Search

In small-scale societies hunting is a high-risk, high-reward activity which impacts status and reproductive success. The question of whether men hunt to provision families or as a costly signal of their phenotypic qualities has been hotly debated in the anthropological literature. To shed new light on this question, we explored audience assessments of a hunter's phenotypic quality and desirability as a function of the composition of prey acquired by the hunter. A combination of ranking and forced-choice tasks were administered to 52 informants (46% female, aged 15–76 years) from the Aché hunter-gatherer tribe of Paraguay between May and July of 2015. Ratings of a hunter's provisioning ability, strength, fighting ability, disease resistance, and desirability as a mate or ally were all positively associated with killing large and hard-to-kill prey, and negatively associated with killing hard-to-find prey. However, killing a single large animal resulted in a worse assessment of hunter phenotype and desirability than killing an equivalent biomass of small animals. These findings highlight the potential of small prey hunting as a mechanism for advertising both quality and consistent provisioning ability. Critically, no conflict was observed between the goal of advertising quality/desirability and the goal of effective provisioning, since hunters who acquired more meat, even if the source of the meat was small game, were generally perceived as having better phenotypes and as more desirable. [ABSTRACT FROM AUTHOR]

Distinguishing between selective and opportunistic hunting is a major challenge in Paleolithic archaeology, requiring the comparison of the human hunting record to the usually unknown natural prey abundance. Open-air hunting camps are ubiquitous in the Eurasian Middle Paleolithic (MP) record, alongside cave sites, and are often dominated by large-bodied species. In the Levant, MP faunal records differ between caves and open-air sites: Caves are dominated by mountain gazelle and fallow deer, while open-air sites are more aurochs-dominated. This discrepancy can be explained by transport patterns, but whether the abundance of aurochs in open-air sites is due to deliberate targeting or natural abundance in the landscape is unclear. The Nesher Ramla open-air site is a natural sinkhole in central Israel with an 8-m-deep MP sequence. Detailed zooarchaeological, dental wear, and isotope analyses of the upper sequence fauna found a highly diverse assemblage dominated by medium-sized ungulates in the uppermost phases (Units I and IIa). Results concerning ungulate dietary niches and isotopic signatures demonstrate that animals from different biomes and topographies congregated at the site. Evidence of human butchery is infrequent and fewer than carnivore modifications. Several articulated vertebral columns attest to in situ preservation. Our results demonstrate that the Nesher Ramla's uppermost sequence formed primarily under natural conditions, suggesting that it was a site of opportunistic hunting by humans and carnivores, probably targeting ungulates that came to the sinkhole to drink. Therefore, we consider this assemblage representative of the site's "natural" environment and use it as a benchmark for comparing assemblages and hunting strategies. Thus, we observe a clear difference between our case study and those recovered from the site's lower layers (Unit IIB and below) and other open-air sites. For the first time, we can show that the abundance of large bovines in MP open-air sites is not necessarily due to their abundance in the environment but to deliberate human planning and selective hunting. • Nesher Ramla (NR) is an MIS 5 open-air Levantine site with an 8 m-thick sequence. • Latest phase fauna was deposited by natural deaths, human and carnivore predations. • Ungulates came to the site from afar to drink from the seasonal waterhole. • High ungulate diversity of the faunal assemblage suggests opportunistic hunting. • Aurochs abundance in Levantine MP open-air sites is due to selective human hunting. [ABSTRACT FROM AUTHOR]

Livestock predation is an important cause of endangerment of the snow leopard ( Panthera uncia ) across its range. Yet, detailed information on individual and spatio-temporal variation in predation patterns of snow leopards and their kill rates of livestock and wild ungulates are lacking. We collared 19 snow leopards in the Tost Mountains, Mongolia, and searched clusters of GPS positions to identify prey remains and estimate kill rate and prey choice. Snow leopards killed, on average, one ungulate every 8 days, which included more wild prey (73%) than livestock (27%), despite livestock abundance being at least one order of magnitude higher. Predation on herded livestock occurred mainly on stragglers and in rugged areas where animals are out of sight of herders. The two wild ungulates, ibex ( Capra ibex ) and argali ( Ovis ammon ), were killed in proportion to their relative abundance. Predation patterns changed with spatial (wild ungulates) and seasonal (livestock) changes in prey abundance. Adult male snow leopards killed larger prey and 2–6 times more livestock compared to females and young males. Kill rates were considerably higher than previous scat-based estimates, and kill rates of females were higher than kill rates of males. We suggest that (i) snow leopards prey largely on wild ungulates and kill livestock opportunistically, (ii) retaliatory killing by livestock herders is likely to cause greater mortality of adult male snow leopards compared to females and young males, and (iii) total off-take of prey by a snow leopard population is likely to be much higher than previous estimates suggest. [ABSTRACT FROM AUTHOR]

Optimal foraging models are commonly used to determine the strategy maximizing the proxies for fitness, such as foraging success. The strategies maximizing the proxy for fitness and fitness are assumed to be the same. However, this study shows that this assumption can be invalid when the relationship between the proxy for fitness and fitness is nonlinear and the foraging success is uncertain. A well-known prey choice model that uses long-term energy intake rate as the proxy for fitness was used as an example. This model considers a situation where predators predate on two types of prey that differ in quality, that is, one (primary prey) has higher quality than the other (alternative prey). A strategy can be represented by the probability of attacking alternative prey upon encounter while always attacking primary prey. The probability of attacking alternative prey that maximizes the expected rate of energy intake is either 0 or 1 depending on the density of primary prey (known as the zero–one rule). Meanwhile, the density of alternative prey has no influence on the optimal strategy. A simulation model was used to characterize the stochastic outcomes in the rate of energy intake in a finite foraging duration. The results revealed that foraging strategy influences the expected rate of energy intake and the uncertainty around the expectation. Consequently, the strategies maximizing the rate of energy intake and fitness may not be the same when the relationship between the rate of energy intake and fitness is nonlinear due to Jensen's inequality. Previous results such as the zero–one rule and the independence of the optimal strategy on the availability of alternative prey are no longer valid when fitness, rather than the proxy for fitness, is explicitly considered in a finite foraging duration. • An optimal foraging model that identifies the strategy maximizing the proxy for fitness was examined. • The proxy for fitness is foraging success. • Uncertainty in the proxy for fitness may vary with behavioral strategy. • The relationship between the proxy for fitness and fitness may be nonlinear. • The strategies maximizing the proxy for fitness and fitness may not be the same. [ABSTRACT FROM AUTHOR]

Ghar-e Boof is a Paleolithic cave site in Iran, known for being the type locality for the early Upper Paleolithic (UP) Rostamian lithic industries. Defining the Rostamian cultural group has significant archaeological implications for the Zagros Mountains. First, it highlights the cultural diversity of the UP in the Zagros. Second, it evinces a more complex scenario for the spread of anatomically modern humans (AMHs) across Southwest Asia. Despite this, little is known about human subsistence strategies during the Rostamian. In this paper, we present the results of a zooarchaeological analysis that allows us to reconstruct prey choice, transport decisions, and carcass processing at Ghar-e Boof. Wild sheep/goat was the main prey at the site, but other taxa such as partridges, tortoises, and gazelles represented important dietary supplements. Mortality data indicate that Rostamian hunters primarily targeted prime-aged adult ungulates. Anatomical representation also shows that there was no selective transport of animal carcasses to the site, so hunting activities most likely took place nearby. Although many specimens in the assemblage were covered by thick concretions, the presence of cut marks demonstrates defleshing, filleting, dismemberment, and even the removal of internal organs of prey. Percussion impacts and cone fractures also suggest the processing of bones for marrow. Chronologically, moving from the oldest to the youngest layers, there is a decrease in large game in parallel with a progressive increase in small, fast-moving animals. Following the prey choice model of optimal foraging theory, this diachronic variation might track regional resource stress or an increase in hunting pressure. Our results, along with the analysis of lithic artifacts and changes in the rates of sedimentation during the Rostamian sequence, indicate an increase in occupation intensity through time. Thus, the archaeological record of Ghar-e Boof and the ubiquity of UP sites across the Dasht-e Rostam region most probably reflect population growth within a few millennia after the arrival of AMHs. • First zooarchaeological study of the Rostamian sequence of Ghar-e Boof (42–35 ka cal BP). • Human exploitation of diverse animal prey. • Preferential hunting of prime-aged caprines near the site. • Evidence for changes in hunting pressure and site occupation intensity. [ABSTRACT FROM AUTHOR]

Correctly quantifying the impacts of rare apex marine predators is essential to ecosystem-based approaches to fisheries management, where harvesting must be sustainable for targeted species and their dependent predators. This requires modelling the uncertainty in such processes as predator life history, seasonal abundance and movement, size-based predation, energetic requirements, and prey vulnerability. We combined these uncertainties to evaluate the predatory impact of transient leopard seals on a community of mesopredators (seals and penguins) and their prey at South Georgia, and assess the implications for an ecosystem-based management. The mesopredators are highly dependent on Antarctic krill and icefish, which are targeted by regional fisheries. We used a state-space formulation to combine (1) a mark-recapture open-population model and individual identification data to assess seasonally variable leopard seal arrival and departure dates, numbers, and residency times; (2) a size-based bioenergetic model; and (3) a size-based prey choice model from a diet analysis. Our models indicated that prey choice and consumption reflected seasonal changes in leopard seal population size and structure, size-selective predation and prey vulnerability. A population of 104 (90¿125) leopard seals, of which 64% were juveniles, consumed less than 2% of the Antarctic fur seal pup production of the area (50% of total ingested energy, IE), but ca. 12¿16% of the local gentoo penguin population (20% IE). Antarctic krill (28% IE) were the only observed food of leopard seal pups and supplemented the diet of older individuals. Direct impacts on krill and fish were negligible, but the ¿escapement¿ due to leopard seal predation on fur seal pups and penguins could be significant for the mackerel icefish fishery at South Georgia. These results suggest that: (1) rare apex predators like leopard seals may control, and may depend on, populations of mesopredators dependent on prey species targeted by fisheries; and (2) predatory impacts and community control may vary throughout the predator's geographic range, and differ across ecosystems and management areas, depending on the seasonal abundance of the prey and the predator's dispersal movements. This understanding is important to integrate the predator needs as natural mortality of its prey in models to set prey catch limits for fisheries. Reliable estimates of the variability of these needs are essential for a precautionary interpretation in the context of an ecosystem-based management. [Copyright &y& Elsevier]

Abstract: The giant waterbugs are predators that utilize extra-oral digestion and are known to capture a wide variety of prey. Herein we describe the differences in salivary enzyme composition between large and small species of giant waterbug (Lethocerus uhleri, Lethocerinae and Belostoma lutarium, Belostomatinae, respectively). The saliva of L. uhleri contains 3 proteolytic enzymes and no amylase, while the salivary gland of B. lutarium produces 2 proteolytic enzymes and amylase. This fundamental difference in salivary enzyme composition correlates with the difference in diet preference between the Lethocerinae and Belostomatinae. Furthermore, we describe the ultrastructure of the salivary gland complex of B. lutarium and present data on the division of labor with respect to compartmentalization of enzyme production. Proteolytic enzymes are produced in the accessory salivary gland and amylase is produced in the main salivary gland lobe. This is the first reported evidence of protease production in the accessory salivary gland in the Heteroptera. [Copyright &y& Elsevier]

• The spiders Faiditus caudatus and Argyrodes elevatus are described as obligate kleptoparasites. • Both spiders showed nitrogen isotopic signatures like another araneophagic predator, Gelanor zonatus. • The invaders were found mainly in host webs with adults and egg sacs and in webs with egg sacs only. • In laboratory conditions, A. elevatus preferred to feed on prey captured by the host spider instead of its egg sac. • We discussed ecological contexts and host traits that may influence kleptoparasitism and araneophagy in these spider species. Kleptoparasitism is assumed to be the main foraging strategy in some animal groups, such as the spiders of the subfamily Argyrodinae (Theridiidae). However, some species may also feed on silk threads, egg sacs, or even their hosts. The conditions determining these alternative foraging tactics remain unknown for most species. We performed field observations, stable isotope analysis and laboratory experiments to investigate kleptoparasitism and araneophagy of Argyrodes elevatus and Faiditus caudatus in webs of Manogea porracea (Araneidae). We evaluated the following hypotheses: (1) both species exhibit higher trophic positions than their hosts and closest to an araneophagic sympatric species; (2) host web selection is influenced by the presence of alternative resources (adult male and female, and egg sacs); and (3) they preferentially consume egg sacs instead of stored prey items. Both argyrodines showed higher trophic positions than their female hosts and closest to an araneophagic spider species. The invaders were found mainly on host webs with one adult and egg sacs and with egg sacs only. Finally, A. elevatus preferred to feed on prey captured by the host spider instead of egg sacs. We discussed the factors that can potentially determine the choices between foraging exclusively as kleptoparasites and consuming the hosts. [ABSTRACT FROM AUTHOR]

• Long foreleg and short body guard hairs were sampled from adult male polar bears. • Trace elements were measured every 3 mm along each hair (laser ablation ICP-MS). • Concentrations differed between elements, individuals, and hair types. • A number of elements had cyclical patterns over the length of the hair. • Such data may have application for monitoring polar bear populations. Elements and compounds circulating in the body are incorporated into hair as it grows. Because of this, hair analyses are increasingly being incorporated in investigations of temporal trends in e.g. hormones and diet in wildlife species such as polar bears (Ursus maritimus). For this study, guard hair (GH; mean length 62 mm) and foreleg guard hair (FGH; mean length 164 mm) were collected from 15 adult male polar bears in western Hudson Bay, Canada. Our aim was to quantify the trace elements arsenic (As), cadmium (Cd), copper (Cu), iron (Fe), lead (Pb), mercury (Hg), selenium (Se), strontium (Sr), and zinc (Zn) every 3 mm in GH and FGH using laser ablation inductively coupled plasma mass spectrometry (laser ablation ICP-MS). Quantitative data was obtained at spatial scales as small as 50 μm – the smallest laser spot diameter used. Mean trace element concentrations increased in the order Pb < As < Cd < Se < Hg < Cu < Sr < Fe < Zn for both GH and FGH (pooled across all individuals). However, mean trace element concentrations were all significantly different between GH and FGH, except for Hg. Hg concentration varied along the length of both GH and FGH; each bear exhibited a unique pattern in Hg variation along the hair. For the remaining eight trace elements, the most common pattern was that of smaller fluctuations near the base of the hair, followed by an increase towards the tip. These fluctuations in trace element concentrations were likley related to hair growth and temporal changes. In this pilot study, we found quantifying trace elements in polar bear hair using laser ablation ICP-MS to be a promising monitoring technique across multiple temporal scales. [ABSTRACT FROM AUTHOR]

Prey selection by marine fishes is highly dependent on whether available food resources are abundant or deficient in their feeding grounds. The influence of fishing method on prey choice was analyzed via stomach content analyses of three coastal fishes: Pennahia argentata , Sillago japonica , and Thryssa kammalensis. Fish samples were collected from northern Jinju Bay, Korea, using two types of fishing gear that covered two different fishing layers in the water column: beam-trawl (bottom layer) and set-net (surface layer). When caught via beam-trawl, all three target species were function as bottom-feeding carnivores that consumed mainly benthic crustaceans and other invertebrates. In contrast, when caught via set-net, teleosts were the most abundant prey items in the diets of the three species. Significant differences in the diet composition between beam-trawl and set-net samples were revealed using permutational multivariate analysis of variance. Although seasonal changes in diet composition were also evident, the influence of season was weaker than that of fishing gear. Consequently, in this study, stomach content analysis demonstrated that set-net made a strong effect on prey selection by the co-occurring P. argentata , S. japonica , and T. kammalensis in southern Korean waters. • Prey selection by marine fishes is highly dependent on available food resources. • An atypical feeding environment may lead to alternative feeding behaviors for marine fishes. • Semi-benthic coastal fishes chose pelagic food resource during entrapment in the surface layer. • Samplings using set-nets make critical bias in dietary studies of fish species. [ABSTRACT FROM AUTHOR]