Occurrence Of Prey Research Articles

The Pacific harbor seal gut microbiota in Mexico: Its relationship with diet and functional inferences.

Diet is a primary driver of the composition of gut microbiota and is considered one of the main routes of microbial colonization. Prey identification is fundamental for correlating the diet with the presence of particular microbial groups. The present study examined how diet influenced the composition and function of the gut microbiota of the Pacific harbor seal (Phoca vitulina richardii) in order to better understand the role of prey consumption in shaping its microbiota. This species is a good indicator of the quality of the local environment due to both its foraging and haul-out site fidelity. DNA was extracted from 20 fecal samples collected from five harbor seal colonies located in Baja California, Mexico. The V4 region of 16S rRNA gene was amplified and sequenced using the Illumina technology. Results showed that the gut microbiota of the harbor seals was dominated by the phyla Firmicutes (37%), Bacteroidetes (26%) and Fusobacteria (26%) and revealed significant differences in its composition among the colonies. Funtional analysis using the PICRUSt software suggests a high number of pathways involved in the basal metabolism, such as those for carbohydrates (22%) and amino acids (20%), and those related to the degradation of persistent environmental pollutants. In addition, a DNA metabarcoding analysis of the same samples, via the amplification and sequencing of the mtRNA 16S and rRNA 18S genes, was used to identify the prey consumed by harbor seals revealing the consumption of prey with mainly demersal habits. Functional redundancy in the seal gut microbiota was observed, irrespective of diet or location. Our results indicate that the frequency of occurrence of specific prey in the harbor seal diet plays an important role in shaping the composition of the gut microbiota of harbor seals by influencing the relative abundance of specific groups of gut microorganisms. A significant relationship was found among diet, gut microbiota composition and OTUs assigned to a particular metabolic pathway.

The menu varies with metabarcoding practices: A case study with the bat Plecotus auritus.

Metabarcoding of feces has revolutionized the knowledge of animal diets by providing unprecedented resolution of consumed resources. However, it is still unclear how different methodological approaches influence the ecological conclusions that can be drawn from such data. Here, we propose a critical evaluation of several data treatments on the inferred diet of the bat Plecotus auritus using guano regularly collected from various colonies throughout the entire active season. First and unlike previous claims, our data indicates that DNA extracted from large amounts of fecal material issued from guano accumulates yield broader taxonomic diversity of prey than smaller numbers of pellets would do, provided that extraction buffer volumes are adapted to such increased amounts of material. Second, trophic niche analyses based on prey occurrence data uncover strong seasonality in the bat’s diet and major differences among neighboring maternity colonies. Third, while the removal of rare prey items is not always warranted as it introduces biases affecting particularly samples with greater prey species richness. Fourth, examination of distinct taxonomic depths in diet analyses highlights different aspects of food consumption providing a better understanding of the consumer’s diet. Finally, the biologically meaningful patterns recovered with presence-absence approaches are virtually lost when attempting to quantify prey consumed using relative read abundances. Even in an ideal situation where reference barcodes are available for most potential prey species, inferring realistic patterns of prey consumption remains relatively challenging. Although best practice in metabarcoding analyses will depend on the aims of the study, several previous methodological recommendations seem unwarranted for studying such diverse diets as that of brown long-eared bats.

Ground greening in vineyards promotes the Woodlark Lullula arborea and their invertebrate prey

Vineyards are intensively managed monocultures, constituting homogeneously cultivated landscapes. They often have a mineral appearance, not only because they occur mostly in xeric biomes but also as a result of the herbicide treatments used to combat ground vegetation. However, new vineyard management practices are being developed that tolerate more vegetation cover on the ground, potentially having positive impacts on biodiversity. We have investigated the effects of ground greening on habitat preferences of the Woodlark (Lullula arborea), an emblematic, insectivorous passerine typical of vineyards in central and southern Europe. We first investigated the role of ground vegetation cover and plant species richness on habitat use by Woodlarks, while accounting for various additional habitat characteristics. Second, we assessed whether the dependence of Woodlarks on ground vegetation cover could be mediated by an increased occurrence of invertebrate prey. Ground-dwelling invertebrates were sampled with pitfall traps placed in vineyard fields visited by Woodlarks (presence fields) and in adjacent vineyards where Woodlarks had not been observed (pseudo-absence fields). We show that increased ground vegetation cover, plant species richness and wider inter-rows were the main drivers of Woodlark occurrence. Overall invertebrate prey abundance increased with ground vegetation cover. Similarly, the abundance and number of beetle and spider families were primarily driven by increased ground vegetation cover, plant species richness or wider inter-rows. We conclude that less intensive management, which involves the restricted use of herbicides and concomitantly favors a diverse plant community, promotes Woodlarks and their invertebrate prey, thus having a positive impact on vineyard biodiversity at multiple trophic levels.

Diel vertical migration of sablefish (Anoplopoma fimbria)

AbstractTo investigate their diel vertical migration (DVM), 599 sablefish (Anoplopoma fimbria) were implanted with electronic archival tags in the Gulf of Alaska, Aleutian Islands, and the eastern Bering Sea. Of these tags, 98 were recovered with usable depth data (7,852,773 recordings representing 81,233 days) that we used to identify DVM and to classify DVM into one of two types: normal DVM (rise from the bottom during nighttime) and reverse DVM (rise from the bottom during daytime). The results of our study highlight three important attributes of DVM for sablefish. First, all tagged sablefish carried out DVM, although the occurrence was intermittent (26% of the days with usable data) and most commonly for short durations (10 days or less). Second, bottom depth for normal DVM was about 78 m shallower than for reverse DVM. Third, normal DVM occurred most often in fall and least often in spring, whereas this high/low pattern was shifted about 3 months later for reverse DVM; reverse DVM occurred most often in winter and least often in summer. Normal DVM likely occurred to increase foraging opportunity (e.g., nightly shift to match depth of prey). Reverse DVM more commonly occurred during winter and may represent an increase in foraging by sablefish during the daytime to compensate for decreased pelagic resources. The default foraging strategy for sablefish may be benthic because of the uncertainty of vertically migrating to a location where the occurrence of prey is not guaranteed; sablefish may invoke DVM when the non‐DVM foraging benefit is reduced.

Feline predator–prey relationships in a semi‐arid biome in Brazil

AbstractThe spatiotemporal distribution of a predator within an environment tends to be synchronized with that of its prey, to maximize the efficiency of its hunting behavior. However, small predators may also be obliged to avoid potentially agonistic encounters with larger predators due to interspecific competition and intraguild predation. We used occupancy models and indices of temporal overlap to evaluate whether the occurrence of prey species, ocelots (Leopardus pardalis) and top predators (puma Puma concolor and jaguar Panthera onca) influenced the habitat use and activity patterns of the northern tiger cat (Leopardus tigrinus) and jaguarundi (Herpailurus yagouaroundi) in a region of the semi‐arid Caatinga biome in Bahia, northeastern Brazil. The occurrence of prey had a positive influence on the use of habitat by the small felids. The northern tiger cat was nocturnal‐crepuscular and presented a high degree of temporal overlap with Spix's cavy (Galea spixii) and the rock cavy (Kerodon rupestris). The jaguarundi was diurnal, by contrast and overlapped temporally with the agouti (Dasyprocta nigriclunis). The occurrence of the ocelot did not influence the habitat or daily activity pattern of the jaguarundi, but presented a high degree of temporal overlap with the northern tiger cat, which adopted a strategy of spatial segregation to avoid direct contact with this dominant competitor. The top predators did not influence the spatiotemporal distribution of the small felids, indicating that their niches are segregated by dietary parameters related to differences in body size. Our results indicate that the availability of prey has a more profound influence on the spatiotemporal ecology of the small felids than the occurrence of the top predators, although the presence of the northern tiger cat appeared to be correlated negatively with that of the ocelot. We believe that environmental factors, such as the conservation status, size and isolation of native habitats, may have a fundamental influence on the strategies adopted by the northern tiger cat to mediate its coexistence with the ocelot.

Diet and prey selection by snow leopards in the Nepalese Himalayas.

Visual attractiveness and rarity often results in large carnivores being adopted as flagship species for stimulating conservation awareness. Their hunting behaviour and prey selection can affect the population dynamics of their prey, which in turn affects the population dynamics of these large carnivores. Therefore, our understanding of their trophic ecology and foraging strategies is important for predicting their population dynamics and consequently for developing effective conservation programs. Here we concentrate on an endangered species of carnivores, the snow leopard, in the Himalayas. Most previous studies on snow leopard diet lack information on prey availability and/or did not genetically check, whether the identification of snow leopard scats is correct, as their scats are similar to those of other carnivores. We studied the prey of snow leopard in three Himalayan regions in Nepal (Sagarmatha National Park (SNP), Lower Mustang (LM) and Upper Manang (UM) in the Annapurna Conservation Area, during winter and summer in 2014–2016. We collected 268 scats along 139.3 km linear transects, of which 122 were genetically confirmed to belong to snow leopard. Their diet was identified by comparing hairs in scats with our reference collection of the hairs of potential prey. We determined prey availability using 32–48 camera-traps and 4,567 trap nights. In the SNP, the most frequent prey in snow leopard faeces was the Himalayan tahr in both winter and summer. In LM and UM, its main prey was blue sheep in winter, but yak and goat in summer. In terms of relative biomass consumed, yak was the main prey everywhere in both seasons. Snow leopard preferred large prey and avoided small prey in summer but not in winter, with regional differences. It preferred domestic to wild prey only in winter, and in SNP. Unlike most other studies carried out in the same area, our study uses genetic methods for identifying the source of the scat. Studies solely based on visual identification of samples may be strongly biased. Diet studies based on frequency of occurrence of prey tend to overestimate the importance of small prey, which may be consumed more often, but contribute less energy than large prey. However, even assessments based on prey biomass are unlikely to be accurate as we do not know whether the actual size of the prey consumed corresponds to the average size used to calculate the biomass eaten. For example, large adults may be too difficult to catch and therefore mostly young animals are consumed, whose weight is much lower. We show that snow leopard consumes a diverse range of prey, which varies both regionally and seasonally. We conclude that in order to conserve snow leopards it is also necessary to conserve its main wild species of prey, which will reduce the incidence of losses of livestock.

Assessing the relationship between illegal hunting of ungulates, wild prey occurrence and livestock depredation rate by large carnivores

Abstract Illegal hunting of ungulates can reduce the prey base of carnivores, which can increase human–carnivore conflict (HCC) through livestock depredation. However, the relationship between ungulate poaching, wild prey abundance and livestock depredation has rarely been empirically studied. We surveyed 18 sites across the Hyrcanian forest in northern Iran; a global biodiversity hotspot under pressure from illegal hunting of ungulates, prey depletion, livestock grazing and HCC. We conducted three field surveys across 1,204 km in 93 4 × 4 km cells to count signs of ungulate poaching as well as encounters with livestock and prey species of the Persian leopard Panthera pardus saxicolor and the grey wolf Canis lupus. We documented sheep/goat and cattle depredation from interviews with 201 herders and analysed the effects of illegal hunting of ungulates, forest cover, IUCN categories of reserves, elevation, distance to villages, and wild prey and livestock encounter rates on carnivore depredation rates using generalized linear models. Illegal hunting of ungulates was the most influential depredation predictor. An increase in the illegal hunting of ungulates by one sign/km significantly increased depredation by up to four times. We also found significantly lower levels of ungulate poaching in national parks (IUCN category II) compared to protected areas (V), wildlife refuges (IV) and no‐hunting areas, though poaching signs were frequently found in most cells (58%). Encounters with livestock was inversely linked to wild prey species, but positively coupled with signs of ungulate poaching. Synthesis and applications. Our study reveals that: (a) an increase in the intensity of illegal hunting of ungulates can intensify livestock depredation by carnivores; (b) future efforts in reducing human‐carnivore conflict to acceptable levels require a combination of law enforcement, prey recovery approaches and mitigation measures; (c) it is essential to understand the root causes of poaching to help minimize human‐carnivore conflict (HCC).

The diet of denning female European\xa0pine martens (Martes martes) in Galloway Forest District, South West Scotland, Great Britain

Populations of European pine marten (Martes martes) across Great Britain declined dramatically during the 18th and 19th centuries due to deforestation and human-wildlife conflicts. Pine marten recovery from their northern Scottish stronghold is limited following reintroduction in Galloway Forest District, south-west Scotland, in the 1980s. With suggestions that martens have influenced red squirrel population increases in neighbouring Ireland, marten reintroduction efforts are a priority in Great Britain. Reintroduction requires establishment of recruiting populations that depend on suitable food availability to meet the associated higher energy demands of recruitment. We, therefore, investigated the diet of reproductive denning female martens during denning (March–April), and the mixed sex population in summer for the first time in Galloway. Scats (n = 114) were analysed from clumps collected from occupied artificial den boxes in 2015 and 2016, as well as genetically verified scats (n = 44) from summer transects in 2014. We compared our results with other Scottish studies and found that carrion frequency of occurrence and biomass of prey ingested differed most significantly between the regional mixed sex spring diets and the diet of denning females in Galloway. Anurans, birds, and small mammals were the likely substitution of carrion; we hypothesise that these differences are related to sex-specific behaviours and scavenging risk. We, therefore, suggest that there are differences in the diet of denning female martens compared to mixed sex spring populations and that future translocations should consider abundances of anurans in Galloway, and even more importantly than before, small mammals and birds across Great Britain.

Spatial distribution and dietary niche breadth of the leopard Panthera pardus (Carnivora: Felidae) in the northeastern Himalayan region of Pakistan

Knowledge of a predato's diet is important for understanding its ecology and for predicting its influence on the dynamics of prey populations. We investigated the spatial distribution and diet composition of the leopard ( Panthera pardus ) in the northeastern Himalayan region of Pakistan. We used molecular scatology technique to identify scats of common leopard collected from the field. The leopard was recorded at 30 different surveyed sites with an elevational range between 757-1891 m a.s.l. Its diet comprised 17 prey species, including both wild and domestic prey. Frequency of occurrence of wild prey was approximately 35% of the total leopard diet, while domestic prey contributed approximately 59%. The dietary niche breadth of the leopard was found to be broad during the spring but narrow during the winter. Prey species diversity index was high during summer but low during winter. Results of the current study highlight that common leopard is mainly subsisting on domestic animals, which may result in negative human-leopard interactions. We suggest that local communities should be educated to conserve the leopard and its wild prey species.

Habitat use, seasonality and demography of an apex predator: sevengill shark Notorynchus cepedianus in northern Patagonia

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 603:147-160 (2018) - DOI: https://doi.org/10.3354/meps12715 Habitat use, seasonality and demography of an apex predator: sevengill shark Notorynchus cepedianus in northern Patagonia Alejo J. Irigoyen1,*, Agustín M. De Wysiecki1, Gastón Trobbiani1, Nelson Bovcon2, Cynthia A. Awruch1,3, Federico Argemi4, Andrés J. Jaureguizar5,6 1Centro para el Estudio de Sistemas Marinos (CESIMAR), Consejo Nacional de Investigaciones Científicas y Técnicas (CCT CENPAT-CONICET), Puerto Madryn U9120ACD, Argentina 2Departamento de Pesca Deportiva, Secretaría de Pesca de la Provincia del Chubut 9020, Argentina 3School of Natural Sciences, University of Tasmania, Hobart, Tasmania 7001, Australia 4Aquarium Fundación Temaiken, Buenos Aires 1625, Argentina 5Comisión de Investigaciones Científicas de la Provincia de Buenos Aires (CIC), La Plata 1900, Argentina 6Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), Mar del Plata B7600EEP, Argentina *Corresponding author: alejo@cenpat-conicet.gob.ar ABSTRACT: Gaining insight on how species relate to their environment and other members of the trophic community is critical for their management. We investigated habitat use, seasonal patterns of abundance and population structure of the broadnose sevengill shark Notorynchus cepedianus in the marine temperate environment of a northern Patagonian bay (Argentina). We expected N. cepedianus to exhibit strong seasonality in the bay driven by the seasonal occurrence of important marine mammal prey. However, an alternative or complementary hypothesis arose from the possibility that N. cepedianus uses the area seasonally as mating grounds. To explore these hypotheses, a suite of baited remote underwater video stations and catch per unit effort data indices were used to estimate the seasonal relative abundance of the species inside the bay. Reproductive hormone levels were measured to determine reproductive status and maturity stages of the population. Results indicated that N. cepedianus uses the bay year-round, showing a peak abundance during spring when individuals aggregate, likely for feeding and mating purposes. Male and female total lengths at maturity were 170 and 190 cm, respectively. Contrary to other studies in the Southwest Atlantic, population composition remained similar throughout the seasons, with adults dominating over juveniles, and adult females prevailing in the population at all times. Considering the historical abundance decline recently reported for the species, protection and enforcement within protected areas across the Southwest Atlantic must remain of high priority in government initiatives. KEY WORDS: Baited remote underwater video station · BRUVS · Catch per unit effort · CPUE · Reproductive hormones · Seasonal occurrence · Caleta Valdés · Southwest Atlantic Full text in pdf format PreviousNextCite this article as: Irigoyen AJ, De Wysiecki AM, Trobbiani G, Bovcon N, Awruch CA, Argemi F, Jaureguizar AJ (2018) Habitat use, seasonality and demography of an apex predator: sevengill shark Notorynchus cepedianus in northern Patagonia. Mar Ecol Prog Ser 603:147-160. https://doi.org/10.3354/meps12715 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 603. Online publication date: September 17, 2018 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2018 Inter-Research.

Thermal forest zone explains regional variations in the diet composition of the Japanese marten (Martes melampus)

Examining biogeographical variations in species’ diet is important for linking key ecological traits between consumers and their environment. While the trophic ecology of the Holarctic martens has been globally synthesised, systematic information on the feeding ecology of martens (Martes spp.) in Asia is still deficient compared to species in Europe and North America. Here we conduct a meta-analysis based on literature describing regional and seasonal variation in diet composition of the Japanese marten (Martes melampus). Across nine study areas in the Japanese archipelago, annual marten diet mainly comprised fruits, invertebrates, and mammals. Cluster analysis divided these into three groups according to the similarity in composition. Dietary niche breadth and the relative frequency of occurrence of the mammalian prey was significantly higher in sub-alpine/cool-temperate than warm-temperate thermal forest zones, whereas the occurrence of fruits was significantly higher in warm-temperate than sub-alpine/cool-temperate zones. Seasonal analysis showed significant effects across all four seasons on the frequency of occurrence of mammals, invertebrates, and fruits. The Japanese marten is a flexible and opportunistic feeder with the potential to maintain its key macronutrient requirements by adapting its feeding strategy to changes in resource variability and environmental conditions. This trophic plasticity may advantage the Japanese marten in coping with human-induced rapid environmental change, as global analysis has projected for martens across other regions.

Prey selectivity by feral cats at central Australian rock-wallaby colonies

Threatened warru, or black-footed rock-wallaby (Petrogale lateralis MacDonnell Ranges race), populations in northern South Australia continued to decline despite baiting for foxes (Vulpes vulpes), which improved their short-term conservation status elsewhere. To investigate whether feral cats (Felis catus) also represent a risk to warru we compared frequencies of prey occurrence in 103 feral cat and 14 fox stomachs shot near warru colonies in northern South Australia during 2001–17 with measures of prey abundance from pitfall trapping and opportunistic searches. We hypothesise that one fresh adult warru kill and the presence of warru remains in four other cats suggests predation by cats on adult and juvenile warru. Small reptiles and invertebrates were the most frequently recorded prey of cats in summer, whereas rodents and small dasyurids were the most frequent prey items in winter. Small mammals, small snakes and pygopodid lizards were over-represented in the diet of cats compared with estimated encounter frequencies, whereas fast-running dragons, knob-tailed geckoes (Nephrurus) and echidnas (Tachyglossus aculeatus) were not recorded from cat stomachs despite being relatively abundant. Rabbits (Oryctolagus cuniculus), rodents and fruits were the most frequently recorded items in fox stomachs. This study reinforces that targeted management of feral cat populations should be considered in concert with control of canids in sustainable recovery programs for warru and other cat-vulnerable species.

Mercury Stable Isotopes Reveal Influence of Foraging Depth on Mercury Concentrations and Growth in Pacific Bluefin Tuna.

Pelagic ecosystems are changing due to environmental and anthropogenic forces, with uncertain consequences for the ocean's top predators. Epipelagic and mesopelagic prey resources differ in quality and quantity, but their relative contribution to predator diets has been difficult to track. We measured mercury (Hg) stable isotopes in young (<2 years old) Pacific bluefin tuna (PBFT) and their prey species to explore the influence of foraging depth on growth and methylmercury (MeHg) exposure. PBFT total Hg (THg) in muscle ranged from 0.61 to 1.93 μg g-1 dw (1.31 μg g-1 dw ±0.37 SD; 99% ± 6% MeHg) and prey ranged from 0.01 to 1.76 μg g-1 dw (0.13 μg g-1 dw ±0.19 SD; 85% ± 18% MeHg). A systematic decrease in prey δ202Hg and Δ199Hg with increasing depth of occurrence and discrete isotopic signatures of epipelagic prey (δ202Hg: 0.74 to 1.49‰; Δ199Hg: 1.76-2.96‰) and mesopelagic prey (δ202Hg: 0.09 to 0.90‰; Δ199Hg: 0.62-1.95‰) allowed the use of Hg isotopes to track PBFT foraging depth. An isotopic mixing model was used to estimate the dietary proportion of mesopelagic prey in PBFT, which ranged from 17% to 55%. Increased mesopelagic foraging was significantly correlated with slower growth and higher MeHg concentrations in PBFT. The slower observed growth rates suggest that prey availability and quality could reduce the production of PBFT biomass.

Volume-concentrated searching by an aerial insectivore, the common swift, Apus apus

How predators search for prey is a cornerstone question in behavioural ecology, which has yet to be investigated for animals foraging in 3D airspace. Do insectivorous birds such as swifts (Apodidae), swallows and martins (Hirundinidae) use similar strategies to those performed by terrestrial predators in 2D, or do they rely on different spatial search strategies because of some properties of the aerial open space? We addressed this question in the common swift, one of the most aerial birds, using a novel 3D optical tracking method. The analysis of fine-scale flight tracks revealed how birds distribute their presence in 3D space while foraging near their breeding colony. Common swifts concentrated the time spent per volume unit by adopting a tortuous path, and, to a much lesser extent, by decreasing their movement speed. By independently observing the birds' posture on tracking images, we were able to identify the occurrence of putative prey captures along flight tracks. We show that swifts' presence was concentrated mainly in the vicinity of prey captures, unveiling a volume-concentrated search (VCS) strategy in this aerial insectivore. This is an extension in 3D of the area-concentrated search classically described in terrestrial 2D space. VCS can (but does not necessarily) take place in thermal updrafts, where small insects can be concentrated in patches. In contrast to terrestrial and aquatic predators that can easily slow down or stop their movement in profitable places, a different speed–cost relationship underlying aerial movement prevents swifts from stopping in prey patches and explains why these birds rely mainly on movement tortuosity to perform intensive search. Our study thus shows how some physical properties of the environment can modulate the way an animal concentrates its search in profitable places.

Increased sightings of subArctic cetaceans in the eastern Chukchi Sea, 2008–2016: population recovery, response to climate change, or increased survey effort?

Cetacean occurrence in the Chukchi Sea is seasonal and primarily driven by annual sea ice retreat and prey occurrence in spring through fall. Humpback whales (Megaptera novaeangliae), fin whales (Balaenoptera physalus), and minke whales (Balaenoptera acutorostrata), although often found in polar waters elsewhere, are not common in the eastern Chukchi Sea, and here are referred to as “subArctic” species. Increasing numbers of these subArctic cetacean species were documented during aerial surveys in the eastern Chukchi Sea (67°–72°N, 157°–169°W) in July–October 2008–2016. The majority (78%) of these sightings occurred on the continental shelf in the south-central Chukchi Sea (67°–69°N, 166°–169°W) in August and September. During similar aerial surveys in 1982–1991, there was a complete lack of sightings of subArctic species. The disparity in sightings between the two time periods could be due to increased marine mammal survey effort in recent years during the months when subArctic cetacean species would be expected to occur, population recoveries from commercial whaling, climate change, or, most likely, a combination of all three.

Domestic carnivore interactions with wildlife in the Cape Horn Biosphere Reserve, Chile: husbandry and perceptions of impact from a community perspective.

BackgroundHundreds of millions of domestic carnivores worldwide have diverse positive affiliations with humans, but can provoke serious socio-ecological impacts when free-roaming. Unconfined dogs (Canis familiaris) and cats (Felis catus) interact with wildlife as predators, competitors, and disease-transmitters; their access to wildlife depends on husbandry, perceptions, attitudes, and behaviors of pet owners and non-owners.MethodsTo better understand husbandry and perceptions of impacts by unconfined, domestic carnivores, we administered questionnaires (n = 244) to pet owners and non-owners living in one of the last wilderness areas of the world, the Cape Horn Biosphere Reserve, located in southern Chile. We used descriptive statistics to provide demographic pet and husbandry information, quantify free-roaming dogs and cats, map their sightings in nature, and report experiences and perceptions of the impact of free-roaming dogs and cats on wildlife. We corroborated our results with an analysis of prey remains in dog feces (n = 53). With generalized linear models, we examined which factors (i.e., food provisioning, reproductive state, rural/village households, sex, and size) predicted that owned dogs and cats bring wildlife prey home.ResultsThirty-one percent of village dogs (n = 121) and 60% of dogs in rural areas (n = 47) roamed freely day and/or night. Free-roaming dog packs were frequently observed (64% of participants) in the wild, including a feral dog population on Navarino Island. Dogs (31 of 168) brought home invasive muskrats (Ondatra zibethicus) and avian prey, and over half of all cats (27 of 51) brought home mainly avian prey. Birds were also the most harassed wildlife category, affected by one third of all dogs and cats. Nevertheless, dog-wildlife conflicts were hardly recognized (<9% of observed conflicts and suspected problems), and only 34% of the participants thought that cats might impact birds. Diet analysis revealed that dogs consumed livestock (64% of 59 prey occurrences), beavers (Castor canadensis, 14%), and birds (10%). The probability that dogs brought prey to owners’ homes was higher in rural locations and with larger dogs. There was also evidence that cats from rural households and with an inadequate food supply brought more prey home than village cats.DiscussionAlthough muskrat, beavers, and birds were brought home, harassed, or found in dog feces, free-roaming dogs and, to a lesser extent, cats are perceived predominantly in an anthropogenic context (i.e., as pets) and not as carnivores interacting with wildlife. Therefore, technical and legal measures should be applied to encourage neutering, increase confinement, particularly in rural areas, and stimulate social change via environmental education that draws attention to the possibility and consequences of unconfined pet interaction with wildlife in the southernmost protected forest ecoregion of the globe.

When roads appear jaguars decline: Increased access to an Amazonian wilderness area reduces potential for jaguar conservation.

Roads are a main threat to biodiversity conservation in the Amazon, in part, because roads increase access for hunters. We examine how increased landscape access by hunters may lead to cascading effects that influence the prey community and abundance of the jaguar (Panthera onca), the top Amazonian terrestrial predator. Understanding such ecological effects originating from anthropogenic actions is essential for conservation and management of wildlife populations in areas undergoing infrastructure development. Our study was conducted in Yasuní Biosphere Reserve, the protected area with highest potential for jaguar conservation in Ecuador, and an area both threatened by road development and inhabited by indigenous groups dependent upon bushmeat. We surveyed prey and jaguar abundance with camera traps in four sites that differed in accessibility to hunters and used site occupancy and spatially explicit capture-recapture analyses to evaluate prey occurrence and estimate jaguar density, respectively. Higher landscape accessibility to hunters was linked with lower occurrence and biomass of game, particularly white-lipped peccary (Tayassu pecari) and collared peccary (Pecari tajacu), the primary game for hunters and prey for jaguars. Jaguar density was up to 18 times higher in the most remote site compared to the most accessible site. Our results provide a strong case for the need to: 1) consider conservation of large carnivores and other wildlife in policies about road construction in protected areas, 2) coordinate conservation initiatives with local governments so that development activities do not conflict with conservation objectives, and 3) promote development of community-based strategies for wildlife management that account for the needs of large carnivores.

Diet of endangered Steller sea lions (Eumetopias jubatus) in the Aleutian Islands: new insights from DNA detections and bioenergetic reconstructions

The endangered western stock of Steller sea lion (Eumetopias jubatus (Schreber, 1776)) still declines in the western Aleutian Islands and accurate diet information is vital to test leading hypotheses. We undertook the first bioenergetic diet reconstruction using both molecular and hard part prey identifications from &gt;600 scats collected in March–April 2008 and 2012. Atka mackerel (Pleurogrammus monopterygius (Pallas, 1810)) remained a primary prey (17%–27% by energy), but large (mean 60 cm) Pacific cod (Gadus macrocephalus Tilesius, 1810) also emerged as important prey (20%–24%) in a more diverse diet than previously reported, with Cottidae and smooth lumpsucker (Aptocyclus ventricosus (Pallas, 1769)) also contributing ∼10%. DNA detections highlighted a potentially important and previously underestimated prey, giant Pacific octopus (Enteroctopus dofleini (Wülker, 1910) (diet contribution 2%–15%, dependent on prey size assumptions). Although 504 unique DNA identifications resulted in significant increases for cephalopods, Pacific cod, and smooth lumpsucker, hard part alone species rankings were similar to composite ones and bioenergetic species rankings similar to occurrence-based ones. Retention or regurgitation of large cephalopod beaks, the removal of large cod heads, and skeletal fragility of lumpsuckers may explain these differences. DNA identifications provide valuable comparative and complementary prey occurrence data for pinnipeds, but composite diet estimates are optimal.

Assessing the efficacy of aerial culling of introduced wild deer in New Zealand with analytical decomposition of predation risk

Native and introduced wild deer have significant unwanted impacts in many countries. Lethal control, usually by hunting, is the most cost-effective method of reducing their number and impact. However, deer habitat use varies spatially and temporally, meaning that hunters (the predator) may search in habitats with few or no deer. Also, deer may modify their behaviour in response to hunting pressure in ways that decrease the risk of being killed, reducing the efficacy of lethal control programmes. To address these issues we decomposed the predation process into its four constituent stages–prey occurrence, predator search, predators encounter prey, predators kill prey they encounter–to reveal what makes female sika deer (Cervus nippon) in the North Island, New Zealand, more susceptible to control by professional helicopter-based hunters. Female sika deer were encountered more in some habitats or landscape features than in others, but the likelihood of kill given an encounter in those habitats was not always correspondingly high. Similarly, variables that positively influenced the probabilities of encounter and kill did not similarly influence deer occurrence, and variables most likely to be searched often poorly correlated with the other predation stages. These disparities contributed to suboptimal searching for and killing of deer by helicopter-based hunters during winter and spring, but not summer. Our study demonstrates how decomposing predation risk can identify risk and refuge areas for target species, and can be used to alter tactics as target species adjust to changing predation risk. This analytical approach is highly applicable to other human hunter–prey systems.

Ecological preferences of large carnivores in remote, high-altitude protected areas: insights from Buxa Tiger Reserve, India

AbstractDifficult terrain and inclement weather limit our knowledge of large predators, such as the tigerPanthera tigris, in the Himalayas. A lack of empirical data on large carnivores can lead to mismanagement of protected areas and population declines. We used non-invasive genetic and remote sensing data to inform the management of such high-altitude protected areas. We used the tiger as a focal species to investigate prey preference and habitat suitability in India's Buxa Tiger Reserve, which encompasses several eco-geographical regions in the Himalayan and subtropical zones. During 2010–2013, 909 faecal samples were collected, of which 372 were confirmed, using genetic analysis, to be of tiger origin. Fourteen prey species/groups were identified in 240 tiger faecal samples, largely dominated by goatsCapraspp. (26.59%), rhesus macaquesMacaca mulatta(22.22%) and cattleBosspp. (20.63%). Considering only the wild prey species for which survey data are available, however, and frequency of occurrence of prey in faecal samples, hog deerAxis porcinus, sambar deerRusa unicolorand spotted deerAxis axiswere the most preferred prey species. Using faecal sample locations to examine the relationship between tiger presence and environmental features indicated that the niche for tigers is narrower than the available protected area: c. 62% of core protected area is suitable, of which only 17% is highly suitable for tigers. Tigers prefer dense vegetation, open forests, riverine vegetation and areas close to water sources. Faecal sample-based studies have the potential to generate data that can help us understand the ecology of elusive carnivore species inhabiting high-altitude landscapes.