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Specialist predators are innately and distinctively proficient at targeting specific prey types. This is enabled by behavioural, perceptual and cognitive mechanisms that can only be understood using carefully designed experiments. Evarcha culicivora is an East African jumping spider that feeds on vertebrate blood acquired indirectly by actively targeting blood-carrying female mosquitoes as preferred prey. Here we asked whether these spiders use the colour red to identify this prey. In Objective 1, we used spectrophotometry to document the changing redness of mosquitoes in the first 17 h following blood meals. In Objective 2, we used vision-based choice tests to document how E. culicivora 's preference for blood-carrying mosquitoes changes over time (using an interval comparable to that in Objective 1). We found the strongest preference for blood-carrying mosquitoes during the first 6 h after those mosquitoes had fed on blood and that this time interval corresponded to when mosquitoes exhibit the reddest coloration. Based on this, we then took mosquitoes that had never fed on blood and manipulated their colour using a blend of red food dye to make them appear blood-fed (i.e. by matching their spectral properties to mosquitoes that had fed on blood within the previous 6 h). We also created grey-dyed mosquitoes that matched the spectral properties of those that had never fed on blood. In Objective 3, there was no evidence of E. culicivora visually discriminating between our red-dyed mosquitoes and blood-carrying mosquitoes; this indicates that, to E. culicivora , our red-dyed mosquitoes appropriately resembled blood-carrying mosquitoes. Finally, in Objective 4, we show that E. culicivora consistently preferred red-dyed mosquitoes over grey-dyed mosquitoes, supporting the hypothesis that E. culicivora uses some aspect of red coloration to identify their preferred prey. We discuss how these findings relate to cognitive processes, colour-based communication and sensory exploitation. • Evarcha culicivora, a jumping spider, targets blood-carrying mosquitoes as prey. • They prefer mosquitoes that have had a recent blood meal, with visibly red abdomens. • Tests with artificially coloured mosquitoes show they use red colour to select prey. [ABSTRACT FROM AUTHOR]

Natal dispersal is common in animals but the fitness cost of moving from the natal area is not well understood. One reason for a fitness cost is that foraging skills and prey preference learned early in life may be less efficient if the individual settles in a new, unfamiliar habitat. In a 4-year study, we found that immigrant parent blue tits, Cyanistes caeruleus , and great tits, Parus major , were inferior food providers compared to local recruits. In blue tits, immigrants provided smaller prey items than local recruits, whereas in great tits, the immigrants provided fewer green larvae, but relatively more brown larvae, to the offspring than local recruits. We also found that immigrant females laid later or smaller clutches than females locally recruited. The results are consistent with the hypothesis that natal dispersal carries costs related to the learning of foraging skills. However, alternative explanations are that the differences were caused by genetic and/or quality differences between the two groups of birds. We discuss various ecological and behavioural traits that may influence, and be influenced by, the mismatch of foraging between natal and breeding habitats. In altricial birds, yearlings will not have previous foraging experience during breeding and, in addition, immigrants will not have spent a long postfledging period in the new local habitat with their parents. If there are foraging-habitat mismatches as a result of dispersal, researchers should include natal origin in models of optimal foraging, time budgets, reproductive success and survival because performance may be directly related to the early learning environment rather than genetic differences. [ABSTRACT FROM AUTHOR]

We studied olfactory responses of Nesidiocoris tenuis Reuter (Heteroptera: Miridae), an omnivorous mirid bug, to volatiles from eggplants infested by different developmental stages of tobacco cutworms, Spodoptera litura Fabricius (Lepidoptera: Noctuidae) and of female two-spotted spider mites, Tetranychus urticae Koch (Acari: Tetranychidae). We first conducted predation experiments and found that N. tenuis preyed on first and second stadium larvae, but not on third and fourth stadium S. litura larvae. N. tenuis also preyed upon T. urticae females that had been reported to be less suitable prey species. When offered first stadium S. litura larvae and T. urticae females simultaneously, N. tenuis , preferred to prey upon S. litura larvae. We then tested the olfactory responses of N. tenuis to volatiles from eggplants using a Y-tube olfactometer. A significant preference for volatiles from uninfested eggplants over clean air was found. Volatiles of eggplants infested by either first, second or fourth stadium S. litura larvae were preferred over volatiles from uninfested eggplants. The olfactory preferences of N. tenuis to S. litura -infested eggplants were: eggplants infested by 10 first stadium larvae = eggplants infested by 10 second stadium larvae > eggplants infested by 1 fourth stadium larva. Volatiles from eggplants infested by 200 T. urticae females also attracted N. tenuis , but the volatiles were not as attractive as those from eggplants infested by 10 first stadium larvae. Chemical analyses showed that volatiles from eggplants infested by different developmental stages of S. litura larvae had qualitative differences. First stadium larvae induced higher amounts of volatiles than second and fourth stadium larvae, despite the first stadium S. litura larvae doing the least damage. T. urticae female-induced volatiles were both qualitatively and quantitatively different from those induced by first stadium S. litura larvae. The specific olfactory responses of N. tenuis to different prey species/developmental stages were discussed in terms of prey availability and biological control. [ABSTRACT FROM AUTHOR]

The southern ladybird ( Cleobora mellyi Coleoptera: Coccinellidae) is a voracious predator of the invasive tomato–potato psyllid (TPP) ( Bactericera cockerelli Hemiptera: Triozidae) in New Zealand. We examined important aspects of the southern ladybird’s ecology to obtain further insight into its potential as a biocontrol agent of TPP in potato crops. We found that the southern ladybird did not prefer TPP over either Myzus persicae Sulzer or Macrosiphum euphorbiae Thomas in choice tests, but avoided consumption of greenhouse whitefly, Trialeurodes vaporariorum (Westwood). Ladybird longevity was tested under the conditions of low prey provision, a floral resource (buckwheat), and a combination of buckwheat and low density of TPP, over a 3 month period. There was no difference in longevity between ladybirds supplied with TPP only or buckwheat only. However, those with access to TPP and buckwheat lived longer than those with only TPP. In a glasshouse microcosm study, the ladybird was able to significantly reduce TPP densities after 3 weeks, and maintain the reduced numbers for 7 weeks. A species-level trophic cascade was found for both number and weight of potato tubers. These results indicate that the southern ladybird has potential as a biological control agent of the invasive tomato–potato psyllid in New Zealand. [ABSTRACT FROM AUTHOR]

Foraging animals must choose between familiar prey and novel prey of uncertain profitability and potential toxicity. Owing to a healthy aversion to potentially dangerous prey, foragers show an initial transient wariness of novel food (neophobia). In addition, some individuals display a much longer period of avoidance before incorporating the novel food into their diet (termed dietary conservatism). There are two stable foraging strategies found within forager populations: (1) adventurous consumers (AC) which rapidly accept novel foods and (2) foragers showing dietary conservatism (DC). The expression of these two strategies may also vary with environmental conditions. We measured the effect of competition on the plasticity of foraging strategies when domestic chicks, Gallus gallus domesticus, foraged for familiar and novel coloured crumbs with or without competitor chicks. In addition we investigated the effect of prey detectability on the response of foragers to a competitor, by making the familiar food cryptic or conspicuous. AC birds responded to competition by accepting the novel prey more quickly than when foraging alone, regardless of how hard familiar food was to find. In contrast, DC birds failed to reduce their wariness in response to competition when the competitor's food choice was obscured. The foraging strategies of the birds were thus found to be plastic in their expression, but this plasticity differed between inherently AC and DC individuals. The implications of these results are discussed in relation to the foraging strategies of wild and domestic birds. [ABSTRACT FROM AUTHOR]

Abstract: The reasons for megafaunal extinction in Australia have been hotly debated for over 30 years without any clear resolution. The proposed causes include human overkill, climate, anthropogenic induced habitat change or a combination of these. Most protagonists of the human overkill model suggest the impact was so swift, occurring within a few thousand years of human occupation of the continent, that archaeological evidence should be rare or non-existent. In Tasmania the presence of extinct megafauna has been known since the early twentieth century () with earlier claims of human overlap being rejected because of poor chronology and equivocal stratigraphic associations. More recent archaeological research has not identified any megafauna from the earliest, exceptionally well-preserved late Pleistocene cultural sites. In 2008 however an argument for human induced megafaunal extinctions was proposed using the direct dates from a small sample of surface bone from two Tasmanian non-human caves and a museum sediment sample from an unknown location in a cave, since destroyed by quarrying (). supplemented their data with published dates from other Tasmanian caves and open sites to argue for the survival of at least seven megafauna species from the last interglacial to the subsequent glacial stage. To investigate the timing of extinctions in Tasmania and examine the latest claims, new excavations and systematic surveys of limestone caves in south central Tasmania were undertaken. Our project failed to show any clear archaeological overlap of humans and megafauna but demonstrated that vigilance is needed when claiming survival of megafauna species based on old or suspect chronologies. The results of our six-years of fieldwork and dating form the first part of the present paper while, in the second part we assess the data advanced by for the late survival of seven megafauna species. A model of human prey selection and the reasons for the demise of a range of marsupials, now extinct, are discussed in the third part of the paper. [Copyright &y& Elsevier]

Abstract: We investigated potential prey preference of the mass-produced generalist predator Mallada basalis (Walker) when offered two mites, Tetranychus kanzawai Kishida and Panonychus citri (McGregor), both important pests on papaya. Laboratory choice tests revealed that none of the three larval instars of M. basalis showed a preference for either species of mite or discriminated among the four mite life stages. Direct observations also showed that lacewing larvae mostly consumed whichever mite was encountered. Previous feeding experience on one mite species did not influence subsequent prey choice when lacewings were presented with both mite species. High acceptability of all life stages of both mite pests suggests that mass-produced M. basalis has potential as an effective biological control agent for T. kanzawai and P. citri when the two mites occur simultaneously or sequentially in papaya plantations. [Copyright &y& Elsevier]

Abstract: Human decision-making processes are usually hierarchical in that higher-level decisions impose constraints on lower-level decisions. As a result, prey choices during individual foraging trips are governed to a large degree by higher-level decisions regarding how to supply resources to satisfy demands, with higher-level decisions typically made prior to foraging trips. Resource selectivity and search bias sometimes take place in this context. By dividing resource procurement modes into opportunistic and target, I discuss how choice of mode on the basis of an overall economic plan affects prey choice during foraging trips and faunal assemblage composition resulting from those trips. An analysis of taxonomic diversity in shellmidden assemblages from the central-western Korean Late Chulmun Period (3500–1300 BC) and Middle and Late Mumun Period (700–100 BC) shows that Late Chulmun people adopted a target mode, while Middle/Late Mumun people adopted an opportunistic mode in their exploitation of marine resources. A decrease in the importance of marine resource in Middle/Late Mumun produced a change in taxonomic diversity by increasing the opportunistic cost of marine resource exploitation. [Copyright &y& Elsevier]

Abstract: This paper summarizes results from excavations at Üçağızlı Cave (Hatay, Turkey) between 1999 and 2002 and 2005. This collapsed karstic chamber contains a sequence of early Upper Paleolithic deposits that span an interval between roughly 29,000 and 41,000 (uncalibrated) radiocarbon years BP. Lithic assemblages can be assigned to two major chronostratigraphic units. The earliest assemblages correspond with the Initial Upper Paleolithic, whereas the most recent ones fit within the definition of the Ahmarian. Substantial assemblages of stone tools, vertebrate faunal remains, ornaments, osseous artifacts, and other cultural materials provide an unusually varied picture of human behavior during the earliest phases of the Upper Paleolithic in the northern Levant. The sequence at Üçağızlı Cave documents the technological transition between Initial Upper Paleolithic and Ahmarian, with a high degree of continuity in foraging and technological activities. The sequence also documents major shifts in occupational intensity and mobility. [Copyright &y& Elsevier]

Abstract: The letter-winged kite Elanus scriptus is unique in being the only truly nocturnal raptor (Falconiformes). An endemic of arid/semi-arid Australia, the kite is sympatric with the barn owl, Tyto alba, throughout most of its range. Although the letter-winged kite is nocturnal, it seems to possess intermediate degrees of adaptation for nocturnal hunting, whereas the barn owl is specialized for nocturnal activity. We studied sympatric populations of both species during a rodent population outbreak in the north-west Simpson Desert to understand how their different nocturnal adaptations influenced diet and prey selection. The commonest rodents, in order of abundance, were Pseudomys australis (body mass: 40–75g), P. hermannsburgensis (9–17g), and Notomys alexis (27–45g). Rodents dominated the diets of kites (96% of 225 prey items) and owls (98% of 303 prey items). Dietary niche breadth was relatively low for both kites (B A=0.16) and owls (B A=0.13), whereas niche overlap was extremely high (O=0.98). Barn owls exhibited greater prey choice, specifically; they selected the larger P. australis and avoided the small P. hermannsburgensis, whereas kites captured Pseudomys species in proportion to their availability. [Copyright &y& Elsevier]

Abstract: Generalist predators have the capacity to restrict pest population growth, especially early in the season before densities increase. However, their polyphagous feeding habits sometimes translate into reduced pest consumption when they target alternative prey. An order-specific monoclonal antibody was developed to examine the strength of trophic connections between Diptera, a major category of non-pest prey, and linyphiid spiders in alfalfa. We report the development and characterization of a monoclonal antibody with order-level specificity to Diptera. This antibody elicited strong absorbance to 22 Diptera from 13 families, no false-positive reactivity to non-dipteran invertebrates, and antigen detection periods following prey consumption that were comparable between spiders. Over 900 field-collected females of the linyphiid spiders Erigone autumnalis and Bathyphantes pallidus were screened for Diptera antigen. Significantly more B. pallidus screened positive for Diptera (40%) compared to E. autumnalis (16%), indicating differential reliance on these prey. In parallel with the collection of spiders for gut-content analysis, prey availability was estimated at web sites. The two spiders exhibited different feeding responses to prey availability. Consumption of Diptera by B. pallidus was strongly correlated with Diptera abundance whilst the availability of other potential prey did not influence predation rates. Conversely, E. autumnalis did not prey upon Diptera in proportion to availability, but increased Collembola activity-density reduced dipteran consumption. Integration of molecular gut-content analysis with precise sampling of prey demonstrated how two closely related linyphiid spiders exhibit different feeding responses to the availability of prey under natural field conditions. Elucidating the feeding preferences of natural enemies is critical to effective incorporation of biological control by generalist predators in the management of agricultural pests. [Copyright &y& Elsevier]

Abstract: The food habits of the Barn Owl (Tyto alba) are relatively well documented across its Madagascar range based on pellet contents, with the exception of the arid zone of the extreme southwest. New data are presented herein to fill this void. The diet of this owl consists largely of introduced rodents and there are some marked seasonal differences in the other types of prey taken. Evidence is presented to support the hypothesis that this owl has been able to expand its distribution in the wake of human habitat disturbance and the associated trophic proliferation of non-native rodents in disturbed habitats. [Copyright &y& Elsevier]

Abstract: The diet of the Barn Owl (Tyto alba) is well known in different habitats but a lack of data persists for arid and subarid environments. We provide preliminary information on food selection of barn owls in Tunisia by the analysis of the composition of pellets. The diet consists largely of rodents and the three-toed Jerboa (Jaculus jaculus) that accounted for more than 50% of total prey biomass. Results suggest that barn owls show a nonrandom tendency toward rodent species especially small and young individuals. [Copyright &y& Elsevier]

Abstract: Archaeological analyses of faunal assemblages often rely on rationale derived from the prey choice model to explain temporal and spatial changes in taxonomic measures of diversity and/or abundances. In this paper, we present analyses of ethnoarchaeological observations and bone assemblages created by Central African Bofi and Aka forest foragers which show that different small prey hunting technologies target specific suites of prey and that hunters vary their technological choice depending on their foraging goals. Analysis of ethnoarchaeological bone assemblages produced by the Bofi and Aka shows that variability in target prey can create spatially distinct, but contemporaneous, faunal assemblages with different diversity values and abundance indices. These data reveal important variation in how individuals within a contemporary human population rank prey and challenge current assumptions about the meaning of diversity and abundances measures in archaeological contexts. We argue that the use of diversity and abundance indices can obscure important intrasite variability in prehistoric foraging effort and suggest strategies that might enhance current techniques. [Copyright &y& Elsevier]

While many archaeological sites from the eastern Snake River Plain attest to the successful acquisition of bison by native hunters, site data alone are not sufficient to assess the relative importance of bison in the regional prehistoric diet. This paper presents a prey choice model that compares the net caloric return rates of bison with other resources available on the eastern Snake River Plain using data from early 19th century fur trapper''s journals. The model predicts that although bison likely had a higher net return rate than any other resource, overall diet breadth in the region would have been broad. Although further evaluation of the model is needed, a preliminary examination of bison assemblages from the eastern Snake River Plain suggests that relatively limited numbers of bison were being acquired. If bison were only rarely encountered due to low population densities, the bulk of the diet would have been made up of lower ranked items included in the optimal set, as predicted by the model. [Copyright &y& Elsevier]

Several studies show increased generalist predator abundance because of specific landscape features or farm management, but it is not evident that enhanced biological control will always result. High abundance of prey species other than the target pest (alternative prey) may decrease generalist predator predation on the pest via prey substitution. In this paper, I have recorded the removal rate of experimentally added aphids, and abundance of generalist predators and alternative prey in spring barley fields in Sweden. I hypothesized that the aphid removal rate would increase with generalist predator abundance and decrease with alternative prey abundance at given alternative prey- and generalist predator abundances, respectively. The aphid removal rate increased with generalist predator abundance, whereas there was no clear relationship with alternative prey abundance. Because of a positive correlation between generalist predator- and alternative prey abundance, a positive correlation between alternative prey abundance and aphid removal rate was detected when not adjusted for generalist predator abundance. This suggests the effect of generalist predators substituting alternative prey for the pest was small, and other factors may confound the putative relationship between generalist predator abundance and biological control efficacy. [Copyright &y& Elsevier]

Although measures of evenness of archaeological faunas are increasingly used in zooarchaeological analyses, the widely accepted hypothesis that increasing evenness should indicate increasing dietary breadth has not been tested. In this paper, I examine three factors that can contribute to changing evenness values—changing encounter rates with high-ranked prey types, changing diet breadth, and similarity between the return rates of the highest-ranked resources—and discuss ways of controlling the latter two factors. I then test the “evenness hypothesis” using ethnographic data collected by Smith [E.A. Smith, Evolutionary Ecology and the Analysis of Human Foraging Behavior: An Inuit Example from the East Coast of Hudson Bay, Ph.D. thesis, Cornell University, 1980, E.A. Smith, Inujjamiut Foraging Strategies: Evolutionary Ecology of an Arctic Hunting Economy, Aldine de Gruyter, Hawthorne, NY, 1991] in Inukjuak, northern Canada. Although the results support the evenness hypothesis, they also show that the nature of archaeological data may make evenness measures difficult to use accurately. Evenness can be used to understand changing prehistoric encounter rates with prey, but many conditions must be met for it to do so. [Copyright &y& Elsevier]

Human beings are unique in the degree to which they rely on technology to interface with their environment. Applications of biologically derived foraging models have typically taken this technology as a given when analyzing ethnographic and prehistoric subsistence practices. This paper departs from the standard approach by treating investment in technology as a decision variable and looking at how investment decisions might be expected to vary with changes in both the time available to forage and the nature of the local resource base. The study draws attention to the importance of understanding both the costs and the benefits of technological investment and how they relate to one another. We use ethnographic and hypothetical data to demonstrate how one might represent these relationships mathematically, discuss the importance for understanding investment decisions, and explore their implications in circumstances where resources are randomly and non-randomly encountered. [Copyright &y& Elsevier]