scholarly journals Selection of prey size and prey species by 1-group cod Gadus morhua:effects of satiation level and prey handling times

2000 ◽  
Vol 198 ◽  
pp. 225-238 ◽  
Author(s):  
SA Arnott ◽  
L Pihl
1987 ◽  
Vol 119 (2) ◽  
pp. 189-194 ◽  
Author(s):  
B.G. Rehnberg

AbstractMore than 94% of all spiders captured by Trypoxylon politum (Say) were from three genera: Neoscona, Araneus, and Eustala. The contribution of these spider genera to provisions of T. politum in the eastern and southeastern United States was estimated as follows: Eustala, 17%; Araneus, 21%; and Neoscona, 59%. Provisions in early summer were dominated by Araneus marmoreus Clerck, Eustala sp., and Neoscona hentzii (Keyserling); in mid-summer by N. hentzii; and in late summer by A. marmoreus and Neoscona domiciliorum (Hentz). The proportions of juvenile, subadult, and adult spiders captured depended on the time of year and the developmental stage of the spider. Trypoxylon politum captured male and female subadults, and female adults, but took very few male adults. Trypoxylon politum was found to be stenophagous with respect to prey species and euryphagous with respect to prey size.


2020 ◽  
Vol 21 (11) ◽  
Author(s):  
KHWANRUTAI CHARASPET ◽  
Ronglarp - Sukmasuang ◽  
NORASET KHOEWSREE ◽  
MANANYA PLA-ARD ◽  
YUWALUK CHANACHAI

Abstract. Charaspet K, Sukmasuang R, Khoewsree N, Pla-ard M, Chanachai Y. 2020. Prey species and prey selection of dholes at three different sites in Thailand. Biodiversitas 21: 5248-5262. The study of prey species and prey selection of Dholes at 3 different sites was conducted at Khao Yai National Park, Salak Pra, and Huai Kha Khaeng Wildlife Sanctuaries from 2013 to 2020. Information on Dhole prey at the sites was collected from the residues of dhole scats, from which the selection index, the relative biomass of the prey, and the relative amounts of the consumed prey were calculated. The data were collected simultaneously with the use of camera traps at each site. The study revealed that there were 13 species of Dhole prey with body weight over 5 kg. The result indicated that there were 7 species of even-toed ungulates. The relative biomass of even-toed ungulates ranged between 76.78 - 90.50% of the total biomass of all the Dholes’ consumed prey for all study sites. The dietary diversity index unveiled a similar index in all areas, which proved the adequacy of the analyzed scats. However, the Niche breadth index, which indicates the relevance of prey selection and prey species to the appearances of the prey at each site, was found to be high at Huai Kha Khaeng Wildlife Sanctuary, Khao Yai National Park, while the index was found to be low at Salak Pra Wildlife Sanctuary. The results revealed that Dholes consumed viverrid species and Malayan porcupine more often at the site where there were large carnivores. The recommendation from this study was the conservation and restoration of the ungulate populations, the main prey, as it greatly affects the conservation of the Dhole populations in Thailand.  Grassland and salt lick sites, water sources improvements are also important to promote prey population. The conservation of wildlife prey by releasing them to nature, as currently conducted, has an effect on the increase of Dholes’ prey species.


2020 ◽  
Author(s):  
B Cristescu ◽  
S Bose ◽  
LM Elbroch ◽  
ML Allen ◽  
Heiko Wittmer

© 2019 The Zoological Society of London Many predators specialize on one or several prey species that they select from the range of potential prey. Predator specialization on primary versus alternative prey is driven in part by encounter rates with prey and a predator’s habitat selection. Although habitat selection changes with behavioural state, this has not been well-recognized in the resource selection function (RSF) literature to date, often because auxiliary data on the predator’s behavioural states (e.g. hunting) are absent. We monitored habitat selection of pumas Puma concolor in a multi-prey system in northern California, where pumas specialized on black-tailed deer Odocoileus hemionus columbianus. We employed multiple RSF analyses on different datasets to test the following three hypotheses: (1) Pumas utilize habitats in proportion to their availability; (2) Pumas select specific habitat features when killing black-tailed deer, their primary prey; (3) Pumas do not select distinct habitats from those identified under hypothesis 1 when killing alternative prey. We found that pumas in our study selected for specific habitats and habitat features in general, but that their selection was more pronounced when killing black-tailed deer. In summer, kill sites of deer were associated with rugged terrain, but gentle slopes and northerly aspects. In winter, pumas killed deer at low elevations, on gentle slopes and on northerly and westerly aspects. Overall, evidence suggested that pumas tracked their primary prey across seasonal migrations, which were short in distance but resulted in pronounced changes in elevation. When killing alternative prey, pumas showed little evidence of habitat selection, suggesting they may kill alternative prey opportunistically. Our results hold implications for how data should be partitioned when modelling baseline habitat selection of predators, hunting habitat selection and predation risk for prey species, as well as for how we model ecological processes such as apparent competition.


1986 ◽  
Vol 2 (1) ◽  
pp. 73-85 ◽  
Author(s):  
David Dudgeon ◽  
Christina Y. M. Wat

ABSTRACTZygonix iris is widespread in tropical Asia, and larvae are sprawlers/clingers on rock surfaces in fast-flowing streams and rivers. In the Lam Tsuen River, Hong Kong, this species is univoltine; emergence occurs prior to the summer monsoon and larval recruitment during the wet season. Studies on larval dietary composition in four habitats indicated that Z. iris is a generalist predator, consuming epibenthic prey taxa in proportion to their abundance in the environment. Larval Chironomidae (Diptera) and Baetis (Ephemeroptera) were the commonest food items at all sites and there was little consistent evidence of preference for individual taxa. Larger Z. iris larvae tended to consume more prey taxa than did smaller larvae, and Baetis prey size was positively correlated with predator size. No size selection of chironomid larvae was apparent. Despite its unusual larval habit, Z. iris is a generalist feeder resembling lotic and lentic temperate-zone Odonata.


Behaviour ◽  
1999 ◽  
Vol 136 (3) ◽  
pp. 345-365 ◽  
Author(s):  
Leszek Rychlik

AbstractPrey size preferences in successive stages of foraging of Mediterranean water shrews Neomys anomalus Cabrera, 1907 were investigated in a terrarium. Seven shrews were tested individually in five experimental variants (simulating different habitat conditions) totally for 504 hours. Water shrews displayed partial preferences for prey size but they were selective from the very beginning of the foraging period. When searching for food, N. anomalus preferred big food portions, abandoning significantly more small than big portions. This tendency was especially strong when few food portions were available on land and there were no natural structures in the terrarium. Selection of big portions was intensified probably by their easier detection. Shrews hoarded proportionally more big than small portions in the scattered hiding-places. This tendency was intensified by the presence of natural structures, dispersion of food and reduction of food quantity placed on land. Later, however, more small than big food portions were eaten, apparently because small portions were easier to manipulate. Scattered food hoarding and preference of large prey are proposed to be the strategy of N. anomalus to maximise the energy net gain and minimise the predation risk and competition for food.


Paleobiology ◽  
2020 ◽  
pp. 1-13
Author(s):  
Emily S. Hughes ◽  
James C. Lamsdell

Abstract Eurypterids are generally considered to comprise a mixture of active nektonic to nektobenthic predators and benthic scavenger-predators exhibiting a mode of life similar to modern horseshoe crabs. However, two groups of benthic stylonurine eurypterids, the Stylonuroidea and Mycteropoidea, independently evolved modifications to the armature of their anterior appendages that have been considered adaptations toward a sweep-feeding life habit, and it has been suggested the evolution toward sweep-feeding may have permitted stylonurines to capture smaller prey species and may have been critical for the survival of mycteropoids during the Late Devonian mass extinction. There is a linear correlation between the average spacing of feeding structures and prey sizes among extant suspension feeders. Here, we extrapolate this relationship to sweep-feeding eurypterids in order to estimate the range of prey sizes that they could capture and examine prey size in a phylogenetic context to determine what role prey size played in determining survivorship during the Late Devonian. The mycteropoid Cyrtoctenus was the most specialized sweep-feeder, with comblike appendage armature capable of capturing mesoplankton out of suspension, while the majority of stylonurines possess armature corresponding to a prey size range of 1.6–52 mm, suggesting they were suited for capturing small benthic macroinvertebrates such as crustaceans, mollusks, and wormlike organisms. There is no clear phylogenetic signal to prey size distribution and no evolutionary trend toward decreasing prey sizes among Stylonurina. Rather than prey size, species survivorship during the Late Devonian was likely mediated by geographic distribution and ability to capitalize on the expanding freshwater benthos.


2010 ◽  
Vol 50 (1) ◽  
pp. 19-26 ◽  
Author(s):  
Roohallah Mirzaei ◽  
Mahmud Krami ◽  
Afshin Danehkar ◽  
Asghar Abdoli ◽  
Jim Conroy

Author(s):  
Manuel Mendoza-Carranza ◽  
João Paes Vieira

Ontogenetic diet changes (prey species richness and size) in juveniles of white sea catfish (Genidens barbus) were tested in three southern Brazilian estuaries: Mampituba (29°12′S), Tramandaí (30°02′S), Chuí (33°44′S). Cluster analysis revealed that white sea catfish juvenile populations in the three estuaries are composed of two feeding groups. These two feeding groups are coincident with a bimodal size–age distribution of the juveniles of white sea catfish. In small catfish (5 to 10 cm TL) copepods were the most numerous prey (Chuí = 86.66%N, Tramandaí = 85.52%N and Mampituba = 52.34%N). In large catfish (10 to 20 cm TL) the most abundant and frequent prey was fish (Chuí: 73.19%N and 74.56%FO; Tramandaí: 85.92%N and 73.33%FO; Mampituba: 52.34%N and 61.54%FO). The Morisita overlap index among small and large fish was low in all estuaries; high values of Morisita's similarity index were observed among same size catfish groups. In all cases, no differences were observed among prey bio-volume curves of same size predator groups (small, F = 0.41, P = 0.65; large, F = 2.19, P = 0.11). In all estuaries, prey size increased significantly with increasing predator size. The 90th regression quantile estimated with most precision the predator–prey size relationship.


1977 ◽  
Vol 55 (7) ◽  
pp. 1118-1128 ◽  
Author(s):  
Richard Shine

Six species of elapid snakes were studied in a highlands region of eastern Australia. Major results were as follows. (1) These snakes are opportunistic feeders, relatively unselective with respect to prey type or prey size. (2) Despite this unselective feeding, over 60% of the diet (by weight) in all species consists of lizards and frogs. Published data show a preponderance of these prey types in Australian snakes as a whole, and I suggest that this is due to the scarcity of other potential prey items (especially small mammals and freshwater fish) in Australia. (3) Sympatry is less common in the elapids studied than among North American snakes in comparable climatic regions. I attribute the scarcity of sympatry among the Australian snakes to the restricted number of prey types available. This argument is supported by previous empirical work which suggests that prey species diversity determines snake species diversity. Observed prey-size differences between sympatric elapid species are consistent with the interpretation of interspecific competitive exclusion.


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