scholarly journals Changes in prey importance and prey niche overlap of sexes during the alpine newt breeding season

2020 ◽  
Vol 146 (2) ◽  
Author(s):  
Oldřich Kopecký
Keyword(s):  
Breeding Season ◽  
Stomach Contents ◽  
Niche Overlap ◽  
Trophic Niche ◽  
Sexual Differences ◽  
Food Sources ◽  
Quantitative Composition ◽  
Important Prey ◽  
Alpine Newt ◽  
Prey Items

Urodeles, including European newts, are usually sexually dimorphic predators. Among newts, the alpine newt has the most pronounced sexual size dimorphism (in favour of females). Gender is a factor that is often associated with intra-specific diet differences. Despite the significant number of dietary studies on the alpine newt, some topics such as the breadth of the trophic niche and its overlap between sexes, or inter-sexual differences in qualitative and quantitative composition of prey remain unresolved. The present study dealing with these questions was conducted at two localities (ponds at an elevation of about 450 m) in the Czech Republic. Newts were captured from the banks during the entire breeding season using a dip net, and the stomach contents were extracted using a stomach flushing technique. Altogether 190 individuals were sampled, and a total of 1,417 prey items were obtained. The available food sources differed over the course of the breeding season, as newts changed the taxa they preyed on. This reflects the ability of newts to switch between several hunting strategies. The overall food niche overlap between the sexes was relatively large (C = 0.761, resp. C = 0.797). Inter-sexual differences were detected at both localities, mainly in the number of prey items consumed from the most important prey categories such as Rana eggs or Isopoda, which were consumed in higher numbers by females. The findings of this study suggest that females are more sensitive to the trade-off between energy intake and expenditure during the breeding season.

Trophic ecology of large pelagic fish in the Saint Peter and Saint Paul Archipelago, Brazil

2019 ◽  
Vol 70 (10) ◽  
pp. 1402 ◽  
Author(s):  
F. V. Albuquerque ◽  
A. F. Navia ◽  
T. Vaske ◽  
O. Crespo ◽  
F. H. V. Hazin
Keyword(s):  
Trophic Ecology ◽  
Feeding Habits ◽  
Saint Paul ◽  
Pelagic Fish ◽  
Trophic Niche ◽  
Trophic Relationships ◽  
Main Prey ◽  
Important Prey ◽  
Saint Peter ◽  
Prey Items

Trophic relationships of large pelagic predators can determine the structure and dynamics of oceanic food webs. The feeding habits and trophic ecology of five large pelagic fish (Acanthocybium solandri, Coryphaena hippurus, Elagatis bipinnulata, Thunnus albacares and Thunnus atlanticus) in the Saint Peter and Saint Paul Archipelago were evaluated to determine whether there is a trophic-niche overlap or resource partitioning among them. Eighty prey items found in 1528 stomachs were identified and grouped into Cephalopoda, Cnidaria, Crustacea, Gastropoda, Teleostei and Tunicata. Exocoetidae and Scombridae were the main prey in the diet of Acanthocybium solandri. In C. hippurus, Cheilopogon cyanopterus and Exocoetus volitans were the most important prey items, whereas C. cyanopterus was the main prey for T. albacares. Thunnus atlanticus consumed a great proportion of invertebrate species, with shrimps of Sergestidae family being particularly important. The gastropod Cavolinia sp. was the most important prey for E. bipinnulata. The five species had a high trophic specialisation and a high trophic level (>4.4), whereas most dietary overlaps were consistently low. The most important factor for diet dissimilarity was the consumption of Exocoetidade. All species were classified as top predators with varied diets, indicating their structural and functional importance in the food web of the Archipelago.

scholarly journals Competition and feeding ecology in two sympatric Xenopus species (Anura: Pipidae)

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3130 ◽  
Author(s):  
Solveig Vogt ◽  
F. André de Villiers ◽  
Flora Ihlow ◽  
Dennis Rödder ◽  
John Measey
Keyword(s):  
Food Preferences ◽  
Stomach Contents ◽  
Niche Overlap ◽  
Niche Differentiation ◽  
Shannon Index ◽  
Trophic Niche ◽  
Western Cape ◽  
The South ◽  
Amphibian Species ◽  
Study Sites

The widespread African clawed frog (Xenopus laevis) occurs in sympatry with the IUCN Endangered Cape platanna (Xenopus gilli) throughout its entire range in the south-western Cape, South Africa. In order to investigate aspects of the interspecific competition between populations of X. laevis and X. gilli, an assessment of their niche differentiation was conducted through a comprehensive study on food composition and trophic niche structure at two study sites: the Cape of Good Hope (CoGH) and Kleinmond. A total of 399 stomach contents of X. laevis (n = 183) and X. gilli (n = 216) were obtained together with samples of available prey to determine food preferences using the Electivity index (E*), the Simpson’s index of diversity (1 − D), the Shannon index (H′), and the Pianka index (Ojk). Xenopus gilli diet was more diverse than X. laevis, particularly in Kleimond where the Shannon index was nearly double. Both species were found to consume large amounts of tadpoles belonging to different amphibian species, including congeners, with an overall higher incidence of anurophagy than previously recorded. However, X. laevis also feeds on adult X. gilli, thus representing a direct threat for the latter. While trophic niche overlap was 0.5 for the CoGH, it was almost 1 in Kleinmond, suggesting both species utilise highly congruent trophic niches. Further, subdividing the dataset into three size classes revealed overlap to be higher in small frogs in both study sites. Our study underlines the importance of actively controlling X. laevis at sites with X. gilli in order to limit competition and predation, which is vital for conservation of the south-western Cape endemic.

scholarly journals Diet of Chiasmocleis cordeiroi Caramaschi and Pimenta, 2003 from the Atlantic Rainforest in southern Bahia, Brazil

2020 ◽  
Vol 30 (30) ◽  
pp. 52-56
Author(s):  
Indira Maria Castro ◽  
Caio Vinícius de Mira-Mendes ◽  
Mirco Solé
Keyword(s):  
Atlantic Forest ◽  
Stomach Contents ◽  
Foraging Strategy ◽  
The State ◽  
Atlantic Rainforest ◽  
Prey Category ◽  
Taxonomic Level ◽  
Important Prey ◽  
Southern Bahia ◽  
Prey Items

We studied the diet of a Chiasmocleis cordeiroi population in a fragment of the Atlantic Forest in the state of Bahia, Brazil. Frogs were collected at night after an explosive breeding event and were transferred to the lab where they were measured, weighed and had their stomach contents retrieved following a stomach flushing protocol. Individuals were later released back into the pond from which they had been collected. Stomach contents were measured and identified to the lowest possible taxonomic level. The most important prey category in the diet of C. cordeiroi was Hymenoptera (Formicidae), as has been already observed for other microhylids. The large number of prey items in the stomach and the low niche amplitude suggest that C. cordeiroi is a specialist using an active foraging strategy to detect its prey.

scholarly journals Dietary composition of birds species at an inland airport in South Africa

2002 ◽  
Vol 21 (1) ◽  
pp. 16-18
Author(s):  
A. C. Kok ◽  
O. B. Kok
Keyword(s):  
Bird Species ◽  
Stomach Contents ◽  
Total Sample ◽  
Dry Mass ◽  
Food Sources ◽  
Mass Composition ◽  
Potential Threat ◽  
Important Prey ◽  
Lesser Kestrel ◽  
Main Food Source

Stomach contents of 51 bird species that posed a potential threat to aviation were collected at the Bloemfontein airport over a period of 11 years (1985-1995). Numerically the crowned plover (Vanellus coronatus), and the lesser kestrel (Falco naumanni), blacksmith plover (V. armatus), whitewinged korhaan (Eupodotis afraoides), doublebanded courser (Smutsornis africanus), spotted dikkop (Burhinus capensis), cattle egret (Bubulcus ibis), Swainson’s francolin (Francolinus swainsonii) and Orange River francolin (F. levaillantoides) in sequence of importance, constituted 91,0% of the total sample (3 544). In general insects can be considered the main food source of the birds concerned. Based on dry mass composition the Isoptera, followed by the Coleoptera and Orthoptera, constituted the most important component in the diet. The Isoptera, more specifically the harvester termite (Hodotermes mossambicus), is, moreover, the only important prey taxon showing a conspicuous utilisation peak during the relative food shortage of the dry season. Evidently, temporary superabundant food sources that periodically come about in grassland habitats are opportunistically utilised by the birds.

scholarly journals Feeding aspects of Knodus heteresthes (Eigenmann, 1908) and Moenkhausia lepidura (Kner, 1858) (Characiformes, Characidae) in the Teles Pires and Juruena Rivers, southern Amazon

2020 ◽  
Author(s):  
E. Oliveira ◽  
A. R. A. Ignácio ◽  
W. L. Lázaro ◽  
C. C. Muniz ◽  
D. V. S. Campos ◽  
...  
Keyword(s):  
Stomach Contents ◽  
Niche Overlap ◽  
Trophic Niche ◽  
Frequency Of Occurrence ◽  
Dietary Preference ◽  
Importance Index

Abstract The composition of the diet of two species of characids (Knodus heteresthes and Moenkhausia lepidura) was evaluated in the Teles Pires and Juruena Rivers, sampled in September and October 2016. We analyzed 226 stomachs of K. heteresthes and 425 of M. lepidura. The analysis of the stomach contents was based on volumetric and frequency of occurrence methods, applying the food importance index. For the similarity of the diets between the species we calculated the niche overlap with Pianka’s index. Both species in the Juruena River have a dietary preference for arthropods (IAi > 0.95). In the Teles Pires River the diet is concentrated in three sources for both species: arthropods (IAi > 0.52), vegetables (IAi > 0.33) and fish (IAi > 0.12). The diet was dissimilar when compared to environments (ANOSIM, R ≥ 0.57, p < 0.001) with high trophic niche overlap (α > 0.97), regardless of the sampled environment. In the Teles Pires River, both species were classified as omnivorous with an insectivorous tendency and in the Juruena River the insectivorous behaviour occurs.

scholarly journals Diet and trophic niche overlap of Boana bischoffi and Boana marginata (Anura: Hylidae) in southern Brazil

2018 ◽  
Vol 19 (1) ◽  
Author(s):  
Camila F. Moser ◽  
Mateus de Oliveira ◽  
Fernanda R. de Avila ◽  
Diogo Dutra-Araújo ◽  
Renata K. Farina ◽  
...  
Keyword(s):  
Natural History ◽  
Atlantic Forest ◽  
Diet Composition ◽  
Niche Breadth ◽  
Niche Overlap ◽  
Food Composition ◽  
Trophic Niche ◽  
Southern Brazil ◽  
Important Prey ◽  
History Of

Abstract: The species Boana bischoffi and Boana marginata are endemic to the Atlantic Forest, where they often occur in sympatry. There is a large gap in the knowledge of natural history of both species. In this study, we aimed to describe and compare the diet composition of B. bischoffi and B. marginata in the southern domain of the Brazilian Atlantic Forest. We analyzed the gastrointestinal contents of 43 individuals of B. bischoffi and 30 individuals of B. marginata. Both showed a high trophic niche overlap (0.90 Ojk). The most important prey categories for both species belonged to the orders Araneae and Coleoptera. The species niche breadth (Bsta) varied from 0.35 to 0.42, suggesting a generalist feeding behavior for both species. Our data provide unprecedented information on these species' food composition, contributing to a better knowledge of the natural history of neotropical anurans.

Striped marlin (Kajikia audax) diet variability off Cabo San Lucas, B.C.S., Mexico during El Niño–La Niña events

2017 ◽  
Vol 98 (6) ◽  
pp. 1513-1524 ◽  
Author(s):  
Sofía Ortega Garcia ◽  
Dana I. Arizmendi-Rodríguez ◽  
Marcela S. Zúñiga-Flores
Keyword(s):  
Annual Variation ◽  
Stomach Contents ◽  
Diet Breadth ◽  
Dosidicus Gigas ◽  
Important Prey ◽  
Jumbo Squid ◽  
Diet Variability ◽  
Analysis Of Similarity ◽  
Index Of Relative Importance ◽  
Prey Items

The stomach contents of 1261 striped marlins caught from 2007 to 2010 by the sport-fishing fleet of Cabo San Lucas, Baja California Sur, Mexico, were analysed, taking into account sea surface temperatures estimated using satellite images of the study area and the Oceanic Niño Index (ONI). The analysis allowed the identification of three anomalously cold periods during 2007, 2008 and 2010 and a warm period in 2009. The stomach content results showed 89 different prey items eaten during the study period. Of the specimens captured, 868 (69%) stomachs contained food items. The most important prey items were cephalopods (Dosidicus gigas and Argonauta spp.) and fish (Scomber japonicus, Selar crumenophthalmus and Sardinops caeruleus). Despite having a broad trophic spectrum, the striped marlin was classified as a specialist consumer, with Bi = 0.03. Based on the diet breadth value and the prey-specific index of relative importance (PSIRI), the jumbo squid, D. gigas, was the main prey species, coinciding with cold periods. On the other hand, the fishes S. caeruleus and S. japonicus showed the highest PSIRI values during the 2009 warm anomalies. Analysis of similarity showed the formation of four groups in relation to PSIRI values. According to a non-metric multidimensional scaling ordination, these groups were formed with a similarity of 30% and a stress of 0.17. These results demonstrate inter-annual variation in the diet as well as in the availability and abundance of prey items.

scholarly journals Similarities and contrasts in the diets of foxes, Vulpes vulpes, and cats, Felis catus, relative to fluctuating prey populations and drought

1988 ◽  
Vol 15 (3) ◽  
pp. 307 ◽  
Author(s):  
P. C. Catling
Keyword(s):  
Breeding Season ◽  
Small Mammals ◽  
Vulpes Vulpes ◽  
Age Groups ◽  
Stomach Contents ◽  
Arid Environment ◽  
Felis Catus ◽  
Food Sources ◽  
South Wales ◽  
Semi Arid

The diets of the fox, Vulpes vulpes, and feral cat, Felis catus, were studied at Yathong Nature Reserve in semi-arid western New South Wales. The overall occurrence of rabbit was 45.1% in stomachs of foxes and 54.0% in cats, representing 51.3 and 82.6% respectively of the weight of stomach contents. Both predators exhibited a functional response to rabbits, Oryctolagus cuniculus, (their staple prey) during the rabbit breeding season. Predation on rabbits was greatest on an increasing prey population during good pasture conditions and a decreasing population during drought. After the rabbit breeding season, diet changed to other prey and resulted in an annual prey cycle which was similar for foxes and cats. Both predators successfully co-exist in the semi-arid environment by primarily utilising different age groups of the same staple prey and to some extent different supplementary prey. Foxes mainly ate adult rabbits and cats young rabbits. During the drought foxes preyed heavily on adult rabbits; cats ate some rabbits but relied heavily on other food sources. The supplementary prey of foxes were invertebrates, birds, reptiles and carrion; small mammals and fruits opportunely eaten. Invertebrates, birds, reptiles and small mammals were supplementary prey for cats with carrion opportunely eaten.

scholarly journals Changes in trophic characteristics of two fish species of Astyanax (Teleostei: Characidae) in response to aquatic pollution

2019 ◽  
Vol 36 ◽  
pp. 1-12 ◽  
Author(s):  
Mirella B. Alonso ◽  
Débora R. de Carvalho ◽  
Carlos B. M. Alves ◽  
Marcelo Z. Moreira ◽  
Paulo S. Pompeu
Keyword(s):  
Isotopic Composition ◽  
Fish Species ◽  
Environmental Changes ◽  
Stomach Contents ◽  
Niche Overlap ◽  
Trophic Niche ◽  
Metropolitan Region ◽  
Trophic Plasticity ◽  
Polluted Sites ◽  
Belo Horizonte

The trophic plasticity of most fish species of Astyanax Baird &amp; Girard, 1854 in response to environmental changes and resource availability is high. This work evaluates the differences in the trophic characteristics of two congeneric species, Astyanaxtaeniatus (Jenyns, 1842) and Astyanaxlacustris (Lütken, 1875), in Rio das Velhas Basin, which is highly impacted by the discharge of sewage from the Metropolitan Region of Belo Horizonte (MRBH). Eight sites were sampled and grouped into three regions: upper course (two sites upstream of the MRBH); middle course (three sites located in the middle portion of the Rio das Velhas, region with greater influence of the MRBH), and lower course (three sites downstream of the MRBH). Samples of fish and food resources were collected from all sites to obtain the isotopic composition of nitrogen (δ15N) and carbon (δ13C), and the stomach contents of the two species was analized. The most common items in the stomach of A.lacustris and A.taeniatus, respectively, were from plants and insects, followed by algae/periphyton (especially at the low course of Rio das Velhas). In contrast, stable isotope analyses indicated that algae (in polluted sites) and periphyton (in least-disturbed sites) were best assimilated both species. Both analyses indicated that the trophic niches of the two species overlap more in more polluted sites relative to less polluted sites. Astyanaxtaeniatus and A.lacustris only presented different isotopic composition of carbon and nitrogen in the upper course of the Rio das Velhas, probably in response to the greater diversity of food items consumed by each species. In the other regions, the species presented similar isotopic signatures, with δ15N and δ13C notably enriched in the most polluted regions (middle and low course). Our results suggest that pollution acts by increasing trophic niche overlap of these species, altering the type of resources most assimilated, and promoting a greater enrichment of δ15N in fish and resources.

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