Hunted Populations Research Articles

Can survival analyses detect hunting pressure in a highly connected species? Lessons from straw-coloured fruit bats

Animal behaviour, social structure and population dynamics affect community structure, interspecific interactions, and a species' resilience to harvesting. Building on new life history information for the straw-coloured fruit bat (Eidolon helvum) from multiple localities across Africa, we used survival analyses based on tooth-cementum annuli data to test alternative hypotheses relating to hunting pressure, demography and population connectivity. The estimated annual survival probability across Africa was high (≥0.64), but was greatest in colonies with the highest proportion of males. This difference in sex survival, along with age and sex capture biases and out-of-phase breeding across the species' distribution, leads us to hypothesize that E. helvum has a complex social structure. We found no evidence for additive mortality in heavily hunted populations, with most colonies having high survival with constant risk of mortality despite different hunting pressure. Given E. helvum's slow life history strategy, similar survival patterns and rate among colonies suggest that local movement and regional migration may compensate for local excess hunting, but these were also not clearly detected. Our study suggests that spatio-temporal data are necessary to appropriately assess the population dynamics and conservation status of this and other species with similar traits.

‘Flow’ and satisfaction of Michigan youth waterfowl hunters: Implications for hunter retention

A consistent decrease in the number of individuals taking up recreational hunting in North America is cause for concern by game management agencies. As older hunters retire from hunting, young hunters provide a natural segue for future hunting populations. Measures of ‘flow’ and satisfaction with hunting experiences provide valuable information about youth and the potential for retention. Flow theory and satisfaction were used to: (a) characterize the extent to which participation in recreational hunting activities can result in ‘flow’ experiences; (b) explore how ‘flow’ and satisfaction are related to youth waterfowl hunting experiences; and (c) examine intentions to continue hunting. Interest in the hunt, happiness, and intrinsic motivation were important factors in youth’s waterfowl hunting experience. Ninety-seven percent of respondents indicated the intention to continue waterfowl hunting in the future, therefore providing support for special hunting experiences where mentor–mentee relationships are central to satisfaction and ‘flow’ during the hunt.

Line Transect Surveys Underdetect Terrestrial Mammals: Implications for the Sustainability of Subsistence Hunting.

Conservation of Neotropical game species must take into account the livelihood and food security needs of local human populations. Hunting management decisions should therefore rely on abundance and distribution data that are as representative as possible of true population sizes and dynamics. We simultaneously applied a commonly used encounter-based method and an infrequently used sign-based method to estimate hunted vertebrate abundance in a 48,000-km2 indigenous landscape in southern Guyana. Diurnal direct encounter data collected during three years along 216, four-kilometer -long transects consistently under-detected many diurnal and nocturnal mammal species readily detected through sign. Of 32 species analyzed, 31 were detected by both methods; however, encounters did not detect one and under-detected another 12 of the most heavily hunted species relative to sign, while sign under-detected 12 never or rarely collected species relative to encounters. The six most important game animals in the region, all ungulates, were not encountered at 11–40% of village and control sites or on 29–72% of transects where they were detected by sign. Using the sign methodology, we find that tapirs, one of the terrestrial vertebrates considered most sensitive to overexploitation, are present at many sites where they were never visually detected during distance sampling. We find that this is true for many other species as well. These high rates of under-detection suggest that behavioral changes in hunted populations may affect apparent occurrence and abundance of these populations. Accumulation curves (detection of species on transects) were much steeper for sign for 12 of 16 hunted species than for encounters, but that pattern was reversed for 12 of 16 species unhunted in our area. We conclude that collection of sign data is an efficient and effective method of monitoring hunted vertebrate populations that complements encounter and camera-trapping methods in areas impacted by hunting. Sign surveys may be the most viable method for large-scale, management-oriented studies in remote areas, particularly those focused on community-based wildlife management.

Leave before it's too late: anthropogenic and environmental triggers of autumn migration in a hunted ungulate population.

Autumn has to a large extent been neglected in the climate effect literature, yet autumn events, e.g., plant senescence and animal migration, affect fitness of animals differently than spring events. Understanding how variables including plant phenology influence timing of autumn migrations is important to gain a comprehensive understanding of the full annual cycle of migratory species. Here we use 13yr of data from 60 male and 168 female red deer (Cervus elaphus) to identify triggers of autumn migration. We relate the timing of autumn migration to environmental variables like snow fall, temperature, and plant phenology (NDVI), and to onset of hunting, sex, and migration distance. Severe weather has been suggested as the main trigger of autumn migration, but we found that the majority of the individuals had left the summer range well before snow fall (80.3%) and frost (70.5%), and also before the peak deterioration in forage quality (71.9%). Declining temperatures were associated with a higher daily migration potential. Onset of hunting showed the largest effect on migration potential, with a marked increase during the first days of hunting. Individuals still present in the summer range when snow fall, frost, or peak forage deterioration occurred showed a significantly higher migration potential around these events. Males were less responsive to environmental cues, suggesting rutting activity, starting earlier in males, initiate movement prior to such conditions. Also, individuals with longer migration distances had a higher migration potential late in the season than individuals with shorter migration distances. Our study shows that factors beyond weather and plant phenology, such as onset of hunting, may be important triggers of autumn migration. Severe weather and forage deterioration were important triggers for the individuals experiencing this, which suggests a hierarchical response to environmental cues. The trade-off between staying longer in the summer range and increased energy expenditures if surprised by severe weather is asymmetric, and leaving well in advance can be seen as a risk-averse tactic.

Seasonal movements of river dolphins (Inia geoffrensis) in a protected Amazonian floodplain

AbstractDeliberate killing for use as bait in a regional catfish (Calophysus macropterus) fishery is the primary threat affecting the survival of the Amazon river dolphin, or boto (Inia geoffrensis). Establishing and improving freshwater protected areas has been suggested as a possible course of action to protect the species. However, the ecology of the boto is poorly understood and more information is needed on the species’ habitat use and movement patterns to ensure that spatial protection initiatives meet conservation needs. In this study, mark‐recapture/resight data collected in and near the Mamirauá Sustainable Development Reserve, a várzea in the Brazilian Amazon, was used to examine transition probabilities of botos between various habitat types. Our findings suggest that it is imperative that spatial protection initiatives focused on the boto take into account the importance of várzea habitat and bay systems for individuals in early life stages. Moreover, because botos frequently occupy the main rivers, particularly during the low water period, protecting areas of the main river waters adjacent to várzeas could aid in the protection of hunted populations.

Hunted Wildlife Biology and the Application of Its Methods in the North of European Russia

Ways to augment the productivity of hunting grounds in the boreal zone of European Russia are discussed. Both passive manipulation – utilization of the regional features of forest management and agriculture, and active methods – planting of food plots, establishment of feeding stations, organization of mineral supplementation for wildlife, are considered. Many game management methods successfully used in well-organized game ranches in Central Russia were found to poorly perform in the vast expanses of middle and northern taiga, where the density of hunted wildlife populations is rather low. The greatest effect is gained from the measures that enhance food and shelter availability in game ranches even in the seasons most strenuous for the animals.

Compensatory life‐history responses of a mesopredator may undermine carnivore management efforts

Summary Lethal carnivore management, aimed at reducing carnivore impacts, is a global phenomenon threatening the persistence of many carnivores. Black‐backed jackals Canis mesomelas, the dominant cause of livestock predation in southern Africa, are widely hunted to reduce livestock predation. Despite centuries of lethal management, jackals persist. Smaller canids, like jackals, are highly adaptable and display variable responses to mortality sources, which may affect management outcomes. The effects of killing carnivores will depend on their behaviour, social organization, reproduction and dispersal patterns. We predicted that hunted jackals will alter demographic and reproductive patterns to compensate for increased mortality. Here, we collected demographic and reproductive information from harvested jackals and compared it between continually hunted (farms) and unmanaged populations (reserves). The removal of jackals from farms results in a decrease in median age from 5–6 years (reserves) to 2–3 years (farms). Hunting also changed the age structure of jackal populations from a stable population to an expanding population. This may be ascribed to the compensatory immigration of individuals from neighbouring unmanaged areas, suggesting the formation of a source–sink system. Unmanaged areas may act as source populations exporting young, dispersing individuals to hunted areas which may act as sinks. This is likely driven by disruptions in the normal, mutually exclusive territorial system resulting in low densities of conspecifics on farms. The low density of conspecifics allows younger individuals that would be socially precluded from reproducing to reproduce. Jackals on farms compensated for increased mortality by increasing the pregnancy rate of young individuals and increasing the litter size at younger ages, thereby increasing reproductive output. Synthesis and applications. The lethal management of predators is the prevailing strategy to reduce livestock predation. However, the highly adaptable nature of jackals and the combination of compensatory mechanisms such as increased reproduction and potential for immigration allow these predators to persist in the face of severe anthropogenic mortality, possibly through the formation of a source–sink system. These compensatory processes will continue to counter population management actions as long as recruitment from unmanaged areas persists.

Leave before it's too late: Anthropogenic and environmental triggers of autumn migration in a hunted ungulate population

Leave before it's too late: Anthropogenic and environmental triggers of autumn migration in a hunted ungulate population

Physiological evidence for a human-induced landscape of fear in brown bears (Ursus arctos)

Human persecution is a major cause of mortality for large carnivores. Consequently, large carnivores avoid humans, but may use human-dominated landscapes by being nocturnal and elusive. Behavioral studies indicate that certain ecological systems are “landscapes of fear”, driven by antipredator behavior. Because behavior and physiology are closely interrelated, physiological assessments may provide insight into the behavioral response of large carnivores to human activity. To elucidate changes in brown bears' (Ursus arctos) behavior associated with human activity, we evaluated stress as changes in heart rate (HR) and heart rate variability (HRV) in 12 GPS-collared, free-ranging bears, 7 males and 5 females, 3–11years old, using cardiac-monitoring devices. We applied generalized linear regression models with HR and HRV as response variables and chest activity, time of day, season, distance traveled, and distance to human settlements from GPS positions recorded every 30min as potential explanatory variables. Bears exhibited lower HRV, an indication of stress, when they were close to human settlements and especially during the berry season, when humans were more often in the forest, picking berries and hunting. Our findings provide evidence of a human-induced landscape of fear in this hunted population of brown bears.

Epidemiologic trends in medically-attended tree stand fall injuries among Wisconsin deer hunters.

Tree stand falls are the most common injury to hunters in the USA, but there is limited research on the topic. This study examined the 5-year trends in incident tree stand fall injuries in rural north-central Wisconsin and described patient demographics and injury features. A retrospective analysis was conducted on five prior hunting seasons, 2009-2013. Cases were ascertained from electronic health records via natural language processing that identified patients from the Marshfield Epidemiologic Study Area who received medical attention for a tree stand fall. Annual incidence rates were calculated using the number of hunting license holders in the target population, per administrative data from the Wisconsin Department of Natural Resources. There were 16,556-16,902 deer hunters in any given year, with 39 (92% male) confirmed medically-attended tree stand fall injuries in 2009-2013. Injuries mainly occurred in the lower extremities (n=23), and included two fatalities and one paralysis case. The risk of tree stand fall injuries went from 6.0 (95% CI: 3.2, 11.1) per 10,000 hunters in 2009 to 3.6 (95% CI: 1.6, 7.9) per 10,000 hunters in 2013, which was not a significant change over 5 years (p=0.79). Most falls occurred among archery hunters, in the evening and when descending from a tree stand. Cases were demographically similar to the general population of Wisconsin deer hunters. The current seasonal incidence rate of tree stand fall injuries is relatively low in rural Wisconsin, but with limited signs of improvement. Continued efforts are needed to promote the long-term safety of the hunting public.

Effects of male targeted harvest regime on sexual segregation in mountain lion

Male targeted harvest regimes of carnivores are now widely accepted to result in increased sexually selected infanticide (SSI). Male targeted harvest regimes of males should therefore result in increased sexually segregated habitat use in infanticidal carnivores. We tested the effects of low and high levels of male hunting mortality and associated SSI on sexually segregated habitat use in mountain lions. The “no effect of hunting” hypothesis predicts that no sexual segregation would occur or that all female mountain lions would segregate from males because of sexual dimorphism. The “hunting effect” hypothesis predicts that females with kittens would segregate from younger immigrant males in the heavily hunted population during summer when kittens are vulnerable to SSI. We rejected the “no effect” hypothesis and accepted the “hunting effect” hypothesis for mountain lions. Females with kittens avoided immigrant males in the heavily hunted population during summer—others did not. This sexual segregation corresponded with females with kittens selecting for food-poor, high elevations in the heavily hunted population but not in the lightly hunted population. Avoidance of males and selection for high elevations resulted in prey switching by females with kittens from abundant primary prey in lower elevations to rare, sensitive and threatened secondary prey at higher elevations. It appears that remedial sport hunting of mountain lions to reduce predation on declining prey actually caused sexual segregation and increased predation on declining prey. We suggest that excess mortality of male carnivores could result in unanticipated cascade effects including sexual segregation and prey switching to declining prey.

‘HUNTERS-WITH-SHEEP’: THE |XAM BUSHMEN OF SOUTH AFRICA BETWEEN PASTORALISM AND FORAGING

ABSTRACTThe ability of hunting and gathering populations to adopt herding forms of subsistence constitutes the crux of a long-standing debate in southern African archaeological and anthropological scholarship concerning the spread of livestock to the subcontinent. This article takes as a detailed case study the subsistence strategies of the nineteenth-century ǀXam Bushmen of the Northern Cape (South Africa), extracted from a transcription of the entirety of the Bleek–Lloyd Archive. It focuses on ǀXam characterization of and relationships with the various domesticated species that shared their Karoo landscape, and asks whether these relationships differ markedly from their conceptions of non-domesticated animals. Turning to the wider context of hunter-gatherer engagements with domesticates, the article concludes by proposing that, for the ǀXam, domesticated fauna were part of a spectrum of differentiated resources, and did not entail an interaction with a wholly alien suite of new demands.

Horn growth patterns in Alpine chamois

The analysis of horn growth may provide important information about the allocation of metabolic resources to secondary sexual traits. Depending on the selective advantages offered by horn size during intra- and inter-specific interactions, ungulates may show different investment in horn development, and growth variations within species may be influenced by several parameters, such as sex, age, or resource availability. We investigated the horn growth patterns in two hunted populations of Alpine chamois (Rupicapra r. rupicapra) in the Central Italian Alps. We tested the role of individual heterogeneity on the growth pattern and explored the variation in annulus length as a function of different factors (sex, age, hunting location, cohort). We then investigated the mechanisms underlying horn growth trajectories to test for the occurrence of compensatory or recovery growth and their potential differences between sexes and populations. Annulus length varied as a function of sex, age of individuals and, marginally, hunting location; no effect of cohort or individual heterogeneity was detected. Male and female chamois showed compensatory horn growth within the first 5½ years of life, though the partial convergence of horn trajectories in chamois suggests that this mechanisms would best be described as ‘recovery growth’. Compensation rates were greater in males than in females, while only compensatory growth rates up to 2½ years of age were different in the two populations. Besides confirming the sex- and age-dependent pattern of horn development, our study suggests that the mechanism of recovery growth supports the hypothesis of horn size as a weakly selected sexual trait in male and female chamois. Furthermore, the greater compensation rates in horn growth shown by male chamois possibly suggest selective effects of hunting on age at first reproduction, while different compensation rates between populations may suggest the occurrence of some plasticity in resource allocation to sexual traits in relation to different environments.

ABI1 regulates carbon/nitrogen-nutrient signal transduction independent of ABA biosynthesis and canonical ABA signalling pathways in Arabidopsis.

Plants are able to sense and mediate the balance between carbon (C) and nitrogen (N) nutrient availability to optimize metabolism and growth, described as the C/N response. To clarify the C/N signalling mechanism, C/N-insensitive plants were obtained from an Arabidopsis FOX hunting population, which over-expresses full-length cDNAs for individuals. The resulting cni2-D (carbon/nitrogen insensitive 2-dominant) plant was found to overcome the post-germination growth checkpoint and to expand green cotyledons in disrupted high C/low N stress conditions. The CNI2 gene encodes ABI1, a phosphatase type 2C protein, which negatively regulates abscisic acid (ABA) signal transduction. Over-expressors of ABI1 were found to be insensitive to disrupted C/N stress, whereas the loss-of function mutant abi1-2 was hypersensitive, suggesting that ABI1 plays an essential role in the plant C/N response. By contrast, the C/N-dependent growth phenotype observed in wild-type plants was not associated with endogenous ABA content. Accordingly, the ABA-insensitive mutant abi1-1, which could not bind to the ABA-ABA receptor complex, was not insensitive and restored normal sensitivity to high C/low N stress. The canonical ABA signalling mutants abi4 and abi5 were also sensitive to disrupted C/N stress. Further gene expression analysis demonstrated that several genes in the SnRK2s and SnRK1s pathways are transcriptionally affected by high C/low N stress in wild-type plants regardless of the lack of increased endogenous ABA contents, whereas the expression of these genes were significantly suppressed in ABI1 over-expressors. Taken together, these results suggest direct cross-talk between C/N and non-canonical ABA signalling pathways, regulated by ABI1, in plants.

Wild boar populations up, numbers of hunters down? A review of trends and implications for Europe.

Across Europe, wild boar numbers increased in the 1960s-1970s but stabilised in the 1980s; recent evidence suggests that the numbers and impact of wild boar has grown steadily since the 1980s. As hunting is the main cause of mortality for this species, we reviewed wild boar hunting bags and hunter population trends in 18 European countries from 1982 to 2012. Hunting statistics and numbers of hunters were used as indicators of animal numbers and hunting pressure. The results confirmed that wild boar increased consistently throughout Europe, while the number of hunters remained relatively stable or declined in most countries. We conclude that recreational hunting is insufficient to limit wild boar population growth and that the relative impact of hunting on wild boar mortality had decreased. Other factors, such as mild winters, reforestation, intensification of crop production, supplementary feeding and compensatory population responses of wild boar to hunting pressure might also explain population growth. As populations continue to grow, more human-wild boar conflicts are expected unless this trend is reversed. New interdisciplinary approaches are urgently required to mitigate human-wild boar conflicts, which are otherwise destined to grow further.

Les chasseurs du Sahara atlantique ont-ils inventé la métallurgie ? Les haches « à tranchant en éventail » dans l’art rupestre du sud marocain

It is generally accepted that the metal appeared in Morocco under Iberian influence during the second millennium BC (3800–3200 BP). On the base of three main types of “peltiforme” axes represented in rock engravings, we assume the existence of an endogenous and independent invention of metallurgy in southern Morocco. Initially, we will discuss the chronological implications of this proposal, which will be then confronted with historical and ethnological data. Several factors support the hypothesis that a black population of nomadic hunters was established on the north bank of the Moroccan Sahara. This population probably assimilated by paléoberbère society from the late Neolithic would be the inventor of the “Metgourine” axe and Metallurgy. Such a hypothesis is supported by a set of arguments from various disciplinary fields.

Inferring demographic structure with moccasin size data from the Promontory Caves, Utah

The moccasin assemblage Julian Steward recovered from the Promontory caves in 1930-31 provides a novel example in which material culture can be used to understand the structure of an AD thirteenth century population. Several studies shed light on the relationship between shoe size, foot size, and stature. We develop an anthropometric model for understanding the composition of the Promontory Cave population by using moccasin size as a proxy for foot size. We then predict the stature of the individual who would have worn a moccasin. Stature is closely related to age for children, subadults and adult males. Although there are predictable sex and age factors biasing moccasin discard practices, moccasin dimensions suggest a relatively large proportion of children and subadults occupied the Promontory caves. This bison and antelope hunting population appears to have thrived during its stay on Promontory Point.

WILDLIFE RESERVES, POPULATIONS, AND HUNTING OUTCOME WITH SMART WILDLIFE

AbstractWe consider a hunting area and a wildlife reserve and answer the question: How does clever migration decision affect the social optimal and the private optimal hunting levels and population stocks? We analyze this in a model allowing for two‐way migration between hunting and reserve areas, where the populations’ migration decisions depend on both hunting pressure and relative population densities. In the social optimum a pure stress effect on the behavior of smart wildlife exists. This implies that the population level in the wildlife reserve tends to increase and the population level in the hunting area and hunting levels tend to decrease. On the other hand, the effect on stock tends to reduce the population in the wildlife reserve and increase the population in the hunting area and thereby also increase hunting. In the case of the private optimum, open‐access is assumed and we find that the same qualitative results arise when comparing a situation with and without stress effects, but of course at a higher level of hunting. We also show that when net social benefits of hunting dominate the net social benefits of populations, wildlife reserves are optimally placed in areas of low carrying capacity and vice versa.

Managing hunted populations through sex-specific season lengths: a case of the Common Eider in the Baltic-Wadden Sea flyway population

Management of harvested wildlife populations aims to protect species from overexploitation and ultimately extinction, by regulating exploitation towards achievable sustainable levels. However, assessments of impact and sustainability of implemented management actions on a population level are scarce. This study assesses effects of changes in hunting season length imposed on the Baltic-Wadden Sea Common Eider Somateria mollissima population, including differential restriction on hunting of the sexes. The potential impact of these changes on the population was assessed by simple demographic matrix projections. Since the early 1990s, this population has declined at ca. 6.3 % per annum, and the male/female ratio among shot birds has fallen from 3:2 to about 3:1. Concerns in Denmark regarding the conservation status and sustainability of contemporary levels of exploitation resulted in shortening the open season by 44 and 46 days for females and 13 and 15 days for males from the hunting seasons 2004/2005 and 2011/2012 onwards, respectively. These reduced the kill of adult females by 82 %, adult males by 31 %, juvenile females by 58 % and juvenile males by 55 %. The observed reduction in the kill of adult females following both changes in 2004/2005 and 2011/2012 matched the expected changes based on the seasonal distribution of sexes in the bag prior to the change. Post 2004/2005 hunters killed more adult males, but shot markedly fewer juvenile birds than expected. Demographic modelling of the female population showed that the effects of the reduced hunting would correspond to an increase in the annual population growth rate from the previous −6.3 to −3.6 % (post 2004) and −1.6 % (post 2011). The model also predicted that a full ban on hunting female eiders (adults and juveniles) would lead to a positive population growth rate of 0.7 %. Taking into account the conservative model estimates and natural variations in annual breeding success, the implemented changes in sex-specific regulation of hunting may potentially be an effective management tool to halt the decline of the Baltic-Wadden Sea eider population, potentially rendering such levels of hunting sustainable under prevailing conditions.

The Montana deer and Elk hunting population: The importance of cohort group, license price, and population demographics on hunter retention, recruitment, and population change

ABSTRACTBig‐game hunting is a valuable resource for outdoor recreation opportunities, an economic driver for state and local economies, and the primary mechanism for funding game and non‐game wildlife management. However, hunting license sales are declining, leading many state wildlife management agencies to re‐evaluate funding and management structures. Understanding the mechanisms behind such declines, and diagnosing the persistence of such trends is necessary to anticipate license fund fluctuations. To examine hunter recruitment and retention rates, we analyzed a data set of >490,000 deer and elk license records from 2002 to 2011 from the Montana Fish, Wildlife and Parks' Automated Licensing System. We used a temporal symmetry model in a mark–recapture framework to estimate hunter retention, recruitment rates, and population change, and then used population change estimates to forecast future hunter populations. We used covariates of gender, age, residency, and license price to improve model parsimony. Millennial generation hunters increased during the 11‐year analysis, and this was driven by high recruitment rates of young hunters, especially women, but recruitment decreased dramatically as youth aged. Because Baby Boomers constitute such a large proportion of the hunting population, decreases in recruitment and retention in this cohort drove declines in the Montana hunter population. Increasing license price decreased the probability of recruiting and retaining hunters. The hunter population was stable until 2006, but has been declining since that time with nearly a 50% decline in hunter recruitment from 2002 to 2011. © 2014 The Wildlife Society.