Important Prey Categories Research Articles

Southernmost record and diet of Leptobrachella eos (Ohler, Woollen, Grosjean, Hendrix, Vences, Ziegler & Dubois, 2011) in Vietnam

Abstract The Rosy Litter Frog (Leptobrachella eos) is known from Thailand, Laos, and Vietnam. Knowledge about the natural history of this species is virtually lacking. As a result of our field work in Son La, Nghe An, and Ha Tinh provinces of Vietnam, we provide data on the food composition of L. eos for the first time. Using the stomach-flushing method, we analyzed stomach contents of 34 individuals (23 males and 11 females) from a total of 42 frogs, with stomachs of five males and three females (19%) being empty. A total of 13 prey categories were observed in the stomachs of L. eos, with 232 items, comprising 230 items of invertebrates and two unidentified items. The most important (IRI) groups among the prey of L. eos were Blattodea (26.31%), Araneae (17.26%), Orthoptera (13.21%), Coleoptera (12.39%), and Opiliones (10.09%). There was an overlap of 51.11 % in the diet between males and females, The trophic spectrum of males comprising 11 prey categories revealed to be wider than that of females comprising nine prey categories. Despite differences in diets between the sexes, Blattodea, Orthoptera, Araneae, Coleoptera, and Opiliones represented the most important prey category for all of them. In addition, we also report a new find of Leptobrachella eos, with a new subpopulation from Ha Tinh Province, Vietnam.

Trophic niche of four sympatric direct-developing frogs (Anura: Strabomantidae) from Eastern Brazilian Amazonia

Knowledge on the ecology of many Amazonian anuran species is still incipient, especially when it comes to resource partitioning. Here, we studied dietary variation of four Pristimantis species (P. chiastonotus, P. crepitaculus, P. gutturalis and P. zeuctotylus) from Eastern Brazilian Amazonia during the rainy and dry seasons. From 226 stomach contents retrieved through stomach-flushing, we observed that the four sympatric species can explore the generalist, sit-and-wait, and opportunistic foraging strategies, feeding mainly on highly mobile arthropods such as Diptera, Coleoptera, Hymenoptera, Hemiptera and Orthoptera, which were the most important prey categories. We found significant differences among the species for the volumetric composition of prey, and the amount of prey consumed was the main predictor for this condition in most species. The type of microhabitat was also a predictor for feed volumetric composition in some species. We report a higher perching height for P. chiastonotus, and lower perching in P. gutturalis; the first species had a wider dietary spectrum. These findings contribute to the understanding of resource partitioning among sympatric and closely related species.

Diet of Invasive Rough Bent-Toed Geckos, Cyrtopodion scabrum (Heyden, 1827), in Southeastern Algeria.

Rough Bent-Toed Gecko, Cyrtopodion scabrum (Heyden, 1827), is an invasive species in Algeria and northwestern Africa. We provide detailed information on the morphometry and diet of C. scabrum from an urban area in Debila (northeastern Oued Souf), Algeria. We found a significant correlation between morphological characters (body length, snout-vent length, and tail length) in individuals within each sex, but no differences in morphometry between females and males. Analysis of stomach contents of 30 specimens (15 adult males, 15 adult females) resulted in identification of 198 prey items belonging to 2 classes, 8 orders, 20 families, and 29 genera. The diet of C. scabrum was mainly composed of arthropods and was highly diverse (Shannon index = 4.3). Insects were the main food item, accounting for 96.5% of prey consumed, followed by arachnids (3.5%). The most important prey categories were Hymenoptera (40.4%), Diptera (19.7%), Lepidoptera (12.6%), and Coleoptera (12.1%).

Microhabitat use, daily activity pattern, and diet of Liolaemus etheridgei Laurent, 1998 (Reptilia: Liolaemidae) in the Andean Polylepis forests of Arequipa, Peru.

This study describes the microhabitat use, daily activity pattern, and diet of Liolaemus etheridgei Laurent, 1998 in the El Simbral and Tuctumpaya Polylepis forests in Arequipa, Peru. El Simbral is a fragmented forest, whereas Tuctumpaya is unfragmented. Our results reveal that L. etheridgei shows no positive selection for any of the microhabitats we identified in Polylepis forests; on the contrary, it selects negatively against Polylepis trees and nonthorny bushes. The daily activity patterns indicate a bimodal pattern with peaks at 9:00–10:59 and 13:00–13:59 h. The diet of L. etheridgei consists mainly of plant material, and the most important animal prey category is Lygaeidae: Hemiptera, which is selected for positively. In particular, microhabitat selection varied for nonthorny bushes, which were selected negatively in the Tuctumpaya population but neither positively nor negatively in the El Simbral population. According to the proportions of plant material found, the L. etheridgei from El Simbral were found to be omnivorous, whereas the Tuctumpaya population was herbivorous. However, the percentage of plant material consumed in the El Simbral population was close to the critical value for herbivory–omnivory. We conclude that the three ecological aspects of L. etheridgei studied here are virtually identical in El Simbral and Tuctumpaya; therefore, this species is not affected significantly by the current fragmentation of forest.

Trophic ecology of Patagonian flounder Paralichthys patagonicus (Jordan, 1889) in the Argentine-Uruguayan Coastal Ecosystem

Food habits and diet composition of Patagonian flounder Paralichthys patagonicus (Jordan, 1889) were studied on the basis of stomach content analyses from 828 specimens (512 females, 304 males, 12 unsexed) collected during 16 commercial cruises between February 2009 and April 2010 in the Argentine-Uruguayan Coastal Ecosystem (34° S-41° S). A total of 272 stomachs (32.9%) contained food (184 females and 84 males), among which 20 prey taxa were identified. The most important prey category was pelagic fish, primarily Argentine anchovy (Engraulis anchoita), followed by rough scad (Trachurus lathami). Evidence showed that females consumed a higher total wet weight of prey compared to males. Results also suggested a specialised diet over E. anchoita, across all sex and size groups. The estimated trophic level for the population of P. patagonicus was 4.16. This study suggests that P. patagonicus is a tertiary piscivorous consumer of the trophic food web in the region, and reveals changes in the prey consumption compared with previous studies.

Seasonal and intra-populational diet variation in the Colombian Swamp frog Pseudopaludicola pusilla (Anura Leptodactylidae)

Diet is a fundamental aspect of the ecological niche of amphibians and usually varies intra-specifically in response to extrinsic environmental and intrinsic individual factors. Phenotypic variations among individuals can generate intrapopulation differences in trophic resource use, which could have important ecological and evolutionary implications in amphibian populations. Here, we studied the intrapopulation dietary variation of the frog Pseudopaludicola pusilla in an anthropic savanna of the Colombian Caribbean region, considering the effects of seasonality and sex on the size, amount, prey composition and dietary individual specialization. We collected 44 adult frogs during the dry season and 46 during the rainy season and analyzed their stomach contents to determine their dietary composition. Our results indicate that P. pusilla is a generalist and opportunist predator, feeding mainly on insects of the orders Orthoptera, Coleoptera and Hymenoptera, which were the most important prey categories due to their numeric, volumetric and frequency contributions. We observed seasonal variations regarding volumetric prey composition and the importance value of each prey category in the populational diet. Individuals of P. pusilla consume more prey items during the rainy season and bigger prey during the dry season, but the volume of stomach contents did not vary seasonally. Males and females of P. pusilla consumed a similar number of prey items, but females ingested more voluminous prey and had greater volumes of stomach contents than males. Additionally, we observed a pattern of dietary individual specialization, which was not related to morphological trade-offs and did not differ among seasons. These findings contribute to the understanding of the seasonal dynamics of the use of trophic resources by anurans and the effect of sex on dietary characteristics of P. pusilla, in environments strongly influenced by climatic seasonality.

Diet and observations on natural history of Gabohyla pauloalvini (Bokermann 1973) (Amphibia: Hylidae), a poorly known species from cacao agroforestry in southern Bahia, Brazil

Gabohyla pauloalvini is a small Neotropical hylid, known only from three localities besides its type locality. Knowledge about its natural history is scarce and we present the first data about its diet. We conducted our fieldwork during the rainy period between November and December of the years 2014 and 2015. Thirty-eight G. pauloalvini individuals, collected in a semi-permanent pond inside a “cabruca” (cacao plantation shaded by trees), municipality of Ilheus, Bahia, Brazil, were stomach-flushed. All stomach contents were identified to the lower taxonomic category as possible. The Index of Relative Importance (IRI) revealed that Formicidae was the most important prey category for G. pauloalvini. We assume that G. pauloalvini is an ant specialist. Diet records for others species of the tribe Sphaenorhynchini showed mainly ants as prey items, which reinforces an ecological synapomorphy for this tribe. Beyond diet, we also reported observations of possible parental care performed by G. pauloalvini females.

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

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.

Feeding habits of the horn sharkHeterodontus francisci(Girard, 1855) in the northwest of Baja California Sur, Mexico

The feeding habits of the horn shark, Heterodontus francisci (Girard, 1855), were examined in the area of Bahia Tortugas, Baja California Sur, Mexico in the spring, summer and fall of 2014. A total of 78 stomachs were collected, of which 46 (59%) contained food and 32 (41%) were empty. According to the percent Index of Relative Importance (%IRI), the most important prey categories in H. francisci's diet were anomurans (66%), cephalopods (7.2%), lobsters (4.7%), fishes (4.2%) and sea urchins (2.3%). The main prey were the anomuran Blepharipoda occidentalis (65.2%), the octopus Octopus bimaculatus (5.4%), the lobster Panulirus interruptus (4.7%) and the sea urchin Echinometra vanbrunti (2.6%). According to the Levin standardized Index (Bi), the trophic niche breadth in H. francisci is low (Bᵢ = 0.21), making it a specialist predator. The species was classified as a tertiary consumer (trophic position = 4.06).

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

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.

Dietary composition and feeding strategy of Leptodactylus fuscus (Anura: Leptodactylidae) from a suburban area of the Caribbean Region of Colombia

The use of trophic resources by anurans may be influenced by sexual dimorphism, ontogeneticvariation and resources available in the environment. However, most studies on anuran feedingbehavior lack of environmental prey availability data. In this study, the dietary compositionand the feeding strategy of Leptodactylus fuscus were evaluated considering the availability ofpotential prey in a sub-urban area of the Colombian Caribbean Region. Additionally, differencesin diet composition between adult and juvenile’ frogs were assessed. Prey items were obtainedthrough forced regurgitation technique and prey availability was assessed using pitfall traps.The importance of each prey category and prey selectivity were evaluated through a relativeimportance index and a food selection index, respectively. Twenty-four stomachs were analyzed,being Hymenoptera the most important prey category and the most abundant resourcein the environment. The population of L. fuscus showed a low prey selectivity and prey size wasassociated with frog’s body size. However, there was no variation in numeric and volumetricdietary composition related to ontogeny. Considering the relationship between the diet andprey availability, our results evidenced L. fuscus exhibits a generalist and opportunistic feedingbehavior, which highlight the importance of including information on prey availability to betterunderstand the anurans dietary behavior.

Autecology of the lizard Colobosauroides cearensis (Squamata: Gymnophthalmidae) from Brazilian semiarid Caatinga

Autecology of the lizard Colobosauroides cearensis (Squamata: Gymnophthalmidae) from Brazilian semiarid Caatinga. Colobosauroides cearensis is a diurnal lizard with a relictual distribution associated with forested habitats in the Brazilian Caatinga Domain. Knowledge of the natural history of this secretive lizard is scarce. Herein, the diet, reproduction, sexual dimorphism, microhabitat use, and thermal ecology of C. cearensis are described based on feldwork in 2015–2017 in the state of Ceará, Brazil. The diet of the lizards is composed exclusively of arthropods, with Formicidae being the most important prey category. Numerical and volumetric niche breadths are 5.52 and 9.2 respectively, and trophic niche overlap between females and males is 0.3. Males are distinguished from females by the larger size of the males and the presence of femoral pores. Colobosauroides cearensis is cryptozoic, inhabiting the leaf litter and having no direct contact with the soil or solar radiation. The average body temperature of the lizards is 30.4 ± 3.3°C, which is positively correlated with the air temperature. Gravid females with fxed clutch size of two eggs are found in early rainy season. Oviposition occurs between April and May (when the highest number of juveniles are observed). Sexual maturity occurs early in males and testicular volume is signifcantly correlated with body size.

Seasonal variation in diet and prey availability in the wall lizard Podarcis vaucheri (Boulenger, 1905) from the Djurdjura Mountains, northern Algeria

ABSTRACTWe studied the composition and seasonal changes in diet and prey selection in the wall lizard Podarcis vaucheri of the Djurdjura Mountains throughout its activity period, from April to October 2014. The analysis of 238 faecal pellets revealed 1 206 prey items distributed in 19 prey categories. The most important prey categories were: Formicidae, Coleoptera, Aranea, Homoptera, and Orthoptera. Significant seasonal variation in the taxonomic composition of the diet and prey availability was found. A significant difference in diet composition was observed between males and females in spring. This lizard species displayed a more diverse dietary spectrum during this period, followed by a slight decrease in summer. However, a severe decrease in the food niche breadth was observed in autumn, resulting in a high consumption of ants. A comparison of diet composition and prey availability showed that lizards exhibited a clear selection of certain prey types, in contrast to what is often suggested for lacertid lizards.

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

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.

DỊ HÌNH KÍCH THƯỚC GIỚI TÍNH VÀ SINH THÁI DINH DƯỠNG CỦA LOÀI CHÀNG XANH (Hylarana erythraea) Ở VÙNG PHÚ LỘC, TỈNH THỪA THIÊN HUẾ

The Common Green Frog, Hylarana erythraea (Schlegel, 1837), is an important species in both terrestrial and aquatic ecosystems. However, information on sexual size dimorphism (SSD) and the feeding ecology of this species in Vietnam is currently lacking. We used the stomach-flushing method to obtain food items from 223 stomach specimens. The results showed that the average snout-vent length was significantly larger in adult females than in adult males, with an SSD index of 0.57. The most important prey categories of H. erythraea were Coleoptera, unidentified insect larvae, Odonata, Orthoptera, and Araneae (occurrence frequency 65.45 %, representing 65.89 % of the number of items, and 81.04 % of the total volume). The mouth width and snout-vent length had significant effects on the prey size and on the volume of food items. However, air temperature and relative humidity did not have significant effects on the prey volume or size of individual food items. These results supported the hypothesis that “the mouth size is the limiting factor on the food size” in anuran species.

Diet and first report of batracophagy in Leptodactylus podicipinus (Anura: Leptodactylidae)

In this study, we describe the diet of Leptodactylus podicipinus in South Pantanal. We analysed the stomach content of 30 individuals collected in September 2017 in the Miranda sub-region, Mato Grosso do Sul. We identified 19 prey categories to Order level, out of which Coleoptera was the most representative group and the most important prey category, followed by Orthoptera and Hemiptera. We recorded a post-metamorphic individual of Rhinella schneideri in the diet of L. podicipinus, the first record of batracophagy for this species. Our results provide evidence for the opportunistic and generalist feeding behaviour of L. podicipinus.

Vole abundance and reindeer carcasses determine breeding activity of Arctic foxes in low Arctic Yamal, Russia

BackgroundHigh latitude ecosystems are at present changing rapidly under the influence of climate warming, and specialized Arctic species at the southern margin of the Arctic may be particularly affected. The Arctic fox (Vulpes lagopus), a small mammalian predator endemic to northern tundra areas, is able to exploit different resources in the context of varying tundra ecosystems. Although generally widespread, it is critically endangered in subarctic Fennoscandia, where a fading out of the characteristic lemming cycles and competition with abundant red foxes have been identified as main threats. We studied an Arctic fox population at the Erkuta Tundra Monitoring site in low Arctic Yamal (Russia) during 10 years in order to determine which resources support the breeding activity in this population. In the study area, lemmings have been rare during the last 15 years and red foxes are nearly absent, creating an interesting contrast to the situation in Fennoscandia.ResultsArctic fox was breeding in nine of the 10 years of the study. The number of active dens was on average 2.6 (range 0–6) per 100 km2 and increased with small rodent abundance. It was also higher after winters with many reindeer carcasses, which occurred when mortality was unusually high due to icy pastures following rain-on-snow events. Average litter size was 5.2 (SD = 2.1). Scat dissection suggested that small rodents (mostly Microtus spp.) were the most important prey category. Prey remains observed at dens show that birds, notably waterfowl, were also an important resource in summer.ConclusionsThe Arctic fox in southern Yamal, which is part of a species-rich low Arctic food web, seems at present able to cope with a state shift of the small rodent community from high amplitude cyclicity with lemming dominated peaks, to a vole community with low amplitude fluctuations. The estimated breeding parameters characterized the population as intermediate between the lemming fox and the coastal fox ecotype. Only continued ecosystem-based monitoring will reveal their fate in a changing tundra ecosystem.

Diet and reproduction in coastal and inland populations of the Tawny Owl Strix aluco in southern Finland

In generalist predators the energy needed for reproduction is derived from various prey categories, the profitability of which may vary according to the biomass or accessibility of the prey items. We examined the relationships between the diet and production of young in two Tawny Owl (Strix aluco) populations in southern Finland. We found a positive correlation between the amount of remnants of different prey in samples of litter collected from the nest bottoms after breeding and the production of young. Three important prey categories in the diet of owls during the nestling period, i.e. Water Voles, Field Voles and thrush-sized birds, seemed to be significantly related to the number of fledglings. However, only thrush-sized birds showed a significant relationship to the number of fledglings when all prey variables were analysed together in one model. The total prey mass was the best predictor of owl brood size. There were no significant local differences between the effects of different prey categories on the production of Tawny Owl young. Our results, combined with some earlier findings, outline the relationship between food supply and the production of Tawny Owl young in southern Finland. With regards to the Tawny Owl this outline can be generalized to other areas with other kinds of food supply within the distribution range of the species. Similar outlines are probably applicable also to many other generalist predators.

Diet ofAmphisbaena heathiSchmidt, 1936 (Squamata: Amphisbaenidae) from Remnants of the Atlantic Forest, Northeastern Brazil, with Notes on Distribution, Diagnosis and Conservation

Abstract. We analyzed the diet of Amphisbaena heathi, a species with restricted geographic distribution in northeastern Brazil. We also present data on morphometric and meristic characters of the examined specimens and update the geographic distribution of the species. The diet analysis was based on the contents of the digestive tract of 21 specimens collected in two urban Atlantic Forest fragments in Natal municipality, Rio Grande do Norte state, from 2008–2010. We collected 80.1% of the specimens near the surface (depth of ca. 3–5 cm) in moist earth under the leaf litter and 19.9% underground (ca. 15 cm beneath the surface). In total, we identified 60 prey items in the digestive tracts of A. heathi. The most important prey categories were ants, insect larvae, and cockroach nymphs. Ants predominated in frequency and number, while insect larvae and cockroaches predominated in volume. Besides insects, A. heathi also consumed earthworms, leeches, and centipedes. Considering our sample (n = 34) and the type ...

On the natural history of the Caatinga Horned Frog, Ceratophrys joazeirensis (Anura: Ceratophryidae), a poorly known species of northeastern Brazil

Sobre a história natural do Sapo-de-chifre da Caatinga, Ceratophrys joazeirensis (Anura: Ceratophryidae), uma espécie pouco conhecida do nordeste do Brasil. Apresentamos aqui dados sobre a reprodução, dimorfismo sexual e dieta de Ceratophrys joazeirensis, a única espécie do gênero que ocorre no Bioma brasileiro semiárido Caatinga. Os anuros foram observados e coletados no Município de Santa Maria, estado do Rio Grande do Norte, nordeste do Brasil. O trabalho de campo foi realizado à noite, durante ou após as chuvas ao longo da estação chuvosa no período 2010–2013. Foram realizadas buscas perto de locais onde os machos estavam vocalizando, geralmente em torno de corpos d’água. A reprodução é explosiva, com atividade reprodutiva ocorrendo quando as chuvas se intensificaram durante as estações chuvosas de 2011–2013. No entanto, em 2010, nem machos vocalizando nem fêmeas ativas foram encontrados, mesmo depois de dias chuvosos. Embora os machos vocalizem em poças temporárias e permanentes, a maioria dos indivíduos vocalizou na vegetação marginal de poças temporárias. As fêmeas de C. joazeirensis são significativamente maiores que os machos. O tamanho médio da desova é de 2555.0 ± 1551.1 ovos; o tamanho da ninhada não está significativamente correlacionado com o tamanho do corpo das fêmeas. Em ordem decrescente de volume, as categorias de presas mais importantes na dieta de C. joazeirensis foram anuros, seguidos por coleópteros e material vegetal. A aparente importância dos anuros na dieta provavelmente está relacionada com o número de espécies de anuros que co-ocorrem com C. joazeirensis e do comportamento alimentar voraz dos Ceratophryidae.