Mechanisms of group-hunting in vertebrates

Group-hunting is ubiquitous across animal taxa and has received considerable attention in the context of its functions. By contrast much less is known about the mechanisms by which grouping predators hunt their prey. This is primarily due to a lack of experimental manipulation alongside logistical difficulties quantifying the behaviour of multiple predators at high spatiotemporal resolution as they search, select, and capture wild prey. However, the use of new remote-sensing technologies and a broadening of the focal taxa beyond apex predators provides researchers with a great opportunity to discern accurately how multiple predators hunt together and not just whether doing so provides hunters with a per capita benefit. We incorporate many ideas from collective behaviour and locomotion throughout this review to make testable predictions for future researchers and pay particular attention to the role that computer simulation can play in a feedback loop with empirical data collection. Our review of the literature showed that the breadth of predator:prey size ratios among the taxa that can be considered to hunt as a group is very large (<10⁰ to >10²). We therefore synthesised the literature with respect to these predator:prey ratios and found that they promoted different hunting mechanisms. Additionally, these different hunting mechanisms are also related to particular stages of the hunt (search, selection, capture) and thus we structure our review in accordance with these two factors (stage of the hunt and predator:prey size ratio). We identify several novel group-hunting mechanisms which are largely untested, particularly under field conditions, and we also highlight a range of potential study organisms that are amenable to experimental testing of these mechanisms in connection with tracking technology. We believe that a combination of new hypotheses, study systems and methodological approaches should help push the field of group-hunting in new directions.     

Human‐horse sensory engagement through horse archery

The Mongol horse stems from ancient stock, similar to the first horses ridden on the Central Asian grassland steppe. Mongol horses subsequently migrated with their human counterparts throughout Eurasia, as far to the east as Japan. During archery festivals in Japan, horses gallop along a narrow runway within a temple complex in the heavily populated city of Kyoto. In Mongolia, with the recent re‐emergence of the ancient practice, horse and rider still gallop across the expansive grassland steppe. The euphoria one feels in riding fast on horseback with the wind against one's face can be symbolised by the concept of khii mor’ in Mongolia, which is connected with the vitality between human and horse in the practice of horse archery. Through sensory ethnography, in combination with multi‐species ethnography, this article explores embodiment between horse and rider in two quite different socio‐ecological contexts.     

The changing otter population of Britain 1700–1989

Otters Lutra lutra were persecuted increasingly in Britain for fishery protection and for sport throughout the 18th and 19th centuries. There are indications of a population recovery occurring during the 1914–1918 war with the temporary cessation of hunting and keepering. Intensive otter hunting with packs of hounds throughout the 1920s and 1930s appears to have stressed the population by altering the age structure. A catastrophic decline occurring simultaneously over England, Wales and southern Scotland, but most severe in the south-east and starting in 1957–1958, appears to have been triggered in this stressed population by a single new factor, pollution of the rivers by organochlorine insecticides. The trough in the decline may have occurred around 1977— 1979. The first signs of rivers being re-occupied by otters have been seen by the early 1980s and partial recovery seems possible with legal protection and improved water quality.     

A game theoretical model of deforestation in human-environment relationships

We studied a two-person game regarding deforestation in human-environment relationships. Each landowner manages a single land parcel where the state of land-use is forested, agricultural, or abandoned. The landowner has two strategies available: forest conservation and deforestation. The choice of deforestation provides a high return to the landowner, but it degrades the forest ecosystem services produced on a neighboring land parcel managed by a different landowner. Given spatial interactions between the two landowners, each landowner decides which strategy to choose by comparing the expected discounted utility of each strategy. Expected discounted utility is determined by taking into account the current and future utilities to be received, according to the state transition on the two land parcels. The state transition is described by a Markov chain that incorporates a landowner's choice about whether to deforest and the dynamics of agricultural abandonment and forest regeneration. By considering a stationary distribution of the Markov chain for land-use transitions, we derive explicit conditions for Nash equilibrium. We found that a slow regeneration of forests favors mutual cooperation (forest conservation). As the forest regenerates faster, mutual cooperation transforms to double Nash equilibria (mutual cooperation and mutual defection), and finally mutual defection (deforestation) leads to a unique Nash equilibrium. Two different types of social dilemma emerge in our deforestation game. The stag-hunt dilemma is most likely to occur under an unsustainable resource supply, where forest regenerates extremely slowly but agricultural abandonment happens quite rapidly. In contrast, the prisoner's dilemma is likely under a persistent or circulating supply of resources, where forest regenerates rapidly and agricultural abandonment occurs slowly or rapidly. These results show how humans and the environment mutually shape the dilemma structure in forest management, implying that solutions to dilemmas depend on environmental properties.     

The Impact of Animal Welfare Advertising on Opposition to the Canadian Seal Hunt and Willingness to Boycott the Canadian Seafood Industry

The purpose of this research was to measure and compare the initial and carryover effects of a video advertisement developed by an animal welfare organization, namely Harpseals. org. The ad was designed to educate the public about an egregious act against wildlife (i.e., the Canadian seal hunt), increase opposition to this act, and recruit participation to boycott the industry (i.e., the Canadian seafood industry). After initial opposition to the egregious act had been measured, respondents were exposed to the ad, and subsequently asked again about their opposition to the seal hunt as well as their willingness to join the Canadian Seafood Boycott. About two months later, a follow-up study investigated whether the respondents' opposition to the seal hunt and their participation in the Canadian Seafood Boycott were still affected by the advertisement to which they had been exposed during the first contact. The results show that respondents' level of opposition to the seal hunt—even though it had somewhat leveled off in two months—was still significantly higher (42% higher) than before respondents had been exposed to the advertisement. The results further show that the single exposure to the ad increased boycott participation from 3.1% (as measured in December 2010) to 13.8% (as reported in February/March 2011), an increase of 350%.     

Searching for sustainability: are assessments of wildlife harvests behind the times?

The unsustainable harvest of wildlife is a major threat to global biodiversity and to the millions of people who depend on wildlife for food and income. Past research has called attention to the fact that commonly used methods to evaluate the sustainability of wildlife hunting perform poorly, yet these methods remain in popular use today. Here, we conduct a systematic review of empirical sustainability assessments to quantify the use of sustainability indicators in the scientific literature and highlight associations between analytical methods and their outcomes. We find that indicator type, continent of study, species body mass, taxonomic group and socio‐economic status of study site are important predictors of the probability of reported sustainability. The most common measures of sustainability include population growth models, the Robinson & Redford (1991) model and population trends through time. Indicators relying on population‐specific biological data are most often used in North America and Europe, while cruder estimates are more often used in Africa, Latin America and Oceania. Our results highlight both the uncertainty and lack of uniformity in sustainability science. Given our urgent need to conserve both wildlife and the food security of rural peoples around the world, improvements in sustainability indicators are of utmost importance.     

Direct measure of functional importance visualized atom-by-atom for photoactive yellow protein: application to photoisomerization reaction

Photoreceptor proteins serve as efficient nano-machines for the photoenergy conversion and the photosignal transduction of living organisms. For instance, the photoactive yellow protein derived from a halophilic bacterium has the p-coumaric acid chromophore, which undergoes an ultrafast photoisomerization reaction after light illumination. To understand the structure-function relationship at the atomic level, we used a computational method to find functionally important atoms for the photoisomerization reaction of the photoactive yellow protein. In the present study, a "direct" measure of the functional significance was quantitatively evaluated for each atom by calculating the partial atomic driving force for the photoisomerization reaction. As a result, we revealed the reaction mechanism in which the specific role of each functionally important atom has been well characterized in a systematic manner. In addition, we observed that this mechanism is strongly conserved during the thermal fluctuation of the photoactive yellow protein. We compared the experimental data of fluorescence decay constant of several different mutants and the present analysis. As a result, we found that the reaction rate constant is decreased when a large positive driving force is missing.     

The dynamics of landscape change and snow geese in mid-continent North America

The Mid‐Continent Population of the lesser snow goose, which breeds in the eastern and central Canadian Arctic and sub‐Arctic, and winters in the southern United States and northern Mexico has increased 5–7% annually from the late 1960s to the mid‐1990s, largely because of increased survival in response to an agricultural food subsidy. The rise in numbers complements the increased use of nitrogen fertilizers and a corresponding rise in yields of rice, corn, and wheat along the flyways and on the wintering grounds. In sub‐Arctic migration areas and at Arctic breeding colonies, foraging by high numbers of birds has led to loss of coastal vegetation, adverse changes in soil properties and the establishment of an alternative stable state of exposed sediment, which can be detected with LANDSAT imagery. At a local scale, gosling growth, size and survival decreased in affected areas and other taxa have been adversely affected. The food subsidy on wintering and migration areas appears insufficient to meet reproductive demands as foraging in spring continues to occur on southern Hudson Bay staging and nesting areas. The recent introduction of liberal hunting regulations may reduce population size in the near term, but the revegetation of these coastal ecosystems will take decades to achieve. The present pattern of vegetation loss in these Arctic coastal systems is likely to continue in the forseeable future.     

Effect of archer density on elk pregnancy rates and conception dates

Archery hunting in Oregon has increased dramatically over the past 2 decades. At the same time, spring juvenile to adult female ratios of Rocky Mountain elk (Cervus elaphus) have been declining. This has raised concern that archery seasons may be disrupting elk breeding and contributing to the decline in recruitment. Two mechanisms could contribute to reduced juvenile:female ratios: 1) reduced pregnancy rates, and 2) delayed conception dates because of human disturbance during the rut. We varied the number of archery hunters at the Starkey Experimental Forest and Range over 13 years to evaluate effects of archer density on reproduction of elk. Archer densities were maintained at high densities during 4 years , low densities during 3 years , and no archers during 6 years. We determined pregnancy status, age, kidney fat index (KFI), lactation status, and fetus conception dates for 622 female elk harvested in December. We found pregnancy rate differences of 0.105, 0.080, and 0.021 between high and no archer density years (P = 0.004), high and low archer density years (P = 0.054), and low and no archer density years (P = 0.616), respectively. Conception dates were 4 days later for high archer density compared to low archer density (P = 0.006), but did not differ between high and no archer years (2 days; P = 0.136) or between low and no archer years (2 days; P = 0.108). We compared generalized linear model estimates of pregnancy rates and determined pregnancy rates for 28% of the lactating female elk to be affected by high archer density, whereas archer densities had no significant affect on pregnancy rate estimates for non-lactating females. We found no difference in conception dates among archer densities when comparing model estimates. Our results suggest that archer density and its interaction with nutritional condition of elk influence pregnancy rates of lactating females with low KFI levels; however, the effect of archer density alone does not explain the magnitude of decline in juvenile to female ratios observed in Oregon. © 2012 The Wildlife Society.