Different Types Of Prey Research Articles

The effect of abiotic and biotic factors on the importance of macroplankton in the diet of Northeast Arctic cod in recent years

AbstractUsing cod feeding data, this paper considers the distribution and abundance of macroplankton from different ecological groups (euphausiids and hyperiids) and the variability in their consumption by cod over a period of years during which different water mass temperatures were observed. These years were also characterized by variable abundance of capelin, cod's main food source. Differences in intensity and duration of cod consumption of euphausiids and hyperiids species are shown, depending on their abundance, temperature conditions, cod distribution, and the supply of capelin for cod. This paper discusses the energetics of consuming different types of prey and the role euphausiids play in the energy balance of cod. The low fat content of cod is sometimes associated with feeding on postspawning euphausiids in summer and autumn.

TEMPORAL PATTERNS IN THE DIET AND FOOD PARTITIONING IN IMPERIAL CORMORANTS (PHALACROCORAX ATRICEPS) AND ROCK SHAGS (P. MAGELLANICUS) BREEDING AT BAHÍA BUSTAMANTE, ARGENTINA

We studied the diet of Imperial Cormorants (Phalacrocorax atriceps) and Rock Shags (P. magellanicus) at Bahia Bustamante, Argentina, between 1992 and 1994. We analyzed pellet casts (1887 from Imperial Cormorants and 799 from Rock Shags) and regurgitations of stomach contents (260 from Imperial Cormorants and 24 from Rock Shags). Imperial Cormorants and Rock Shags fed on at least 22 and 21 different types of prey, respectively. The main prey species during all study years were fish: Engraulis anchoita for Imperial Cormorants and Patagonothen sp. for Rock Shags. For both species, the consumption of the main food categories as estimated by pellet analysis was similar among years. A significant relationship was found between Imperial Cormorant and Rock Shag diets during the three years, while the diet overlap index was relatively high. During all years, Imperial Cormorants consumed a significantly larger proportion of pelagic or demersal fish than did Rock Shags, while Rock Shags consumed benthic fish in a greater proportion than did Imperial Cormorants. Mean maximum diving depth, determined using capillary tube depth gauges, of Imperial Cormorants (24.4 m ± 18.8 SD) was significantly greater but more variable than that of Rock Shags (9.3 m ± 4.1 SD).

Observations of the common vampire bat (Desmodus rotundus) and the hairy-legged vampire bat (Diphylla ecaudata) in captivity

Summary We investigated roosting patterns, reproduction, morphometry, and ontogeny of a group of common vampire bats ( Desmodus rotundus ) and a group of the hairy-legged vampire bats ( Diphylla ecaudata ) both maintained for > 3 years in captivity. The basic social structure observed in Desmodus was of a “principal colony” or “harem” composed of females and their offspring and a few adult males, termed “resident males” and a separate group of the other males, termed “non-resident males”. The roosting patterns of Diphylla differed little from those observed in Desmodus , but the hierarchical segregation of non-resident males appeared to be less strict. In both species the non-resident males are accepted into the principal colony when the ambient temperature lowers. This behavior suggests social thermoregulation. Parturition of both species occurred once a year, and most of the births took place in spring or summer. The average duration of palpable pregnancy and lactation was longer in Desmodus than in Diphylla . In both species some lactating females that had lost their young continued suckling the babies of other females. Desmodus is larger in size than Diphylla . This may be related to the size and type of prey; Desmodus preys principally on large mammals and Diphylla preys on birds. We observed female biased sexual dimorphism in Desmodus and isometrical sexes in Diphylla . This may be related to the differential duration of lactation and maternal care periods, as the breeding cycle in Desmodus is longer than in Diphylla . The average time of reaching maturity: epiphysis closure of wing bones, adult weight, scrotal testes, and first pregnancy, as well as the first flight time and the time when males begin to roost apart from the principal colony, were later in Desmodus than in Diphylla . The variation between the two genera for duration of ontogeny and maternal care periods may be related to the learning needs for predation on different types of prey.

Type of prey influences biology and consumption rate of Orius insidiosus (Say) (Hemiptera, Anthocoridae)

Generalist predators are capable of consuming different types of prey, and as each prey may have distinct nutritional values, each may have a distinct impact on the biology of the predator. Therefore, the aim of this study was to determine how the consumption of different prey influences certain biological characteristics and the predatory capacity of Orius insidiosus (Say). The investigation was performed in climatic chamber at 25 ±1 oC, RH 70 ± 10% and fotophase 12. Eggs of Anagasta kuehniella (Zeller), adults of Caliothrips phaseoli (Hood) and nymphs of Aphis gossypii Glover were used as prey and were provided daily ad libitum for all the mobile stages of the predator. The results showed that biological parameters of O. insidiosus are affected differently depending on the type of prey ingested. The development time of the nymphal stage was 13.1, 11.23 and 10.25 days for O. insidiosus feeding on eggs of A. kuehniella, nymphs of A. gossypii and adults of C. phaseoli, respectively. Longevity was five times larger for adults fed on eggs of A. kuehniella (56.25 days) compared to that of adults that preyed on nymphs of A. gossypii (11.44 days), and four times larger when the prey were adults of C. phaseoli (13.58 days). The consumption of eggs of A. kuehniella by predator females resulted in a shorter pre-oviposition period (3.2 days) and a longer oviposition period (44.4 days) when compared to the consumption of other types of prey. In addition, fecundity was increased with the consumption of eggs of A. kuehniella (195.25 eggs laid / female) when compared to feeding on the other prey, C. phaseoli (70.00 eggs laid / female) or A. gossypii (22.50 eggs laid / female). However, the consumption of aphids was larger (148.28 nymphs/ nymphal stage) than that of thrips (74.10 thrips / nymphal stage) or eggs of A. kuehniella (37.03 eggs /nymphal stage) for all of the nymphal stages of the predator. The results indicate that the eggs of A. kuehniella are the type of prey best suited for rearing this predator insect under laboratory conditions. Also fecundity was better with this prey even though the predator consumed during its nymphal stage a lesser quantity of eggs compared to the other prey.

Kinematic analysis of a novel feeding mechanism in the brook trout Salvelinus fontinalis (Teleostei: Salmonidae): behavioral modulation of a functional novelty.

The tongue-bite apparatus (TBA) of salmonids represents an impressive novel feeding mechanism. The TBA consists of a set of well-developed teeth on the dorsal surface of the anterior hyoid (basihyal) and an opposing set of teeth on the roof of the mouth (vomer). A kinematic analysis of behaviors associated with the TBA in the brook trout Salvelinus fontinalis was performed using high-speed video (250 frames s(-1)). Two distinct behaviors were identified, raking and open-mouth chewing. Univariate analysis demonstrated that these behaviors were significantly different from one another. The power stroke of raking is characterized by significantly greater neurocranial elevation (raking, 36 degrees; open-mouth chewing, 16 degrees ) and retraction of the pectoral girdle (raking, 0.85 cm or 21 % of head length; open-mouth chewing, 0.41 cm or 10 % of head length). Open-mouth chewing is characterized predominantly by dorso-ventral excursions of the anterior hyoid (open-mouth chewing, 0.26 cm; raking, 0.14 cm). Raking is significantly shorter in duration (mean 49 ms) than open-mouth chewing (mean 77 ms). When presented with three different types of prey (crickets, fish or worms), Salvelinus fontinalis showed no variation in raking behavior, indicating that raking is highly stereotyped. In contrast, when feeding on worms, Salvelinus fontinalis modulated open-mouth chewing behavior with shorter durations to maximum displacement (at least 20 ms shorter than for either fish or cricket), although the magnitude of displacements did not vary. The reasons for the shorter duration of displacement variables while feeding on worms remains unclear. During post-capture processing behaviors in Salvelinus fontinalis, the magnitude of displacement variables is highly variable between individuals, but temporal patterns are not. This study characterizes two novel post-capture feeding behaviors and modulation of those behaviors in salmonids.

Prey preferences ofPhaeacius malayensis, a spartaeine jumping spider (Araneae: Salticidae) from Singapore

Phaeacius malayensis (Salticidae: Spartaeinae) is an atypical jumping spider that routinely includes other jumping spiders in its diet. This paper presents the first detailed study of P. malayensis' prey preferences. Three basic types of tests of prey preference were used: different types of prey were provided on alternate days (alternate-day tests), two types of prey were provided simultaneously (simultaneous-presentation tests), and an alternative prey type was provided while the predator was already feeding (alternative-prey tests). In alternate-day and simultaneous-presentation testing, but not in alternative-prey testing, (i) P. malayensis preferred spiders (salticids and hunting spiders) to insects; (ii) P. malayensis preferred salticids to hunting spiders; (iii) these preferences were not exhibited in some paired choices when the background was nonmatching, indicating that visual concealment is important with respect to some, but not all, prey; (iv) P. malayensis' prey preferences were not affected by a prior 14-day period without food; (v) after 21 days of fasting, P. malayensis took different types of prey indiscriminately. The adaptive significance of preferences for particular types of prey is discussed in the context of optimal-foraging theory.

Digestive efficiency and dry-matter digestibility in Steller sea lions fed herring, pollock, squid, and salmon

Dry-matter digestibility and energy digestive efficiency were measured in six juvenile Steller sea lions (Eumetopias jubatus) fed three diets each consisting of a single species: herring, pollock, and squid. Two of the animals were also fed pink salmon. Dry-matter digestibility (DMD) and digestive efficiency (DE) were measured using the energy and manganese concentration in fecal and food samples. DE values were high for all prey species (herring: 95.4 ± 0.7% (mean ± SD), pollock: 93.9 ± 1.4%, salmon: 93.4 ± 0.5%, squid: 90.4 ± 1.3%). Steller sea lions appear to digest prey of high energy density more efficiently than prey of low energy density. DMD values were also high for all prey species (herring: 90.1 ± 1.8%, pollock: 86.5 ± 3.4%, salmon: 87.3% ± 2.6, squid: 90.5 ± 1.2%). The low DMD value for pollock compared with herring and squid was due to the high proportion of bony material in pollock. There was a strong linear relationship between DE and DMD for each prey type, but the terms cannot be used interchangeably. DE measures are more meaningful than DMD in conveying the energetic benefits derived by sea lions from different types of prey. Species-specific measures of the digestible energy obtained from an array of prey items are a necessary component in understanding the bioenergetic consequences of consuming different prey species.

Prey preferences and visual discrimination ability of Brettus, Cocalus and Cyrba, araneophagic jumping spiders (Araneae: Salticidae) from Australia, Kenya and Sri Lanka

Brettus adonis, Brettus albolimbatus, Cocalus gibbosus, Cyrba ocellata and Cyrba simoni (Salticidae: Spartaeinae) are genera of aberrant jumping spiders from Australia, Kenya and Sri Lanka that routinely include web‐building spiders in their diet. The present paper is the first detailed study of prey choice by these five species. Three basic types of tests were used: different types of prey provided on successive days (alternate‐day tests), two types of prey provided at the same time (simultaneous‐presentation tests), or a second prey type provided while the predator was already feeding (alternative‐prey tests). Each species during alternate‐day and simultaneous‐presentation tests chose web‐building spiders in preference to insects, both when ‘well fed’ (last meal 7 days before testing) and when starved (last meal 14 days before testing). Insects and spiders were taken indiscriminately after 21 days of fasting. The same preferences were evident when dead, motionless lures instead of living prey were used, indicating that, while relying on optical cues alone, each species can distinguish between spiders and insects independent of the different movement patterns of these different prey. There was no evidence of preference in alternative‐prey tests.

Development, feeding and reproduction of the predatory mite, Hypoaspis miles (Acari: Mesostigmata: Laelapidae) on different types of prey

The developmental times, food consumption, fecundity and adult size of Hypoaspis miles were studied in the laboratory using Acarus siro, Lycoriella solani and Heteropeza pygmaea as food sources. Hypoaspis miles successfully developed when fed on A. siro, and L. solani in the laboratory. Food types greatly affected predator development time, feeding capacity, female fecundity and adult size. Statistically significant differences were recorded for all biological aspects of Hypoaspis miles. Acarus siro and Lycoriella solani were proved to be the most suitable type of food for the predator mite.

Dietary immunoassay of pelagic nemerteans by use of cross-reacting polyclonal antibodies: preliminary findings

With little data on the diet of pelagic nemerteans, apreliminary immunoassay survey of the gut contents ofthree species from the Pacific Ocean was performedusing non-specific, cross-reacting polyclonalantibodies. Results suggest that Nectonemertescf. mirabilis, Phallonemertes cf. murrayi, and Cuneonemertes elongata containedsomewhat different types of prey. Worms elicitedstrong responses when probed with antibodies tosquid-like mollusks and to mysids and shrimp. Heteropods are more likely ingested than pteropods. Additional studies must be done to confirm thesehighly suggestive results.

Modulation of prey‐capture behavior in Plethodon cinereus (Green) (Amphibia: Caudata)

AbstractMany feeding kinematic studies do not identify sources of mechanical variation related to the type or size of prey. Studies of salamanders have concentrated on determining the morphological basis of feeding mechanics or on phylogenetic comparisons; few have examined variability within a species. A series of feeding trials was designed to test whether Plethodon cinereus of different age/size classes exhibits stereotypic patterns in capturing prey of differing type and size. Stopframe video analyses of feedings were made using 19 salamanders of varying body size and four prey types chosen to resemble items in the natural diet of the species. Five morphological features of each salamander, length and width of prey items, and 15 kinematic variables were used to describe each feeding trial.Statistical analyses of kinematic and morphological variables show that the feeding behavior of this species varies significantly with prey type. Effects of salamander size and prey size within prey types were a source of variation in some kinematic variables; among‐individual variation partitioned with salamander body size. Different feeding modes resulted from distinctive combinations of distances from prey, amount of tongue protrusion, body movements, and duration of mouth closure, which varied with the use of jaw prehension and lingual prey capture. Presence of a repertoire of behaviors, composed of versatile combinations of movements, suggests that Plethodon cinereus modulates feeding mechanics to capture different types of prey. Consideration of natural prey in experiments, and of prey type in comparisons made across taxa, are necessary to investigations of the evolution of feeding behaviors. © 1995 Wiley‐Liss, Inc.

Aposematic coloration enhances chemosensory recognition of noxious prey in the garter snakeThamnophis radix

Considerable recent research has suggested that predators learn to avoid noxious or unpalatable prey more rapidly if those prey have conspicuous (aposematic) colour patterns. However, the precise psychological mechanisms by which predators associate conspicuous coloration with unpalatability remain poorly understood. In this study, the relative importance of visual and chemosensory information in learned aversions to noxious prey was examined by offering garter snakes two different types of prey (fish and earthworms) on forceps with varying colour patterns. Experimental subjects received injections of LiCl to induce illness immediately following the consumption of fish offered on either aposematic (yellow-and-black) or non-aposematic (green) forceps. Following their induced illness, snakes within both the aposematic and non-aposematic treatment groups showed significant aversions to fish, and avoided fish regardless of the colour of the forceps with which fish were offered. However, the aversion to fish was markedly stronger among snakes in the aposematic treatment group than in the non-aposematic group. These results indicate that aposematic coloration enhances chemosensory learning; aversions to unpalatable prey are formed more readily if the prey is conspicuously coloured, even though recognition of unpalatable prey depends on the prey's chemosensory characteristics rather than its coloration. Future responses to unpalatable prey are therefore influenced by an unexpectedly complex interaction of visual and chemosensory information acquired during the initial encounter.

The diets ofLoligo vulgarisandL. forbesi(Cephalopoda: Loliginidae) in northwestern Spanish Atlantic waters

Abstract The stomach contents of 723 Loligo vulgaris and 440 Loligo forbesi caught in the northwestern Spanish Atlantic waters have been examined. The diets of both species are described and compared. Loligo vulgaris shows 28 different types of prey belonging to four groups (Teleostei, Crustacea, Cephalopoda and Polychaeta) and Loligo forbesi 27 different types of prey belonging to three groups (Teleostei, Crustacea and Cephalopoda). Both species catch similar prey species but in different proportions. Cannibalism was observed in both species. Estimated prey sizes were smaller than squid sizes. No differences in feeding habits of males and females of both species were observed, but females seem to increase food intake during maturation. No significant changes were found in the diet of Loligo vulgaris within the size (DML) range studied (65–465 mm). Importance of cephalopods increased and importance of fish decreased in the diet of Loligo forbesi with growth (65–685 mm). Diet and food intake varied with se...

Energetic Cost of Feeding on Different Kinds of Prey for the Lizard Chalcides ocellatus

1. Skinks (Chalcides ocellatus) used 50% more energy to crush and swallow hard-bodied insect prey (Tenebrio molitor beetles) than medium- and soft-bodied prey (Tenebrio molitor larvae and Manduca sexta larvae, respectively). 2. Even for beetles, however, the energy cost of prey handling was no more than 1% of the energy assimilated. 3. Differences in handling times are probably more important than differences in energetic costs in determining the desirability of different types of prey

Morphological variation in a larval salamander: dietary induction of plasticity in head shape.

We examined diet-dependent plasticity in head shape in larvae of the eastern long-toed salamander, Ambystoma macrodactylum columbianum. Larvae in some populations of this species exhibit trophic polymorphism, with some individuals possessing exaggerated trophic features characteristic of a cannibalistic morphology in larval Ambystoma; e.g. a disproportionately broad head and hypertrophied vomerine teeth. We hypothesized that 1) head shape variation results from feeding upon different types of prey and that 2) cannibal morphs are induced by consumption of conspecifics. To induce variation, we fed three groups of larvae different diets: 1) brine shrimp nauplii only; 2) nauplii plus anuran tadpoles; 3) nauplii, tadpoles and conspecific larval salamanders. Comparisons of size (mass)-adjusted means revealed that this manipulation of diet induced significant variation in six measures of head shape, but not in the area of the vomerine tooth patch. For five of the six head traits, larvae that ate tadpoles and brine shrimp nauplii developed significantly broader, longer and deeper heads than did larvae that only ate brine shrimp nauplii. The ingestion of conspecifics, in addition to nauplii and tadpoles, significantly altered two head traits (interocular-width and head depth), compared to larvae only fed nauplii and tadpoles. Canonical discriminant function analysis detected two statistically reliable canonical variables: head depth was most highly associated with the first canonical variable, whereas three measures of head width (at the jaws, gills and eyes) and interocular width were most highly associated with the second canonical variable. Despite this diet-enhanced morphological variation, there was no indication that any of the three types of diet (including conspecific prey) induced the exaggerated trophic features of the "cannibal" morph in this species. These results illustrate that ingestion of different types of prey contributes to plasticity in head shape, but that some other proximate cue(s), either alone or in combination with diet variation, is essential to induce the extremes of trophic polymorphism in this species.

Individual-Based Model of Young-of-the-Year Striped Bass Population Dynamics. I. Model Description and Baseline Simulations

Abstract An individual-based model of population dynamics of age-0 striped bass Morone saxatilis is described and model predictions are analyzed. The model begins with spawning and simulates the daily growth and mortality of the progeny from each egg clutch as the fish develop through the life stages of egg, yolk-sac larva, feeding larva, and juvenile during their first year of life in a single, well-mixed compartment. Day of spawning and development rates of eggs and yolk-sac larvae depend on temperature. Daily growth of feeding individuals is represented by a bioenergetics equation, for which consumption is based on random encounters by individuals with different types of prey. Larvae feed on four zooplankton types and juveniles feed exclusively on size-classes of four benthic types. Mortality of eggs and yolk-sac larvae has both temperature-dependent and constant terms; mortality of feeding larvae and juveniles depends on an individual's weight and length. Most of the computations in the simulation inv...

Bacteria or microflagellates as a major food source for marine ciliates: possible implications for the microzooplankton

Direct visual observations were made on the vacuole contents of the oligotrichous ciliate Strombidium cf. sulcatum fed 12 different types of food. These ranged in size from 0.6 to 11.9 pm and included one fluorescently labelled bacterium, 2 types of cyanobacteria and 9 species of algae. We determined (i) the turnover time of food vacuoles as a function of prey quality and size, (ii) rates of grazing and filtration, and volume-specific clearance as a functlon of prey quality and size, (iii) the food concentration threshold for effective food intake in S. sulcatum when fed different types of prey, and (iv) an optimal particulate food size for S. sulcatum. Our results indicate the shortest feeding turnover time (13.7 ? 2.2 min.) for 2.5 pm prey (Nannochloris sp.). The average number of prey per vacuole and the feeding rate increased with food size to reach a maximum for this flagellate. Feeding efficiency then decreased to zero for particles w i t h the size range 6.6 to 11.9 pm (Platymonas sp., Hymenomonas elongata). Finally, it 1s shown that for food particle concentrations comparable to those of oligotrophic marine environments (e.g. 0.1 to 0.2 ppm by volume) S. sulcatum depends on food particles measuring around 2.5 pm for growth.

Altitudinal and Seasonal Differences in the Diets of Antechinus-Swainsonii and Antechinus-Stuartii (Marsupialia, Dasyuridae) in Relation to the Availability of Prey in the Snowy Mountains

The diets of Antechinus stuartii and A. swainsonii and the availability of their prey were studied in the Snowy Mountains in areas subjected to a winter cover of snow. Active prey were found to be less common in winter than summer and less common at higher than lower altitudes. The prey taken were more likely to reflect availability (as measured either by pitfall traps or litter samples) where prey was scarce. The diet varied between years but within years was more variable for A. stuartii than for A. swainsonii, possibly because A. stuartii was able to feed in trees in summer but not in winter, whereas A. swainsonii foraged only on the ground in all seasons. Antechinus stuartii and A. swainsonii fed on different types of prey at low subalpine altitudes (1600 m), where they foraged in different microhabitats; this difference was also reflected in the sizes of prey consumed. At high subalpine altitudes (1850 m), A. stuartii and A. swainsonii fed on both the same type and the same size of prey, indicating that the two species did not select different prey sizes but that prey size was determined by the size of food available to each species. Predation on a particular group by A. swainsonii in summer was more likely if that prey group was also available in winter. This suggests that by improving its skills at finding and catching these prey, A. swainsonii was better fitted for survival through the winter. This may help explain the greater abundance of A. swainsonii and the decline in numbers of A. stuartii almost to local extinction in snow-covered areas.

Predator-prey interactions, resource depression and patch revisitation

Generalist predators may be confronted by different types of prey in different patches: sedentary and conspicuous, cryptic (with or without refugia), conspicuous and nonsocial, or conspicuous and social. I argue that, where encounter rates with prey are of most importance, patch revisitation should be a profitable tactic where prey have short “recovery” times (conspicuous, nonsocial prey), or where anti-predator response (e.g. shoaling) may increase conspicuousness. Predictions are made for how temporal changes in prey encounter rates should affect revisit schedules and feeding rates for the 4 different prey types.

Predator-prey interactions, reosurce depression and patch revisitation

Generalist predators may be confronted by different types of prey in different patches: sedentary and conspicuous, cryptic (with or without refugia), conspicuous and nonsocial, or conspicuous and social. I argue that, where encounter rates with prey are of most importance, patch revisitation should be a profitable tactic where prey have short “recovery” times (conspicuous, nonsocial prey), or where anti-predator response (e.g. shoaling) may increase conspicuousness. Predictions are made for how temporal changes in prey encounter rates should affect revisit schedules and feeding rates for the 4 different prey types.