Carnivore Predation Research Articles

On the polysemic nature of traces and co-occurring patterns in anthropized material — contribution of a “Retoucher” with a flaked bone aspect from Roc-en-Pail (France)

This article presents a new archaeological material to discuss methodological issues encountered by scientists working both on minimally-modified bones from Mousterian assemblages, to those dealing with the identification of “retouchers” having a flaked bone aspect. The technological approach integrates complementary analytical study-frames in order to assess archaeological information. On the one hand, analogies with similar experimentally produced patterns reduce the functional identification of the archaeological specimen. They do not deal with a single artefact-type in the category of “retouchers”, which thus remains generic. On the other hand, the recording of the patterns in their chronological order, combined together with that of modifications relative to the diagenesis of the bone as an artefact, suggests the “retoucher” was reduced in a relatively fresh state by a carnivorous predator also. The evidence of this co-occurrence, if characterizing the successive anthropic-originated bone beds ultimately degraded by predators in situ, would suggest a relatively short period of human occupation generated by the use of the site in a singular cyclical conception “prey-hunter-predator” at regional scale.

Fecal DNA metabarcoding reveals the winter diet of Eurasian otter (Lutra lutra) in Northeast China

As the top predator of freshwater ecosystems, the Eurasian otter (Lutra lutra) plays a vital role in maintaining food web structure and ecosystem stability. Understanding the dietary composition and dynamics of the Eurasian otter is crucial for comprehending its ecosystem function and interspecies interactions, providing vital information for determining conservation and management strategies. Currently, DNA metabarcoding technology has been extensively applied in dietary studies as a more effective and accurate method for identifying prey species. However, there remains an insufficient amount of research on otter diet using this technology, especially in Northeast China. In this study, we analyzed the vertebrate dietary composition and spatial variation of otters during the winter in Northeast China using DNA metabarcoding technology. We confirm 106 fecal samples belonging to Eurasian otter DNA from 118 putative otters fecal samples, and then performed polymerase chain reaction (PCR) amplifications using vertebrate universal primers with the otter blocking primer (OBS1) and the human blocking primer (HomoB) to the sequence. Subsequently, high-throughput sequencing was performed to analyze the dietary composition of Eurasian otter. We identified a total of 34 prey taxa, including 31 fish, 2 frog and 1bird. Our results showed that the winter diet of the Eurasian otter was dominated by fish (60.11 %), (e.g., Cottidae, Cyprinidae), followed by Ranidae (39.88 %). Furthermore, geographical variations in dietary preferences were observed. This study confirms that Eurasian otter is a generalist piscivorous predator, and that its diet could be related to the availability of resources in the habitat. This study enriches the information on the diet of Eurasian otter, and can be used to provide a reference for the development of effective conservation strategies. At the same time, it confirms the reliability of the fecal DNA metabarcoding technique for carnivore predation analysis, and provides a new perspective for the investigation and research of otters and other mammals.

Biology of the Bombayduck Harpadon nehereus (Hamilton, 1822) from the north-eastern Arabian Sea, India

The Bombayduck Harpadon nehereus (Hamilton, 1822) is a common species and majorcontributor to the fishery in the northern Arabian Sea. The biology of H. nehereus, exploitedby set bagnets (SBN, dol netters) and trawlers from the northern Arabian Sea coast of India(Gujarat and Maharashtra) was investigated during 2014 to 2019. Fishes with a size rangeof 30-408 mm mainly contributed to the fish landing. The sex ratio (male: female) was 1:1.5.Length at maturity (Lm) for females was estimated at 207 mm TL. Mature ovaries containedova of all maturity stages indicating the species to be a continuous spawner. The absolutefecundity ranged from 23,444 to 1,34,432 eggs per fish and relative fecundity ranged from235-430 eggs g-1. The gonadosomatic index and monthly maturity stages suggested thatH. nehereus is a continuous spawner with peaks occurring from February to April. The ‘b’value in the length-weight relationship was 3.31 showing a positive allometric growth. Thediet analysis showed H. nehereus to be a highly carnivorous predator which fed mainly oncrustaceans (Index of Relative Importance, IRI = 82.7%) followed by teleosts (17.3%). Thepresent article discusses the biology of H. nehereus in the north-eastern Arabian Sea. Keywords:Biology, Bombayduck, Fisheries, Harpadon nehereus,Indian Ocean, Trophic level

We the hunted

Classic depictions of human evolutionary ecology cast Homo as predator and other hominins, including Paranthropus robustus, as prey. Such hypotheses rest on a small number of fossils that exhibit evidence of carnivore predation, including the iconic SK 54 cranium from Swartkrans in South Africa. Here we demonstrate that the SK 54 cranium shares its closest affinities with H. erectus sensu lato rather than P. robustus. Demonstrating that Homo was prey for leopards at Swartkrans weakens the historically significant hypothesis that Homo was better able to avoid predation because of being behaviourally and technologically advanced compared to Paranthropus. Subsequent ideas about hominin palaeobiology derived from this hypothesis warrant reconsideration.

A positive presentation of wolves affects the explicit and implicit attitudes of schoolchildren towards them

ABSTRACT Large carnivore predators can be controversial animals, but sustainable coexistence with humans depends on peoples’ tolerance and willingness to support their conservation. We conducted a short-term study on a sample of Slovak schoolchildren (aged 9–15) aimed at changing attitudes toward the grey wolf. The intervention consisted of videos and PPT presentations showing the wolf as a predator with positive characteristics crucial for ecosystem functioning (experimental group) or as a pest of farm animals with negative characters depicted in fairy tales. Participants in the experimental group showed significantly better explicit and implicit attitudes toward wolves than participants in the control group. Our research shows that a well-designed short-term intervention highlighting the importance of wolves in nature contributes to building positive attitudes toward wolves in young people.

Small mammals as a bioindicator of mercury in a biodiversity hotspot – The Hengduan Mountains, China

Due to toxicities, capacities for long-range transportation, bioaccumulation, and biomagnification, mercury (Hg) presents a unique concern to wildlife in remote ecosystems, including “the roof of the world”. Large carnivorous predators are thought to be exposed to elevated Hg due to their high trophic positions, but the direct assessment for Hg contamination is a challenge. Given the poorly understood Hg exposure in these carnivores, establishing a reliable and straightforward assessment would be essential to identify targeted species at Hg exposure risk for effective conservation, particularly in fragile biodiversity hotspots. Small mammals are abundant and serve as prey for large top predators. Combined with local observations, we provided an assessment to estimate the daily Hg exposure via consumption of small mammals for large carnivorous mammals recorded in the Hengduan Mountains, a world biodiversity hotspot, China. Within an altitude span from 2043 to 4251 m a.s.l., the average topsoil total mercury concentration (hereafter [THg]) was 44.65 ± 25.80 μg/kg (mean ± sd; 10.54 – 135.15 μg/kg, n = 41), while the hair [THg] in small mammals was 104.66 ± 91.96 μg/kg (mean ± sd; 7.73 to 385.70 μg/kg, n = 13). Furthermore, the daily intake of Hg was calculated among the 22 investigated/historical-recorded carnivore mammals belonging to 5 families. We found a large variance in daily intake of Hg via small mammals: Felidae (median: 205.93 μg/day) > Ursidae (135.02 μg/day) > Canidae (92.92 μg/day) > Viverridae (19.88 μg/day) > Mustelidae (7.18 μg/day). Specifically, Tiger Panthera tigris was found with the highest Hg daily intake (1701.39 μg/day) via consuming small mammals, while species belonging to Mustelidae generally have low Hg daily intake (<3 μg/day). This study provides a feasible approach to identifying species at environmental Hg risk in this fragile remote high-elevation region. The limitations and future improvements were discussed.

Trophic chain of the pelagic thresher, Alopias pelagicus, in the Southeastern Pacific Ocean: An approach through stable isotopes of carbon and nitrogen

The pelagic thresher, Alopias pelagicus, plays a vital role in coastal and marine ecosystems as a top predator that feeds on species from low trophic levels. It is a commercial species relevant in Ecuador. The feeding chain of A. pelagicus was analyzed through carbon and nitrogen stable isotopes in the Southeast Pacific Ocean. Considering the lack of studies regarding this topic, this would elucidate the flow of nutrients and energy from the base up to this predator. Its diet composition included 19 prey species, out of which 10 were cephalopods and nine Osteichthyes. The most relevant species were the squid Ommastrephes bartramii, Dosidicus gigas, Stenoteuthis oualaniensis, and the fish Merluccius gayi peruanus. The pelagic thresher is a carnivore predator, and its prey species belong to tertiary and quaternary trophic levels. The carbon and nitrogen male isotopic ratios were similar to those of females, as were immature and mature organisms. This suggests that this species feeds in oceanic regions of low depths and could be exploiting and sharing an area with similar feeding resources. According to the mixing models, squids were the most important prey group, in which the squid Ommastrephes bartramii contributed most to its diet. Furthermore, this shark was characterized as a specialist predator with a trophic overlap by sex and maturity stages.

Spatio-Temporal Analysis of Game Harvests in Sweden

The benefits and costs of wildlife are contingent on the spatial overlap of animal populations with economic and recreational human activities. By using a production function approach with dynamic spatial panel data models, we analyze the effects of human hunting and carnivore predation pressure on the value of ungulate game harvests. The results show evidence of dynamic spatial dependence in the harvests of roe deer and wild boar, but not in those of moose, which is likely explained by the presence of harvesting quotas for the latter. Results suggest the impact of lynx on roe deer harvesting values is reduced by 75% when spatial effects are taken into account. The spatial analysis confirms that policymakers’ aim to reduce wild boar populations through increased hunting has been successful, an effect that was only visible when considering spatial effects.

Endogenous l- to d-amino acid residue isomerization modulates selectivity between distinct neuropeptide receptor family members

The l- to d-amino acid residue isomerization of neuropeptides is an understudied post-translational modification found in animals across several phyla. Despite its physiological importance, little information is available regarding the impact of endogenous peptide isomerization on receptor recognition and activation. As a result, the full roles peptide isomerization play in biology are not well understood. Here, we identify that the Aplysia allatotropin-related peptide (ATRP) signaling system utilizes l- to d-residue isomerization of one amino acid residue in the neuropeptide ligand to modulate selectivity between two distinct G protein-coupled receptors (GPCRs). We first identified a novel receptor for ATRP that is selective for the D2-ATRP form, which bears a single d-phenylalanine residue at position 2. Using cell-based receptor activation experiments, we then characterized the stereoselectivity of the two known ATRP receptors for both endogenous ATRP diastereomers, as well as for homologous toxin peptides from a carnivorous predator. We found that the ATRP system displayed dual signaling through both the Gαq and Gαs pathways, and each receptor was selectively activated by one naturally occurring ligand diastereomer over the other. Overall, our results provide insights into an unexplored mechanism by which nature regulates intercellular communication. Given the challenges in detecting l- to d-residue isomerization from complex mixtures de novo and in identifying receptors for novel neuropeptides, it is likely that other neuropeptide-receptor systems may also utilize changes in stereochemistry to modulate receptor selectivity in a manner similar to that discovered here.

The Aterian site of Phacochères (northern Algeria): a zooarchaeological perspective

ABSTRACT The Phacochères site (formerly known as Les Allobroges) is a small ravine belonging to a karst system in northern Algeria. The rescue excavations conducted in 1960s at this site have yielded an exceptionally rich assemblage of vertebrates associated with Aterian stone tools. These faunal fossils collected in sandy clay levels are characteristic of the North African Upper Pleistocene and they represent a remarkable model for understanding the structure of prehistoric mammalian associations, palaeoenvironmental reconstruction and past habitat diversity. Based on biochronological and palaeoenvironmental data, the assemblage is attributed to Marine Isotopic Stage 5 (MIS 5) defined by a forest and grassland ecosystem. This paper reports the results of an analysis of the modifications of this faunal assemblage produced by human and carnivore activity. It suggests that the Aterian occupants of the site preferentially oriented their hunting towards large prey such as buffalo and aurochs and that they were able to compete with other carnivore predators. Nevertheless, the assemblage represents a palimpsest accumulated by different predators, both human and carnivore, that results from events that overlapped with brief human occupations of the site.

A field test of R package GPSeqClus: For establishing animal location clusters

Abstract The ability to track animals with Global Positioning System (GPS) collars opened an enormous potential for studying animal movements and behaviour in their natural environment. One such endeavour is to identify clusters of GPS locations as a way to estimate predator kill rate. Clapp et al. (2021) developed an R package (GPSeqClus) to assess a location dataset based on user‐defined parameters to identify clusters and their characteristics. These characteristics can then help to distinguish resting‐site clusters from kill sites of their large (&gt;50 kg) prey. We identified location clusters of an adult male wolf Canis lupus on Ellesmere Island, Nunavut, Canada in July 2009 and tracked him until he died in April 2010. Identifying location clusters was challenging because the collar only obtained two GPS locations per day (12 h apart). In July 2010, we searched 30 of 52 location‐clusters we identified as kill/scavenge sites and found 17 of them as such, given they had muskox Ovibos moschatus or caribou Rangifer tarandus pearyi remains nearby. We also documented five wolf rendezvous sites, two den sites, and the wolf's death site to total 60 location‐clusters in all. We used a two‐step process in testing the R Package GPSeqClus (hereafter GPSeqClus): (1) compare the number of clusters our method discerned with the number identified by the new algorithm, and (2) compare the number of biologically significant clusters (e.g. den sites, kill/feeding sites) we found with the number the new algorithm located. We made these tests with GPSeqClus by varying the search radius, number of days at a site, and minimum number of locations required for a cluster. GPSeqClus compared well to our technique, with the best sub‐algorithm among the 25 we tested only missing three of our identified clusters and yielding six additional clusters. GPSeqClus identified 16 of the 17 confirmed sites of remains, all wolf home sites, and the wolf's carcass site. Identifying clusters using a 500‐m search radius, a 1.5‐day window, and a minimum of two GPS locations per cluster was suitable for a coarse GPS acquisition rate of two locations per day when prey are large, such as muskox or caribou. Given that GPSeqClus performed well with our coarse location dataset, we expect it will also perform even better with a collar acquiring more than two locations per day. Having a field‐tested utility such as GPSeqClus will enhance carnivore predation studies elsewhere.

Brown bear–sea otter interactions along the Katmai coast: terrestrial and nearshore communities linked by predation

AbstractSea otters were extirpated throughout much of their range by the maritime fur trade in the 18th and 19th centuries, including the coast of Katmai National Park and Preserve in southcentral Alaska. Brown bears are an important component of the Katmai ecosystem where they are the focus of a thriving ecotourism bear-viewing industry as they forage in sedge meadows and dig clams in the extensive tidal flats that exist there. Sea otters began reoccupying Katmai in the 1970s where their use of intertidal clam resources overlapped that of brown bears. By 2008, the Katmai sea otter population had grown to an estimated 7,000 animals and was likely near carrying capacity; however, in 2006–2015, the age-at-death distribution (AADD) of sea otter carcasses collected at Katmai included a higher-than-expected proportion of prime-age animals compared to most other sea otter populations in Alaska. The unusual AADD warranted scientific investigation, particularly because the Katmai population is part of the Threatened southwest sea otter stock. Brown bears in Katmai are known to prey on marine mammals and sea otters, but depredation rates are unknown; thus, we investigated carnivore predation, especially by brown bears, as a potential explanation for abnormally high prime-age otter mortality. We installed camera traps at two island-based marine mammal haulout sites within Katmai to gather direct evidence that brown bears prey on seals and sea otters. Over a period of two summers, we gathered photo evidence of brown bears making 22 attempts to prey on sea otters of which nine (41%) were successful and 12 attempts to prey on harbor seals of which one (8%) was successful. We also developed a population model based on the AADD to determine if the living population is declining, as suggested by the high proportion of prime-age animals in the AADD. We found that the population trend predicted by the modeled AADDs was contradictory to aerial population surveys that indicated the population was not in steep decline but was consistent with otter predation. Future work should focus on the direct and indirect effects these top-level predators have on each other and the coastal community that connects them.

Community attitudes towards Amur tigers (Panthera tigris altaica) and their prey species in Yanbian, Jilin province, a region of northeast China where tigers are returning.

Community attitudes towards large carnivores are of central importance to their conservation in human-dominated landscapes. In this study, we evaluate community attitudes and perceptions towards the Amur tiger (Panthera tigris altaica), Amur leopard (Panthera pardus orientalis) and bears (Ursus thibetanus and Ursus arctos), as well as their prey species, namely sika deer (Cervus nippon), roe deer and wild boar (Sus scrofa), in Yanbian Korean Autonomous Prefecture, Jilin province, northeast China. We surveyed 139 households and found that community members’ perceptions of large carnivores and their prey species were influenced by their predominant economic activities; their prior interactions with wildlife; their household income level; and whether they were either long-term residents of Yanbian or had migrated to the region from elsewhere in China. We recorded fairly neutral attitudes towards large carnivores among the communities we surveyed, but strongly negative attitudes were shown towards wild boar, particularly where respondents had lost agricultural products to crop raiding by wild boar. We recommend conservation stakeholders in northeast China utilise this finding to encourage support for large carnivore recovery and conservation by targeting messaging around the importance of the tiger as a key predator of wild boar in the ecosystem. Furthermore, our findings suggest that government provided compensation paid for cattle lost to large carnivore predation (notably, by tigers) may be helping to reduce animosity from cattle owners towards large carnivores. However, we also highlight that compensation for loss of livestock is therefore performing a useful role in mitigating human-wildlife conflict, that there are potentially unintended consequences of the current compensation program, for example it fails to dissuade livestock grazing in protected areas.

Bush Encroachment and Large Carnivore Predation Success in African Landscapes: A Review

Bush encroachment is a habitat change phenomenon that threatens savanna and grassland ecosystems worldwide. In Africa, large carnivores in bush encroached landscapes must adjust to increasing woody plant cover and biomass, which could affect predation success at multiple stages through complex and context-dependent pathways. We highlight, interpret, and compare studies that assessed how bush encroachment or related habitat parameters affect the predation stages of large African carnivores. Bush encroachment may directly or indirectly affect predation success in various ways, including by: (1) altering habitat structure, which may affect hunting efficiency and prey accessibility; (2) changing prey abundance/distribution, with smaller species and browsers being potentially favoured; (3) influencing interference competition within the carnivore guild. For habitat or dietary specialists, and subordinate predators that are vulnerable to both top-down and bottom-up ecosystem effects, these alterations may be detrimental and eventually incur population fitness costs. As the threat of bush encroachment continues, future studies are required to assess indirect effects on competitive interactions within the large African carnivore guild to ensure that conservation efforts are focused. Additionally, to better understand the effects of bush encroachment across Africa, further research is necessary in affected areas as overall little attention has been devoted to the topic.

Generalization of threats attributed to large carnivores in areas of high human-wildlife conflict.

Fear-induced generalization of threats to noninimical stimuli is a behavioral tendency of humans to minimize exposure to potential threats. In human-carnivore conflict zones, people often generalize their fear of predation by obligate carnivores to nonobligate carnivores despite differences in species' predation rates. We investigated the effect of a perceived threat of large obligate carnivores to livestock on tolerance and perception of striped hyena (Hyaena hyaena) in an area of high human-carnivore conflict. We surveyed 197 households through asemistructured questionnaire to determine people's perception and tolerance of striped hyenas in Sathyamangalam and Mudumalai Tiger Reserves after identification of the current distribution range of hyena determined through camera trap and sign surveys. Through the random forest algorithm, we modeled the level of tolerance of striped hyena as a function of loss of livestock to predation and from disease, the perceived threat of predation by hyena, and other socioeconomic attributes. Animal husbandry was a major source of income but was severely affected by livestock loss due to predation and disease. Sixty-nine percent of people were uncertain about predatory behavior of hyena; out of that, 23% reported a negative conservation attitude. Only 6 instances of hyena depredation on livestock and 2 on dogs were reported. Our model confirmed that economic instability associated with increased loss to predation and disease, livestock dependency, and a decrease in family annual income negatively affected people's tolerance of hyena. Perceptual uncertainty related to predatory behavior of hyena also negatively affected people's tolerance. In our study area, economic instability and perceptual uncertainty led to generalization of fear of large carnivores to a nonobligate predator. Such generalization may affect the attitude of people toward many other species. Understanding the role of economic instability and perceptual uncertainty should facilitate conservation of species, such as the hyena, that are vulnerable to false generalization.

Vertebrate coprolites from Middle Triassic Chang 7 Member in Ordos Basin, China: Palaeobiological and palaeoecological implications

The early Ladinian lacustrine ecosystem of the Chang 7 Member in the Ordos Basin was proposed as the earliest known Mesozoic-type, trophically multileveled lacustrine ecosystem after the end-Permian mass extinction (EPME). However, limited evidence of higher-order trophic levels represented by predatory fish has made this conclusion elusive. In this study, we investigated the external morphology, food inclusions, and geochemical composition of 54 vertebrate coprolites from organic-rich lacustrine sediments of Chang 7 Member, Yanchang Formation, in the Bawangzhuang section, Tongchuan City, Shaanxi Province, China. These coprolites were identified as seven morphotypes in three groups: three heteropolar spiral forms, two amphipolar spiral forms, and two non-spiral forms. Preserved inclusions (fish scales, bone fragments, teeth) indicated that the producers of these coprolites were piscivorous animals. Compared with coprolites previously researched, all coprolites described herein were inferred to be produced by fish: three heteropolar types of spiral coprolites derived from three types of hybodonts, two amphipolar spiral coprolites from coelacanth or Saurichthys with simple spiral valves, and non-spiral coprolites from at least two predatory actinopterygians. Thus, the biodiversity of the lacustrine paleoecosystem, particularly that of predators with upper trophic levels, was substantially enriched. The existence of large carnivorous predators of different taxa as apex predators in a trophically multileveled (at least six levels) lacustrine ecosystem indicates that the early Ladinian lacustrine ecosystem of the Ordos Basin marks the rebuilding of the top-predator trophic structure in the lacustrine ecosystem after the EPME.

Regional landscape change triggered by Andean uplift: The extinction of Sparassodonta (Mammalia, Metatheria) in South America

Sparassodonta, a Metatherian monophyletic group, was the main mammalian carnivore predator clade in South America from the Paleogene to the Early Pliocene (c. 66–3.5 Ma). However, there is still no consensus on the causes of their demise. Here, we use the fossil record and Bayesian diversification models to infer the origination and extinction rates for Sparassodonta. Then, we evaluate if their demise can be attributed to global temperature changes, Andean uplift, biotic interactions with their competitor and prey clades, and body mass evolution. That is biotic aspects in the context of the Red Queen model, abiotic aspects in the context of the Court Jester model, and an intrinsic lineage attribute. Our results show that this lineage is characterized by a positive near-zero net diversification rate indicating that the clade maintained a relatively low but stable diversity until the Middle Miocene when an increase in extinction rate drove them to decline and eventual extinction. Moreover, our results support the idea that a drastic regional landscape change triggered by the Andean uplift process affected their diversification dynamics, eventually driving them to extinction. These environmental changes could explicitly affect Sparassodonta lineages due to their ever-present vulnerability to extinction by near-zero net diversification rate and their highly specialized ecology that could have constrained adaptation to new South American landscapes. • We evaluate biotic and abiotic hypotheses to understand the causes of the Sparassodonta extinction. • We estimate the Sparassodonta macroevolutionary trajectories and evaluate their relationship with biotic and abiotic factors. • We find that Sparassodonts did not succumb to biotic interactions (competition and predation) or body size evolution. • The Sparassodonta decline resulted from the regional landscape changes during the Miocene associated with Andean uplift.

Feeding habits of Paralabrax nebulifer (Serranidae) during reproductive and non-reproductive seasons in an adjacent area to Magdalena Bay, Baja California Sur, Mexico

The barred sand bass Paralabrax nebulifer is a commercially important fish off the west coast of Baja California Sur. To assess the diet of this species and variations as a function of sex and reproductive condition, 60 specimens were captured using traps during seven seasonal sampling trips from August 2016 to August 2018 in an adjacent area to Magdalena Bay, Baja California Sur, Mexico. The stomach contents of 50 specimens were obtained (23 males and 27 females). Sex was diagnosed by direct observation of the gonads. Based on the gonadosomatic index, hepatosomatic index, and histological analyses, the reproductive season of the barred sand bass was corroborated for August 2016, April, August, and September 2017, and August 2018, and the non-reproductive season was corroborated for November 2016 and March 2018. The Index of Relative Importance (IRI) was used to classify the main diet components, which comprised three fish species, seven crustacean species, and one mollusk species. According to the IRI, the South American pilchard Sardinops sagax and the red pelagic crab Pleuroncodes planipes were the prey that contributed the most (55%) to the barred sand bass diet. The ANOSIM showed that there were significant differences in the amount and type of prey consumed by sex; the SIMPER analysis revealed that the species contributing the most to differences between the sexes were S. sagax (16.58%), Euphylax dovii (15.95%), Stenocionops ovata (12%), and P. planipes (11.82%) for females. There were significant differences in the amount and type of prey consumed between types of reproductive season; the species contributing the most to differences between seasons were Anchoa spp. (27.76%), and P. planipes for non-reproductive season (22.67%), and S. sagax (11.08%) for reproductive season. The feeding strategy of the barred sand bass was that of a specialist carnivorous predator that fed mainly on the fish Sardinops sagax during the reproductive season, which supply the dietary nutritional requirements of the lipids HUFA (arachidonic acid, 20:4n-6; eicosapentaenoic acid, 20:5n-3; docosahexaenoic acid, 22:6n-3), nutrients required to achieve reproductive success.

CHARACTERISATION OF FOOD GUILDS OF THE CLASS GASTROPODA ON THE NORTHEAST ROCKY COAST OF THE GULF OF CALIFORNIA

Few detailed studies are available on class Gastropoda ecology in rocky intertidal areas of the Gulf of California, and none have been conducted in significant latitudinal scale for the region in the last 30 years. This study outlines food guilds of the macrogastropod community (≥1 cm) found in the rocky intertidal zone of 13 coastal sites of the northeast Gulf of California (latitudes 27° N - 31° N) through visual census in transects of 40 m perpendicular to the coast with 2 m2 quadrants every 20 m. The results gathered a total of 5823 records of 41 species. The classification for food type included five guilds, of which algivores stood out with the highest (50.87%) abundance; carnivorous predators represented 19.22% of species abundance; carnivores 14.19%, omnivores 14.51% and microalgivores less than 2% of the total. In the intertidal zone algivore abundance significantly decreased at the lowest level while carnivores were well represented in middle and lower levels. Food guild latitudinal distribution was heterogenous without a specific latitudinal pattern, but trophic diversity tended to be higher in sites on latitudes 29° N - 30° N. Non-metric multidimensional scaling demonstrated four principal areas that grouped algivores, predatory carnivores, omnivores, and carnivores (stress = 0.1). This study shows for the first time the diversity of trophic macro-mollusc guilds northeast of the Gulf of California, which highlights the importance and necessity of generating a solid base for detailed class research in the region.

Behavioral effects of wolf presence on moose habitat selection: testing the landscape of fear hypothesis in an anthropogenic landscape

Landscape of fear refers to the spatial variation in prey perception of predation risk, that under certain conditions, may lead to changes in their behavior. Behavioral responses of prey in relation to large carnivore predation risk have mainly been conducted in areas with low anthropogenic impact. We used long-term data on the distribution of moose in different habitat types in a system characterized by intensive management of all three trophic levels (silviculture, harvest of wolves and moose) to study effects on moose habitat selection resulting from the return of an apex predator, the wolf. We assumed that coursing predators such as wolves will cause an increased risk for moose in some habitat types and tested the hypotheses that moose will avoid open or young forest habitats following wolf establishment. After wolf recolonization, moose reduced their use of one type of open habitat (bog) but there was neither change in the use of the other open habitat type (clear-cut), nor in their use of young forest. Wolf establishment did not influence the use of habitat close to dense habitat when being in open habitats. Thus, the effect of wolves varied among habitat types and there was no unidirectional support for a behavioral effect of wolves’ establishment on moose habitat use. Human-driven habitat heterogeneity, concentration of moose forage to certain habitat types, and the effects of a multiple predator guild on moose may all contribute to the results found. We conclude that the landscape of fear is likely to have weak ecological effects on moose in this system.