Hunting Pressure Research Articles

Does the presence of Oil and gas infrastructure potentially increase risk of harvest in northern bobwhite?

Beyond organisms experiencing direct impacts (mortality) from the presence of anthropogenic features, interactive relationships may exacerbate the effects of anthropogenic disturbance within the context of these features. For example, mortality risk may be affected by the road infrastructure associated with energy development by influencing space use of predators including human hunters. To assess these relationships, we conducted research on northern bobwhiteColinus virginianusacross a hunted and non‐hunted area of Beaver River Wildlife Management Area, Oklahoma, using radiotelemetry from 2012–2015. We found that bobwhite mortality risk decreased as the distance from primary roads (m) increased across weeks (hazard ratio [HR] = 1.008, 95% confidence interval [CI] = 1.0003 to 1.0013). The interaction between unit (hunted and non‐hunted) and distance from primary roads was not significant (HR = 1.00, 95% CI = 0.999 to 1.001) indicating that hunting pressure was not a likely explanation for the observed decrease in survival related to primary roads. Bobwhite on the hunted unit avoided exposed soil/sparse vegetation (= ‐0.01, CI = ‐0.02 to ‐0.002) and bare ground (=‐0.01, CI =‐0.02 to ‐0.002) more than bobwhite on the non‐hunted unit, however these were weak relationships. No other differences in bobwhite space use were detected related to hunting. Though we were limited to estimating theoretical rather than empirical amounts of hunting pressure during our study, we were unable to detect any negative compounding effects of anthropogenic development and hunting pressure on bobwhite ecology during the hunting season.

The feral pig as prey for jaguars: A reply to the ‘Letter from the Conservation Front Line’ by Verdade et al.

Due to habitat loss, poaching and high hunting pressure on their prey, the jaguar Panthera onca is one of the most endangered top predators in the Americas (Galetti et al., 2013; Treves & Bruskotter, 2014). The population of jaguars in the Brazilian Atlantic Forest was estimated to be less than 250 mature individuals, split into many isolated populations (Haag et al., 2010; Beisiegel, Sana & Moraes, 2012). In addition, most of its prey, white-lipped peccaries Tayassu pecari and tapirs Tapirus terrestris, are extinct or restricted to only a few areas (Jorge et al., 2013). In their ‘Letter from the Conservation Front Line’ published in Animal Conservation, Verdade et al. (2015) suggested that feral pigs (Sus scrofa) (Pedrosa et al., 2015), could be an alternative prey for jaguars and may help their populations to recover in Atlantic forest. Although jaguars are known to prey on feral pigs in Pantanal (Cavalcanti & Gese, 2010), we are skeptical that the jaguar's population size would increase and the distribution expand based upon preying on the pigs, and we doubt that jaguars will control the invasion of feral pigs in Brazil. First, feral pigs in the Pantanal are much smaller (body mass ~40 kg, Desbiez et al., 2009) than in the Atlantic forest (body mass ~100 kg, Oliveira, 2012), where they are therefore less likely to be preyed upon by jaguars, unless jaguars selectively prey upon juveniles and piglets. Second, prey's behavior is as important as their body size in determining the predator's success (Hopcraft, Sinclair & Packker, 2005); feral pigs are more aggressive (Graves, 1984) than native species or cattle (Montenegro, 1998; Cavalcanti et al., 2010; Cavalcanti & Gese, 2010). Third, although prey availability is one of the main issues for recovering top predator populations (Galetti et al., 2013; Ripple et al., 2014), jaguars are seen as a significant threat to cattle ranching (Ripple et al., 2014; Tortato et al., 2015). Currently, there are 10 million head of cattle in São Paulo state (Bueno, Martins & Caser, 2015) and they are probably a more logical choice for jaguars (Cavalcanti et al., 2010; Cavalcanti & Gese, 2010). Although cattle are bigger than feral pigs, they are constrained within fenced fields and are less aggressive due to domestication (Cavalcanti et al., 2010). Therefore, any increase in the population of jaguars is likely to negatively impact the attitude of farmers to this predator. We believe that the most effective means of garnering support for controlling invasive feral pigs is to demonstrate their socioeconomic impacts (Jeschke et al., 2014; Massei et al., 2015). Increasing human hunting pressure on feral pigs may decrease hunting pressure on jaguar's prey (Desbiez et al., 2011), thus indirectly benefiting jaguars.

Hunting as a management tool? Cougar-human conflict is positively related to trophy hunting.

BackgroundOverexploitation and persecution of large carnivores resulting from conflict with humans comprise major causes of declines worldwide. Although little is known about the interplay between these mortality types, hunting of predators remains a common management strategy aimed at reducing predator-human conflict. Emerging theory and data, however, caution that such policy can alter the age structure of populations, triggering increased conflict in which conflict-prone juveniles are involved.ResultsUsing a 30-year dataset on human-caused cougar (Puma concolor) kills in British Columbia (BC), Canada, we examined relationships between hunter-caused and conflict-associated mortality. Individuals that were killed via conflict with humans were younger than hunted cougars. Accounting for human density and habitat productivity, human hunting pressure during or before the year of conflict comprised the most important variables. Both were associated with increased male cougar-human conflict. Moreover, in each of five regions assessed, conflict was higher with increased human hunting pressure for at least one cougar sex.ConclusionAlthough only providing correlative evidence, such patterns over large geographic and temporal scales suggest that alternative approaches to conflict mitigation might yield more effective outcomes for humans as well as cougar populations and the individuals within populations.Electronic supplementary materialThe online version of this article (doi:10.1186/s12898-016-0098-4) contains supplementary material, which is available to authorized users.

Empty forest or empty rivers? A century of commercial hunting in Amazonia.

The Amazon basin is the largest and most species-rich tropical forest and river system in the world, playing a pivotal role in global climate regulation and harboring hundreds of traditional and indigenous cultures. It is a matter of intense debate whether the ecosystem is threatened by hunting practices, whereby an "empty forest" loses critical ecological functions. Strikingly, no previous study has examined Amazonian ecosystem resilience through the perspective of the massive 20th century international trade in furs and skins. We present the first historical account of the scale and impacts of this trade and show that whereas aquatic species suffered basin-wide population collapse, terrestrial species did not. We link this differential resilience to the persistence of adequate spatial refuges for terrestrial species, enabling populations to be sustained through source-sink dynamics, contrasting with unremitting hunting pressure on more accessible aquatic habitats. Our findings attest the high vulnerability of aquatic fauna to unregulated hunting, particularly during years of severe drought. We propose that the relative resilience of terrestrial species suggests a marked opportunity for managing, rather than criminalizing, contemporary traditional subsistence hunting in Amazonia, through both the engagement of local people in community-based comanagement programs and science-led conservation governance.

Living on the boundary of a post-disturbance forest area: The negative influence of security cover on red deer home range size

In the face of climate change and the probable rise in the frequency of severe natural disturbances, successful management of forest ecosystems requires profound knowledge, including the one connected with the temporal and spatial relations between populations of wild herbivores and their habitats. Animal location data collected with VHF collars and spatial GIS data were used to investigate home range size of red deer living along the boundary of two contrasting forest environments which were created after a large-scale (10,000ha) stand-replacing fire in south-western Poland. We found male home ranges to be nearly twice as large as female ones. Surprisingly, the percentage of the burned area (less penetrated by humans, although of lower food availability) was negatively correlated with deer home range sizes in all seasons. The conditions in the post-disturbance forest were relatively stable during the year, which could explain the lack of differences between seasonal home ranges. Our findings suggest that the relationship between home range size and open habitats may be determined by the distribution of the latter: patches offering the best forage seem to be worth the effort of travelling, even at the cost of home range expansion. Heterogeneity features (patch and edge density) of forest interior habitats in this study did not emerge as an important determinant of the total size of home ranges. When burned and unburned areas were analysed separately, the results revealed that their size could be at least seasonally adjusted to habitat heterogeneity: in the burned area, deer seemed to travel longer distances between preferred patches (an increase in patch density was positively correlated with home range size), whereas the opposite was observed in the undisturbed forest in winter and spring. Our findings suggest that in populations under strong hunting pressure, security cover is a key resource, determining deer space use, especially in post-disturbance forests. We concluded that large areas of cover-offering habitats may lead to local increase in deer population and higher browsing pressure also in surrounding forests. Proper planning and introduction of feeding places (open areas) might help to control the population size by hunters and thus mitigate this effect.

Influence of war on hunting patterns and pressure in Sierra Leone

SUMMARYBushmeat hunting poses a huge challenge for biodiversity conservation, but bushmeat is also an important source of essential protein in many locations. Although war may have substantial impacts on hunting, how these effects vary across different spatial scales and over multiple stages of warfare remain largely unknown. In addition, despite serious conflicts that may have affected hunting patterns in West Africa, no studies have examined the impacts of war on hunting in Sierra Leone. We used the randomized response technique together with semi-structured interviews to examine variations in hunting techniques and the proportion of the population that engages in hunting over three time periods (before, during and after war) among different communities bordering a protected area. At the scale of the whole protected area, the proportion of people hunting did not vary significantly over time. Similarly, the methods used for hunting were generally consistent over time and space. However, within each community, the proportion of the population hunting varied significantly over time, and the locations with the greatest participation rates in hunting changed at each time period. Access to alternative livelihood options and the severity of the war's impact shaped patterns of change in hunting participation across different communities. Our results point to the importance of adaptive management approaches that can adjust management strategies in order to account for spatial or temporal variations in hunting behaviour.

Responses of two sympatric species of peccaries (Tayassu pecari and Pecari tajacu) to hunting in Calakmul, Mexico

The white-lipped peccary ( Tayassu pecari) and the collared peccary ( Pecari tajacu) are social ungulates of great ecological and economic importance. Both species represent important sources of animal protein in the diet of indigenous and rural communities in Neotropical forests, which has contributed to reducing their populations throughout their geographic distribution. It is still not well understood how the social ecology of peccaries is affected by hunting. This study analyzed the relationship between hunting and group size, group composition, daily activity patterns, and the relative abundance of the two peccary species. Camera-traps and direct observation were used from February 2014 through February 2015 in two sites differing in their degree of protection and hunting pressure: the first was Calakmul Biosphere Reserve (a site with no hunting) and the second was the community of Nuevo Becal (a hunting site). Our analyses suggest that hunting negatively affects group size, structure, composition and the relative abundance of both peccary species. We propose that management and conservation plans, particularly for key resources such as water, and monitoring and hunting controls in the habitats of both peccary species, might ensure their survival in the Calakmul region.

Levels of fecal glucocorticoid metabolites do not reflect environmental contrasts across islands in black-tailed deer (Odocoileus hemionus sitkensis) populations

Animals face stressful situations to which they can respond by mounting a physiological response. Few studies have compared the relative effects of two or more stressors on this response. We compared how low food abundance and hunting affected levels of fecal glucocorticoid metabolites (FGM), an indicator of stress, in Sitka black-tailed deer (Odocoileus hemionus sitkensis) on the Haida Gwaii archipelago (Canada). We monitored monthly FGM levels over a year on three islands: on two, there was no hunting but deer were exposed to increased risk of severe food depletion; and on one, deer had access to abundant food but were exposed to a few days of hunting each year. Based on the context of the study, we tentatively predicted that FGM levels would be higher in low food abundance/safe islands. We also predicted that FGM levels would be higher in winter when food is rarer, particularly in low food abundance/safe islands. The three deer populations presented similar average FGM levels and seasonal variations. Our predictions were therefore not supported. Our results rather suggested that environmental contrasts, perceived by us as large (increased risk of starvation on ELI and Kunga islands) or associated with differences in animal behavior (human avoidance on Reef island), did not lead to increased stress responses. We discuss plausible explanations, including the down-regulation of the stress response in depleted environments and the lack of stress response to low hunting pressure when behavioral responses to risk are unlikely to be costly.

When does selective hunting select, how can we tell, and what should we do about it?

AbstractPotential evolutionary consequences of selective hunting of mammals are controversial because of limited evidence and important socio‐economic impacts. Several ecological and management variables facilitate evolutionary responses to selection for horn, tusk or antler size, including strong selective hunting pressure; harvest of males with large horns, tusks or antlers before they can breed; unavailable or ineffective sources of unselected immigrants; and age‐dependent relationships between horn, tusk or antler size and male mating success. Plastic responses of male horns, tusks and antlers to environment are probably more common than evolutionary changes. Evidence for evolutionary effects of selective hunting is strong for large mammals where biological characteristics and hunting regulations combine to favour them.

Night and day: evaluating transect methodologies to monitor duikers in the Dzanga‐Sangha Protected Areas, Central African Republic

AbstractAcross the Congo Basin, human hunting pressure poses the biggest threat to small‐ and medium‐bodied forest ungulates (genus Philantomba and Cephalophus, commonly known as duikers). The exploitation of these species has cascading effects on larger ecosystem processes, as well as on human subsistence practices. This study compares encounter rates and estimated population densities of duiker species, specifically Philantomba monticola (blue duiker) in the Dzanga‐Sangha Protected Areas (APDS), Central African Republic (CAR). Data were collected using direct observations of individual animals during diurnal (135 km) and nocturnal (150 km) transects in the APDS, with abundance estimates produced using DISTANCE software. Transect data demonstrate that within hunted forests similar to APDS, nocturnal rather than diurnal transects yield more individual observations of ungulates. Despite hunting pressure in the region, estimates presented for APDS suggest some of the highest density estimates reported for blue duikers in western and central Africa (58.6 blue duikers per km2). This study directly contributes current regional data on the status of duiker populations at APDS and in the larger Sangha Trinational Landscape (TNS, UNESCO). More broadly, we highlight the potential importance of nocturnal transect data to the development of adaptive management regimes in hunted forests.

Assessment of the hunting of mammals using local ecological knowledge: an example from the Brazilian semiarid region

The hunting of wild animals remains a common activity in various parts of the world, especially in rural communities with poor socioeconomic conditions. To investigate patterns of mammal hunting, this study adopted a rural community located in semiarid Brazil as a model to test whether variables such as perceived abundance, activity period (day or night) and animal biomass could influence the consumption potential of mammal taxa. For this study, a checklist/interview technique using 32 photographs of mammals recorded in the region and two photographs of species that did not occur in the region, which acted as “control” species, was used, in addition to other visual stimuli and free lists. All species presented in the photographs, with the exception of the “control” species, were recognized as occurring in the region. Fourteen species were cited as being those most hunted locally. The species cited as most hunted had an average perceived abundance higher than the group of the least-hunted species. However, there was no significant relationship between hunting of a species and its locally perceived abundance. No significant difference in hunting pressure between diurnal and nocturnal species was found, nor was a relationship between animal biomass and hunting pressure observed. Our findings suggest that perceived abundance is an important factor for choosing a resource fauna, but other factors such as intended use, meat flavor and vulnerability to hunting, among others, may influence the potential use of a species.

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.

On the evolutionary consequences of increasing litter size with multiple paternity in wild boar (Sus scrofa scrofa).

Understanding how some species may be able to evolve quickly enough to deal with anthropogenic pressure is of prime interest in evolutionary biology, conservation, and management. Wild boar (Sus scrofa scrofa) populations keep growing all over Europe despite increasing hunting pressure. In wild boar populations subject to male-selective harvesting, the initially described polygynous mating system may switch to a promiscuous/polyandrous one. Such a change in the mating system, where potentially more males sire a litter at one reproductive event, may be associated with the retention of high genetic diversity and an increase of litter size. We tested these hypotheses by estimating the number of sires per litter based on a six-year long monitoring of a wild boar population subject to particularly high harvesting pressure. Our results show a high and stable genetic diversity and high rates of multiple paternity compared to other populations, thus depicting a promiscuous/polyandrous mating system in this population. We also show that litter size is positively linked to the number of sires, suggesting that multiple paternity increases fecundity. We finally discuss that multiple paternity may be one of the factors allowing rapid evolution of this population by maintaining both genetic and phenotypic diversity.

Subsistence-Level Chelonian Exploitation on the Rio Negro and One Viable Alternative

In the Rio Negro, the third-largest tributary of the Amazon, many turtle species have been important commercial and protein resources for centuries for populations of humans living in the region. For many years, this had been a sustainable activity, but nowadays the outlook for turtle populations in the Amazon is unfavorable due to increasing hunting pressure. Based on 20 yrs of conservation work in the Amazon, we report on the pressure faced by turtle populations in the area and report a sustainable chelonian exploitation alternative developed in the Rio Negro region. We describe the materials and the hand processing artisans use to transform natural resources into artworks. Based on this community program model, we discuss the current government support to local communities of the Rio Negro and provide insights on the application of this economic alternative to substitute for turtle commercialization in the Amazon. The outcomes of this manuscript have direct applications for environmental managers, nongovernmental organizations, and policymakers in Brazil and aim to call government and environmental managers to promote turtle conservation in the Amazon, securing economic safety for local communities.

Hunting, pet trade, and forest size effects on population viability of a critically endangered Neotropical primate, Sapajus xanthosternos (Wied-Neuwied, 1826).

The yellow-breasted capuchin monkey (Sapajus xanthosternos) is one of the seven Brazilian primates that are currently threatened with extinction. Although the species is known to be threatened by habitat loss, hunting, and illegal pet trade, few data exist on how these threats influence its long-term population persistence. We conducted population viability analyses (PVAs) to estimate minimum viable populations of S. xanthosternos under 10 threat scenarios (i.e., varying hunting pressure and varying number of infants captured for the pet trade) for five forest fragments with different estimated carrying capacities (K). We also estimated the minimum forest fragment size required to sustain viable populations living under the same 10 threat scenarios, based on critical numbers of K obtained in sensitivity tests, below which the population would be unviable. Our PVAs suggests that hunting has a higher impact on population viability in comparison to threats from the pet trade. Annual losses of adult and young females from hunting had the most detrimental effect on population persistence under all forest fragment sizes. Such hunting pressure is not sustainable for populations living in areas ≤3,460 ha, since these areas may not support populations of ≥84 individuals. The seven largest of the 13 protected areas currently harboring capuchins should be effective at maintaining viable populations in the long term even under the greatest threat scenarios we modeled. Other large forest patches, mainly in the western part of the species distribution, are recommended as priority areas for protection to increase the chances of capuchins' survival for the long term. In addition, forest fragments of ≤782.8 ha cannot maintain viable populations, even when there are no threats from hunting or from captures for the pet trade. Increased law enforcement is necessary to prevent the hunting and capture of capuchins, especially within larger forest fragments. Am. J. Primatol. 78:950-960, 2016. © 2016 Wiley Periodicals, Inc.

The winter distribution of the Spoon-billed Sandpiper Calidris pygmaeus

SummaryDeclines in populations of the Critically Endangered Spoon-billed Sandpiper Calidris pygmaeus have been rapid, with the breeding population now perhaps numbering fewer than 120 pairs. The reasons for this decline remain unresolved. Whilst there is evidence that hunting in wintering areas is an important factor, loss of suitable habitat on passage and wintering areas is also of concern. While some key sites for the species are already documented, many of their wintering locations are described here for the first time. Their wintering range primarily stretches from Bangladesh to China. Comprehensive surveys of potential Spoon-billed Sandpiper wintering sites from 2005 to 2013 showed a wide distribution with three key concentrations in Myanmar and Bangladesh, but also regular sites in China, Vietnam and Thailand. The identification of all important non-breeding sites remains of high priority for the conservation of the species. Here, we present the results of field surveys of wintering Spoon-billed Sandpipers that took place in six countries between 2005 and 2013 and present species distribution models which map the potential wintering areas. These include known and currently unrecognised wintering locations. Our maximum entropy model did not identify any new extensive candidate areas within the winter distribution, suggesting that most key sites are already known, but it did identify small sites on the coast of eastern Bangladesh, western Myanmar, and the Guangxi and Guangdong regions of China that may merit further investigation. As no extensive areas of new potential habitat were identified, we suggest that the priorities for the conservation of this species are habitat protection in important wintering and passage areas and reducing hunting pressure on birds at these sites.

Gender-related amino acid intake of adult wild Red-legged Partridge (Alectoris rufa)

The Red-legged Partridge (Alectoris rufa) is under an enormous hunting pressure. It is bred intensively in game farms. The hunting season is during the non-reproductive resting period when partridges are at maintenance conditions.There is a lack of information about the amino acid (AA) composition of the natural diet of the adult birds in their habitat or differences in dietary AA composition related to gender. The objective of this work was to establish a first approach to the AA composition of the natural diet of adult wild Red-legged Partridge.Food content in crops and gizzards of female and male birds hunted in the same hunting season and area was analysed for AA composition.Females food had higher concentrations of individual essential AA (EAA) and non-essential AA (NEAA) than males.There are important differences in the concentration of AA in the natural diet of wild females and males. It may be advisable to use diets differing in the proportion of individual AA in the game farms during the non-reproductive resting period.

Black Curassow habitat relationships interra firmeforests of the Guiana Shield: A multiscale approach

ABSTRACT The Black Curassow (Crax alector) is a large game bird with Vulnerable conservation status found in north-central South America. We examined its distributional pattern across French Guiana using a large number of environmental descriptors at 3 scales of analysis: landscape, forest type, and microhabitat. We used a hierarchical model with temporary emigration and imperfect detection for data collected by standard distance sampling methods at 35 study sites. At the landscape scale, Black Curassow density decreased with hunting pressure and increased with steeper slopes in both hunted and unhunted areas. Topography appeared to be a good proxy for Black Curassow ecological requirements and probably reflected habitat quality. At the forest scale, population density was negatively correlated with the abundance of palms and Mimosoideae and positively correlated with the abundance of Lauraceae. Botanical families did not directly influence Black Curassow distribution, but rather determined spatial patter...

Contribution of released captive-bred Mallards to the dynamics of the natural population

The consequences of releasing captive-bred game animals into the wild have received little attention, despite their potential demographic impact, as well as costs and/or benefits for recipient populations. If restocking aims at increasing harvest opportunities, increased hunting pressure is expected, which would then be supported by either wild or released individuals. On the other hand, the wild recipient population may benefit from the release of captive-bred conspecifics if this reduces hunting pressure on the former through dilution of risk or selective harvesting of captive-bred individuals. Here, we modelled a Mallard (Anas platyrhynchos) population consisting of wild individuals supplemented by captive-bred conspecifics, a very common practice in Europe over the last 40 years. The objective was to test the effect of an increase of harvest rate on released and wild individuals, respectively. Our results show that, due to the low reproductive value of the released Mal-lards, the population was hardly affected by a change in harvest of these low performance individuals. Conversely, a 15 percent increase in harvest rate of the wild individuals would lead to a quick decline of the population. We discuss these results in the context of the Camargue population, located in the South of France, which has experienced an increase in Mallard harvest without apparent reduction of population size. We suggest that this has only been possible due to the release of captive-bred Mallards.

The Role of Anthropogenic Influence on Biological Signal Field (BSF) Characteristics of the Wolf, Canis lupus lupus (Canidae, Carnivora)

Abstract The main goal of the current research includes studying the biological signal field (BSF) characteristics of the wolf (Canis lupus lupus Linnaeus, 1758) at different values of anthropogenic load on territories with conservation (Białowieża National park (Poland)) and hunting status of the species (Chornobyl Exclusion Zone (Ukraine)). The research in Białowieża Primeval Forest was conducted in two stages: study of the BSF characteristics of the wolf and finding correlation between data acquired from Ukraine (the first stage), and over-time study of intensity of the biological signal field (the second stage). In result of the first stage, there was no significant dependence on the characteristics of the territory and the differences between the behavior of wolves in the Białowieża Primeval Forest (conservation status of the species) and the Exclusion Zone (game status). During the second stage it was determined that provided variance of the intensity between territory groups was insufficient, the degree of significance to animals of area categories varied with the stages of the pack’s life. It was found that the main factors which govern the character of wolf activity are not the level of the anthropic load and hunting pressure, but periods of the life cycle and spatial structure of groups.