English

ABSTRACTAfrican clawless otters (Aonyx capensis) are opportunistic feeders with a broad dietary niche. Variation in their diet can be influenced by environmental and anthropogenic factors, which can affect seasonal and longitudinal prey availability. Flexibility in the diet allows African clawless otters to adapt to these changes and exploit novel prey items when available. Seasonal examination of otter spraints from three different locations across South Africa demonstrates that African clawless otters are able to shift from their preferred crab‐based diet to a fish‐ or insect‐based diet in response to environmental and anthropogenic drivers. Here we provide direct evidence of African clawless otters in terrestrial environments shifting to an insect‐dominated diet when this resource is available. The dietary plasticity and response of this species to the shifts in available prey items may be an important factor for future consideration in conservation management of the species.

The feeding habits of Thryssa kammalensis was studied using 430 specimens collected from October 2010 to September 2011 in the coastal waters of Gadeok-do, Korea. T. kammalensis in the coastal waters of Gadeok-do was carnivorous predator and planktonic feeder with a wide variety of prey items such as arrowworm, copepods, crab larvae, shrimp larvae, and fish eggs. In addition, T. kammalensis consumed mainly arrowworm, copepods, crab larvae, shrimp larvae, fish eggs, and the diet also included small quantities of cladocerans, amphipods, bivalve larvae, mysids, and euphausiids. On the other hand, the body length (BL) of T. kammalensis specimens ranged from 5.9 to 15.1 cm. Size-related variations in dietary composition of T. kammalensis were not significant that overlap indexes of each major food items that showed very high values in all size classes, representing more than 0.80. Arrowworms were the dominant prey item in all sizes, and copepods were the next most frequent prey item consumed in all size classes. Seasonal changes in dietary composition of T. kammalensis were significant. However, overlap indexes of each major food items in some season showed very high values of 0.80 (between spring and winter) and 0.85 (between summer and autumn). Copepods were most frequently eaten in the spring and winter. Moreover, arrowworm were the dominant prey item in summer and autumn. Mean numbers of prey per stomach (mN/ST) changed significantly with size groups (P < 0.05), but mean wet weight of preys per stomach (mW/ST) showed an opposite tendency (P > 0.05).

ABSTRACTInformation about food web dynamics is crucial for the success of ecosystem-based management. In order to collect such information, it is necessary to establish the dietary contents of species in the food chain. In this study, the diet of Atlantic bonito Sarda sarda (Bloch, 1793), one of the most important species in the Black Sea ecosystem, has been examined. The aim of this study was to investigate the prey preferences of Atlantic bonito over an eleven-year period during their feeding migration to the Black Sea. Sampling was carried out by commercial purse seine and gill nets along the Turkish Black Sea coast during migration of the Atlantic bonito from 2005 to 2016. Stomach contents were identified to the lowest possible taxonomic level. Atlantic bonito dietary composition was analyzed by fishing season, sex and size classifications. Results revealed a Vacuity Index value (V %) of 67% while 33% of individuals sampled had at least one prey species in their stomach content. Since S. sarda predominantly feed on small fish species, stomach contents contained mainly Engraulis encrasicolus, Trachurus mediterraneus, Sprattus sprattus, Mullus barbatus, Gobius niger, Merlangius merlangus, Pomatomus saltatrix, Alosa immaculata, Parablennius tentacularis and small unidentified prey items (tissue particles, … etc.). The most frequent prey item was E. encrasicolus with a percentage occurrence of 94%. In conclusion, the main prey species was determined as E. encrasicolus and statistical analyses of X2 was found significant (P < 0.005) according to year, sex and size.

We radio‐tracked seven Cape clawless otters (Aonyx capensis) (Schinz, 1821) in two rivers in the Western Cape Province, South Africa, providing data on their habitat selection. Habitat type was investigated at a scale that enabled us to separate the effects of types of riparian vegetation, geomorphology and anthropogenic influences. Otters selected areas with boulders and/or reed beds, which provided high crab density and shelter. Direct observations showed that they used two foraging modes depending on the habitat selected. Otters could select open water within c. 8 m of the shore, dive and surface with or without prey. Otherwise hunting involved them moving into shallow water (c. 0.2 m deep), and walking along the substrate feeling for prey with their forefeet. Disturbed possible prey items were then caught with the forefeet.

The Baillon's Crake Zapornia (Porzana) pusilla is considered as one of the least known Rallidae species of the Palaearctic. Very little information exists about its ecological requirements and knowledge on diet refers to very few observations. Based on the analysis of faecal samples (N = 59) from two study sites in Djoudj National Park (NW Senegal), we describe the major diet components and examine how seasonal and environmental factors influence its dietary composition. All faeces contained remains of invertebrates. Coleopterans were the most frequent prey items with an occurrence in 95% of the samples. Other important food items were: Odonata (82%), Aranaea (78%), Nematocera (59%), and Brachycera (44%). Remains of gecko skin were the only evidence for vertebrate prey. 75% of the faeces contained plant matter, especially seeds of Eleocharis mutata which constituted in some individuals > 90% of the sample content. Generalized linear models (GLMs) were used to assess whether occurrence of prey items was an effect of selection or environmental variation, considering both consumed items as well as prey availability. Sweep netting was used to provide an estimate of relative abundance of potential invertebrate prey.Despite pronounced seasonal changes in temperature and humidity, models revealed a lower influence of meteorological variables on prey composition and availabilty. Rather we found water level, date and site having the highest impact in the models. In contrast to decreasing diversity of available food items in the course of the season, diversity in the faeces remained constant indicating Baillon's Crakes prey less selectively when resources diminish. Furthermore, diversity of Baillon's Crakes' diet was lower at higher water levels, suggesting stronger selectivity when prey abundances are high as implied by positive relationships of several invertebrate groups with water level. Despite the rapidly declining water levels and decreasing abundances of e.g. Nematocera, Odonata and Mollusca in the course of the season, we found no clear shift from aquatic to a more terrestrial dominated composition of taxa in the birds' diet. This might be due to the selection of profitable prey such as araneans or molluscs but could also be explained by better accessibility due to physical changes in the habitats e.g in the case of consumed Odonata and Saltatoria. High disintegration of invertebrates in the faeces rendered quantification of prey items impossible. Biomass estimates could support the assessment of specialization of the Baillon's Crakes as well as the detection of seasonal succession of the wetlands' biotic communities.

Plasticity and specialisation in the isotopic niche of African clawless otters foraging in marine and freshwater habitats

The Isles Dernieres Barrier Island Refuge in Louisiana, USA, constitutes a major colonial waterbird breeding site, and several restoration projects have been undertaken to sustain waterbird populations on the refuge. However, very little is known about food resources that colonial waterbirds depend on in the Gulf of Mexico. Royal (Thalasseus maximus) and Sandwich (T. sandvicensis) tern diet composition was investigated to determine important food resources during the breeding period. Regurgitated prey items in the 2013 and 2014 breeding seasons were used to compare diet composition, prey item frequency, and prey item mass among four groups: Royal Tern adults, Royal Tern chicks, Sandwich Tern adults, and Sandwich Tern chicks. The two most frequent prey items were Atlantic croaker (Micropogonias undulatus) and bay anchovy (Anchoa mitchilli). Royal Tern adults consumed significantly more Sciaenids than any other tern group, and Sandwich Tern adults consumed more Engraulids than any other tern group. Royal and Sandwich tern adults partitioned food resources by prey species and prey size, while chick diet showed more overlap in prey species composition. Royal and Sandwich tern diet closely reflected the species composition of trawls from nearby waters, suggesting opportunistic prey selection. The diets of both tern species contained a variety of demersal prey items indicating use of discards from local fisheries activities. Interactions between breeding waterbirds and fisheries in coastal Louisiana may be an important conservation consideration with profound implications on breeding abundance and breeding success of waterbirds.

Length frequencies and diets of smallmouth bass (Micropterus dolomieui) captured from two small ponds by sport fishing and by electrofishing were compared to determine if fishermen's catches were similar to those acquired by electrofishing. The sport-caught fish (N=79) had a mean total length of 32.5 cm (range = 15.6 to 52.0 cm); the electrofished smallmouth bass (N=134) had a mean length of 26.2 cm (range = 8.0 to 47.1 cm). There was no significant difference in total lengths of smallmouth bass from the two ponds. Sport-caught fish were significantly larger than electrofished fish (p < .001). Of 213 smallmouth bass, 93 had empty stomachs, 113 had only one prey type, either crayfish (Orconectes virilis) or fish (Lepomis sp.). There was a highly significant difference in prey items of smallmouth bass captured by sport fishing and by electrofishing (p < .001). Crayfish was the most frequent prey item in angler-caught smallmouth bass while fish (Lepomis sp.) was a more frequent prey item among electrofished smallmouth bass.

We examined the seasonal food habits of wolverine Gulo gulo in subboreal and interior wet-belt montane environments in British Columbia by analyzing scats collected during the course of two concurrent wolverine studies. Understanding foraging ecology for a wide-ranging carnivore such as the wolverine is important, particularly because reproduction has been demonstrated to be closely linked to food abundance. Wolverine diet was shown to vary regionally and seasonally. Regional variation was related to differences in prey availability between study areas. Moose Alces alces, caribou Rangifer tarandus, and hoary marmots Marmota caligata were abundant and common prey items within both study areas. Mountain goats Oreamnos americanus and porcupine Erithizon dorsatum were more abundant and more frequent prey items in the Columbia Mountains, while snowshoe hare Lepus americanus and beaver Castor canadensis were more abundant and more frequent prey items in the Omineca Mountains. Within the winter season, ...

We studied the diet of nestling Spectacled Tyrants (Hymenops perspicillatus) in the southeast Pampas region, Argentina. From November 2012 to January 2013, we used video footage to determine prey items that the parents fed to their chicks. We obtained 54 hrs of recording time to survey 18 nests. We identified a total of 125 prey items, representing 33 different taxa, grouped into four classes: Insecta, Arachnida, Chilopoda, and Amphibia. Insects accounted for 94% of total prey. The most frequent prey items were orthopterans (Caelifera), unidentified lepidopteran larvae, and odonats (Zygoptera). Lepidopterans were numerically the most important prey item in November, odonats in December, and orthopterans in January. Diet of the nestling birds was generalist in terms of the consumption of insects, and the changes in prey consumption during the course of the breeding season support an opportunistic feeding behavior by Spectacled Tyrants.

We studied the diet of Cape clawless otters (Aonyx capensis) at three sites along the eastern and southern coast of South Africa to assess possible spatial variation along a community species richness and biomass gradient associated with rocky shores. A total of 309 spraints representing two seasons (summer 2013/2014 and winter 2014) were collected and subsequently analysed. The percentage occurrence and percentage dry mass of numerous prey categories were compared between sites and seasons. Variation in the importance of prey items was found between sites, whilst no variation was found between seasons within the same site. Crab was the most important prey item in the southernmost study area (Tsitsikamma National Park) and at the northernmost study site (KwaZulu-Natal Coast), whilst lobster was the most important prey item in the central area (Mkambati Nature Reserve). Fish was the second most important prey item at all three sites. Our results suggest that otters are opportunistic feeders that are likely able to adapt to potential prey species and abundance changes associated with current and future anthropogenically driven changes. Furthermore, long-term, site-specific stability in diet suggests that monitoring the diet of otters could provide some useful information on the status of shoreline communities.

Event Abstract Back to Event Feeding preferences and diet overlap of introduced Atlantic and native Danube lineages of brown trout (Salmo trutta) from Croatia Marina Piria1*, Ivan Špelić1, Luana Velagić1, Ivana Lisica1, Tamara Kanjuh2, Ana Marić2 and Predrag Simonović2, 3 1 Faculty of Agriculture, University of Zagreb, Croatia 2 Faculty of Biology, University of Belgrade, Serbia 3 Institute for Biological Research Sinisa Stankovic, University of Belgrade, Serbia Brown trout has been widely introduced/translocated into suitable environments globally. In Croatia, the Danube (DA) lineage of brown trout is native. However, due to anglers’ activities, brown trout of the Atlantic (AT) lineage were stocked into Croatian streams and rivers. They hybridize with native brown trout causing a loss in native genetic variability. Brown trout of the AT lineage have been determined as invasive, posing a threat to native DA populations. Feeding habits of brown trout are related to insects of both terrestrial and aquatic origin. Introduced AT brown trout compete with native ones for food resources, possibly causing deficiency in available prey. Until now, no research related to feeding competition between AT and DA lineage of brown trout from inland waters has been performed. The purpose of this research is to examine the natural diet of brown trout of AT and DA lineages and to compare their feeding overlapping. In total 10 streams at the Gorski kotar (Bresni p., Mala les., Curak), Žumberak (Kupčina, Slapnica) and Papuk (Jankovac, Brzaja, Veličanka, Toplica and Orljava) Mountains were sampled in May 2017 and 2018, using electrofishing device. After sampling, fish specimens were stored on -20oC. Data of specimens’ haplotype was taken from Kanjuh et al. (2018). In laboratory each specimen was measured for total length (TL, in cm) and weight (W, in g). Stomach content was removed, measured and prey items determined to the lowest possible systematic category. Assessment of the fish diet was based on the frequency of occurrence (F%), numerical frequency (N%) and mass frequency (W%), (Hyslop, 1980). The index of relative importance IRI was calculated for each prey category (Hodgson et al., 1989). Diet overlap was calculated using the index proposed by Schoener (1970) based on IRI. Also, determined prey items were chosen as response variables to analyse the relationships between fish feeding habits from different streams and genetic origin (locations and haplotype used as nominal explanatory variables) using Canonical Correspondence Analysis (CCA) by CANOCO software package. To test the importance of each prey items for AT and DA lineages, the gut content data were analysed using the Poisson generalized linear model with log link (GLM). In total, 92 brown trout specimens were captured and analysed. TL was between 10.0 and 30.3 cm and mass from 10.19 to 323.52 g (TLAT = 15.4 – 30.3 cm; TLDA = 10.0 – 27.6 cm). Four specimens have been found with empty stomach. Sex ratio was 75: 14: 3 (females: males: juveniles). Based on IRI coefficient, the main prey items for brown trout of both lineages were aquatic Coleoptera, Trichoptera, Amphipoda and Diptera and terrestrial Formicidae (Fig.1.). However, brown trout from the Žumberak and Gorski kotar consumed different prey items than specimens from the Papuk Mountain (Fig. 2). Although only 9 specimens of AT haplogroup were detected, according to Schoener index (S), statistically significant diet overlap has been found between AT and DA specimens (S = 0.65, p < 0.05). According to each prey item importance for lineages, IRI coefficient showed that Capniidae, Caelifera, fish prey (Cottus gobio) and Diptera larvae were significantly more important prey for the AT than for the DA lineage (Fig. 1), which was confirmed by GLM analysis (p<0.05). This research confirmed that brown trout of the AT lineage compete in food resources with those from native populations. However, it seems that brown trout of the AT lineage possess better abilities to catch terrestrials as a prey that falls into the water (Formicidae, Caelifera, Vespidae) than those of the DA lineage, who take mostly available aquatic prey (larvae of Trichoptera and Coleoptera). Such difference in feeding strategy between brown trout of different lineages implies that brown trout of the AT lineage could be more attractive for fly fishing, which may complicate the implementation of conservation measures necessary to preserve the indigenous brown trout of the DA lineage. Figures Fig. 1. IRI prey importance for AT and DA lineages of brown trout from Žumberak, Gorski kotar and Papuk Mountains Fig. 2. Canonical Correspondence Analysis ordination diagram representing mass percentage of main prey items of brown trout at each sampling sites; total variation is 7.89, explanatory variables account for 20.8% of the variation; Monte Carlo permutation test results on all axes: pseudo- F = 1.7, P = 0.002 (▲ –nominal explanatory variables, Δ – prey item) Figure 1 Figure 2 Acknowledgements This research was supported by the grant from the Croatian Science Foundation (IP-06-2016) and by the Croatia-Serbia bilateral programme 2019-2020 References Kanjuh, T., Tošić, A., Špelić, I., Piria, M., Simonović, P., Maguire, I. (2018): Human influence on the native brown trout (Salmo trutta) genepool in the continental western Croatia. HydroMediT 2018, 3rd International Congress on Applied Ichthyology & Aquatic Environment, Book of Proceedings, Berilis, P., Karapanagioditis, I. (ed.). Volos: University of Thessaly, School of Agricultural Sciences, Department of Ichthyology and Aquatic Environment, 2018, pp 555-558. Schoener, T.W. (1970): Non-synchronous spatial overlap of lizards in patchy environments. Ecology, 51: 408-418. Hyslop, E.J. (1980): Stomach content analysis – a review of methods and their application. Journal of fish biology, 17:411-429. Hodgson, J.R., Carpenter, S.R., Gripentrog, A.P. (1989): Effect of sampling frequency on intersample variance and food consumption estimates of nonpiscivorus largemouth bass. Transactions of the American Fisheries Society, 118, 11–19. Keywords: alien trout, Prey items, competition, Fly fishing, Danube River Basin Conference: XVI European Congress of Ichthyology, Lausanne, Switzerland, 2 Sep - 6 Sep, 2019. Presentation Type: Oral Topic: ECOLOGY AND LIFE CYCLES Citation: Piria M, Špelić I, Velagić L, Lisica I, Kanjuh T, Marić A and Simonović P (2019). Feeding preferences and diet overlap of introduced Atlantic and native Danube lineages of brown trout (Salmo trutta) from Croatia. Front. Mar. Sci. Conference Abstract: XVI European Congress of Ichthyology. doi: 10.3389/conf.fmars.2019.07.00003 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 14 May 2019; Published Online: 14 Aug 2019. * Correspondence: Prof. Marina Piria, Faculty of Agriculture, University of Zagreb, Zagreb, Croatia, mpiria@agr.hr Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Marina Piria Ivan Špelić Luana Velagić Ivana Lisica Tamara Kanjuh Ana Marić Predrag Simonović Google Marina Piria Ivan Špelić Luana Velagić Ivana Lisica Tamara Kanjuh Ana Marić Predrag Simonović Google Scholar Marina Piria Ivan Špelić Luana Velagić Ivana Lisica Tamara Kanjuh Ana Marić Predrag Simonović PubMed Marina Piria Ivan Špelić Luana Velagić Ivana Lisica Tamara Kanjuh Ana Marić Predrag Simonović Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Food habits of Geoffroy's cat (Leopardus geoffroyi) in the central Monte desert of Argentina

This study quantitively compares the diets of the Stygian Owl (Asio stygius) and the Short-eared Owl (A. flammeus) in the south-west of the Bogotá Savanna, Colombia. We identified 130 prey items from 111 A. stygius pellets and 579 prey items from 149 A. flammeus pellets. In terms of the numbers of preys, the diet of A. stygius consisted of the following: 88.1% birds, mainly pigeons, rails and cuckoos; and a smaller proportion of beetles (11.4%). In the diet of A. flammeus, insects were the most frequent prey item (59.8%), followed by rodents (39.8%), and birds (0.5%). In terms of biomass contribution, the main preys in the diet of A. stygius were Eared Doves (Zenaida auriculata) (54%) and Purple Gallinules (Porphyrio martinica) (19.3%), while the diet of A. flammeus consisted mainly of House Mice (Mus musculus) (65.2%). Diet diversity varied between the owl species: A. flammeus was more selective in its hunting habits, while A. stygius was more of an opportunistic predator. It is important to quantify the ecosystem services these owls provide not only by controlling M. musculus, Z. auriculata, and Shiny Cowbird (Molothrus bonariensis) populations, which can affect human well-being and threatened species populations, but also through secondary seed dispersion and birdwatching opportunities.

The aim of this study was to use scat analysis to analyse the dietary composition of the South American sea lion (SASL, Otaria byronia) over a short temporal scale and in different but closely located colonies in the Humboldt Current System of northern Chile. Scat samples were collected at Arica (18°34′S), Iquique (20°48′S) and Mejillones (23°04′S) during the summer (January to March) and winter (July) of 2015. A total of 16 595 individual prey items from nine species were found in 194 of the 215 scat samples. In general, squat lobster (Pleuroncodes monodon) was the most important prey item for the sea lion diet, both by number and according to the index of relative importance (%IRI), followed by anchovy (Engraulis ringens), which was the most frequent prey item in the scats and the most important by weight. Patagonian squid (Loligo gahi) ranked third in importance in the sea lion diet. However, some spatiotemporal variations in the consumption of prey were found. Squat lobster was the most important prey for sea lions in Arica and Iquique, while anchovy was the dominant prey in Mejillones. Regarding seasonal variation, squat lobster was more important in winter than in summer in the three localities, while anchovy was also more important during winter, except in Mejillones where the levels of consumption of this prey were similar in both seasons. These results show that SASL adjust their dietary preferences, modifying the contribution of different prey both spatially and temporally. Spatiotemporal variations in the SASL diet can be explained by temporal changes in the distribution and abundance of their prey.