Main Prey Research Articles

Mercury concentrations, biomagnification and isotopic discrimination factors in two seabird species from the Humboldt Current ecosystem

Assessing mercury (Hg) biomagnification requires the description of prey-predator relationships, for each species and ecosystem, usually based on carbon and nitrogen isotope analyses. Here, we analyzed two seabirds from the Humboldt Current ecosystem, the Guanay cormorant (Phalacrocorax bougainvillii) and the Peruvian booby (Sula variegata), as well as their main prey, the Peruvian anchovy (Engraulis ringens). We reported Hg concentrations, Hg biomagnification (BMF) and isotopic discrimination factors (Δ13C and Δ15N) in seabird whole blood. BMFs and Δ13C in our study (on wild birds where diet was not controlled) were similar to other piscivorous seabirds previously studied in captive settings, but Δ15N were lower than most captive experiments. We observed lower Hg concentrations in Humboldt seabirds compared to other oligotrophic ecosystems, possibly due to Hg biodilution in the high biomass of the first trophic levels. This work calls for a better characterization of Hg trophic dynamics in productive upwelling ecosystems.

Insect cuticular hydrocarbon composition influences their interaction with spider capture threads.

Insects represent the main prey of spiders, and spiders and insects co-diversified in evolutionary history. One of the main features characterizing spiders is their web as a trap to capture prey. Phylogenetically, the cribellate thread is one of the earliest thread types that was specialized to capture prey. In contrast to other capture threads, it lacks adhesive glue and consists of nanofibres, which do not only adhere to insects via van der Waals forces but also interact with the insects' cuticular hydrocarbon (CHC) layer, thus enhancing adhesion. The CHC layer consists of multiple hydrocarbon types and is highly diverse between species. In this study, we show that CHC interaction with cribellate capture threads is affected by CHC composition of the insect. We studied the interaction in detail for four insect species with different CHC profiles and observed a differential migration of CHCs into the thread. The migration depends on the molecular structure of the hydrocarbon types as well as their viscosity, influenced by the ambient temperature during the interaction. As a consequence, adhesion forces to CHC layers differ depending on their chemical composition. Our results match predictions based on biophysical properties of hydrocarbons, and show that cribellate spiders can exert selection pressure on the CHC composition of their insect prey.

Pronounced Seasonal Diet Diversity Expansion of Golden Eagles (Aquila chrysaetos) in Northern Greece during the Non-Breeding Season: The Role of Tortoises

Golden Eagles are resident in Greece and known to feed mainly on tortoises when breeding. However, information on alternative prey is scarce, especially during the tortoise brumation, that roughly coincides with the eagles’ non-breeding season. We analyzed 827 prey items collected from 12 territories over five territory years and 84 records of eagles hunting or feeding behavior. Tortoises dominated the breeding season diet (71% of prey categories on average) and over half of all hunting/feeding observations. While no spatial structure was evident, habitat variables such as forest canopy cover were important associates in golden eagle diet seasonally. A significant seasonal pattern emerged in diet diversity, using a subset of six territories with at least 10 samples per season. Eagles shifted from a narrow, reptile- based breeding season diet dominated by tortoises to a broader non-breeding season diet, that included more carrion, mammals and birds. Breeding season specialization on ectothermic prey is a trait usually associated with migratory raptors in the Western Palearctic. The observed dietary diversity expansion accompanied by residency in the absence of ectothermic prey, highlights the adaptability of the golden eagle, a generalist predator. Tortoise populations in Greece are of conservation concern and land use changes as well as climate change, such as development and land abandonment may increase the prevalence of catastrophic megafires, exacerbating the threats to the golden eagle’s main prey when breeding. We discuss this and other diet related conservation implications for the species in northern Greece.

Response of Long-Tailed Duck (Clangula hyemalis) to the Change in the Main Prey Availability in Its Baltic Wintering Ground.

Simple SummaryExtreme change in the benthic macrofauna community after invasion of the bottom fish round goby (Neogobius melanostomus) in the eastern Baltic Sea, challenged the declining long-tailed duck (Clangula hyemalis) population at the wintering ground. The aim of this study was to assess the change in the diet of the long-tailed duck in two different seabed types: highly impacted hard-bottom and adjacent pristine soft-bottom habitats. The results showed a significant change in the diet in hard-bottom habitats, while the diet in soft-bottom habitats remained similar over time. At the same time, the body condition did not differ over time or between habitats, confirming the high foraging flexibility and the quick species response to the extreme changes in prey composition and availability.The long-tailed duck (Clangula hyemalis) is a vulnerable and declining species wintering in the Baltic Sea. The introduction of the invasive fish, the round goby (Neogobius melanostomus), dramatically impacted the benthic macrofauna in hard-bottom habitats, while no significant changes occurred in soft-bottom benthic macrofauna. Therefore, we aimed to assess the extent to which the diet of long-tailed ducks changed in two different bottom types. We analysed the stomach content of 251 long-tailed ducks bycaught in gillnets from 2016 to 2020 in hard- and soft-bottom habitats and compared these results with those published by Žydelis and Ruškyte (2005). The results show that the long-tailed duck experienced a change in diet in hard-bottom habitats, shifting from the blue mussel to Hediste diversicolor, barnacles, and fish. In soft-bottom habitats, their diet remained similar over time and was based on H. diversicolor, a few bivalve species, and Saduria entomon. There was no evidence of significant differences in diet between sex or age. Despite the abovementioned changes in diet, the average body condition of the species did not change over time or between habitats. This confirms that long-tailed ducks have high feeding flexibility and quick species response to changes in prey availability, as they are capable of shifting their diet to new prey.

New zooarchaeological perspectives on the early Upper Paleolithic Rostamian sequence of Ghar-e Boof (southern Zagros Mountains, Iran)

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

Fear effects on bank voles (Rodentia: Arvicolinae): testing for repellent candidates from predator volatiles.

BACKGROUNDArvicolinae rodents are known pests causing damage to both agricultural and forest crops. Today, rodenticides for rodent control are widely discouraged owing to their negative effects on the environment. Rodents are the main prey for several predators, and their complex olfactory system allows them to identify risks of predation. Therefore, the potential use of predators' scents as repellents has gained interest as an ecologically based rodent control method. In a two‐choice experiment, we investigated the potential repellent effects of five synthetic predator compounds: 2‐phenylethylamine (2‐PEA), 2‐propylthietane (2‐PT), indole, heptanal and 2,5‐dihydro‐2,4,5‐trimethylthiazoline (TMT), at 1% and 5% doses, using the bank vole (Myodes glareolus) as a rodent model.RESULTSThe compound 2‐PEA reduced both the food contacts and the time spent by voles in the treatment arm compared to the control arm. Likewise, 2‐PT‐treated arms reduced the food contacts, and the voles spent less time there, although this latter difference was not significant. Indole also showed a tendency to reduce the time spent at the treatment arm; however, this result was not significant. Unexpectedly, TMT had the reverse effect in showing attractive properties, possibly due to odor cues from differently sized predators and intraguild predation in nature. We found no dose‐related effects for any compounds tested.CONCLUSIONOur results suggest that the 2‐PEA and 2‐PT are both effective odor stimuli for triggering reduced food contacts and area avoidance, and they may be good repellent candidates. We suggest further testing of 2‐PEA and 2‐PT in field experiments to further determine their dose‐efficiency as repellents against rodents in more natural environments. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Late Holocene triangular lithic projectile points, their morphometric variability and hafting systems in the Southern Pampean Hills (Córdoba, Argentina)

The shape variability of triangular stone projectile points and their hafting systems are analyzed to understand the technological practices during the Late Holocene in the Southern Pampean Hills (Córdoba, Argentina). Archaeometric studies were carried out on archaeological triangular lithic projectile points and plant remains. We present results of geometric morphometrics, functional analysis for the determination of microwear use traces and analysis of FT-IR organic residue recovered from the basal and middle blade areas. Complementary anthracological investigations were developed for the taxonomic identification of plants for comparison with the organic remains recovered from the projectile points. Archaeological and actualistic samples come from two multicomponent archaeological sites of Ongamira valley, Córdoba, Argentina where camelids (Lama guanicoe) and cervids (Ozotoceros sp. and Mazama sp.) were the main hunted prey. From our results, we discuss previous typological approaches based on the similar shapes and different weapon systems for the various hunter-gatherer occupations during the Late Holocene. Accordingly, it is assumed that there is technological continuity at least for 2000 years (between 3900 and 1900 BP) not only in flaked stone technology but also in hafting practices based on the preparation of the base shape of triangular projectile points and the use of local plant resins.

Molecular Diet Analysis of Adélie Penguins (Pygoscelis adeliae) in the Ross Sea Using Fecal DNA.

Simple SummaryThe diet of Adélie penguins, Pygoscelis adeliae, in the Ross Sea was studied applying quantitative polymerase chain reaction (qPCR) protocols to their feces. Two krill species (Euphausia superba and Euphausia crystallorophias) and notothenioid fish (mainly Pleuragramma antarctica and Pagothenia borchgrevinki) were among the most abundant components of the diet. The composition of the two krill species and notothenioid fish was found to be strongly related to the geographic characteristics of the Ross Sea.The diet of Adélie penguins, Pygoscelis adeliae, is a useful indicator in understanding the ecological conditions of their habitats. The diets of Adélie penguins were studied using metabarcoding and quantitative PCR (qPCR) analyses of fecal DNA from seven habitats along the Ross Sea region. Using metabarcoding analysis with dual universal primers (18Sv9 and miniFish), the overall diet composition and detailed information about piscine prey were clearly elucidated. It was found that two krill species (Euphausia superba and Euphausia crystallorophias) and notothenioid fish were the most abundant in the diets of Adélie penguins. Among the notothenioid prey, Pleuragramma antarctica (56.50%) and Pagothenia borchgrevinki (18.21%) were the two most abundant species. qPCR analysis showed a significant geographic difference in the composition of main prey. Penguins inhabiting outbound parts of the Ross Sea (Capes Adare (CA) and Duke of York Island (DY)) mainly preyed on E. superba, without any significant changes in prey composition. By contrast, those inhabiting the inbound parts of the Ross Sea (Edmonson Point (EP) and Inexpressible Island (II)) preyed on E. crystallorophias and notothenioid fish rather than E. superba. Compared with the outbound habitats, prey compositions for penguins inhabiting the inbound regions were significantly different year to year, which was presumably due to the food availability based on the annual environmental and meteorological conditions of the coastal region along with the inbound parts of the Ross Sea.

Whips and Boats

Whips were tools used for approaching large animals and thus they were part of the equipment of individuals engaged in the catching of local large preys, who can be understood as hunters. However, the environment plays a key-role in the understanding of this professional figure, as it determined the range of other animals they could catch and, accordingly, a basic differentiation between land hunters and fishermen/hunters, the latters specifically tied to the use of boats. Sofar, no specific Sumerian words have been recognized as defining the figure of the hunter; this paper proposes an interpretation as (land) hunter of the Sumerian title usan3/usan5-du3, a profession usually understood as bird-catcher or fowler. Despite it is clear that in South Mesopotamia the main prey was in any case fowl, the professional title hints to the use of whips, therefore to the equipment suitable for catching large preys, equids and ungulates, when possible or required. On the other side, this paper suggests that individuals equipped for catching large preys in wet environments are mostly hidden among the fishermen; texts concerning boat transport can however offer some hints on their presence among the individuals having some acquaintance with boats.

Food and Feeding Biology of Nile Tilapia (Oreochromis niloticus) in Lake Langeno, Ethiopia

This study aimed to investigate the natural feeding behavior of Nile tilapia in Lake Langeno, Ethiopia, with emphasis on potential spatial, size and seasonal effects on ingested food items. This study of the food and feeding biology of O. niloticus in Lake Langeno, Ethiopia, was conducted from March 2016to February 2017. Fish samples were collected monthly from six different sampling sites using different mesh sizes of gillnets. A total of 610 fish specimens with full stomachs were considered for the assessment of feeding biology. In total, seven food items, namely phytoplankton, zooplankton, insects, detritus, macrophytes, fish parts and nematodes, were identified from the fish stomach contents. Phytoplankton was the most commonly consumed food prey, followed by detritus, zooplankton and macrophytes. The other food items were occasionally and randomly consumed. Phytoplankton and detritus were the dominant food prey in the dry season, with zooplankton and macrophytes the main prey during the wet months. The contribution of phytoplankton, zooplankton and insects were slightly highest in small-sized groups (<10 cm), whereas detritus, macrophytes and fish parts were highest in larger-size groups (>20 cm) (p < 0.05). The present results point to a concurrence of the relative importance of dietary items at the individual level, species level and among the study sites. Phytoplankton was the primary consumed food item, which indicates the specialist feeding strategy of Nile tilapia in the lake. Generally, food items of plant origin, typically associated with less protein content than animal origin food items, dominated the stomach contents of Nile tilapia. The dietary pattern of Nile tilapia in Lake Langeno shifts with size and season, aspects that might warrant further study in view of aquaculture applications as well as climate change.

Diet of Eastern Imperial Eagle (Aquilaheliaca) in Bulgaria: composition, distribution and variation.

The Eastern Imperial Eagle (EIE) is a top predator exploiting different prey in different parts of its distribution. In this study, we summarise data collected over a long period of time (for 25 consecutive years), identifying key prey species in the different regions, as well as clarifying seasonal preferences in the eagle’s diet. Most studies on the EIE food composition covering different parts of the species distribution range analyse the breeding season, while data about the winter diet are scarce. To the best of our knowledge, this is the first study detailing the differences in EIE’s dietary preferences between the breeding and the winter periods. We identified 4891 specimens belonging to 196 different taxa, which represents the most comprehensive study considering the diet diversity of this threatened species. Mammals represented the largest proportion of the diet, followed by birds and reptiles. Northern White-breasted Hedgehog was the most common prey, accounting for 25.7% of the total prey caught and 26.75% of the biomass. The European Souslik was the second most important prey with 14.35% participation in the eagle’s diet, but with a 3.75% contribution to the biomass. As we predicted, prey composition and main prey species varied spatially and seasonally. Modelling differences in the EIE diet, we found that the “territory effect” had the strongest impact on the dietary variations. Diet diversity differed significantly between regions (F = 12.6, df = 4, p = 0.01). During the breeding season, eagles fed mainly on Hedgehogs (29.88%), Sousliks (16.85%) and Storks (7.74%), while the winter diet was predominantly small rodents (44.17%) and songbirds (13.96%). We found that top predators, such as EIE, have successfully adapted to a novel food source, which is abundant in the area. The detected flexibility in the diet of the species and its ability to switch to alternative prey, if available, when the primary prey decreased, should be considered when planning species conservation efforts. Investigating the temporal change of the main prey in the eagle’s diet is also crucial for further species conservation measures.

Dietary overlap of carcharhinid sharks in the Gulf of Papua

Assessing the feeding patterns of sharks provides insight into ecological interactions. Three coastal sharks are common by-catch in the Gulf of Papua prawn fishery in Papua New Guinea. The diets of Carcharhinus coatesi (n = 122), Rhizoprionodon acutus (n = 83) and Rhizoprionodon taylori (n = 177) were assessed using stomach content analysis. Teleosts, crustaceans and molluscs were the main prey. Percentage frequency of occurrence (%FO) and percentage frequency by number (%N) were computed to describe dietary compositions. Non-metric multidimensional scaling and Morisita Index determined the level of feeding overlap. Rhizoprionodon taylori was a generalist feeder having the broadest diet, R. acutus was the most selective feeder, preying predominantly on teleosts and C. coatesi consumed the greatest proportion of crustaceans that increased with size. The pairwise ANOSIM tests showed significant difference in dietary compositions of R. acutus and R. taylori (P = 0.1%, R = 0.318) and R. acutus and C. coatesi (P = 0.1%, R = 0.589), which indicate potential resource partitioning. Further work should aim to adequately characterise diets, improve prey identification and investigate spatial and temporal resource use patterns. Understanding ecological processes informs ecosystem approaches fisheries management.

Characterization of Jaguar Utilization Distributions in the Brazilian Pantanal

Jaguars (Panthera onca) have been eradicated from 50% of their historical range across Mexico, Central America, and South America. The Brazilian Pantanal in west-central Brazil represents a stronghold of core habitat for the species and is an important site for conservation. Habitat in the Pantanal is threatened largely due to expanding human activity causing habitat loss and fragmentation, making remaining habitat vitally significant. This study seeks to characterize the utilization distributions of jaguars in the area to better understand the habitat use and spatial ecology of a threatened species. GPS locations taken from 13 jaguars were used to calculate estimates of kernelhomesrangesatthe50% (core range)and 95% (home range)isopleth levels. These ranges were used to quantify habitat use in relation to land cover types. Patterns of distribution heavily followed waterways, perhaps following that of their main prey,caimans(Caiman crocodilus yacare). Wetlands were the most heavily utilized among all jaguars at the 95% home range followed by grasslands. However, at the 50% core range level there was a shift in greater utilization of forest habitat over grassland. Additionally, females generally had smaller home ranges than that of males and exhibited less overlap between home ranges(27 km2) than between male home ranges(217 km2) – a key indicator of female spatial avoidance.

Spatio-temporal diet variability of the California sea lion Zalophus californianus in the southern California Current Ecosystem

Characterizing predator diets is essential to understanding food web dynamics. We investigated the dietary breadth and variation of the California sea lion (CSL) Zalophus californianus at 3 of the California Channel Islands from 1981-2015. Prey species were identified from hard parts and soft-tissue remains of pyrosomes recovered from fecal samples, revealing a diverse diet of fish and cephalopods. Percent frequency of occurrence and percent split-sample frequency of occurrence were used to describe long-term trends, correlations between prey taxa, diet diversity, and diet similarity. The most common of 142 prey taxa identified to species were market squid Doryteuthis opalescens, northern anchovy Engraulis mordax, shortbelly rockfish Sebastes jordani, jack mackerel Trachurus symmetricus, Pacific sardine Sardinops sagax, Pacific hake Merluccius productus, and Pacific mackerel Scomber japonicus. Dietary differences were observed between male and female sea lions, and between animals from different islands and seasons. Intra-island diets at 2 locations were more similar than inter-island diets. Important inter-annual and decadal changes in diet were identified. CSL diet shifted from an anchovy-based diet in the 1980s to a market squid based-diet in the 1990s and 2000s, with other prey taxa being consumed more frequently when consumption of those 2 main prey declined. Prey-switching likely provides flexibility needed in the dynamic California Current Ecosystem, and may allow CSLs to adapt to changes in food supply and availability driven by climate change.

Lion (Panthera leo) diet and cattle depredation on the Kuku Group Ranch Pastoralist area in southern Maasailand, Kenya

Context African lion (Panthera leo) populations are declining throughout Africa, but the problem is particularly acute in southern Kenya, where human–lion conflict is common. Aims Using the Kuku Group Ranch (KGR) in southern Kenya as a case study, we investigated lion diet and the potential drivers of temporal variation in cattle depredation. Methods Using GPS clusters, we investigated the main prey species consumed by lions to determine lion diet. Prey preference of lions in relation to prey availability was then assessed using a Jacobs index to determine whether cattle or wild prey were preferred. We used reported depredation events recorded by verification officers over 36 months (2016–2018) to investigate whether temporal variation in cattle depredation by lions was linked to variation in lag rainfall, normalised difference vegetation index (NDVI) or availability of the most important large non-domestic prey items. Key results Six prey species (cattle, Bos taurus; Burchell’s zebra, Equus quagga; Coke’s hartebeest, Alcelaphus cokeii; Maasai giraffe, Giraffa tippelskirchi; blue wildebeest, Connochaetes taurinus; and eland, Tragelaphus oryx) made up 92% of the biomass consumed by lions on KGR. Cattle are the most consumed prey item and contribute the second most to consumed biomass after giraffe. However, once prey availability is considered, lions preferred wild prey. Verification officers identified 330 cattle depredation events over 3 years, and we show that the most important predictor of monthly cattle depredation by lions was cumulative rainfall in the preceding 3 months. Conclusions Our results on cattle depredation by lions showed that rainfall and its influence on the environment are important drivers of cattle depredation. Understanding the mechanistic link between lion depredation and rainfall enables us to predict when depredation events may increase and allows hypotheses on the reason why this spike in depredation takes place to be explored. Implications Given that climate-change models indicate that East Africa will experience prolonged and increased seasonal rainfall, we predict that periods when cattle are vulnerable to lion depredation may increase. Therefore, it is imperative to ensure that cattle husbandry is improved during these wetter periods to minimise the risk of conflict and retaliatory killing of lions.

Lobos marinos de un pelo sudamericanos Otaria flavescens ¿buenos indicadores de cambios espaciales y temporales relativos en la distribución y abundancia de los recursos marinos?

ABSTRACT. Oceanographic fluctuations and changes in ocean productivity directly affect the abundance and distribution of prey species, which in turn, affect the population status of their predators. In order to have a better understanding of this predator-prey relationship, the aim of the present study was to analyze the diet of the South American Sea Lion Otaria flavescens (Shaw, 1800) in two rookeries of the San Matias Gulf, in northern Patagonia (Argentina). A total of 52 scat samples of O. flavescens were collected in the Promontorio Belén colony and 35 in Caleta de los Loros during the late spring of 2011. The analysis of the samples indicated that at both localities fish occurred in 100% of scats with prey remains, followed by cephalopods (32.3%) and crustaceans (21.4%). The fish Raneya brasiliensis (Kaup, 1856) constituted the main prey taxon, both in terms of occurrence and numerical abundance. The octopod Octopus tehuelchus (d’ Orbigny, 1834) and squids of the genus Doryteuthis constituted the dominant cephalopod prey. It is concluded that sea lions focused their foraging activity on those species of demersal and benthic habits, associated with coastal and shelf waters. Furthermore, this study reports for the first time the feeding habits of the South American Sea Lion colony of Promontorio Belén, second in population size of Río Negro province.

Fecal DNA metabarcoding shows credible short-term prey detections and explains variation in the gut microbiome of two polar bear subpopulations

This study developed and evaluated DNA metabarcoding to identify the presence of pinniped and cetacean prey DNA in fecal samples of East Greenland (EG) and Southern Beaufort Sea (SB) polar bearsUrsus maritimussampled in the spring of 2015-2019. Prey DNA was detected in half (49/92) of all samples, and when detected, ringed sealPusa hispidawas the predominant prey species, identified in 100% (22/22) of EG and 81% (22/27) of SB polar bear samples with prey DNA detected. Bearded sealErignathus barbatusDNA was found in 19% (5/27) of SB polar bear samples for which prey DNA was detected. Prey DNA detection frequencies and relative abundances were compared to estimates from quantitative fatty acid signature analysis (QFASA) for a subset of SB polar bears. Ringed seal and bearded seal were the main prey identified by both methods, but QFASA also identified 2 cetacean prey species not found by prey DNA. Differences in DNA metabarcoding vs. QFASA results were likely related to the different dietary timescales captured by each approach, i.e. short-term vs. long-term diet, respectively. Prey DNA detection, sex/age class, and subpopulation significantly explained variation in polar bear gut bacterial composition. Polar bear samples with prey DNA detected were associated with higher abundances of the bacterial classes Clostridia and Bacilli and lower abundances of Negativicutes. Fecal DNA metabarcoding is thus useful for identifying recent prey of polar bears, complementing quantitative and likely longer-term QFASA estimates, and may help understand variation in the polar bear gut microbiome.

Diet composition and feeding habits of Oreochromis niloticus (Linnaeus, 1758) in Lake Shala, Ethiopia

The present study was carried out to investigate the food and feeding habits of Oreochromis niloticus in Lake Shala to manage this species in this high Soda Lake. Stomachs of 226 fish (65.9%) had different food items,while those of 117 fish (34.1%) were empty. Phytoplankton was the dominant food categories occurring in 90.3% of the stomachs estimated and contributed 75.5% of the total volume. Bacillariophyceae (Nitzschia, Anomoeoneis, Navicula and Melosira) were identified as the most desired phytoplankton item. The prey items of O. niloticus differed among size classes (ANOVA, p < 0.05). The main prey items were zooplankton by the smaller-size class, and phytoplankton in fish of the larger-size class. Seasonal variation in the diet composition was evident (t-test, p < 0.05) and zooplankton, chironomids, nematodes, fish scales and detritus were important during the wet season, while phytoplankton predominates during the dry season. This study concludes that O. niloticus had a phytoplanktivores feeding mainly on phytoplankton and their feeding habits influenced by season and fish size in Lake Shala.

Food habits of two species of tube-nosed bats, Murina hilgendorfi and Murina ussuriensis, in Hayakawa, central Japan

Abstract Knowledge of food habits is essential for understanding the life history of a species; however, such information about the enigmatic Murina genus of bats is little known. In this study, we examined the food habits of Murina hilgendorfi and Murina ussuriensis over four years in Hayakawa, central Japan, using traditional morphological fecal analysis. Fragments of arthropods of six orders (five identified families), and of five orders (five identified families), were found in the feces of M. hilgendorfi and M. ussuriensis, respectively. Both species consumed wingless arthropods (caterpillars and spiders), insects that rarely fly (ground beetles and bush crickets), or diurnal insects (dragonflies and hoverflies; i.e., that are resting at night) during the night, which is a clear indication of gleaning behavior in these bats. In spring, the large-bodied M. hilgendorfi more frequently consumed hard-bodied insects such as beetles and bush crickets, whereas the small-bodied M. ussuriensis more frequently consumed soft-bodied insects such as caterpillars, moths, spiders, and dipterans, suggesting that the body size difference influences their food habits, which may have contributed to food resource partitioning between these closely related bats. For M. hilgendorfi, beetles were the main prey in spring and autumn, while caterpillars and grasshoppers were more frequently consumed in spring and autumn, respectively, suggesting that they may have changed prey items according to seasonal fluctuations in food availability. To our knowledge, this study provides the first record of differences in the food habits of these two species.

A Glimpse of Blue Sheep (Pseudois nayaur) Hunting in Api Nampa Conservation Area (ANCA) Nepal

Higher altitudes of Api Nampa Conservation Area have become a hunting destination for the local people bringing a threat to blue sheep and other wildlife. Blue sheep has been a national concern in Nepal due to being the main prey species of snow leopard and trophy hunting. The purpose of this paper is to examine the impact of hunters in Api Nampa Conservation Area (ANCA), Darchula, Nepal. This study was carried out around Api Nampa Conservation Area in 2016. Mixed methods of questionnaires were developed to collect data, and quantitative analysis was done by applying SPSS 16. A hundred percent of hunters like to hunt in this protected area. The hunted animals were goral, blue sheep, barking deer, boar and tahr. Site-specific characteristics like vegetation density, terrain and rugged land topography often vary markedly across surveys. Due to the regular and yearly use of grazing by the livestock in the area, it becomes imperative to study their feeding habits and document their food plants. Consequently, poaching and livestock grazing are important challenges for the conservation of blue sheep. Hunting, deforestation, forest fires, grazing and shifting agriculture are identified as major threats to the wildlife of Api Nampa Conservation Area. Envisioning, critical thinking, building partnership in decision-making, awareness, and stringent action against hunting activities must be adopted early. Api Nampa Conservation Area has received little research attention from grassland ecologists and specialists in pastoral management.