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Feeding Ecology (feeding + ecology)
Selected AbstractsFeeding ecology of fishes associated with Egeria spp. patches in a tropical reservoir, BrazilECOLOGY OF FRESHWATER FISH, Issue 1 2006F. M. Pelicice Abstract ,, This research characterised feeding ecology of fishes associated with patches of Egeria najas and Egeria densa, two submerged macrophytes, in Rosana Reservoir, Upper Paraná River basin, Brazil. Fishes were sampled using a 1 m2 throw trap in patches of different macrophyte biomass and in three diel periods during a wet season. Fish diet (10 species) was primarily composed of autochthonous items (zooplankton, algae and aquatic insect larvae). Almost all intra-specific diet patterns had moderate to low levels of diet similarity, indicating a high variability in diet. Some species showed no diel patterns in feeding activity, whereas others were primarily diurnal or nocturnal. No differences in feeding activity were observed among habitats of medium and high macrophyte biomasses, and species tended to feed on the same items among these habitats. The most abundant fish species demonstrated low inter-specific diet overlap and appear not to compete for food resources. We suggest that Egeria patches are feeding grounds and shelter for small-sized fish species. Resumen 1. Esta investigación caracterizó la ecología trófica de las especies de peces asociadas a manchas de Egeria najas e E. densa, dos macrofitas sub-aquaticas, en la represa de Rosana (alto Río Paraná, Brasil). Los peces fueron colectados con un throw trap de 1 m2 en manchas con distintas biomasas de macrófitas y en tres períodos del día, durante la estación lluviosa. 2. La dieta de 10 especies estuvo compuesta principalmente de componentes autóctonos (zooplancton, algas y larva de insectos acuáticos). Casi todas las especies presentaron patrones de dieta intra-específica con similitudes moderadas o bajas (elevada variabilidad). Algunas especies no mostraron ningún patrón de actividad alimenticia durante el día mientras que otras fueron principalmente diurnas o nocturnas. No se observó ninguna diferencia de actividad alimenticia entre los habitats de media y alta biomasa de macrófitas, y las especies tendieron a alimentarse de los mismos componentes entre estos habitats. 3. Las especies de peces más abundantes mostraron un solapamiento alimenticio bajo y parecen no competir por recursos alimenticios. Sugerimos que las manchas de Egeria funcionan como lugar de alimentación y abrigo para los peces de pequeño tamaño. [source] Feeding ecology and habitat of the threespine stickleback, Gasterosteus aculeatus microcephalus, in a remnant population of northwestern Baja California, MéxicoECOLOGY OF FRESHWATER FISH, Issue 4 2001S. Sánchez-Gonzáles Abstract , The feeding ecology and habitat of the threespine stickleback (Gasterosteus aculeatus microcephalus Girard, 1854) was studied from November 1996 to May 1997 in a remnant population of northwestern Baja California, México. The analysis of the stomach content of 179 individuals (25 to 56 mm standard length [SL]) showed a diet dominated by cyclopoid copepods (43.8%) and chironomid larvae (39.1%). Diet in relation to size and sex of the fish was dominated by copepods in autumn and winter and by chironomid larvae during spring. Diet overlap (Schoener's index) was significant (,60%) between fish size-classes in January, March and April and between sexes for most sampling months. The average size of prey consumed was independent of fish mouth size. The feeding strategy of the threespine stickleback shifted from opportunist in winter to specialist in spring., [source] Feeding ecology of wild migratory tunas revealed by archival tag records of visceral warmingJOURNAL OF ANIMAL ECOLOGY, Issue 6 2008Sophie Bestley Summary 1Seasonal long-distance migrations are often expected to be related to resource distribution, and foraging theory predicts that animals should spend more time in areas with relatively richer resources. Yet for highly migratory marine species, data on feeding success are difficult to obtain. We analysed the temporal feeding patterns of wild juvenile southern bluefin tuna from visceral warming patterns recorded by archival tags implanted within the body cavity. 2Data collected during 1998,2000 totalled 6221 days, with individual time series (n = 19) varying from 141 to 496 days. These data span an annual migration circuit including a coastal summer residency within Australian waters and subsequent migration into the temperate south Indian Ocean. 3Individual fish recommenced feeding between 5 and 38 days after tagging, and feeding events (n = 5194) were subsequently identified on 76·3 ± 5·8% of days giving a mean estimated daily intake of 0·75 ± 0·05 kg. 4The number of feeding events varied significantly with time of day with the greatest number occurring around dawn (58·2 ± 8·0%). Night feeding, although rare (5·7 ± 1·3%), was linked to the full moon quarter. Southern bluefin tuna foraged in ambient water temperatures ranging from 4·9 °C to 22·9 °C and depths ranging from the surface to 672 m, with different targeting strategies evident between seasons. 5No clear relationship was found between feeding success and time spent within an area. This was primarily due to high individual variability, with both positive and negative relationships observed at all spatial scales examined (grid ranges of 2 × 2° to 10 × 10°). Assuming feeding success is proportional to forage density, our data do not support the hypothesis that these predators concentrate their activity in areas of higher resource availability. 6Multiple-day fasting periods were recorded by most individuals. The majority of these (87·8%) occurred during periods of apparent residency within warmer waters (sea surface temperature > 15 °C) at the northern edge of the observed migratory range. These previously undocumented nonfeeding periods may indicate alternative motivations for residency. 7Our results demonstrate the importance of obtaining information on feeding when interpreting habitat utilization from individual animal tracks. [source] Feeding ecology of silverperch, Terapon plumbeus Kner, and the impact of fish-pens in Laguna de Bay, PhilippinesJOURNAL OF APPLIED ICHTHYOLOGY, Issue 6 2000M. Kock Summary Aquaculture is an important factor in the fishery of Laguna de Bay in the Philippines; fish-pens and net-cages covered ,10% of the lake surface in the late 1990s. The present study was carried out to assess the possible influences of aquaculture on a wild fish species, silverperch, Terapon plumbeus Kner, with a special emphasis on the feeding ecology of this fish. For the purposes of the investigation, 24-h samples were taken at 2-month intervals close to a fish-pen as well as in open water over a one-year period to acquire more information on this species. Significant differences in standard length and total weight were found between stations and sampling months. In open water, a mean standard length of 53.6 mm and a mean total weight of 4.2 g were found, whereas close to the fish-pen, the corresponding values were 57.6 mm and 5.4 g, respectively. The maximum mean standard length was attained around December 1996 and February 1997 (59.5 mm in open water; 66.1 mm close to the fish-pen), and the minimum was found in June 1996 (49.1 mm in open water; 46.2 mm close to the fish-pen). Noticeable differences were found in the food spectrum between the two sampling stations. Zooplankton, the major food source at both stations, was more important in the stomach content of fish in open water. The same was true for insects (i.e. chironomid larvae), although these did not make up such a large fraction of the diet. On the other hand, close to the fish-pen, aufwuchs- algae, phytoplankton and fish were more important. Generally, benthic organisms were consumed more frequently close to the fish-pen. Zooplankton was more important in the diet of smaller fish. In all size groups, the importance of zooplankton decreased during the rainy season. [source] Feeding ecology and growth of neonate and juvenile blacktip sharks Carcharhinus limbatus in the Timbalier,Terrebone Bay complex, LA, U.S.A.JOURNAL OF FISH BIOLOGY, Issue 3 2008K. P. Barry Stomach contents and vertebrae from neonate and juvenile blacktip sharks Carcharhinus limbatus (n= 334) were examined to describe their diet, feeding patterns and growth within the Timbalier,Terrebone Bay complex, LA, U.S.A. In the study area, both neonate and juvenile C. limbatus feed primarily on gulf menhaden Brevoortia patronus. However, based on the index of relative importance (IRI), gulf menhaden constituted a larger portion of the diet of neonates (84·05 %IRI) than for juveniles (47·91 %IRI). An increase in the index of relative fullness between the afternoon and dusk time intervals and a large decrease in the percentage of empty stomachs between the night and early morning time intervals suggested that these fish exhibited a diel feeding pattern with crepuscular periods being the times of highest feeding activity. A higher percentage of empty stomachs (neonates 68% and juveniles 39%) and a significantly lower growth rate (age 0+ year C. limbatus, 0·62 mm day,1; age 1+ year fish, 0·89 mm day,1) could indicate that neonate C. limbatus are less efficient predators than older conspecifics. [source] Feeding ecology of Xenoturbella bocki (phylum Xenoturbellida) revealed by genetic barcodingMOLECULAR ECOLOGY RESOURCES, Issue 1 2008SARAH J. BOURLAT Abstract The benthic marine worm Xenoturbella is frequently contaminated with molluscan DNA, which had earlier caused confusion resulting in a suggested bivalve relationship. In order to find the source of the contaminant, we have used molluscan sequences derived from Xenoturbella and compared them to barcodes obtained from several individuals of the nonmicroscopic molluscs sharing the same environment as Xenoturbella. Using cytochrome oxidase 1, we found the contaminating sequences to be 98% similar to the bivalve Ennucula tenuis. Using the highly variable D1,D2 region of the large ribosomal subunit in Xenoturbella, we found three distinct species of contaminating molluscs, one of which is 99% similar to the bivalve Abra nitida, one of the most abundant bivalves in the Gullmarsfjord where Xenoturbella was found, and another 99% similar to the bivalve Nucula sulcata. These data clearly show that Xenoturbella only contains molluscan DNA originating from bivalves living in the same environment, refuting former hypotheses of a bivalve relationship. In addition, these data suggest that Xenoturbella feeds specifically on bivalve prey from multiple species, possibly in the form of eggs and larvae. [source] Feeding ecology of Bornean orangutans (Pongo pygmaeus morio) in Danum Valley, Sabah, Malaysia: a 3-year record including two mast fruitingsAMERICAN JOURNAL OF PRIMATOLOGY, Issue 9 2010Tomoko Kanamori Abstract We observed the diet and activity of Bornean orangutans (Pongo pygmaeus morio) in the primary lowland dipterocarp forests of Danum Valley, Sabah, Malaysia, during 2005,2007, including two mast fruitings. We collected 1,785,hr of focal data on 26 orangutans. We identified 1,466 samples of their food plants and conducted a fallen fruit census to monitor fruit availability in the study area. Their activity budget was 47.2% feeding, 34.4% resting, and 16.9% traveling. Fruits accounted for the largest part (60.9%) of feeding time, especially during mast fruiting periods (64.0,100%), although the percentages of leaves (22.2%) and bark (12.3%) were higher than those reported for P. abelii and P. pygmaeus wurmbii. Although 119 genera and 160 plant species were consumed by focal animals, only 9 genera accounted for more than 3% of feeding time (total: 67.8% for 9 genera). In particular, the focal orangutans fed intensively on Ficus and Spatholobus during most of the study period, especially in periods of fruit shortage. The percentage of fruit feeding changed markedly from 11.7 to 100% across different months of the year, and was positively correlated with the amount of fallen fruit. When fruit feeding and availability decreased, orangutans fed primarily on leaves of Spatholobus and Ficus, and the bark of Spatholobus and dipterocarp. The percentage of time devoted to feeding during mast fruitings, when the orangutans foraged almost exclusively on fruits, was lower than during seasons when the orangutan diet included leaves and bark as well as fruits. Resting increased as feeding decreased in the late stage of each fruiting season, suggesting that the orangutans adopted an energy-minimizing strategy to survive the periods of fruit shortage by using energy stored during the fruit season. Am. J. Primatol. 72:820,840, 2010. © 2010 Wiley-Liss, Inc. [source] Feeding ecology of a group of buffy-headed marmosets (Callithrix flaviceps): fungi as a preferred resourceAMERICAN JOURNAL OF PRIMATOLOGY, Issue 6 2010Renato R. Hilário Abstract Mycophagy is a relatively rare behavior in primates and has only been recorded in five callitrichid species. Here, we present data on the feeding ecology of a free-ranging group of Callithrix flaviceps, which was studied in the Augusto Ruschi Biological Reserve, Southeastern Brazil, in 2008. In contrast with other marmosets, which are typically gummivorous, the study group was predominantly mycophagous,insectivorous, with fungi corresponding to 64.8% of total feeding records, and gum (6.1%) and fruit (3.3%) together providing only a minor part of the diet. Prey corresponded to 25.8% of the group's diet. The fungi (Mycocitrus spp.) consumed by the marmosets were found attached to the stems of Merostachys bamboo. As the animal component of the group's diet was similar to that recorded in studies of other marmosets, we propose that fungi were exploited primarily as a substitute for plant material, in particular exudates. This highly mycophagous diet may be determined by two principal factors: (1) the abundance of fungi within the study area, and (2) the avoidance of bark gouging, for which C. flaviceps may be less specialized than most other marmosets. These conclusions are supported by comparisons with other marmoset groups, which indicate an ecological specialization for mycophagy in C. flaviceps, and that the species will resort to gummivory in habitats where fungi are scarce. Am. J. Primatol. 72:515,521, 2010. © 2010 Wiley-Liss, Inc. [source] CONVERGENCE AND REMARKABLY CONSISTENT CONSTRAINT IN THE EVOLUTION OF CARNIVORE SKULL SHAPEEVOLUTION, Issue 5 2007Stephen Wroe Phenotypic similarities between distantly related marsupials and placentals are commonly presented as examples of convergence and support for the role of adaptive evolution in shaping morphological and ecological diversity. Here we compare skull shape in a wide range of carnivoran placentals (Carnivora) and nonherbivorous marsupials using a three-dimensional (3-D) geometric morphometric approach. Morphological and ecological diversity among extant carnivorans is considerably greater than is evident in the marsupial order Dasyuromorphia with which they have most commonly been compared. To examine convergence across a wider, but broadly comparable range of feeding ecologies, a dataset inclusive of nondasyuromorphian marsupials and extinct taxa representing morphotypes no longer present was assembled. We found support for the adaptive paradigm, with correlations between morphology, feeding behavior, and bite force, although skull shape better predicted feeding ecology in the phylogenetically diverse marsupial sample than in carnivorans. However, we also show that remarkably consistent but differing constraints have influenced the evolution of cranial shape in both groups. These differences between carnivorans and marsupials, which correlate with brain size and bite force, are maintained across the full gamut of morphologies and feeding categories, from small insectivores and omnivores to large meat-specialists. [source] Explaining isotope trophic-step fractionation: why herbivorous fish are differentFUNCTIONAL ECOLOGY, Issue 6 2007A. C. MILL Summary 1An assumed constant trophic fractionation of 15N/14N between consumer and diet (usually 3·4 for diet,muscle tissue differences) allows inferences to be made about feeding interactions and trophic level in food web studies. However, considerable variability surrounds this constant, which may conceal subtle differences about the trophodynamics of consumers. 2The feeding ecologies of herbivores and carnivores differ in terms of diet quality (in C : N terms) and food processing mechanisms, which may affect fractionation. 3We present a new model that explores how consumer feeding rates, excretion rates and diet quality determine the 15N/14N ratios in the consumer's tissues and hence influence the magnitude of trophic fractionation. 4Three herbivorous reef fish Acanthurus sohal, Zebrasoma xanthurum and Pomacentrus arabicus were chosen as study organisms. Empirical estimates of diet,tissue stable isotope fractionation were made in the field, and model parameters were derived from feeding observations and literature data. 5The trophic fractionation values of A. sohal, Z. xanthurum and P. arabicus were 4·69, 4·47 and 5·25, respectively, by empirical measurement, and 4·41, 4·30 and 5·68, respectively, by model, indicating that herbivores have a higher trophic fractionation than the currently accepted value of 3·4. 6The model was most sensitive to the excretion rate, which may differ between herbivores and carnivorous animals. This model is the first to determine stable isotope signatures of a consumer's diet mixture without applying a constant fractionation value. [source] Origins of diverse feeding ecologies within Conus, a genus of venomous marine gastropodsBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2001THOMAS F. DUDA JR Specialized predators on polychaetes, fishes, hemichordates or other molluscs, members of the predominantly tropical gastropod genus Conus diversified rapidly during the Miocene to constitute the most species-rich modern marine genus. We used DNA sequence data from mitochondrial and nuclear loci of 76 Conus species to generate species-level phylogenetic hypotheses for this genus and then mapped known diets onto the phylogenies to elucidate the origins and evolutionary histories of different feeding specializations. The results indicate that dramatically new feeding modes arose only a few times, that the most derived feeding modes likely arose in the Miocene, and that much of the known diversity of Conus that was generated during Miocene radiations has survived to the present. [source] Feeding ecology of fishes associated with Egeria spp. patches in a tropical reservoir, BrazilECOLOGY OF FRESHWATER FISH, Issue 1 2006F. M. Pelicice Abstract ,, This research characterised feeding ecology of fishes associated with patches of Egeria najas and Egeria densa, two submerged macrophytes, in Rosana Reservoir, Upper Paraná River basin, Brazil. Fishes were sampled using a 1 m2 throw trap in patches of different macrophyte biomass and in three diel periods during a wet season. Fish diet (10 species) was primarily composed of autochthonous items (zooplankton, algae and aquatic insect larvae). Almost all intra-specific diet patterns had moderate to low levels of diet similarity, indicating a high variability in diet. Some species showed no diel patterns in feeding activity, whereas others were primarily diurnal or nocturnal. No differences in feeding activity were observed among habitats of medium and high macrophyte biomasses, and species tended to feed on the same items among these habitats. The most abundant fish species demonstrated low inter-specific diet overlap and appear not to compete for food resources. We suggest that Egeria patches are feeding grounds and shelter for small-sized fish species. Resumen 1. Esta investigación caracterizó la ecología trófica de las especies de peces asociadas a manchas de Egeria najas e E. densa, dos macrofitas sub-aquaticas, en la represa de Rosana (alto Río Paraná, Brasil). Los peces fueron colectados con un throw trap de 1 m2 en manchas con distintas biomasas de macrófitas y en tres períodos del día, durante la estación lluviosa. 2. La dieta de 10 especies estuvo compuesta principalmente de componentes autóctonos (zooplancton, algas y larva de insectos acuáticos). Casi todas las especies presentaron patrones de dieta intra-específica con similitudes moderadas o bajas (elevada variabilidad). Algunas especies no mostraron ningún patrón de actividad alimenticia durante el día mientras que otras fueron principalmente diurnas o nocturnas. No se observó ninguna diferencia de actividad alimenticia entre los habitats de media y alta biomasa de macrófitas, y las especies tendieron a alimentarse de los mismos componentes entre estos habitats. 3. Las especies de peces más abundantes mostraron un solapamiento alimenticio bajo y parecen no competir por recursos alimenticios. Sugerimos que las manchas de Egeria funcionan como lugar de alimentación y abrigo para los peces de pequeño tamaño. [source] Influence of feeding ecology on blood mercury concentrations in four species of turtlesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2007Christine M. Bergeron Abstract Mercury is a relatively well-studied pollutant because of its global distribution, toxicity, and ability to bioaccumulate and biomagnify in food webs; however, little is known about bioaccumulation and toxicity of Hg in turtles. Total Hg (THg) concentrations in blood were determined for 552 turtles representing four different species (Chelydra serpentina, Sternotherus odoratus, Chrysemys picta, and Pseudemys rubriventris) from a Hg-contaminated site on the South River (VA, USA) and upstream reference sites. Methylmercury and Se concentrations also were determined in a subset of samples. Because the feeding ecology of these species differs drastically, stable isotopes of carbon (,13C) and nitrogen (,15N) were employed to infer the relationship between relative trophic position and Hg concentrations. Significant differences were found among sites and species, suggesting that blood can be used as a bioindicator of Hg exposure in turtles. We found differences in THg concentrations in turtles from the contaminated site that were consistent with their known feeding ecology: C. serpentina , S. odoratus > C. picta > P. rubriventris. This trend was generally supported by the isotope data, which suggested that individual turtles were feeding at more than one trophic level. Methylmercury followed similar spatial patterns as THg and was the predominant Hg species in blood for all turtles. Blood Se concentrations were low in the system, but a marginally positive relationship was found between THg and Se when species were pooled. The blood THg concentrations for the turtles in the present study are some of the highest reported in reptiles, necessitating further studies to investigate potential adverse effects of these high concentrations. [source] CONVERGENCE AND REMARKABLY CONSISTENT CONSTRAINT IN THE EVOLUTION OF CARNIVORE SKULL SHAPEEVOLUTION, Issue 5 2007Stephen Wroe Phenotypic similarities between distantly related marsupials and placentals are commonly presented as examples of convergence and support for the role of adaptive evolution in shaping morphological and ecological diversity. Here we compare skull shape in a wide range of carnivoran placentals (Carnivora) and nonherbivorous marsupials using a three-dimensional (3-D) geometric morphometric approach. Morphological and ecological diversity among extant carnivorans is considerably greater than is evident in the marsupial order Dasyuromorphia with which they have most commonly been compared. To examine convergence across a wider, but broadly comparable range of feeding ecologies, a dataset inclusive of nondasyuromorphian marsupials and extinct taxa representing morphotypes no longer present was assembled. We found support for the adaptive paradigm, with correlations between morphology, feeding behavior, and bite force, although skull shape better predicted feeding ecology in the phylogenetically diverse marsupial sample than in carnivorans. However, we also show that remarkably consistent but differing constraints have influenced the evolution of cranial shape in both groups. These differences between carnivorans and marsupials, which correlate with brain size and bite force, are maintained across the full gamut of morphologies and feeding categories, from small insectivores and omnivores to large meat-specialists. [source] Temperature-sensing telemetry , possibilities for assessing the feeding ecology of marine mammals and their potential impacts on returning salmonid populationsFISHERIES MANAGEMENT & ECOLOGY, Issue 5-6 2008B. BENDALL Abstract, Adult salmonids returning to the River Tees (north-east England) tagged with temperature-sensing acoustic transmitters provided some unexpected and novel information on the possible impact of seal predation at a tidal barrage 16 km from the sea. Predation events of tagged fish by seals were inferred by an increase in the temperature transmitted by the acoustic tags. Subsequent events of feeding or drinking by the seals were also inferred from further changes in temperature recorded by tags whilst in their stomachs. Rates of inferred predation on tagged individuals were high (47%). This is the first time that temperature-sensing transmitters deployed inside wild salmonids have revealed instances of predation by, and subsequent feeding ecology of, marine mammals. The results are discussed in relation to the use of such technology in future studies attempting to address the interactions between marine mammals and their fish prey species. [source] Combined measurements of egg fatty acids and stable isotopes as indicators of feeding ecology in lake-dwelling birdsFRESHWATER BIOLOGY, Issue 9 2009FRANCISCO RAMÍREZ Summary 1.,We examined whether egg fatty acid (FA) profiles and stable isotopes (SIA) could be used in a comparative way to infer the diet of two aquatic bird species with contrasting feeding habits: a surface forager, the pheasant-tailed jacana (Hydrophasianus chirurgus), and a pursuit-diving forager, the little cormorant (Phalacrocorax niger), at Haleji Lake (Pakistan). 2.,The species differed markedly in the overall percentage of saturated and polyunsaturated fatty acids. Moreover, among jacanas, two groups of birds had relatively high or low concentrations of long-chain essential PUFAs (such as 18:2 n-6 and 20:4 n-6), suggesting differing contributions from animal prey and plant material. 3.,These trophic differences were corroborated by ,15N values which indicated both a higher trophic position in cormorants relative to jacanas, and differences in trophic position for the two groups of jacanas. In this latter species ,13C values in both groups also pointed to differing diets, involving mainly grazing plants or a contribution from animal resources (aquatic invertebrates or insects). 4.,Both lower values of ,13C and higher percentages of 18:1 n-7 detected in little cormorants may indicate the influence of the anoxic water, typical of a freshwater system densely covered by macrophytes. 5.,These results indicate how both biomarkers offer complementary information in studies of feeding ecology, refining interpretations of trophic pathways which are usually based on FA or SIA alone. Comparisons of FA profiles and SIA among species also proved to be a reliable approach for inferring the diet of species for which information is scarce or contradictory, as is the case for the pheasant-tailed jacana. [source] Leaf Quality of Some Tropical and Temperate Tree Species as Food Resource for Stream ShreddersINTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 1 2010Manuel A. S. Graça Abstract We tested the hypotheses that (1) plant defenses against consumers increase in the tropics, and that these differences in quality are perceived by detritivores; and (2) microbial conditioning of leaf litter is important for the feeding ecology of shredders from both geographical regions. We compared quality parameters of 8 tree species from Portugal and 8 from Venezuela. The tropical leaves were tougher, but did not differ from temperate leaves in terms of N, C: N, and polyphenols. In multiple-choice experiments, shredders from Portugal (Sericostoma vittatum and Chaetopteryx lusitanica) and from Venezuela (Nectopsyche argentata and Phylloicus priapulus) discriminated among conditioned leaves, preferentially consuming softer leaves. In another set of experiments, all shredders preferentially fed on conditioned rather than unconditioned leaves, grew faster when fed conditioned than unconditioned leaves and fed more on temperate than tropical leaves. We conclude that leaf litter from the tropics is a low-quality resource compared to leaves in temperate systems, because of differences in toughness, and that tropical shredders benefit from microbial colonization, as previously demonstrated for temperate systems. We suggest that leaf toughness could be one explanation for the reported paucity of shredders in some tropical streams. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The complexity of formulating diets for zoo animals: a matrixINTERNATIONAL ZOO YEARBOOK, Issue 1 2005S. Crissey The nutrition matrix presented here identifies a variety of factors that need to be considered when formulating diets for wild animals in captivity. The matrix is designed to be adapted so that it can be customized as required. Food consumption, nutritional requirements, health status and management constraints and opportunities are the four main categories to focus on when developing diets. Each of these categories may, in turn, be affected by other factors. (1) Food consumption is affected by the diet offered, client (zoo animal manager, keeper or veterinarian) wishes and animal preferences. (2) Nutritional requirements are defined by known species requirements and National Research Council recommendations, morphology and feeding ecology. Nutritional requirements may also be influenced by season, life-stage, activity, health status, stress and body temperature. (3) Health status can be affected by nutritional deficiencies or toxicities in the diet offered. Certain health conditions may require specific dietary input. (4) Animal-management protocols, such as housing, breeding opportunities and environment, are affected by other animals, food storage and preparation capacity, and feeding regime, which, in turn, can be affected by training, exercise and enrichment. [source] Feeding habits and trophic morphology of inshore lizardfish (Synodus foetens) on the central continental shelf off Veracruz, Gulf of MexicoJOURNAL OF APPLIED ICHTHYOLOGY, Issue 6 2005V. H. Cruz-Escalona Summary The inshore lizardfish, Synodus foetens, is one of the most common coastal demersal predators on the continental shelf of the Gulf of Mexico (GOM), but the biology and feeding ecology of this species is virtually unknown. Between November 2001 and January 2003 (10 collections), 603 individuals of S. foetens ranging from 112 to 420 mm standard length (SL) and 13 to 630 g (wet weight) were collected from the continental shelf of Alvarado, Veracruz, Mexico. About 60% of the individuals had empty stomachs with the stomach fullness of the remaining individuals being distributed as follows: 5% full (24.8%), 50,75% full (13.5%), and completely full (1.7%). The mean (± SD) wet weight of stomach contents was 12.1 ± 10.8 g during the rainy season, and 19.0 ± 13.0 g during the nortes season. Seventeen prey items were identified, with the majority thereof being fish. The most important prey items were Upeneus parvus, Loligo pealei, Engyophrys senta, Trachurus lathami, and Anchoa hepsetus. Seasonal changes in the diet were observed, with U. parvus and L. pealei being the most important prey during the nortes season, whereas E. senta and L. pealei were the main items during the rainy season. Prey size selection was evident among size classes of S. foetens, although no trophic overlap was observed among size classes (Cik , 0.004). High trophic level values were determined for all size classes by season (rainy season = 4.67, nortes season = 4.84), and indicated this species belongs to the piscivorous trophic guild that preys upon both demersal and pelagic species. [source] Feeding ecology of silverperch, Terapon plumbeus Kner, and the impact of fish-pens in Laguna de Bay, PhilippinesJOURNAL OF APPLIED ICHTHYOLOGY, Issue 6 2000M. Kock Summary Aquaculture is an important factor in the fishery of Laguna de Bay in the Philippines; fish-pens and net-cages covered ,10% of the lake surface in the late 1990s. The present study was carried out to assess the possible influences of aquaculture on a wild fish species, silverperch, Terapon plumbeus Kner, with a special emphasis on the feeding ecology of this fish. For the purposes of the investigation, 24-h samples were taken at 2-month intervals close to a fish-pen as well as in open water over a one-year period to acquire more information on this species. Significant differences in standard length and total weight were found between stations and sampling months. In open water, a mean standard length of 53.6 mm and a mean total weight of 4.2 g were found, whereas close to the fish-pen, the corresponding values were 57.6 mm and 5.4 g, respectively. The maximum mean standard length was attained around December 1996 and February 1997 (59.5 mm in open water; 66.1 mm close to the fish-pen), and the minimum was found in June 1996 (49.1 mm in open water; 46.2 mm close to the fish-pen). Noticeable differences were found in the food spectrum between the two sampling stations. Zooplankton, the major food source at both stations, was more important in the stomach content of fish in open water. The same was true for insects (i.e. chironomid larvae), although these did not make up such a large fraction of the diet. On the other hand, close to the fish-pen, aufwuchs- algae, phytoplankton and fish were more important. Generally, benthic organisms were consumed more frequently close to the fish-pen. Zooplankton was more important in the diet of smaller fish. In all size groups, the importance of zooplankton decreased during the rainy season. [source] High individual repeatability and population differentiation in stable isotope ratios in winter-grown collared flycatcher Ficedula albicollis feathersJOURNAL OF AVIAN BIOLOGY, Issue 2 2009Mårten B. Hjernquist For migrants, we often lack complete information of their spatial distribution year round. Here, we used stable carbon, nitrogen and hydrogen isotope ratios extracted from feathers grown at the wintering sites of the long-distance migratory collared flycatcher Ficedula albicollis, to study how individuals from different breeding populations are distributed at the wintering sites. A sub-sample of birds was also sampled in two consecutive years to test for the repeatability of isotope ratios. Birds from the same breeding populations had more similar isotope ratios compared to birds from other nearby populations (10,100 km apart). Furthermore, isotope repeatability within individuals was high, implying that the observed pattern of isotope variation is consistent between years. We put forward two hypotheses for these patterns; 1) strong wintering site philopatry and migratory connectivity, suggesting that migratory connectivity may potentially be found on a much smaller spatial scale than previously considered, and 2) consistent interpopulation differentiation of feeding ecology at their wintering site. [source] Large-scale spatio-temporal shifts in the diet of a predator mediated by an emerging infectious disease of its main preyJOURNAL OF BIOGEOGRAPHY, Issue 8 2009Marcos Moleón Abstract Aim, To explore the influence of an emerging infectious disease (EID) affecting a prey species on the spatial patterns and temporal shifts in the diet of a predator over a large geographical scale. We reviewed studies on the diet of Bonelli's eagles (Hieraaetus fasciatus) in order to determine the repercussions of the reduction in the density of its main prey, the rabbit (Oryctolagus cuniculus), caused by outbreaks of rabbit haemorrhagic disease (RHD) since 1988. Location, Western continental Europe. Methods, We compiled published and unpublished information on the diet of breeding Bonelli's eagles from Portugal, Spain and France for a 39-year study period (1968,2006). Nonparametric tests were used in order to analyse temporal shifts in diet composition and trophic diversity (H,) between the periods of ,high' (before outbreak of RHD) and ,low' rabbit density (after outbreak of RHD). A combination of hierarchical agglomerative clustering and non-metric multidimensional scaling (NMDS) analyses were used to test for the existence of geographical patterns in the diet of Bonelli's eagles in each period. Results, The diet of the Bonelli's eagle consisted of rabbit (28.5%), pigeons (24.0%), partridges (15.3%), ,other birds' (11.6%), ,other mammals' (7.1%), corvids (7.0%), and herptiles (6.4%). However, RHD had large consequences for its feeding ecology: the consumption of rabbits decreased by one-third after the outbreak of RHD. Conversely, trophic diversity (H,) increased after outbreak of RHD. At the same time, the analyses showed clear geographical patterns in the diet of the Bonelli's eagle before, but not after, RHD outbreak. Main conclusions, Geographical patterns in the diet of the Bonelli's eagle in western Europe seem to be driven mainly by spatio-temporal variation in the abundance of rabbits and, to a lesser extent, by the local (territorial) environmental features conditioning the presence and density of alternative prey species. We show that an EID can disrupt predator,prey relationships at large spatial and temporal scales through a severe decline in the population of the main prey species. Hence we argue that strict guidelines should be drawn up to prevent human-aided dissemination of ,pathogen pollution', which can threaten wildlife not only at the population and species level but also at the community and ecosystem scale. [source] Trophic diversity of the otter (Lutra lutra L.) in temperate and Mediterranean freshwater habitatsJOURNAL OF BIOGEOGRAPHY, Issue 5 2003Miguel Clavero Abstract Aim To analyse the geographical patterns in the composition and diversity of otter's (Lutra lutra L.) diet and their relationship with climatic characteristics. Location European freshwater habitats under Mediterranean and temperate climatic regimes. Methods Thirty-seven otter diet studies were reviewed, twenty-one from temperate and sixteen from Mediterranean areas. All studies were based on spraint analysis and their results expressed as relative frequency of occurrence of seven main prey categories. Principal Component Analysis was performed to extract the main gradients of diet composition. Pearson's correlation and t -tests were used to assess the relationship between diet characteristics (composition, diversity and taxonomic richness) and geographical and climatic variables. Results A clear latitudinal gradient in diet composition was observed. Otter diet was more diverse and featured more prey classes in southern localities, while the species was more piscivorous towards the north, where it predated upon a higher number of fish families. This pattern was similar when temperate and Mediterranean localities of Europe were compared. Mediterranean otters behaved as more generalist predators than temperate ones, relying less on fish, and more on aquatic invertebrates and reptiles. Main conclusions Geographical differences in otter feeding ecology in Europe seem to be related with the two contrasted climatic conditions affecting prey populations. The otter can act as a highly specialized piscivorous predator in temperate freshwater ecosystems, which do not suffer a dry season and have a comparatively stable water regime compared to Mediterranean ones. However, the unpredictable prey availability in Mediterranean areas, affected by strong spatial and temporal water shortages, favours a diversification of the otter's diet. [source] Spatial and temporal habitat use of kob antelopes (Kobus kob kob, Erxleben 1777) in the Comoé National Park, Ivory Coast as revealed by radio trackingAFRICAN JOURNAL OF ECOLOGY, Issue 3 2001Frauke Fischer Abstract Spatial and temporal habitat use of kob antelopes (Kobus kob kob) have been investigated in the Comoé National Park (Ivory Coast, West Africa) by use of radio telemetry. A total of 23 kob were equipped with radio collars and radio tracked for up to 15 months. Home ranges of males were smaller and those of females larger than expected from theoretical models. Adult males used smaller areas than adult females and did not show seasonal home range shifts. Daily distances travelled did not differ between sexes. Kob walked less during the night than by day and covered shorter distances in the wet season. Whereas an increase in home range overlap between females resulted in higher rates of association among individuals, association of adults of mixed sexes was not correlated with the degree of home range overlap. Territorial behaviour of males and predator avoidance by females are suggested to explain the sex-specific differences in home range size of adults and the deviation from the predicted sizes. Predator avoidance is presumed as the main reason for the reduced walking distances at night as well as in the wet season. Reproductive behaviour and feeding ecology are assumed to determine the degree of association of conspecifics. Résumé On a étudié par radio-télémétrie l'utilisation spatiale et temporelle de l'habitat par les cobes (Kobus kob kob) au Parc National de Comoé (en Côte d'Ivoire, Afrique de l'Ouest). On a équipé un total de 23 cobes de colliers radio et on les a suivis pendant 15 mois (pour certains). L'espace vital des mâles était plus petit et celui des femelles plus grand que ce à quoi on s'attendait d'après les modèles théoriques. Les mâles adultes couvraient une zone plus réduite que les femelles adultes et ne déplaçaient pas leur espace vital en fonction des saisons. Les distances parcourues chaque jour étaient les mêmes pour les deux sexes. Les cobes se déplaçaient moins la nuit que le jour, et couvraient de plus courtes distances pendant la saison des pluies. Alors qu'une augmentation du recouvrement entre espaces vitaux des femelles aboutissait à un taux supérieur d'associations entre individus, l'association d'adultes des deux sexes n'était pas liée au taux de recouvrement des espaces vitaux. On suggère que le comportement territorial des mâles et l'évitement des prédateurs par les femelles pourraient expliquer les différences, spécifiques au sexe, de la dimension de l'espace vital des adultes et la déviation par rapport aux dimensions prévues. On suppose que l'évitement des prédateurs est la raison principale de la limitation des déplacements de nuit ainsi qu'en saison des pluies. On suppose que le comportement reproducteur et l'écologie alimentaire déterminent le degré d'association entre membres de la même espèce. [source] Nests, vocalizations, and conservation status of endangered Cochabamba Mountain-Finches (Compsospiza garleppi)JOURNAL OF FIELD ORNITHOLOGY, Issue 3 2009Noemí Esther Huanca ABSTRACT Cochabamba Mountain-Finches (Compsospiza garleppi) are endangered residents of semihumid shrublands in the high Andes, with a range restricted to a few high valleys surrounding the city of Cochabamba, Bolivia. We examined the breeding behavior, feeding ecology, habitat requirements, vocalizations, and conservation status of Cochabamba Mountain-Finches from November 2006 to April 2007. We observed 10 nests of eight pairs, with nests found in a variety of small woody shrubs as well as bunchgrass and a ground bromeliad. Clutches (N= 2) consisted of one or two eggs, and all broods (N= 4) included one or two young. Our observations suggest that Cochabamba Mountain-Finches are not Polylepis specialists as previously thought, and use a diversity of native shrubs often associated with Polylepis woodlands for foraging and nesting. Pairs inhabited modified habitats where native vegetation and woodland edge persisted, but were not observed in closed canopy woodlands. Cochabamba Mountain-Finches frequently foraged on the edges of potato fields in a rural community and, at least occasionally, consumed parts of unearthed tubers. We recorded two previously unknown song types and three types of calls, and one song type was found to be useful for playback surveys. We recommend that future research and conservation actions include thorough surveys using playback to determine population sizes, and that habitat restoration projects focus on maintaining a diversity of native shrubs rather than only Polylepis trees. SINOPSIS Compsospiza garleppi es una especie residente en peligro de las tierras arbustivas semihúmedas de los altos Andes, con un rango restringido a unos pocos valles en los alrededores de la ciudad de Cochabamba, Bolivia. Nosotros examinamos el comportamiento reproductivo, la ecología alimentaria, los requerimientos de hábitat, vocalizaciones y estado de conservación de Compsospiza garleppi desde Noviembre 2006 hasta Abril 2007. Observamos 10 nidos de ocho parejas, los nidos fueron encontrados en una variedad de pequeños arbustos al igual que en montones de pastos y bromelias de suelo. La nidadas (N= 2) consistieron de uno o dos huevos y uno o dos polluelos (N= 4). Nuestras observaciones sugieren que Compsospiza garleppi no es un especialista de Polylepis como se había pensado anteriormente, y usa una diversidad de arbustos nativos asociados con bosques de Polylepis para buscar alimento y anidar. Se encontraron parejas en hábitat modificado en donde la vegetación nativa y los bordes de bosque persistieron, pero no fueron observadas en bosques con un dosel cerrado. Compsospiza garlepp busco alimento frecuentemente en los bordes de plantaciones de papa en una comunidad rural y, ocasionalmente, consumió partes de tubérculos desenterrados. Nosotros grabamos dos cantos no descritos anteriormente y tres tipos de llamados, un tipo de los cantos fue beneficioso para estudios de playback. Nosotros recomendamos que futuros estudios y acciones de conservación usen playback como herramienta para realizar censos minuciosos para determinar tamaños poblacionales, y que proyectos de restauración de hábitat se enfoquen en el mantenimiento de la diversidad de arbustos nativos en vez de únicamente mantener árboles de Polylepis. [source] Effects of environmental variables on fish feeding ecology: implications for the performance of baited fishing gear and stock assessmentJOURNAL OF FISH BIOLOGY, Issue 6 2004A. W. Stoner The effectiveness of baited fishing gear ultimately depends upon behaviour of the target species , activity rhythms, feeding motivation, and sensory and locomotory abilities. While any environmental parameter that mediates feeding or locomotion can have an important influence on the active space presented by the bait and fish catchability, few biologists have considered how such variation in behaviour might affect catch per unit effort (CPUE) and the resultant stock abundance estimates or population parameters. This review reveals that environment-related variation in feeding behaviour can act through four different mechanisms: metabolic processes, sensory limitations, social interactions and direct impacts. Water temperature, light level, current velocity and ambient prey density are likely to have largest effects on fish catchability, potentially affecting variation in CPUE by a factor of ten. Feeding behaviour is also density-dependent, with both positive and negative effects. Over time and geographic space a target species can occupy wide ranges of environmental conditions, and in certain cases, spatial and temporal variation in feeding biology could have a larger impact on CPUE than patterns of abundance. Temperature, light and current can be measured with relative facility and corrections to stock assessment models are feasible. Making corrections for biological variables such as prey density and bait competitors will be more difficult because the measurements are often not practical and relationships to feeding catchability are more complex and poorly understood. There is a critical need for greater understanding of how environmental variables affect feeding-related performance of baited fishing gear. A combination of field observations and laboratory experiments will be necessary to parameterize stock assessment models that are improved to accommodate variation in fish behaviour. Otherwise, survey data could reveal more about variation in behaviour than abundance trends. [source] Development of feeding structures in larval fish with different life histories: winter flounder and Atlantic codJOURNAL OF FISH BIOLOGY, Issue 4 2001I. Hunt von Herbing The size at which feeding structures developed and shifts in head proportions occurred, differed between Atlantic cod Gadus morhua and winter flounder Pseudopleuronectes americanus. The sequence and timing of the development of feeding structures may not be dependent on size, but may occur because they are necessary to meet specific requirements offish larvae feeding in the plankton. In early larval stages development of feeding structures was similar in number and type and was necessary for first-feeding in both species. In later stages, significant differences between species occurred in the timing of the development of feeding structures. In cod differentiation of new structures and changes in head proportions occurred at about two-thirds of the way through larval life, which coincided with an increase in growth. In flounder changes in feeding morphology did not occur during the symmetrical larval stage, but occurred only after metamorphosis to the asymmetrical demersal juvenile stage. Differences between cod and flounder in the size at which feeding structures develop may reflect life history adaptations expressed in the duration of the pelagic larval stage, as well as differences in juvenile habitat and feeding ecology. [source] Comparative morphology of stingray lateral line canal and electrosensory systemsJOURNAL OF MORPHOLOGY, Issue 11 2008Laura K. JordanArticle first published online: 24 JUL 200 Abstract Elasmobranchs (sharks, skates, and rays) possess a variety of sensory systems including the mechanosensory lateral line and electrosensory systems, which are particularly complex with high levels of interspecific variation in batoids (skates and rays). Rays have dorsoventrally compressed, laterally expanded bodies that prevent them from seeing their mouths and more often than not, their prey. This study uses quantitative image analysis techniques to identify, quantify, and compare structural differences that may have functional consequences in the detection capabilities of three Eastern Pacific stingray species. The benthic round stingray, Urobatis halleri, pelagic stingray, Pteroplatytrygon (Dasyatis) violacea, and benthopelagic bat ray, Myliobatis californica, show significant differences in sensory morphology. Ventral lateral line canals correlate with feeding ecology and differ primarily in the proportion of pored and nonpored canals and the degree of branching complexity. Urobatis halleri shows a high proportion of nonpored canals, while P. violacea has an intermediate proportion of pored and nonpored canals with almost no secondary branching of pored canals. In contrast, M. californica has extensive and highly branched pored ventral lateral line canals that extended laterally toward the wing tips on the anterior edge of the pectoral fins. Electrosensory morphology correlates with feeding habitat and prey mobility; benthic feeders U. halleri and M. californica, have greater electrosensory pore numbers and densities than P. violacea. The percentage of the wing surface covered by these sensory systems appears to be inversely related to swimming style. These methods can be applied to a broader range of species to enable further discussion of the relationship of phylogeny, ecology, and morphology, while the results provide testable predictions of detection capabilities. J. Morphol., 2008. © 2008 Wiley-Liss, Inc. [source] Management of the Nile tilapia (Oreochromis niloticus (L.)) fishery in the Kenyan portion of Lake Victoria, in light of changes in its life history and ecologyLAKES & RESERVOIRS: RESEARCH AND MANAGEMENT, Issue 2 2008M. Njiru Abstract This study reports on the population parameters, catch distribution and feeding ecology of Nile tilapia (Oreochromis niloticus) from bottom trawls and commercial catches obtained in the Kenyan portion of Lake Victoria during 1997,2006. The population parameters were analysed using the FAO-ICLARM stock assessment tool (FISAT). The fish biomass and the food ingested by the fish were estimated using the swept area and point methods, respectively. Immature fish comprised ,70% of the total fish population. The asymptotic length, maximum weight, maximum age, exploitation rate (E) and length at 50% maturity of Nile tilapia have decreased, whereas the growth curvature and fishing mortality have increased. The commercial catches increased from 13.93 t in 1997, to 23.70 t in 1999, decreasing thereafter to 18.73 t in 2005. The bottom trawl catches increased from 46.90 kg ha,1 in 1997, to 401.48 kg ha,1 in 2000, decreasing thereafter to 15.57 kg ha,1 in 2006. The major food items ingested by the fish were algae, insects and other fish. Population parameters, and the catch and diet of O. niloticus, have changed over the years in Lake Victoria. The population characteristics suggest a population under stress, attributable to intense catch exploitation. Even under intense exploitation (E = 0.68), however, the mature fish constituted ,30% of the population. The commercial catches are still high, indicating a very resilient fishery. Nevertheless, despite this resilience, the future of Oreochromis fishery is threatened by increased fishing capacity in the lake, and there is need to re-evaluate the effectiveness of current fishery management measures, with the goal of possibly adopting new measures. Enactment of new fishery policies also should provide for co-management to enhance the management process. Furthermore, there is a need to reduce fishing capacity and illegal fishing methods, and to seek alternative livelihoods for lake fishers and other stakeholders. [source] Indentation as a technique to assess the mechanical properties of fallback foodsAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 4 2009Peter W. Lucas Abstract A number of living primates feed part-year on seemingly hard food objects as a fallback. We ask here how hardness can be quantified and how this can help understand primate feeding ecology. We report a simple indentation methodology for quantifying hardness, elastic modulus, and toughness in the sense that materials scientists would define them. Suggested categories of fallback foods,nuts, seeds, and root vegetables,were tested, with accuracy checked on standard materials with known properties by the same means. Results were generally consistent, but the moduli of root vegetables were overestimated here. All these properties are important components of what fieldworkers mean by hardness and help understand how food properties influence primate behavior. Hardness sensu stricto determines whether foods leave permanent marks on tooth tissues when they are bitten on. The force at which a food plastically deforms can be estimated from hardness and modulus. When fallback foods are bilayered, consisting of a nutritious core protected by a hard outer coat, it is possible to predict their failure force from the toughness and modulus of the outer coat, and the modulus of the enclosed core. These forces can be high and bite forces may be maximized in fallback food consumption. Expanding the context, the same equation for the failure force for a bilayered solid can be applied to teeth. This analysis predicts that blunt cusps and thick enamel will indeed help to sustain the integrity of teeth against contacts with these foods up to high loads. Am J Phys Anthropol 140:643,652, 2009. © 2009 Wiley-Liss, Inc. [source] | ||||||||||||||||||||||||||||