that of mate monopolisation. 4. Although over the last few decades some information has been collected on the biology of Caprinae, our understanding of determinants of their mating systems is still hampered by limited data to estimate opportunities for sexual selection, as well as uncertainties over the occurrence and maintenance of alternative reproductive tactics, and lack of information on female mate choice. 5. The study of mating systems and that of the factors influencing them play a key role from an evolutionary and conservation standpoint. This is relevant to the Caprinae, whose main habitat is expected to be strongly affected by the ongoing climatic change, with potential effects on the phenology of their mating systems, and whose economic value is relevant for consumptive and nonconsumptive uses. A better understanding of the diversity and ecology of mating systems will require a wealth of additional field observations on male and female behaviour, as well as genetic assessments of reproductive success.

Influence of Landscape Characteristics on Hunter Space Use and Success

Article

Full-text available

Jan 2021

Influence of Landscape Characteristics on Hunter Space Use and Success

Article

Full-text available

Jul 2021

Sport hunting of ungulates is a predominant recreational pursuit and the primary tool for managing their populations in North America and beyond, given its influence on ungulate distributions, social organization, and population performance. Similarly, land management, such as motorized vehicle access, influences ungulate distributions during and outside hunting seasons. Although research on ungulate responses to hunting and land use is widespread, knowledge gaps persist about space use of hunters and what landscape features discriminate among hunt types and between successful and unsuccessful hunters. We used telemetry location data from hunters (n = 341) to estimate space use from 2008–2013 during 3 types of controlled, 5‐day hunts for antlered mule deer (Odocoileus hemionus) and elk (Cervus canadensis) in northeastern Oregon, USA: archery elk, rifle deer, and rifle elk. To evaluate space use, we developed utilization distributions for each hunter, created core areas (50% contours) for groups of hunters, and derived several metrics of space‐use overlap between successful and unsuccessful hunters. We also modeled predictors of space use using resource utilization functions with beta regression and stepwise model building. Hunter space use was compressed, with even the largest core area (unsuccessful rifle elk hunters) encompassing <16% (1,178 ha) of the area. We found strong similarities in space use of rifle hunters compared to archers, and core areas of successful hunters were markedly smaller than those of unsuccessful hunters (e.g., = 104 ha vs. 681 ha, respectively, for archers). Percentage cover and distance from open roads were the most consistent covariates in the 6 final models (successful vs. unsuccessful for each of 3 hunts) but with different signs. For example, predicted use of archery and rifle elk hunters increased with cover but decreased for rifle deer hunters. Although the same covariates were in the final models for unsuccessful and successful rifle elk hunters, their negligible spatial overlap suggested they sought those features in different locales, a pattern also documented for rifle deer hunters. Our models performed well (Spearman's rank correlation coefficients = 0.99 for 5 of 6 models), reflecting their utility for managing hunters and landscapes. Our results suggest that strategic management of open roads and forest cover can benefit managers seeking to balance hunter opportunity and satisfaction with harvest objectives, especially for species of special concern such as mule deer, and that differences in space use among hunter groups should be accounted for in hunting season designs. © 2021 The Wildlife Society. This article has been contributed to by US Government employees and their work is in the public domain in the USA. We evaluated space use of successful and unsuccessful elk and mule deer hunters, contrasting archers with rifle hunters, and found minimal spatial overlap between groups but similarities in environmental features influencing space use. Integrated management of forest cover in tandem with roads and trails can aid in providing hunter opportunity while maintaining herd numbers and composition at desired levels.

A Call for More Nuanced Dialogues About Trophy Hunting

Article

Full-text available

Feb 2021

Reported effects of trophy harvest often are controversial. The subject is nuanced and many studies lack details necessary to place their results in context. Consequently, many studies are misunderstood or their conclusions misapplied. We propose that all dialogues about trophy hunting include a definition of how they use the term trophy, details of variables measured and why they were selected, and explanations of temporal and spatial scales employed. Only with these details can potential effects of trophy hunting be understood in context and used for management and policy decisions. © 2021 The Wildlife Society. Effects of trophy harvest often are controversial because many studies lack important details. Dialogues about trophy hunting must include a definition of how they use the term trophy, details of variables measured and why they were selected, and explanations of temporal and spatial scales employed so that potential effects of trophy hunting can be understood in context.

The influence of habitat use on harvest vulnerability of cow elk (Cervus canadensis)

Article

Full-text available

Nov 2020
PLOS ONE

Pressure from hunting can alter the behavior and habitat selection of game species. During hunting periods, cervids such as elk (Cervus canadensis) typically select for areas further from roads and closer to tree cover, while altering the timing of their daily activities to avoid hunters. Our objective was to determine the habitat characteristics most influential in predicting harvest risk of elk. We captured 373 female elk between January 2015 and March 2017 in the Uinta-Wasatch-Cache National Forest and surrounding area of central Utah, USA. We determined habitat selection during the hunting season using a resource selection function (RSF) for 255 adult cow elk. Additionally, we used a generalized linear mixed model to evaluate risk of harvest based on habitat use within home ranges (3rd order selection) as well as the location of the home range on the landscape to evaluate vulnerability on a broader scale. Female elk selected for areas that reduced hunter access (rugged terrain, within tree cover, on private land). Age, elevation and distance to roads within a home range were most influential in predicting harvest risk (top model accounted for 36.2% of AIC weight). Elevation and distance to trees were most influential in predicting risk when evaluating the location of the home range (top model accounted for 42.1% of AIC weight). Vulnerability to harvest was associated with proximity to roads. Additionally, survival in our landscape decreased with age of femaleelk.

Redefining walrus stocks in Canada erratum (vol 61, pg 292, 2008)

Article

Full-text available

Mar 2009

Robert EA Stewart

Quality of Individual Roe Deer Males ( Capreolus capreolus L.) During the 5-Month-Long Hunting Season: Possible Impact on the Reproduction Rate

Article

Full-text available

Jun 2015

The aim of this study was to assess changes in parameters (body weight, fat stores, antler weight, serum creatinine level) describing the condition of individual roe deer males (Capreolus capreolus) in subsequent months of the hunting season. The idea was if the current timing of the buck hunting season affects the quality of specimens obtained from the population, which may result in distorting its reproduction-related processes. The study included 443 carcasses of bucks harvested in the Lublin region (Central Poland) from 2006 to 2011. The average carcass weight in May and June was significantly higher than in the other months. Perirenal fat weight and the kidney fat index (KFI) decreased with the progression of the hunting season. With regard to the average level of serum creatinine in blood, there was no definite trend in the variation of this parameter during the hunting season. However, a significantly higher average antler weight was observed in May compared to June. The shooting of a large number of bucks in the first weeks of the hunting season may cause the elimination of the best individuals in the habitat, which have established and maintained their territory and are fully prepared for reproduction. This results in a complete disruption of the social structure of the local deer population. A solution to this problem could be uniform distribution of volume harvested during the whole hunting season or postponing the hunting season for bucks until September, when the estrus season has finished, and the strongest males have passed on their valuable genes to the population.

Sex ratios of Arabian Sand Gazelle Gazella Marica Thomas, 1897 in the Mahazat as-Sayd Protected Area, Saudi Arabia

Article

Full-text available

Aug 2011
MAMMALIA

The sex ratio of a population of Arabian Sand Gazelle in Mahazat as-Sayd Protected Area in central western Saudi Arabia was compared to that determined from 296 skulls collected from the same area. Skulls were collected between March 2008 and March 2009 during a period of mass die-off caused by a severe drought. Most abundant were male skulls ageing between 18 and 24 months. The skulls of natural mortalities indicated an imbalanced sex ratio skewed towards males (1.39:1), compared to a sex ratio slightly skewed towards adult females (1:1.07) in the living population. Horn lengths of males and females were significantly shorter in the wild population of Mahazat as-Sayd than compared to an analogous population in captivity (King Khalid Wildlife Research Centre, KKWRC, Saudi Arabia). Possible causes for diverging sex ratio were linked to increased male mortality during the drought. Male mortalities and female biased sex ratio are discussed in the light of territoriality, predation, poor environmental conditions and limited opportunities to migrate.

Timing of Reproductive Effort Differs between Young and Old Dominant Male Reindeer

Article

Full-text available

Jun 2012

In polygynous species, male reproductive effort has been measured both directly in the form of somatic costs and indirectly using behavioral data. We used 12 years of data collected from a semi-domesticated reindeer population in northern Finland to inves-tigate age-and time-specific patterns of dominant males' reproductive effort. Overall, we found that activity levels differed both between young and old dominant reindeer males, and among the early, peak, and late rut, the pattern being age-specific. Repro-ductive effort was generally higher for old than young dominant males; however, old males reduced their effort in the late-rut period, while young males maintained the same level of activity. There was a positive relationship between somatic costs and activity level only during the early rut for young dominant males, and only during the peak rut for old dominant males. Thus, old males incur the highest energetic costs from rut-related activities when most of the females in the herd are in oestrus. Conversely, young males appear to time their rut-related energetic cost to coincide with the early rutting period, before most females have reached oestrus. Old males are more efficient in timing their reproductive effort so as to maximize their reproductive success. This can be attributed to young males being less experienced than old males or to using an alternative mating tactic by young males who try to avoid competition with old males during the peak rut.

Does trophy hunting matter to long-term population trends in African herbivores of different dietary guilds?: Trophy hunting and densities of African herbivores

Article

Full-text available

Aug 2014
ANIM CONSERV

The persistence of large African herbivores in trophy hunting areas is still unclear because of a lack of data from long-term wildlife monitoring outside national parks. We compared population trends over the last 30 years in Hwange National Park, Zimbabwe, and the neighbouring Matetsi Safari Area where large herbivores were harvested at an average yearly rate of 2%. We investigated whether trophy hunting altered densities and the proportion of adult males in several large herbivore species. Large herbivores generally thrived as well, or even better, in the hunting areas than in the national park. The proportion of adult males did not differ between the two zones, except for species with higher harvest rates and proportionally more males harvested. Densities were not lower in the hunting areas than in the national park, except for elephant and impala. Large herbivores generally declined throughout the 30-year period in both zones, particularly selective grazers. This is probably because of their greater sensitivity to variation in rainfall compared with other herbivores. Rainfall indeed declined during the study period with droughts being particularly frequent during the 1990s. Browsers, mixed feeders and non-selective grazers generally declined less in the hunting areas than in the national park, possibly because of lower densities of natural predators and elephants outside the park. Our study highlighted that large herbivores may persist in trophy hunting areas as well as in national parks. When rigorously managed, trophy hunting areas may be relevant conservation areas for large herbivores, particularly under the current global decline of wildlife abundance across Africa.

The role of hunting in North American wildlife conservation

Article

Full-text available

Jun 2013

Regulated hunting is the foundation of the North American Model of Wildlife Conservation. This conservation paradigm arose out of a movement, lead by prominent hunters, to stop over-exploitation of wildlife by market hunters and the desire to have wildlife accessible to all people. Since then, hunters have contributed billions of dollars to wildlife management that benefit countless wildlife species. These funds support wildlife management agencies which manage all wildlife species, not just those that are hunted. This unique and successful conservation paradigm is responsible for supporting a wide variety of conservation activities, including law enforcement, research, information and education, habitat management and acquisition, as well as wildlife population restoration and management. Although wildlife conservation activities embrace far more than the hunted species, hunters continue to be the primary agents of financial support, management assistance and organized advocacy.

Dynamique d’une population chassée de sangliers (Sus scrofa scrofa) en milieu forestier.

Thesis

Full-text available

Jul 2007

Sabrina Servanty

Among Ungulates, the wild boar (Sus scrofa scrofa) is characterised by a mixture of particular life history traits which associate a high fecundity and an early age at first reproduction with a large body size and a potential long life expectancy. Moreover, unlike most ungulates which are rather strict herbivores, the wild boar is an omnivore. This uncommon life-history strategy is associated with an increase in population size. Indeed, in Europe, wild boar populations are currently still growing and cause some socio-economical problems due to the damage that wild boars generate to the human activities. Hence the understanding of the factors primarily involved in this increase in population size as well as the modelling of population dynamics is now essential to better manage wild boar populations. This work rely on a long term data set (25 years) of a hunted wild boar population in the eastern part of France (Haute-Marne). The analyses of maternal allocation in reproduction highlighted that in utero, the sex ratio decreased as litter size increased. Sex ratio was male-biased for litter size up to 6 and then became female-biased in larger litters. Producing large female-biased litters may be an adaptive adjustment to avoid strong sibling competition during lactation and therefore to maximise the number of recruited offspring. The threshold weight above which females can reproduce is around 28 kg live weight but once females become sexually mature, they will reproduce every year. However, the onset of oestrus may be delayed according to the available resources and vary year-to-year. Natural mortality was disentangled from hunting mortality by using Capture-Recapture multi-states models. Males’ survival did not vary yearly but did vary with age-classes and the probability to be hunted increased with age up to around 70%. Females’ survival did vary yearly and also differed between age-classes with the yearly survival probability of females younger than one-year old being smaller than that of older females. Compared to other large mammals, adult females’ survival was lower and more variable over time possibly because of higher reproductive investment, especially in young adults. Those demographic characteristics reveal that wild boars could not be managed like other ungulate species. So, we developed a new modelling approach and retained a sex-specific body mass dependent model to assist managers. In this way, managers have the possibility to directly test the outcome of the model by comparing observed and expected distributions of wild boars killed by hunters among sex- and body mass-specific classes. They can assess the performance of a given hunting rule and simulate the respective efficiency of management scenarios. KEY WORDS: Wild boar ; Sus scrofa scrofa ; Ungulate ; France ; population dynamics ; management model ; multi-state model ; Capture-Mark-Recapture ;demography ; sex-ratio ; maternal allocation ; hunted population

Horn antisymmetry in a local goat population

Article

Jan 2014

Fluctuating asymmetry (FA) refers to small random deviations from perfect bilateral symmetry. Directional asymmetry (DA) is defined as population-level deviations from bilateral symmetry that are unimodal and significantly different from symmetry. Lastly, antisymmetry (AS) is a pattern of bilateral variation in which differences exist between sides, but the side that is larger varies randomly among individuals. FA reflects the ability of individuals to undergo stable development, so it may provide a potential measure of individual quality. FA is not likely to be adaptive but both DA and AS are developmentally controlled and are therefore likely to have adaptive significance. Twenty-seven adult females belonging to the Catalan goat population (NE Spain) were studied to assess horn perfect symmetries (in total length and base circumference) as indicators of their fitness. Symmetry was tested by means of Wilcoxon signed test and dispersion values. Platykurtic distributions and plotting the cumulative frequency was used to assess DA and AS. For horn length, but not for horn circumference, AS was revealed. Although AS has been considered to be developmentally controlled and possibly adaptive, the specific processes producing this pattern in Catalan goat horn remain a matter of discussion.

Eur J Wildl Res PRL horn Adolfo

Data

Full-text available

Oct 2013

Prolactin inhibition does not influence horn growth in two wild caprinae species: European mouflon (Ovis orientalis musimon) and Iberian ibex (Capra pyrenaica)

Article

Full-text available

Oct 2012

Studies on seasonal horn development and the endocrine mechanism regulating its pattern in wild ruminants are scarce. The aim of this paper was to study the influence of photoperiod and prolactin (PRL) on horn growth in two wild ruminant species: the European mouflon and the Iberian ibex. Eighteen male ibexes and 13 mouflon rams, maintained in captivity, were divided into three groups: a control group, kept under a natural photoperiod (latitude, 40°25′ N); a long-day group, exposed to an artificial photoperiod of 15-h light and 9-h darkness; and a group treated with bromocriptine (BCR; 10 mg twice weekly during spring and summer) to induce hypoprolactinaemia. Horn length growth (HLG) was recorded weekly for 18 months; plasma PRL concentrations were measured twice monthly by radioimmunoassay. In the ibexes of the long-day group, the period of strong horn development during spring–summer was significantly reduced by 2 months compared with the controls. In the mouflons of the long-day group, this same period was significantly increased by 9 months. In the BCR-treated animals, hypoprolactinaemia was observed in both species, but HLG was the same as in the corresponding controls. The present results suggest that the seasonal pattern of horn growth of wild ruminants is primarily modulated by photoperiod in a species-dependent manner. The persistence of resurgence of horn growth during spring in the BCR-induced hypoprolactinaemic animals of both species suggests that annual variations in blood PRL concentration have no effect on seasonal variation in horn growth.

ECOLOGICAL AND SOCIAL INFLUENCES ON POPULATION DYNAMICS AND GENETICS OF MOOSE IN ALASKA

Article

Full-text available

Jennifer I Schmidt

Intraseasonal Variation in Reproductive Effort: Young Males Finish Last

Article

Full-text available

Dec 2012
AM NAT

Abstract Age-dependent reproductive timing has been observed in females of a number of species; older females often breed earlier in the season and experience higher reproductive success as a result. However, to date, evidence for within-season variation in reproductive effort (RE) for males has been relatively weak. Males are expected to time RE in light of intraseasonal variations in the availability of receptive females and competition with other males. Young males, which are typically smaller and less experienced, might benefit from breeding later in the season, when male-male competition is less intense. Using a long-term data set of Alpine chamois Rupicapra rupicapra, we sought to evaluate the hypothesis that younger males allocate highest RE late in the breeding season, at a time when older male RE has decreased substantially. Our results support this hypothesis, which suggests that intraseasonal variation in RE may be an adaptive life-history trait for males as well as females.

Reduced horn size in two wild trophy-hunted species of Caprinae

Article

Full-text available

May 2011

Factors affecting horn size in wild Caprinae are of biological and socio-economic interest because several species are selectively harvested on the basis of this heritable character. We analysed temporal trends in horn size in two mountain ungulates from south-eastern Spain, the Iberian wild goat Capra pyrenaica and the aoudad Ammotragus lervia. Trophy harvest is the main way in which these two species are exploited, although ‘poor-quality’ aoudads are also selectively removed. In recent years, both populations have suffered drastic decreases in number due to outbreaks of sarcoptic mange that led to the suspension of hunting for several years. Horn length in harvested male wild goats and aoudads declined during our study period. Over an 18-year period, the mean age of male goats shot as trophies rose by four years, while the age of trophy-harvested aoudads decreased by around six months over a 9-year period. Age and environmental conditions during the first few years of life explained 20% of variance in horn size in Iberian wild goat and 53% in aoudad. Population density early in life explained much of the reduction in goat horn size over time. Nevertheless, the major fall in population densities after the sarcoptic mange outbreaks did not lead to a recovery in horn size in either species. We suggest that the selective removal of large-horned animals may contribute to a decline in horn size. Other factors that may also explain the observed pattern include changes in interspecific competition, long-lasting maternal effects and reduced carrying capacity due to overgrazing during high density periods. Unfortunately, our data sets did not allow us to account for the possible effects of these factors.

Antler Size of Alaskan Moose Alces Alces Gigas: Effects of Population Density, Hunter Harvest and Use of Guides

Article

Full-text available

Jan 2009

Moose Alces alces gigas in Alaska, USA, exhibit extreme sexual dimorphism, with adult males possessing large, elaborate antlers. Antler size and conformation are influenced by age, nutrition and genetics, and these bony structures serve to establish social rank and affect mating success. Population density, combined with anthropogenic effects such as harvest, is thought to influence antler size. Antler size increased as densities of moose decreased, ostensibly a density-dependent response related to enhanced nutrition at low densities. The vegetation type where moose were harvested also affected antler size, with the largest-antlered males occupying more open habitats. Hunts with guides occurred in areas with low moose density, minimized hunter interference and increased rates of success. Such hunts harvested moose with larger antler spreads than did non-guided hunts. Knowledge and abilities allowed guides to satisfy demands of trophy hunters, who are an integral part of the Alaskan economy. Heavy harvest by humans was also associated with decreased antler size of moose, probably via a downward shift in the age structure of the population resulting in younger males with smaller antlers. Nevertheless, density-dependence was more influential than effects of harvest on age structure in determining antler size of male moose. Indeed, antlers are likely under strong sexual selection, but we demonstrate that resource availability influenced the distribution of these sexually selected characters across the landscape. We argue that understanding population density in relation to carrying capacity (K) and the age structure of males is necessary to interpret potential consequences of harvest on the genetics of moose and other large herbivores. Our results provide researchers and managers with a better understanding of variables that affect the physical condition, antler size, and perhaps the genetic composition of populations, which may be useful in managing and modelling moose populations.

Combined Effects of Drought and Density on Body and Antler Size of Male Iberian Red Deer Cervus Elaphus Hispanicus: Climate Change Implications

Article

Full-text available

Jul 2009

Hunting management of red deer Cervus elaphus populations may tend to increase population densities to maximise annual yield. Some studies have shown that density and low winter temperatures affect red deer populations in central and northern Europe, but these results cannot be extrapolated to red deer populations in the Mediterranean region where the limiting season is summer instead of winter. The two regions are predicted to experience different climate change effects: while rainfall may increase in northern latitudes, heavier droughts are expected in the Mediterranean region. We studied red deer populations of different densities on 19 hunting estates in southern Spain during two years with contrasting precipitation levels. Our aim was to quantify the combined effects of drought and population density on the development of stags, which is the main economic objective of hunting management in these areas. We found that drought affected body and antler size negatively, and that the effects were more severe in populations of high density. On the basis of our results, we recommend reducing the current densities of red deer in southern Spain to maintain the economic and environmental sustainability of hunting exploitation in the context of global climate change.

4 Hunting seasons in relation to biological breeding seasons and the implications for the control or regulation of ungulate populations

Chapter

Full-text available

Apr 2011

This book considers a number of problems posed by ungulates and their management in Europe. Through a synthesis of the underlying biology and a comparison of the management techniques adopted in different countries, the book explores which management approaches seem effective - and in which circumstances. Experts in a number of different areas of applied wildlife biology review various management problems and alternative solutions, including the impact of large ungulates on agriculture, forestry and conservation habitats, the impact of disease and predation on ungulate populations and the involvement of ungulates in road traffic accidents and possible measures for mitigation. This book is directed at practising wildlife managers, those involved in research to improve methods of wildlife management, and policy-makers in local, regional and national administrations.

Ambient Temperature in Spring Affects Horn Growth in Male Alpine Ibexes

Article

Feb 2002
J MAMMAL

Horn growth in the Caprinae is affected by several factors including age and nutrition, and analysis of annual horn increments can be used to interpret past events. We documented patterns of horn growth in male alpine ibexes (Capra ibex ibex) in the central European Alps and analyzed relationships between annual horn increments, weather, and plant phenology in 2 different climatic regions during 1981-1990. Age accounted for 50% of total variance in horn growth in male alpine ibexes 1-6 years of age. Horn growth differed among climatic regions and calendar years. In years with early onset of vegetation growth, horn growth was enhanced uniformly over all age classes in both climatic regions. Horn growth was a function of ambient temperature during March-May and of plant phenology in spring, implicating onset of growth of vegetation and availability of food resources. Duration of growth of vegetation was assumed to be directly related to date of vegetation onset, but further studies are necessary to test this hypothesis.

Redefining Walrus Stocks in Canada

Article

Full-text available

Sep 2008
ARCTIC

Robert EA Stewart

Defining management units is basic to the sound management of resources. Walrus (Odobenus rosmarus rosmarus) are hunted throughout their range in Canada and are subject to other human activities requiring management decisions. Current management units are based on a comprehensive review and a stock assessment completed in the mid 1990s. Between 1993 and 2004, satellite-linked radio tags provided information on the movements of walrus in Canada's High Arctic. These data were incorporated with other information that has become available since 1995 to reassess walrus management units in Canada. Tagging data and other information suggest that some finer discrimination of walrus populations is needed as a precautionary approach and to formulate testable hypotheses. Specifically, the previous North Water/Baffin Bay walrus stock may be considered to be three stocks: Baffin Bay, west Jones Sound, and Penny Strait-Lancaster Sound stocks. The Foxe Basin population appears to comprise two stocks (North Foxe Basin and Central Foxe Basin) rather than one. Previously suspected subdivisions in the Hudson Bay-Davis Strait population are substantiated by isotopic evidence although sampling on a finer geographic scale is required before this stock can be partitioned. There is new evidence to support the previously postulated separation of the walrus in the Southern and Eastern Hudson Bay stock from all others, but no evidence to warrant subdivision.

Sociality, Mate Choice, and Timing of Mating in American Bison (Bison bison): Effects of Large Males

Article

Nov 2007
ETHOLOGY

We studied group size, composition, and mating activities in American bison (Bison bison) during rut on the Delta Junction Bison Range in interior Alaska, USA, in 1996 and 1997. Our purpose was to determine the effects of large males (≥5 yr old) on mating and associated activities. Groups with large males were larger than those containing smaller males. Most groups of bison were mixed-sex (90%), but large males occurred in only one-half of all groups. Moreover, females in groups with large males were more likely to copulate than those in groups with smaller males, indicating a female preference for large males. Nevertheless, our results are consistent with large males seeking out adult females for mating rather than vice versa. Mating peaked in mid-August during both the study years and was highly synchronous. Scent marking was coincident with mating, an outcome consistent with a hypothesis of such behavior triggering ovulation. Scent marking by large male bison occurred in both male–male and male–female contexts, but was associated most often with sexual activities. No differences in group size occurred with changes in weather or among vegetation types occupied by bison. Group size of bison, however, was larger with increasing distance from the forest edge, which likely was a response to predation risk in this predator-rich environment.

Effects of age, density and sex ratio on reproductive effort in male reindeer (Rangifer tarandus)

Article

Dec 2003
J ZOOL

In sexually dimorphic ungulates, male reproductive success depends on fighting with other males for access to females during a brief rutting season. Large body size is necessary for success in intrasexual competition, and a few large-sized males are often able to monopolize access to female groups. Earlier studies have reported that reproductive effort increases with age until prime-age is reached, and one study that population density lowered effort in (older) males. No study has directly assessed whether there is within-age-class variation in effort resulting from varying levels of intra-male competition. It is reported here the weight loss during the rutting season of 54 individual male reindeer Rangifer tarandus coming from eight herds with varying density (3.3–6.0 deer/km2) and sex ratio (4–28% males). In agreement with earlier studies, reproductive effort was lower for young (1- to 2-year-old) than for prime-aged (3- to 5-year-old) males both on an absolute and relative scale. Among 1-year-old males (n=33), effort was lower as sex ratio became closer to even, but density during the rutting season had no effect. This suggests that yearling males take a more active role when prime-aged males are absent. In addition to the insight into male ungulate life history, understanding male rutting behaviour may also have implications for population dynamics.

Do the determinants of dominance index and social rank in adult rams vary by breed?

Article

Dec 2023
SMALL RUMINANT RES

Dall's sheep horn growth and harvest management in the Mackenzie Mountains, Northwest Territories, Canada

Article

Dec 2023

Across most of their native North American range, the horns of mountain sheep ( Ovis spp.) males are getting smaller, a pattern attributed to selective hunting pressure. We measured the horns of 755 Dall's sheep males ( Ovis dalli dalli ) in the southern Mackenzie Mountains, Northwest Territories, between 2002 and 2017. For each male, we measured the circumference and length of each annulus for the right horn and calculated horn volume for each year. We examined changes in horn size in 4 different outfitter areas, using age at harvest as a covariate. Hunting pressure across years in the study area was consistently low, and this population did not experience the decline in horn size observed in several other mountain sheep populations in Canada. Over the 16‐year period, the average horn volume of harvested males was stable and even increased in 1 outfitter area. Local management of Dall's sheep delivered independently by the guide outfitters in the Mackenzie Mountains appears to contribute to maintaining a population of males that has not been adversely affected by strong selective hunting pressure. The resilience of this management strategy may be challenged by environmental changes associated with rapid warming in northern mountain environments.

Recent advances in ecological research on Asiatic ibex (Capra sibirica): a critical ungulate species of highland landscapes

Article

Full-text available

Mar 2022

Recent Advances in Ecological Research On Asiatic ibex (Capra sibirica): A Critical Ungulate Species of Highland Landscapes

Article

Full-text available

Mar 2022

The Asiatic ibex (Capra sibirica), the largest member of the genus Capra, is widely distributed in Central and South Asia. It is a primitive ibex species of the family Bovidae that is distinct from other ibex species. The Asiatic ibex is distributed in highland landscapes characterized by challenging terrains that have resulted in incomplete knowledge of this species. To understand the research advances in this species, this review summarizes the taxonomic position, global distribution, population size, foraging ecology, sexual segregation, health threat by diseases, and potential threats and conservation biology. Besides, this species is facing increasing impacts of anthropogenic activities and habitat loss induced by global climate change. It also proposes new research perspectives and priorities to understand the advanced ecology of the Asiatic ibex. We also highlight a suite of research gaps that require multidisciplinary approaches. These will increase understanding of the evolution, biology, ecology, and epidemiology of this species.

Consistently high multiple paternity rates in five wild boar populations despite varying hunting pressures

Article

Jan 2021

Intraspecific variations in mating systems have been reported in numerous species, especially when they live in varying ecological contexts. This leads to variability between populations with regard to the proportion of females engaging in multiple male mating, which depends on the number of males available. For hunted ungulate species, hunting is known to influence population structure, especially when males are preferentially targeted for trophy hunting. Here, we investigated how variations in hunting pressure and the yearly proportion of heavy males removed have impacted multiple paternity rates in five wild boar (Sus scrofa scrofa) populations located in similar ecological contexts. We found high rates of multiple paternity in all studied populations, confirming the recently reported promiscuous mating system of wild boar. However, variations in hunting pressure and removal of heavy males did not significantly influence multiple paternity rates, contrary to our expectation. Nonetheless, a slight tendency for a decreasing multiple paternity rate with increasing hunting pressure and for increasing multiple paternity rate with increasing removal of heavy males from the population was detected. Based on these results, we discuss an alternative hypothesis on the ecological processes sustaining the influence of hunting regimes on the mating system. Overall, hunting pressure and management rules might be sufficient to disrupt the mating system in any of the populations, so it is important to continue the sampling of wild boar populations at the European scale, especially in populations with little hunting pressure.

Body size plasticity in North American black and brown bears

Article

Full-text available

Aug 2020

Body size reflects realized physiological niche width at the population level and provides insights into the potential resiliency of a species to natural and anthropogenic perturbations to ecosystems. We analyzed patterns of American black and brown bear body size through a meta‐analysis of data from 18 studies conducted across North America, to evaluate the effects of species, sex, latitude, sympatry, and harvest. We used a bootstrap model selection procedure, which accounted for differences in sample size and population variation between studies, to investigate patterns in body mass. As expected, we found that brown bears were generally larger than black bears and both species were sexually dimorphic (i.e., males were generally larger than females). Black bear body size was not related to latitude, whereas brown bear body size was greatest at intermediate latitudes, possibly due to the presence of salmon. Neither sympatry nor harvest was associated with body size for either species at the geographic scale of our meta‐analyses, but both may warrant consideration at the local scale. Body size, as an index of population health, reflects phenotypic plasticity within species and populations and may serve as a useful indicator of niche utilization. Indeed, understanding large‐scale physiological patterns such as these can assist in understanding past, present, and future changes to realized niches and subsequent resiliency of species and populations.

Ethical issues in trophy hunting

Article

Dec 2011

J. Dobson

Trophy hunting : threat or ally to rare species

Article

Feb 2013

Lucille Palazy

Trophy hunting, which is a form of recreational hunting with the main objective of collecting a trophy of interest, is a controversial subject. This activity could potentially generate an anthropogenic Allee effect (AAE). This demographic process states that the valuation of rarity could drive rare species exploitation and even lead to their extinction. Our project aims at testing the potential for an AEE in trophy hunting. We demonstrate that rare species have a high financial value, regardless of the trophy size, indicating that there is a high demand for those species. We also show that the number of trophies traded internationally and the number of recorded trophies by the Safari Club International (one of the largest clubs for international trophy hunters in the USA) rises as the degree of rarity (as measured by a rarity index) increases. Trophy hunting of rare species has been proposed as a tool to fund their conservation. However, our results indicate that there is a risk of an AAE for rare species. Furthermore, the combined effects of trophy hunting, illegal hunting, corruption as well as the lack of population knowledge and of management controls have potential to result in the unsustainable exploitation of rare species of high financial value. Nonetheless, trophy hunting has potential to generate strong financial incentives that are necessary for wildlife preservation. Such incentives are only likely to be effective if strict measures are required and enforced to prevent overexploitation of rare trophy species

Comportamiento social y de alimentación del rebeco pirenaico (Rupicapra Pyrenaica Pyrenaica)

Article

Full-text available

Nov 2005

Antoni Dalmau

Causes and Consequences of Sexual Selection in a Wild Population

Article

Nov 2011

Katie V. Stopher

Although sexual selection in nature has been studied intensively, much is still unknown about the evolution of mating systems in wild populations: for example, how male competition and female choice interact, or the effect of environmental heterogeneity on selection. Further, important questions remain about the consequences of sexual selection for genetic structuring and genetic variation within populations. In this thesis, I investigate the causes and consequences of sexual selection in a polygynous mammal, the red deer Cervus elaphus. This species is characterized by high male reproductive skew resulting from competition to defend harems of females. Here however, I present evidence for previously unappreciated complexity in the mating system, in terms of female mating behaviour and environmental influences on male-male competition. I then go on to investigate the consequences of non-random mating on co-ancestry and inbreeding in the population. Finally, I investigate methods for separating genetic and environmental sources of covariance between individuals. Specifically, I: (i) Show a surprising degree of female mobility during the breeding season (the 'rut‘). Around 40% of females change harem when in oestrus and almost half of these movements result in paternity for the novel male; however I show that these movements are unlikely to be explained by female choice for mates. (ii) Reveal that variance in male mating success is affected by variation in ecological parameters, in particular the interaction between the number of immigrant males in the rutting population and the temporal synchrony of females. (iii) Demonstrate substantial inter-individual differences in the plasticity of acoustic signals produced by rutting males with changes in social context. (iv) Reveal the existence in this population of three rarely reported mating behaviours in polygynous mammals. I find around a fifth of females mate with the same male in multiple years; female relatives frequently mate with the same male; and males rut in locations close to their relatives. Further, I show these behaviours are associated with higher co-ancestry and inbreeding in the population than expected under random mating. (v) Finally, I investigate how spatial associations between relatives upwardly bias estimates of heritability in four phenotypic traits. I do this by accounting for shared environment effects in animal models by i) inclusion of spatial autocorrelation parameters and ii) a novel multi-matrix approach.

Habitat selection and behavioural strategies of Stone's sheep in northern British Columbia

Article

Jan 2005

Andrew B. D. Walker

Habitat Suitability Model for Bighorn Sheep and Wild Horses in Bighorn Canyon and the Pryor Mountain Wild Horse Range

Article

Antler Characteristics as Related to Social Status of Male Southern Mule Deer

Article

Full-text available

Sep 1986

R. Terry Bowyer

Antler characteristics of southern mule deer (Odocoileus hemionus fuliginatus) and the relationship of these structures to male dominance were studied in Cuyamaca Rancho State Park, San Diego County, California during 1977-1979. Number of antler tines correlated positively with antler characteristics related to the overall size of antlers. The mean date for the shedding of antler velvet was 17 September; the mean date of antler casting was 24 February. Males in larger antler classes tended to shed their velvet and cast their antlers earlier, and performed more aggressive and sexual behaviors than smaller-antlered males. Males interacted aggressively more often with opponents in the same antler class than with those in different classes. Males in larger antler classes typically defeated smaller-antlered opponents. Only males with large antlers were observed to copulate with females. Number of antler times provided a reliable measure of social rank and perhaps reproductive success for male southern mule deer.

The alternative mating strategies of male topi, Damaliscus lunatus

Article

Full-text available

Feb 1991
APPL ANIM BEHAV SCI

Leonard Morris Gosling

Form and flexibility of the mating strategies of male topi (Damaliscus lunatus) appear to be adaptations to patterns of movement by females and their grouping behaviour and to competition with other males for access to females. Most males defend resource territories, but the size and structure of those territories are highly variable. In the productive and homogeneous grass swards where large concentrations of topi congregate in the wet season, intrasexual competition is intense and territories usually measure < 0.2 km2. Where the sward is very heterogeneous, females occur in small groups because the best food for each season is available only in small amounts. Here, male intrasexual competition is less intense and males defend territories of up to 2 or 3 km2. In the homogeneous areas, female ranges include many small male territories; in the areas of heterogeneous grassland, some females remain within single male territories. There is continuous variation between these extremes.

Forced Copulation in Waterfowl

Article

Full-text available

Jan 1983
BEHAVIOUR

Although almost all Anatidae have basically monogamous mating systems, males of 39 species have been observed to perform or attempt forced copulation (FC). In the case of mallard Anas platyrhynchos, the interpretation of FC as a secondary insemination method whereby paired males increase their reproductive success by fertilizing some of the eggs laid by females other than their mate is supported. FCs are performed by paired males; they occur during periods in the breeding season when eggs are being fertilized; they are directed mainly at females in prelaying and laying condition; paired males usually defend their mates against males attempting FC (suggesting defence of genetic paternity); paired males have been sent to copulate forcibly with their own mates after the latter have been subjected to FC (suggesting an antidote insemination strategy). Studies of the lesser snow goose Anser c. caerulescens,northern pintail Anas acuta and lesser scaup Aythya affinis indicate that FC is a secondary reproductive strategy of paired males in these species also. Observations on 13 species of dabbling duck provide additional evidence for the selection of fertile females as FC targets and the development of male tactics for achieving and combating FC. It is difficult to rule out the possibility that females could derive certain benefits from FC inseminations (eg genetic diversity of offspring) but the costs and risks of being involved in FC assaults can be high and the females apparently try to avoid FC. FC probably does not occur in swans, most geese and shelducks because it is incompatible with the major roles that paired males play in defence of breeding territories, mates, nest-sites and broods in these groups. The occurrence of FC in snow geese and Ross goose Anser rossii facilitated by colonial nesting. Among dabbling ducks, male territoriality is associated with strong mate-guarding and these characteristics appear to conflict with male FC activities.-from Authors

Effects of Population Density on Horn Development in Bighorn Rams

Article

Full-text available

Jul 1998
J WILDLIFE MANAGE

Trophy hunting is a management goal for many populations of ungulates and has important implications for conservation because of the economic value of trophy males. To determine whether population density affected horn growth of males, a marked population of bighorn sheep (ovis canadensis) in Alberta, Canada, was studied for 27 years. For the first 9 years, population density was kept stable by removing adult females; afterwards, the numbers of ewes and yearlings tripled before beginning to decline. Horns were measured during repeated captures of marked rams. As the number of adult ewes and yearlings increased, ram horns were shorter and thinner because of decreased horn growth before 4 years of age. Some compensatory horn growth may have occurred at 5 years of age. The effects of population density on horn growth ceased when rams left the nursery groups to join all-male groups. Doubling of male numbers had no detectable effect on net annual horn growth of males greater than or equal to 4 years old. Sp

Survival of Male Bighorn Sheep in Southwestern Alberta

Article

Full-text available

Jan 1989
J WILDLIFE MANAGE

Marco Festa-Bianchet

Yearly mortality averaged 33% for yearling Ovis canadensis and 18% for 2-yr-olds; 7 of 16 deaths in these age classes occurred during a pneumonia epizootic. Yearling males were more likely to die during the epizootic than yearling females. Overwinter survival of male lambs varied among years and was lower after the epizootic. Hunting accounted for 68% of the 28 deaths of males ≥5 yr old. Natural mortality of males ≥3 years old averaged 10% yearly. Mortality of young males was higher than reported by studies based on skull collections. -from Author

Structure and ontogeny of dominance relationships among bighorn rams

Article

Full-text available

Feb 1991

Dominance relationships among bighorn rams (Ovis canadensis) were studied over a 2-year period to quantify structure and development. Rams exhibited a stable, linear hierarchy that was strongly correlated with age. Dominance relationships were not evident until rams were at least 1 year old. Individuals gained in rank as they grew older and by fighting their way up the rank order. Rams aged 4–7 years interacted at the highest rates. After 10 years of age rams declined rapidly in condition, spent more time alone, and interacted less frequently with other rams.

Disruptive mating behavior by subadult Armenian wild sheep in Iran

Article

Full-text available

Feb 1991
APPL ANIM BEHAV SCI

The mating behavior of an insular Armenian wild sheep population (Ovis orientalis gmelini) and a Transcaspian urial (Ovis orientalis arkal) population was quantified during the rutting season in December 1972, and November and December 1973, respectively. Males were grouped into two age classes; Class I (less-than-or-equal-to 4 years) and Class II (greater-than-or-equal-to 5 years). Typically, older rams prevent younger rams from participating in the rut through threatening gestures; subadult rams will not ordinarily challenge adult rams as was the case in the Transcaspian population. In the Armenian population, subadult rams hurriedly approached ewes and chased and mounted ewes. Subadult Armenian rams disrupted the social stability of the population resulting in wasted energy, particularly in ewes, at a critical time of the year. Wildlife managers should monitor wild ungulate populations to determine if such disruptions are occurring and develop preventative management strategies.

Why don't bull moose eat during the rut?

Article

Full-text available

Jan 1990

Dale Miquelle

Reduced forage intake by males is generally believed to coincide with the peak of rutting activities in many ungulates. Activity budgets of bull moose (Alces alces) in Denali National Park and Preserve (DNPP) and Isle Royale National Park (IRNP) were analyzed to assess: (1) if time spent foraging decreased during the rut; (2) the timing of reduced forage intake; (3) whether there was variation in feeding time among bulls of varying size; and (4) the proximate mechanism and adaptive value of reduced forage intake. Time spent feeding by bull moose began to decrease around 1 September: large bulls completely ceased feeding for approximately 2 weeks, with median dates of feeding cessation at 18 and 20 September for IRNP and DNPP, respectively. Small bulls fed at reduced rates, but did not cease feeding. Although large bulls in both study sites spent large amounts of time engaged in social behavior during the period of appetite suppression, much of their active time was also spent standing inattentive, i.e., engaged in no activity (45.5% in IRNP, 29.8% in DNPP), suggesting that a constraint in time budgets did not limit opportunities to feed. Forage intake reduction is more likely mediated through a physiological mechanism. Feeding cessation did not coincide with the peak of the rut: at DNPP the median date of feeding cessation was significantly earlier than the median date of breeding behavior and fighting. The timing of feeding cessation coincided with that of scent-urination at both study sites, raising the possibility that appetite suppression may be a byproduct of physiological processes associated with chemical communication.

Effects of age, sex, disease, and density on survival of bighorn sheep

Article

Jun 1997

Longitudinal studies of survival are valuable because age-specific survival affects population dynamics and the evolution of several life history traits. We used capture-mark-recapture models to assess the relationship between survival and sex, age, population, year of study, disease, winter weather, and population density in two populations of bighorn sheep (Ovis canadensis) in Alberta, Canada. The Ram Mountain population, monitored for 20 yr, more than doubled in density; the Sheep River population, monitored for 13 yr, experienced a pneumonia epizootic. Yearling survival varied among years and was lower than that of older sheep of the same sex, except for yearling males at Ram Mountain. Yearling females at Ram Mountain were the only sex-age class exhibiting density dependence in survival. Senescence was evident for both sexes in both populations. Female survival from age 2 to age 7 was very high in both populations, but males aged 2 and 3 yr enjoyed better survival than males aged 4-6 yr. Our data support the suggestion that where hunters remove many males older than 5 yr of age, the natural mortality of males increases at 3-5 yr, possibly because young males suffer a mortality cost of participating in rutting activity. The decline in survival for sheep older than 7 yr was greater for males than for females. Survival was lower for males than for females, both among prime-aged sheep (0.896 vs. 0.939 at Sheep River; 0.837 vs. 0.945 at Ram Mountain) and among older sheep (0.777 vs. 0.859 at Sheep River; 0.624 vs. 0.850 at Ram Mountain), but not among yearlings. Survival of sheep aged 2-7 yr was not significantly different between the two populations. Winter weather did not affect survival. Survival of sheep 2 yr of age and older did not vary significantly between years, except at Sheep River where survival of prime-aged sheep of both sexes was lower in the year of the pneumonia epizootic. Studies of survival of mountain sheep based upon skull collections may have overestimated survival of young rams. Our results underline the need for accurate information on age-specific survival.

Antler Characteristics of George Reserve White-Tailed Deer

Article

Jul 1982

Dale R. McCullough

Energy Expenditure for Reproduction in Male Red Deer

Article

May 1990

Introduction to the Symposium: Alternative Reproductive Tactics

Article

May 1984

Bivariate versus multivariate analyses of sexual selection in Red deer

Article

Feb 1987

Robert M. Gibson

Social Behavior and Breeding System of the Desert Mule Deer

Article

Aug 1978

Thomas E. Kucera

Desert mule deer (Odocoileus hemionus crooki) were observed in Big Bend National Park, Texas, during rut to determine their breeding system and to describe and quantify social behavior. The deer were gregarious throughout the study; group sizes ranged from one to 24, with a mean of 5.2. Male-male acts such as head-toss, rub-urination, antler thrash-forehead rub, and chase were performed in dominance and agonistic interactions, most frequently by the larger antler classes, and were closely associated with rut. Sparring was inversely associated with rut, and was most frequent in the smaller antler classes. Among female-female acts, the strike and flail were inversely associated with rut. Tending bonds were formed between individual bucks and estrous does. No attempt by bucks to herd or defend groups of does was seen; rather, the dominant buck in any group tended a doe until mating or until displacement by a more dominant buck. Frequency of heterosexual behavior was positively correlated with antler classes and increased among larger classes at an accelerating rate. Heterosexual behavior by males of lesser dominance was not tolerated.

Social maturation and productivity in bighorn sheep: are young males incompetent?

Article

Feb 1991
APPL ANIM BEHAV SCI

D. M. Shackleton

Some wildlife biologists and managers are concerned that ungulate population productivity may decline when hunting causes a bias in the male age structure favoring young males. Young males are assumed to be incapable of successfully courting females, to prolong the mating season, to create confusion during mating because of unstable social hierarchies, or to cause some combination of these. Here, results are presented of a natural experiment involving two bighorn sheep (Ovis canadensis candensis) populations: one unhunted and the other where most of the mature males were removed during the hunting season. One month later, the remaining young males courted and successfully copulated with adult estrous females. Comparing courtship behavior of these young males with that of males more than three times their age in the unhunted population with a “typical” male age structure, showed no significant qualitative or quantitative differences. However, young males in the unhunted population not only failed to copulate with estrous females but also performed mainly immature patterns in male-male interactions, even when they were the largest males in the interaction. Social maturation in mountain sheep is not simply a function of chronological age but is related to a population's social structure and composition.

Dall Sheep Demography in McKinley Park and a Reevaluation of Murie's Data

Article

Oct 1976
J WILDLIFE MANAGE

Population numbers, age-sex composition, and the male age structure of Dall sheep (Ovis dalli) were studied in Mount McKinley National Park, Alaska, in the summer of 1972. Age of living males was estimated either by counting horn annuli from photographs taken in the field or, if annuli could not be discerned in the photographs, on the basis of horn size. The correlation of age with horn size first was determined for the former group by multiple regression analysis; the resultant equation then was used to estimate age in the latter group. Composition ratios and the sample of males whose ages were estimated were used to establish the age structure of the living male segment of the population. The results demonstrated that the age structure had not been stationary over the past several years. Differences in numbers in each age-class were due to marked variability in initial size and in mortality rates of the cohorts comprising the population. Quantitative analysis of skull data collected by A. Murie from 1937 to 1941, which have been used widely in the construction of life tables, demonstrated that the age structure was not stationary during the period the skulls accumulated. Analyses of changes in population size and of variation in natality rates suggested that the pattern of the life tables was due not only to variation in age-specific survivorship but also to marked variation in initial size of the actual cohorts comprising the samples. Natality was inversely correlated with snowfall and density. First-year survivorship was not correlated with natality rate, indicating that the factors affecting these demographic parameters varied substantially from year to year.

Dall Sheep Reproduction

Article

Jul 1978
J WILDLIFE MANAGE

Lyman Nichols

I studied the reproductive cycle of Dall sheep (Ovis dalli dalli) in 3 herds in the Kenai Mountains, Alaska. The rut was predicted to extend from 16 November through 19 December 1970, and from 18 November through 18 December 1971. All adult ewes collected throughout the winter were pregnant. Three of 4 yearling ewes were pregnant and no female lambs had reached puberty. Although some long yearling rams appeared physiologically capable of reproduction, they were unlikely to participate in breeding activities because of behavioral constraints. The mean gestation period was 171 days. Fetal growth curves are presented. Lambing dates were not uniform between years or herds. Peak dates of lambing for the 3 herds over 4 yr ranged from 20 May to 31 May. Lambing success averaged 31.8 lambs per 100 ewes and was not significantly different from the statewide average of 36.6. There were negative correlations between increasing winter snow depth and lambing success and between average maximum winter winds and snow depth. Positive correlation was found between average maximum winter temperatures and snow hardness, which, in turn, was negatively correlated with lambing success.

Activity in a hunted and an unhunted herd of Dall sheep

Article

Feb 1991
APPL ANIM BEHAV SCI

In three sampling areas (two unhunted, one hunted), we compared activity patterns of Dall sheep rams (Ovis dalli) of different horn size during the rut. In all three areas rams with horns and smaller rams were less frequently seen in ewe bands as the rut progressed. In one area where we documented activity budgets, we observed equivalent budgets for ewes and rams with horns . Older rams spent less time foraging than young rams, except that rams with horns curled spent less time foraging than full-curl rams late in the rut. Display frequencies of rams were similar to those of full-curl rams and considerably higher than those of smaller-horned rams early in the rut. These results suggest that the rut is more energy costly for old rams than for young rams, but that it may be most costly for the next-to-largest horn-curl class rams (e.g. rams in unhunted populations) rather than the dominant rams (full-curl and larger). Rams in the next-to-largest horn-curl class in the hunted herd, however, did not acquire the higher display rates (e.g., rams had equally low display rates in both the hunted and unhunted herds).

Validity of Horn Segment Counts in Aging Bighorn Sheep

Article

Jul 1966
J WILDLIFE MANAGE

Valerius Geist

Horn segment counts were compared with chronological age of 21 bighorn rams (Ovis canadensis) of known age, and were found to coincide.

New evidence of high frequency of antler wounding in cervids

Article

Feb 1986

Valerius Geist

Seventy-two tanned, dehaired hides of four species of cervids from western Canada were examined for evidence of injuries. Combat injuries were segregated from injuries incurred from other sources. Forty-six of 55 males 1.5 years of age and older were scarred, as were 14 of 15 females. Of 15 males 1.5 years of age, 7 showed no scars, nor did two 6-month-old male fawns. Only 1of 22 male cervids over 2.5 years of age showed no combat scars. The frequency of wounding in males was 0–225, and in females0–18 per individual. About three-quarters of the scars were on the neck and haunches, about equally divided between these areas. The longest healed scar measured 420 mm; about 20% of the scars exceeded 100 mm in length. Field observations greatly underestimate wounding in cervids. A few males appear to opt out of rutting, but opt in when opportunity allows. The "dove" strategy is rare, but evidence from hides indicates that it does exist, confirming field observation.

Foraging Ecology of Mountain Sheep: Implications for Habitat Management

Article

Jul 1985
J WILDLIFE MANAGE

Ovis canadensis studied in Colorado preferred open habitats with a high density of acceptable forages and avoided habitats with vegetation obstructing visibility. Ewes and rams were more alert than were juveniles during foraging periods; ewes with young lambs were most alert. Intra-group spacing was positively correlated with habitat visibility. Foraging efficiency was negatively related to distance from escape terrain and positively related to habitat visibility and to group size. Foraging in large groups (>10 sheep) appears to be a behavioral adaptation enabling sheep to utilize less secure habitats.-from Authors

Bighorn sheep, climbing accidents, and implications for mating strategy

Article

Jan 1987
MAMMALIA

Marco Festa-Bianchet

Social ontogeny and behavioural diversity: Consequences for bighorn sheep Ovis canadensis inhabiting desert and mountain environments

Article

Jan 1979

J Berger

Effects of Hunting on Survival and Productivity of Dall Sheep

Article

Apr 1990
J WILDLIFE MANAGE

We examined Dall sheep (Ovis dalli) populations in Alaska to determine if the harvest of old rams affected either the survival of young rams or lamb and yearling production. We hypothesized that proportions of young rams would be lowest in areas where old rams were most heavily harvested if survival of young rams is depressed when old rams are culled. However, there were no significant (P > 0.05) relationships between the proportions of young and old rams in analyses of helicopter and ground surveys or fixed-wing aerial surveys. Two comparisons of population composition between nearby unhunted and hunted populations showed no relationship between the harvest of old rams and the proportions of young rams in the populations, and no effect of hunting on lamb or yearling production was evident. Likewise, a comparison of population composition in 2 areas soon after closure to hunting and several years later showed no clear relationship in proportions of old rams and young rams. Overall, survival of young rams and production of lambs and yearlings did not appear to be affected by harvest of old rams, but the hypothesis deserves more rigorous testing.

Group size, foraging, and antipredator ploys: An analysis of bighorn sheep decisions

Article

Mar 1978

Joel Berger

1. Several aspects of the foraging behavior of California bighorn sheep (Ovis canadensis californiana) were studied in homogeneous habitats in the interior of British Columbia, Canada. The manner in which an individual sheep foraged was based upon the size of group within which it was found. 2. In small groups (five or less individuals) sheep foraging efficiency was poor and interruptions of foraging to scan the environment were frequent. 3. Alarm vocalizations and other conspicuous behaviors tend to alert their neighbors to the presence of disturbances. It appears that these signals cannot be based solely as the result of kin selection.

Mating patterns and reproductive strategies in a community of wild chimpanzees (Pan troglodytes schweinfurthii)

Article

Nov 1979

C.E. Tutin

1. The sexual behaviour of a chimpanzee community in the Gombe National Park, Tanzania, was studied intensively for 16 months. Additional information came from 15 years of demographic and behavioural data accumulated by Jane Goodall and members of the Gombe Stream Research Centre. 2. The mating system of the Gombe chimpanzees is flexible and comprises three distinct mating patterns: (a) opportunistic, non-competitive mating, when an oestrous female may be mated by all the community males; (b) possessiveness, when a male forms a special short-term relationship with an oestrous female and may prevent lower-ranking males from copulating with her; and (c) consortships, when a male and a female leave the group and remain alone, actively avoiding other chimpanzees. While males took the initiative in possessive behaviour and consortships, females had to cooperate for a successful relationship to develop. 3. Data from 14 conceptions indicated that the majority of females (9) became pregnant while participating in the restrictive mating patterns, possessiveness and consorting. It could be established definitely that seven of these females were consorting during the cycle in which they conceived. As 73% of the 1137 observed copulations occurred during opportunistic mating, 25% during possessiveness, and only 2% during consortships, there was no correlation between copulation frequency and reproductive success. 4. Adult males showed differential frequencies of participation in the restrictive mating patterns. Male age, dominance rank, and the amount of agonistic behaviour directed to females showed no correlation with participation in the restrictive mating patterns. The following male characteristics did show significant, positive correlations with involvement in the restrictive mating patterns: (a) the amount of time spent in the same group as oestrous females, (b) the proportion of that time spent grooming oestrous females in groups, and (c) the frequency with which males shared food with females. While dominance ranks of the adult males showed no consistent correlation with involvement in the restrictive mating patterns, it was clear that the most dominant male did gain an advantage. He was the only male able to monopolise oestrous females by showing possessive behaviour. 5. Consortships appeared to be the optimal reproductive strategy for males (with the exception of the most dominant) and females, as they gave males the highest probability of reproductive success, and allowed females to exercise choice. However, there appeared to be disadvantages associated with consort formation; the greatest of these was the increased risk of intercommunity encounters. While all individuals have the potential to practice each mating pattern, the strategy actually used at any moment will be determined by variables both within the individual, e.g. age, physical condition, dominance position; and by social factors in the group, e.g. general stability of male dominance relationships, presence of a strong alpha male, existence of special male-female relationships.

Mating in bighorn sheep: Frequent male reproduction via a high-risk 'unconventional' tactic

Article

Jan 1997

Rocky Mountain bighorn rams use three distinct tactics in competition for mates. Two tactics (tending and blocking) feature defense and cooperative mating over a relatively prolonged consort period (up to 3 days). In the coursing tactic, subordinate rams fight dominants for temporary copulatory access (lasting seconds) to defended ewes. By combining population-wide genetic (microsatellite) exclusion of paternity, behavioral data and a model of bighorn reproductive competition, we estimated that coursing rams fathered 44% of 142 lambs assigned paternity in two natural populations. In one population, the probability of successful defense against coursing was lowest among rams that had many female consorts and held highest dominance rank. Even so, per capita annual male reproductive success was positively associated with social rank in both herds when measured in terms of fall conceptions. The proportion of coursing versus defending ram matings in each population (0.36 and 0.39) was similar to the corresponding fraction of lambs (0.43 and 0.47) fathered by coursing rams, suggesting that sperm competition approximated a fair lottery. Male traits important in gaining social status and obtaining cooperative consorts with ewes were different and potentially in conflict with those needed to defend against (and practise) coursing. Although the concussive weapons (horns) of rams are less dangerous than, for example, the piercing weapons of other bovids, injury from falls and horn blows during coursing brawls may cause death, handicap future mating competition or increase the risk of predation. Coursing is a rare example of an unconventional alternative mating tactic that is high-gain and high-risk.

Time-energy budgets and optimization

Article

Jan 1983

Eberhard Curio

Since the process of natural selection entails a comparison of phenotypes and choosing of the best, optimality theory appears appropriate to identify selection pressures. Optimality theory doesnot test whether an organism is designed optimally — it assumes it. The ingredients of a complete optimization model are outlined and two approaches are exemplified. Both time-energy-budgeting and Pontryagin's maximum principle lead to semi-quantitative predictions about, e.g., an animal's behavior; they merely entail an inequality formalism. A discrepancy between prediction and test would not yet show a behavior to be maladaptive since several other explanations are possible. Animals optimize their behavior over intervals ranging from less than a second to months or years. It is unknown whether, with a long interval, the animal makes use of the opportunity to revise its decision(s). Present optimal foraging models predicting, e.g., diet breadth are too simple in that foragers a) may not always maximize energy intake, as postulated, b) have to allow for nutrient, toxin and remedial content of food items, and/or c) have to allow for interaction of items, annihilating their ranking along a unidimensional scale of profitability.

The logical stag: Adaptive aspects of fighting in Red deer (Cervus elaphus L.)

Article

Feb 1979

For red deer stags, fighting both has appreciable costs and yields considerable benefits. Up to 6% of rutting stags are permanently injured each year, while fighting success and reproductive success are closely related, within age groups as well as across them. Fighting behaviour is sensitive to changes in the potential benefits of fighting: stags fight most frequently and most intensely where potential benefits are high and tend to avoid fighting with individuals they are unlikely to beat. The relevance of these findings to theoretical models of fighting behaviour is discussed.

Spatial and temporal components of the mating systems of kudu bulls and red deer stags

Article

May 1984

Norman Owen-Smith

Observations were made on greater kudu (Tragelaphus strepsiceros) in the Kruger National Park in South Africa. Data on movement patterns, courtship, dominance interactions and proportion of time spent in various activities by males during the breeding season are presented. Comparative data on the apportionment of time by red deer (Cervus elaphus) setages were obtained on the Isle of Rhum, Scotland. While spatial components of male reproductive behaviour were similar in the two species, time-investments differed markedly. Kudu bulls showed little change in time spent feeding and moving during the breeding season, did not herd females and tolerated the presence of younger males. In contrast, red deer stags almost ceased feeding and greatly increased their time spent moving and in sexual or dominance-related activities. Thus the spatial and temporal components of male mating strategies can vary independently and require separate evolutionary explanaions. Comparative data for other ungulates are sparse, but suggest that time-investments are influenced by the duration of the breeding season and the breeding sex ratio. However, kudu bulls incur high mortality costs despite their low time-investments in reproductive activities.

Alternative reproductive strategies and tactics: Diversity within sexes

Article

Feb 1996
TRENDS ECOL EVOL

Mart R. Gross

Not all members of a sex behave in the same way. Frequency- and statusdependent selection have given rise to many alternative reproductive phenotypes within the sexes. The evolution and proximate control of these alternatives are only beginning to be understood. Although game theory has provided a theoretical framework, the concept of the mixed strategy has not been realized in nature, and alternative strategies are very rare. Recent findings suggest that almost all alternative reproductive phenotypes within the sexes are due to alternative tactics within a conditional strategy, and, as such, while the average fitnesses of the alternative phenotypes are unequal, the strategy is favoured in evolution. Proximate mechanisms that underlie alternative phenotypes may have many similarities with those operating between the sexes.

Population Growth, Fecundity, and Survivorship in Recovering Populations of Bighorn Sheep

Article

Dec 2000
RESTOR ECOL

The single greatest obstacle to the restoration of large, healthy, populations of bighorn sheep (Ovis canadensis) in the western United States is epizootic outbreaks of bronchopneumonia that may kill 20-100% of the animals in populations. Although the species is capable of rapid initial growth rates following restoration into new habitat (lambda = 1.23-1.30 have been observed), these rates of increase are typical only a few years following the release of a population, and then most populations either decline to extirpation or remnant status (<30 animals) or remain at <100 individuals. We studied the fecundity and survivorship of three increasing, and three declining and suspected diseased, populations of bighorn sheep (the latter were subjected to outbreaks of bronchopneumonia) located in or near several large national parks in the western United States from 1991 to 1996. Titers verified both population categories were exposed to the bacteria Pasteurella haemolytica serotypes 3; 4; and 3, 4, 10; Moraxella sp., and parainfluenza-3 and bluetongue (BT) viruses. Pregnancy rates of adult ewes were not different in increasing or decreasing populations (pooled rate = 0.93; p = 0.57), but pregnancy rates of yearlings were lower (0.00 for decreasing vs. 0.33 for increasing populations), initial production of lambs and annual recruitment of lambs was lower (0.14, decreasing vs. 0.66, p < 0.05). Adult survival was lower during: the first year of an epizootic, 0.62, in one population, but recovered to 0.85 by the second and subsequent years. Survival of adult rams was variable in diseased populations; in two populations rams appeared to be disproportionately impacted, but in a third population rams survived better during the epizootic. In all the increasing park (unhunted) populations, adult ram survival (0.94 +/- 0.01) was higher than adult ewe survival (0.89 +/- 0.02) (p = 0.10), in contrast to published information from hunted populations where ram survival was lower. Removal of about 20% of one population for restorations severely impacted one declining population. Removals of 12-20% appeared to be excessive and were not readily compensated for in the Canyonlands National Park desert bighorn population. Disease was a significant limiting factor to restoration of bighorn sheep in the study areas; six of 11 total recovering populations we monitored closely were negatively influenced by apparent disease at some time during our observations.

On the Interrelation of External Appearance, Social Behaviour and Social Structure of Mountain Sheep

Article

Apr 1968
Z Tierpsychol

V Geist

ZusammenfassungEs werden soziale Verhaltensmuster amerikanischer Wildschafe beschrieben.Die Schafe wurden nach ihrer äußeren Erscheinung in 7 oder 8 Klassen eingeteilt, die stufenförmig vom Lamm zum alten, großgehörnten Widder führen. Es ergab sich:1Schafe von gegenüberliegenden Enden dieser Reihe schließen sich in eigene Gruppen zusammen: eine “Altherrngruppe” und eine “Mutter-Kindgruppe”.2Geschlechtsreife Widder können mit Schafen aller Klassen Beziehungen aufnehmen, Weibchen und Jungtiere dagegen fast ausschließlich mit Schafen von ihren eigenen Körper- und Horngrößen abwärts.3Widder bevorzugen als Sozialpartner ♂♂ gleicher Horngröße oder erwachsene ♀♀4Widder behandeln alle Rangtieferen gleich, ob ♂♂, ♀♀ oder Jungtiere.5Das erwachsene, nicht brünftige ♀ benimmt sich wie ein geschlechtsunreifes Jungtier, das brünftige ♀ wie ein geschlechtsreifes untergeordnetes ♂.6Schafe lassen sich in zwei typische Verhaltensgruppen einteilen: eine der “Männer” und eine der “Jugendlichen”.7Jede Gruppenbildung beruht auf dem Antagonismus dieser beiden Schlüsseltypen, welche ihrerseits auf sozialen, innerartlichen Verhaltensweisen begründet sind. “Männergruppen” bestehen daher nicht nur aus Widdern, sondern schließen auch die brünftigen ♀♀ ein; und die “Mutter-Kindgruppe” setzt sich aus nicht-brünftigen Schafen und nicht-geschlechtsreifen Jungtieren zusammen, welche alle dem Verhaltenstypus der “Jugendlichen” angehören.8Wenn untergeordnete Widder einem Dominanten gegenüberstehen, geben sie sich offenbar für ein brünftiges ♀ aus.9In die Schafsozietät wird das Individuum nicht nach Alter und Geschlecht eingeordnet, sondern nach seiner Größe und Rangordnung.

Mating in Bighorn Sheep: Multiple Creative Male Strategies

Article

Sep 1984

John T Hogg

Rocky Mountain bighorn rams obtained copulations by defending single estrous ewes (tending), fighting tending rams for temporary access to defended ewes (coursing), or moving and holding ewes away from other rams beyond the periphery of a traditional tending area (blocking). Coursing and blocking illustrate a feature of many male alternative mating strategies: the ability of males regularly to create mating opportunities.

Dominance Rank, Copulatory Behavior, and Differential Reproduction

Article

Jul 1982

Donald A. Dewsbury

The view that high social rank is associated with high levels of both copulatory behavior and the production of offspring is widespread in the study of animal behavior. In order to demonstrate the validity of this hypothesis it is necessary first to resolve ambiguities in the concept of dominance and to assign ranks by means of valid procedures. Second, copulatory behavior must be properly sampled, measured, and related to rank. Finally, it must be demonstrated that rank and increased copulatory behavior actually lead to increased reproduction. Each step in this process entails conceptual and methodological difficulties. There have been many studies of rank and copulatory behavior, fewer of rank and differential reproduction, and very few of rank, copulatory behavior, and differential reproduction. The consistency of results obtained varies with taxon; results of particular consistency appear in studies of carnivores and ungulates. Both the concept of dominance and the validity of the hypothesis relating it to copulatory behavior and to differential reproduction appear viable for at least some species, although the body of data relating rank to both copulation and differential reproduction remains minimal.

Influence of trophy hunting and horn size on mating behavior and survivorship of mountain sheep

Abstract

No full-text available

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