Generalist Feeding Research Articles

Feeding strategies and diet variation in livebearing fishes of the genusLimia(Cyprinodontiformes: Poeciliidae) in the Greater Antilles

AbstractFeeding specialisations are known to play an important role in the ecology and evolution of many organisms. In this study, we performed a comparative analysis based on the data of the gut content of eight species of the genusLimia(family Poeciliidae) to explore the potential role of feeding ecology in the radiation of this genus in the Caribbean. We analysed the feeding strategies using the modified Costello's graphical method. In addition, we estimated the contribution of each food item to the diet by calculating the alimentary index of six different functional categories that summarised the variation in main type of consumed items. We also compared the niche breadth for all analysed species and the niche breadth variation between wet and dry seasons in four species we were able to sample in both periods of the year. Most of the analysed species showed preference for detritus and algae. Species that exhibited a more omnivorous diet such asL. versicolorandL. perugiaerevealed moderate levels of consumption of terrestrial and aquatic invertebrates. Nonetheless, some species such asL. yaguajaliandL. nigrofasciatashowed specialisations towards detritus as the dominant food item found in the gut content analysis. In general, niche breadth values were higher in the wet season than in the dry period. Our study showed that the majority of species analysed tend to be feeding generalists, but some degree of specialisation occurs in some species from Hispaniola where the diversity of the genusLimiais remarkably higher compared to the rest of the Greater Antilles.

Evidence of cannibalism in a population of western Galápagos racers Pseudalsophis occidentalis (Serpentes: Colubridae)

Cannibalism is a common behaviour among snakes, but it has not yet been verified for any of the nine species of Galápagos racer (Pseudalsophis spp.), a group endemic to the Galápagos archipelago, Ecuador. Galápagos racers are opportunistic generalists feeding on a variety of vertebrate prey. There are a few anecdotal and suspected attempts of cannibalism among Galápagos racers, but it is unclear whether this behaviour occurs and if so, how frequent it is. We analysed 61 faecal samples from western Galápagos racers (Pseudalsophis occidentalis). In addition to the remains of well known prey items such as lizards, we found snake teeth and skin fragments in 11 samples. Combined with previous observations of attempted cannibalism between western Galápagos racers, our results represent evidence that this species consumes other racers as prey. Our study contributes to a growing knowledge of the natural history of Galápagos racers and highlights the role of these reptiles in complex trophic interactions in the Galápagos islands.

Seasonal Diet and Habitat Use of Large, Introduced Rainbow Trout in an Ozark Highland Stream

AbstractStocking of Rainbow TroutOncorhynchus mykisscommonly provides seasonal or mitigation fisheries; however, these fish are usually small and ecosystem effects are spatially or temporally limited. Yet agencies receive requests to stock Rainbow Trout in relatively natural settings (i.e., not tailwater or mitigation fisheries), where introductions may have greater ecosystem consequences. The size of introduced fish is an important factor in determining biotic interactions with native species; therefore, our objectives were to assess the seasonal feeding ecology and microhabitat use of large (265–530 mm TL) nonnative Emmerson strain Rainbow Trout in a relatively unaltered, groundwater‐influenced, warmwater stream of the Ozark Highlands. Rainbow Trout consumed a variety of prey; however, diets differed between cool (winter and spring) and warm (summer) seasons. Cool‐season Rainbow Trout exhibited a mixed feeding strategy, with individual specialization on crayfishes and fishes and generalist feeding on Ephemeroptera and Diptera, but Gastropoda were the dominant prey. Feeding strategy in the warm season switched to individual specialization on numerous prey types. Overall, larger prey resources were important components of Rainbow Trout diets. Piscivory was relatively high in both seasons, and crayfishes were one of the most important prey types across seasons. Selection of coarse substrates and deeper‐water microhabitats (>0.95 m) was similar between seasons. Rainbow Trout selected the lowest‐velocity microhabitats available during the warm season and moderate velocities in the cool season. Rainbow Trout were five times more likely to be associated with cover in the warm season. Due to their higher temperature tolerance, Emmerson strain Rainbow Trout may persist in Ozark Highland streams, where they disrupt local food webs and occupy habitat otherwise selected by native fish, such as Neosho Smallmouth BassMicropterus dolomieu velox. If native species conservation is a priority for agencies, then caution regarding Rainbow Trout stockings may be warranted.

New hosts and morphological data for the Star pearlfish Carapus mourlani (Ophidiiformes: Carapidae) from collections made in the North Pacific coast of Costa Rica

Introduction: The family Carapidae includes about 40 species of marine fishes distributed in coastal habitats worldwide. The family includes some free-living species, however, most of them are found as commensal inquilines or parasites of marine invertebrates, including several echinoderm species. In the Eastern Tropical Pacific, the biology and host use of the representatives of the Carapidae is relatively poorly known.
 Objective: The present study reports the occurrence of the Star pearlfish Carapus mourlani within three previously unknown hosts in the region: the sea stars Nidorellia armata, Phataria unifascialis, and the sea cucumber Stichopus horrens. Some ecological implications and considerations regarding such symbiotic relationships are raised and discussed. Additional morphometric and meristic data for the fish and the echinoderms are also provided and discussed.
 Methods: Echinoderms were collected, from 25 localities along the North Pacific coast of Costa Rica, and were carefully examined searching for commensal/parasitic fishes. Echinoderms and fishes were identified and characterized in accordance with the specialized literature.
 Results: A total of 497 echinoderms, including about 60 species, were collected and examined. Commensal/parasitic fish (a single species represented by 13 specimens) were found in three echinoderm specimens/species.
 Conclusions: The list of echinoderm hosts for this carapid fish, through its whole distribution range, rises to 12 species (six sea stars and six sea cucumbers) and that could be a consequence of its wide geographic distribution, its generalist feeding habits and opportunistic commensal behavior.

Herbivory increases on freshwater plants exposed to artificial light at night

Artificial light at night (ALAN) is recognized as one of the major anthropogenic pollutants jeopardizing biodiversity at a global scale. Few studies have focused on the impacts of nocturnal light on freshwater ecosystems despite their increasing exposure to light pollution worldwide due to human activities along rivers or lakes. By modifying metabolism, the disruption of natural light regime could modify the leaf palatability and affect the plant-herbivore interactions which can partly determine the structure of macrophyte communities. By experimentally mimicking light conditions from sub-urban areas, we measured the effects of low-level light at night on the leaf traits of an aquatic plant, Ceratophyllum demersum, and herbivory by the snail Lymnaea stagnalis, a generalist feeder. We demonstrate that artificial light at night increases the herbivory rate: leaves of C. demersum that had been exposed to ALAN for three months were 1.6 times more consumed by L. stagnalis than control leaves. The increase in C. demersum palatability to the pond snail when plants were exposed to ALAN was not due to a decrease in dry matter content or to a modification of the biomechanical characteristics of the leaves. Because snails have not been exposed to nocturnal light before or during the herbivory experiment, this increase in leaf palatability, is possibly linked to modifications of primary and/or secondary metabolism. Our results suggest that ALAN is a potential key factor affecting ecological processes in aquatic ecosystems such as trophic networks.

COMPOSICIÓN Y ESTRUCTURA DE LA DIETA DE PAVO OCELADO (MELEAGRIS OCELLATA) EN UN TERRITORIO AGROFORESTAL, CAMPECHE, MÉXICO

<p><strong>Background</strong>: The Ocellated Turkey is a priority species because of its endemic status and being a strategic resource for local communities. An assessment of the state of its populations in the Yucatan Peninsula between 1980 and 2000 reports that the abundance decline is correlated with its weak dispersion capacity, habitat degradation, and availability of food resources. However, detailed information on its habitat requirements and trophic ecology is still very limited. Therefore, qualitative and quantitative information on the food resources consumed by <em>M. ocellata</em> is essential for the implementation of management strategies aimed at promoting the conservation of the species. <strong>Objective:</strong> In an agroforestry territory managed under the Mexican scheme of Units for Wildlife Conservation (UMA), the composition and structure of the Ocellated Turkey male diet were determined. <strong>Methodology:</strong> The study site corresponds to UMA Las Flores, Campeche, Mexico. It is a communally owned agroforestry territory run by Mennonite colonies whose primary economic activities are soybean, sorghum, and maize agriculture. It has an area of 9600 ha, four thousand are farmlands and the rest of forest cover. The taxonomic composition of the male diet was evaluated analyzing food content present in the upper digestive tract (crop and gizzard) of 72 samples of male birds hunted during the breeding season (January to April 2019). The Relative Importance Index was estimated to quantitatively assess the importance of each food component and the Levins Index assessed the degree of specialization in the diet. <strong>Results: </strong>According to the frequency of occurrence and abundance of the food components, we found that the male Ocellated Turkey presented a generalist and opportunistic feeding strategy; the stomach contents consisted of resources from the field crops, whose dietary composition was granivorous. Diet composition was based on the consumption of 39 vegetables belonging to 20 families of 12 orders. Of the six established food categories, the seeds registered the highest value with 94.49% of the total dry weight, being corn, sorghum, and a wild specie belonging to the Convolvulaceae family the most significant resources in the diet. <strong>Implications:</strong> Our results help to determine the importance of agroforestry systems to meet food requirements and evaluate the trophic dynamics of the Ocellated Turkey, as well as the plasticity of the species to use food resources in different scenarios in space and time throughout its distribution range. <strong>Conclusion:</strong> Information on the composition and abundance of food resources consumed by <em>M. ocellata</em> males in an agroforestry system managed under UMA's Mexican scheme is important for understanding and redefining habitat requirements and trophic niche amplitude, to implement management strategies that promote the increase of their wild populations and sustainable hunting.</p>

Individual and population dietary specialization decline in fin whales during a period of ecosystem shift

This study sought to estimate the effect of an anthropogenic and climate-driven change in prey availability on the degree of individual and population specialization of a large marine predator, the fin whale (Balaenoptera physalus). We examined skin biopsies from 99 fin whales sampled in the St. Lawrence Estuary (Canada) over a nine year period (1998–2006) during which environmental change was documented. We analyzed stable isotope ratios in skin and fatty acid signatures in blubber samples of whales, as well as in seven potential prey species, and diet was quantitatively assessed using Bayesian isotopic models. An abrupt change in fin whale dietary niche coincided with a decrease in biomass of their predominant prey, Arctic krill (Thysanoessa spp.). This dietary niche widening toward generalist diets occurred in nearly 60% of sampled individuals. The fin whale population, typically composed of specialists of either krill or lipid-rich pelagic fishes, shifted toward one composed either of krill specialists or true generalists feeding on various zooplankton and fish prey. This change likely reduced intraspecific competition. In the context of the current “Atlantification” of northern water masses, our findings emphasize the importance of considering individual-specific foraging tactics and not only population or group average responses when assessing population resilience or when implementing conservation measures.

Mosquito species associated with horses in Madagascar: a review of their vector status with regard to the epidemiology of West Nile fever.

In Madagascar, the high West Nile virus (WNV) antibody prevalence reported in horse populations suggests a high level of vector-horse contact. This study aims to characterize the mosquito species usually involved in WNV transmission in horse stables in Madagascar. Five horse stables were investigated in October and November 2016 in five distinct inland areas. Mosquitoes were collected using double net traps baited with human, poultry or horse as well as light traps. Blood meal identification from engorged females was performed using host-specific PCRs. A total of 2898 adult mosquitoes were collected with Culex (Culex) antennatus (Becker) (40.7%), and Cx. (Cux.) quinquefasciatus Say (14.9%), being the most abundant species. The mosquito abundance varied between horse stables (P < 10-7 ) and depending on the bait used in the double net traps (P < 0.003). Among the 190 tested blood meals, 119 consisted of single blood meals with 85 from horse, 17 from human, 16 from chicken, one from cattle and 71 consisted of mixed blood meals. The mosquito species collected during this study exhibited a generalist feeding behaviour allowing them to act as bridge vectors between different vertebrate hosts involved in WNV transmission cycle. Their vector status with regard to West Nile fever epidemiology is reviewed.

A review of the biology of Symphrasinae (Neuroptera: Rhachiberothidae), with the description of the egg and primary larva of Plega Navás, 1928

The mantispoid subfamily Symphrasinae is a highly specialized taxon traditionally included within Mantispidae, but recent morphological and molecular studies suggested this group belongs to the family Rhachiberothidae. Knowledge about the biology of the Symphrasinae is summarized, and all biological interactions are tabulated. Larvae of all species whose biology has been documented are ectoparasitoids of larvae and pupae of holometabolous insects. Species of Plega Navás, 1928, and apparently of Anchieta Navás, 1909 probably have a generalist feeding ecology with primary larvae actively seeking for hosts, likely with some degree of “host-searching” ability of the females. Meanwhile, species of Trichoscelia Westwood, 1852 appear to have a specialized feeding on larvae and pupae of the vespid wasps Polybia Lepeletier, 1836, as well as a complex mechanism to invade wasp nests. The egg and first larval instar of Plega are described and illustrated. The main characteristics of the genus are discussed in a comparative context of the known primary larva and egg of Mantispoidea. The genus is distinguished among other Mantispoidea by the presence of a elongate head capsule, with two anterolateral stemmata, inwardly curved mandibulo-maxillary stylets, where the mandibles are robust with serrate apex; in the labium, the postmentum is enlarged and subquadrate and the palpus is 2-segmented, although a first palpomere was probably fused to the prementum; the legs have all the podomeres differentiated as separate subunits, with setal characters providing a landmark to understand the leg morphology of Mantispa Illiger, 1798, in which a partial fusion of the tibia and tarsus has taken place.

Invasive fish keeps native feeding strategy despite high niche overlap with a congener species

Weakfish Cynoscion regalis (Bloch and Schneider, 1801) is one of the most recent invasive fish in the Iberian Peninsula (Europe). Weakfish has established in the Sado estuary (Portugal) since the early 2010s, and fishers and anglers have expressed concern about its impacts on native prize fish. However, almost a decade later, there is no information on the ecology of weakfish in the non-native area. So, we aimed to assess weakfish feeding strategy and feeding plasticity through stomach content analysis to evaluate if these factors may contribute to its invasiveness, as well as to determine the ecological overlap between weakfish and three native prize fish — European bass, white seabream, and particularly meagre (since they are taxonomically closer), through carbon and nitrogen stable isotopes. Our results demonstrate that Sado’s weakfish has a generalist feeding strategy and preys the same functional groups it targets in the native area, therefore feeding strategy may weigh on invasiveness but not feeding plasticity. Weakfish, meagre, and European bass were in the same trophic level and weakfish exhibited higher trophic overlap with meagre, suggesting that weakfish could directly impact meagre if food and habitat become limiting. This study is the first assessment about weakfish ecology in the non-native area and our findings are an excellent starting point to understand this invasion. It can also be useful for management programmes that promote weakfish consumption to minimize its impacts, alleviate fishing pressure on native species, and raise public awareness.

First report on the diet and reproductive biology of red-toothed triggerfishOdonus niger(Ruppell, 1836) from the south-eastern Arabian Sea

AbstractThe feeding habits and reproductive biology of red-toothed triggerfishOdonus niger(Ruppell, 1836) was analysed from 449 specimens collected from the Karnataka coast of the south-eastern Arabian Sea. Of the total stomachs examined, only 54 (12%) were empty and 395 contained food remains. The diet comprised crustacean remains (48.0%), zooplankton (21.4%), algae (16.5%), fish remains (6.1%) and cephalopod remains (5.3%) along with partially digested matter (2.3%) and detritus (0.4%). The species was found to be a generalist feeder and an omnivore. The overall sex ratio between males and females (1: 0.44) was significantly (P&lt; 0.05) different. Histological examination of the ovaries indicated asynchronous ovarian development in females, with males maturing earlier than females. The gonadosomatic index (GSI) patterns of males and females, and the presence of ripe ovaries and spermatozoids suggested that April–May is the peak spawning period. The absolute and relative fecundity estimates ranged from 16,464–312,420 eggs and 251–2812 eggs g−1respectively. Fecundity was positively correlated with total length and body weight. The biological information on diet composition and reproductive traits provided for the first time in this study can facilitate conservation, management and sustainable exploitation of this species in the study area.

Dung preference and trophic association of dung beetles (Coleoptera: Scarabaeidae) in the moist forests of the South-western Ghats of the Indian subcontinent

• Quantitative dung beetle-feeding trophic networks from the Western Ghats in India. • Dung-association pattern and dietary specificity at native mammalian species level. • Assemblage of few dung specialists, species with preferences and more generalists. • Low overall specialisation and low resource partitioning. • Boar dung availability: crucial for sustainability rare species. First quantitative dung beetle-feeding trophic network analysis for the Oriental region is carried out by investigating trophic network interaction between dung beetles and mammal dung types in the moist forests of the Western Ghats a global biodiversity hot spot in south-western India. Dung-beetle assemblage associated with the dung of the prominent mammals, such as the macaque, boar, gaur, elephant and deer, showed differences in richness, abundance and composition among different dung types. Most dung beetles were generalists with low resource specificity and community-wide generalist feeding on herbivore and omnivore dung types. Dung beetles in the region displayed high species richness and abundance in boar dung. The high attraction and specificity of dung beetles towards the odoriferous boar dung indicate that the omnivore mammal Sus scrofa has a major role in maintaining the dung beetle community in the forests of the Western Ghats. Network interaction analysis shows that the vast majority in the assemblage are generalist species, and the few specialist species were all with low abundance. Low overall specialisation and low resource partitioning with high species richness is recorded in the assemblage. The assemblage's trophic level preference is reflected in the high dung specificity recorded in the omnivore and herbivore dung types.

Physical adaptations of butterfly proboscises enable feeding from narrow floral tubes

Abstract Butterflies use a proboscis, a microfluidic probe engineered by natural selection, to feed on nutritive fluids. The structural configuration of proboscises relates to feeding habits; however, the adaptations that enable proboscis entry into narrow floral corollas lack experimental evidence. Here, we investigated proboscis adaptations that enable entry into corollas using funnel‐shaped glass capillary tubes and performed feeding trials with six butterfly species of different feeding habits. Proboscises were either guided (natural treatment) or forced (forced treatment) into the capillary tubes that were filled with a 20% sucrose solution. The treatments were video‐recorded to determine the depth the proboscises reached into the tube and how long they remained there. The results were interpreted in terms of proboscis morphology, friction forces and the material properties of the cuticle. In the natural treatment, butterflies classified as flower visitors were more efficient at feeding from the tubes, reaching an average 1.83× deeper into the tubes than the other species and never getting their proboscises stuck. The non‐flower‐visiting species, in contrast, had their proboscises remain in the tube 17× longer than the flower‐visiting species, with 90% of them getting their proboscises at least partially stuck. The butterfly species with generalist feeding habits fed more efficiently than the non‐flower visitors, but less than the flower visitors. A similar pattern was observed in the forced treatment. Flower‐visiting butterflies had smoother and more tapered proboscises, lower friction forces and a semi‐circular cross‐section that would reduce bendability and was augmented by a more sclerotized cuticle. Proboscises of flower‐visiting butterflies, therefore, have a suite of adaptations that operate synergistically to optimize their feeding habits. A free Plain Language Summary can be found within the Supporting Information of this article.

Specialized predation by deep-sea Solenogastres revealed by sequencing of gut contents

'Who eats whom?' is a fundamental question about the ecological roles and interactions of deep-sea organisms. However, the tools needed to analyze trophic relationships remain limited, especially with regard to studying meiofauna and small macrofauna in abyssal and hadal depths. We present results from indirect molecular analyses of the gut contents of abyssal and hadal Solenogastres (Mollusca, Aplacophora) of the Northwest Pacific. Our data revealed a high food specialization and a surprising diversity of food sources among these inconspicuous worm-shaped predators. We hypothesize that Hydrozoa forms the ancestral food source of Solenogastres, and that specialization on non-cnidarian prey (such as annelids, nemerteans, and bivalves) evolved independently along with modifications in the digestive tract. Despite being intuitively advantageous in the nutrient-limited deep sea, we found only one widespread generalist feeder (potentially associated with scavenging).

Diet composition and feeding habit of Glossogobius sparsipapillus caught from estuarine regions in the Mekong Delta

Glossogobius sparsipapillus is a potential candidate for aquaculture in the Mekong Delta, but information on its food and feeding habit is still fragmented and deficient. This study, therefore, aims to contribute diet and feeding ecology to this fish based on 661 specimens (331 males and 330 females) caught in estuarine areas from December 2019 to November 2020. Data analysis showed that fish diet composition comprised five categories such as Acetes spp., small fish, Polychaeta, Uca spp., and others (e.g., fish scales and detritus). This goby is a generalist feeder, feeding preliminarily on Acetes spp. but rarely on Polychaeta. Feeding intensity is high and does not change with sexes but varies according to fish sizes, seasons, and sites. Moreover, a similar meal size was observed in different sexes, fish sizes, seasons, and sites. The findings supply the fundamental knowledge on the food and feeding of this species, being used for artificially cultivating study.

PREDATION OF Felis catus (LINNAEUS, 1758) BY Boa constrictor amarali (STULL, 1932)

The most mammal preys of B. constrictor are median and small primates, rodents, opossums and bats. In general, predatory mammals are not part of diet of B. constrictor. Here we report the predation of Felis catus by Boa constrictor amarali. Reports of anecdotal events like this are important both to emphasize the opportunistic and generalist feeding habit of B. constrictor and their ability to live in an anthropogenic landscape.

Host Bloodmeal Source Has No Significant Effect on the Fecundity and Subsequent Larval Development Traits of the Progeny in Culicoides furens Poey (Diptera: Ceratopogonidae).

Culicoides Latreille species (Diptera: Ceratopogonidae) are insects of significant medical and veterinary importance worldwide because their bites can cause major annoyance, allergic reactions, and/or pathogen transmission to vertebrates, including humans. In this study, we examined the effect of host bloodmeal source on the fecundity and subsequent larval development traits of the progeny of Culicoides furens Poey, a nuisance species in coastal Florida. Field-collected females were fed on two different classes of hosts: birds (chicken) or mammals (human). Fecundity outcomes of the females and larval developmental traits of the progeny were recorded and compared between the two groups. The percentage of females that developed eggs, percentage of gravid females that deposited eggs, number of eggs produced per female, number of eggs deposited per female, egg hatch rates, larval survival rates, time to pupation, pupal sex-ratios, and adult eclosion rates were not significantly different between the two groups. Our results demonstrate that the host bloodmeal source has no significant effect on the fecundity and subsequent larval developmental life-history traits of the progeny in C. furens. Previous studies reported C. furens to be a generalist feeder that shows no host preference for birds or mammals. Collectively, these findings suggest that C. furens is well adapted, not just behaviorally, but also physiologically to efficiently utilize blood meals from avian and mammalian hosts, a quality that offers a major evolutionary advantage to the success of this midge species as a generalist feeder.

Diet, trophic position of upper St. Lawrence River round goby giants reveals greater dependence on dreissenids with increasing body size

Round gobies (Neogobius melanostomus) from the upper St. Lawrence River (USLR) have an abundance of some of the largest individuals recorded from the Great Lakes (>230-mm total-length). We found a distinct separation in diet and isotopic signatures (δ15N and δ13C) between round goby classified as small (≤130-mm; n = 63) and large (>130-mm total-length; n = 75) from USLR coastal bays. At small sizes, round gobies had variable diets indicative of generalist and opportunistic feeding on native and non-indigenous benthic prey. Between 100 and 130-mm total-length, signatures of assimilated carbon (δ13C) indicated a directed shift towards a dreissenid-centric diet and once larger than 130-mm total-length, round gobies appeared to feed proportionally more on dreissenid mussels. We also found that large round gobies fed proportionally more on Hydrobiidae than small round gobies. A weak negative relationship between δ15N (indicative of trophic position) and round gobies total length resulted where smaller round gobies had slightly higher δ15N values than larger conspecifics. Round gobies larger than 180-mm total-length were common in nearshore habitats (≤2-m) during the spring, and dreissenid mussels and Hydrobiidae were the most frequently encountered prey. Our results demonstrate elevated reliance on dreissenids as round goby increased body size, but the diversity of prey suggest more complex trophodynamic pathways associated with coastal bay habitats.

The diet of Indian foxes in a peri-urban area of eastern India

Urban expansions into natural habitats have forced many carnivores to adapt to the modified areas; however, our understanding of their ecology in such areas is limited. The Indian fox (Vulpes bengalensis) is a small carnivore species that can adapt and exploit urban areas due to its generalist nature, but there is a paucity of data on Indian foxes in these human-modified areas. To understand the resource requirement of Indian foxes in urban habitats, we conducted a diet analysis by examining 119 scats of Indian foxes in a peri-urban habitat of Baripada town, Odisha, eastern India. To determine the diet composition of Indian foxes, we analyzed scat contents by their frequency occurrence (%FO), the relative frequency of occurrence (%RF) and mean percent volume (%Vm). Indian foxes consumed a wide range of food categories, including arthropods, rodents, reptiles, birds, plant parts and anthropogenic resources. In %Vm, rodents showed the highest volume, followed by polythene, Spondias pinnata fruit and Coleoptera. We found anthropogenic foods in considerable quantities, including polythene and paper. The diet of Indian foxes indicates that the species has opportunistic and generalist feeding habits consisting primarily of easily accessible foods. Furthermore, management efforts should focus on the proper management of waste and control of anthropogenic food sources in urban habitats.

Metabolic and nutritional condition of juvenile tiger sharks exposed to regional differences in coastal urbanization.

How varying levels of human activity, such as proximity and size of the nearest market (i.e., market gravity), influence the nutritional ecology and physiological condition of highly migratory marine predators is poorly understood. In the present study, we used a non-lethal approach to compare the concentration of metabolic hormones (i.e. corticosteroids and thyroid hormones) and plasma fatty acids between juvenile female tiger sharks (Galeocerdo cuvier) sampled in two areas of the subtropical north Atlantic, which differed markedly in their levels of coastal urbanization, Florida and the Bahamas (high versus low, respectively). We hypothesized that juvenile female tiger sharks sampled in water surrounding high coastal urbanization (Florida), would exhibit evidence of lower prey quality and higher energetic demands as compared to individuals sampled in relatively less urbanized areas of Northern Bahamas. Results revealed that relative corticosteroid levels (a proxy for energy mobilization) were higher in juvenile female tiger sharks sampled in Florida; however, no differences were found in concentrations of thyroid hormones (proxies of energetic adjustments) between the two locations. We found higher percentages of omega-3 polyunsaturated fatty acids (indicative of high prey quality) in juvenile tiger sharks from Florida, whereas higher percentages of bacterial markers (often indicative of domestic sewage effluent) were detected in the individuals sampled in the Bahamas. Taken together, these findings do not suggest that the differences in nutritional quality and metabolic condition found between the two sampling locations can be fully attributed to foraging in areas exposed to differing levels of urbanization. We speculate that these patterns may be due to the highly migratory nature and generalist feeding strategy of this species, even at the juvenile life stage, as well as proximity of sampling locations from shore.