Size-related shift in feeding strategy and prey-size selection in young grayling (Thymallus thymallus)

1996 ◽  
Vol 74 (9) ◽  
pp. 1597-1603 ◽  
Author(s):  
Philippe Sempeski ◽  
Philippe Gaudin
Keyword(s):  
Body Length ◽  
Feeding Behaviour ◽  
Prey Size ◽  
Feeding Strategy ◽  
River Channel ◽  
Large Prey ◽  
Thymallus Thymallus ◽  
Chironomid Larvae ◽  
Size Selection ◽  
The Mean

Observations of feeding behaviour and analysis of prey-size selection by young grayling revealed a shift in feeding strategy coinciding with a shift in habitat occurring between larval (observed in lateral habitats) and juvenile (observed in the river channel) stages of grayling. The mean number of foraging attempts per minute decreased four times between both stages, while in the same time the mean distance travelled during each foraging attempt decreased from 1.5 body lengths to 1 body length. Gape-limited postemergent larvae fed mainly on small chironomid larvae (<0.5 mm3) but larger larvae and pupae (0.5 – 1 mm3) were consumed with increasing size. The diet spectrum of juveniles >40 mm was characterized by the appearance of very large prey (> 10 mm3), such as simuliid and ephemeropteran larvae, but also by a new increase of the contribution of small chironomid larvae. Changes in the feeding strategy of young grayling are discussed in relation to internal (e.g., morphological limitations) and external (e.g., physical characteristics of habitat) constraints.

Are solitary progressive-provisioning wasps optimal foragers? A study with the digger wasp Bembix merceti (Hymenoptera: Crabronidae)

Behaviour ◽  
2011 ◽  
Vol 148 (2) ◽  
pp. 191-214 ◽  
Author(s):  
◽  
S.F. Gayubo ◽  
◽  
◽  
◽  
...  
Keyword(s):  
Positive Selection ◽  
Natural Enemies ◽  
Prey Size ◽  
Central Place ◽  
Large Prey ◽  
Lift Capacity ◽  
Surrounding Environment ◽  
The Mean ◽  
Selection Of ◽  
Central Place Forager

Abstract Bembix merceti, a central-place forager that captures dipterans to feed its larvae, could be considered a suboptimal forager. The females tend to optimize their provisioning flights, capturing prey in proportions different from those present in the surrounding environment. These wasps make a positive selection of families of flies with greater mean weights even though they are less abundant and, within the families whose weight is not too great, capture individuals whose weight is larger than the mean. Selection is based on prey size and not on the type (family) to which the prey belongs. A significant correlation between the weight of each female and the weight of the largest prey captured by the wasp was found, suggesting that the females capture prey in consonance with their lift capacity. Nevertheless, captures were not optimized maximally; the females maintained a margin with respect to the maximum prey weights that they could transport efficiently. This margin could be related to the low availability of large prey in the environment; to the type of progressive provisioning shown by the females of this species; and to other factors, such as the good manoeuvrability of their prey and the pressure from their natural enemies and congeners.

Diet and feeding strategy of the forkbeard Phycis phycis (Pisces: Phycidae) from the Portuguese continental coast

2017 ◽  
Vol 98 (7) ◽  
pp. 1757-1765
Author(s):  
Ana Rita Silva ◽  
Ana Rita Vieira ◽  
Vera Sequeira ◽  
Rafaela Barros Paiva ◽  
Leonel Serrano Gordo ◽  
...  
Keyword(s):  
Feeding Behaviour ◽  
Feeding Strategy ◽  
Prey Group ◽  
Important Prey ◽  
Decapod Crustacea ◽  
Shift Pattern ◽  
The Mean ◽  
Generalist Diet ◽  
Taxonomic Categories ◽  
Phycis Phycis

The diet and feeding behaviour of the forkbeard Phycis phycis was studied based on 246 stomachs collected between May 2011 and April 2012 from a commercial fleet operating off the central west coast of Portugal. A total of 44 prey items were identified in the stomachs which were merged into major groups to avoid problems with low expected frequencies. The following taxonomic categories were considered: non-decapod Crustacea, Caridea, Anomura, Munida spp., Processa spp., Brachyura, Pisces, Trisopterus luscus. In order to investigate possible diet differences between fish size classes, a cluster analysis was performed using the mean abundance of each prey group by forkbeard 5 cm length class, and three length groups (LG) were obtained: <22.5, 27.5–37.5 and >42.5 cm. Seasonally, Caridea was the main prey group during winter and autumn while Pisces was predominant during the rest of the year. Caridea was the most important prey group for LG1 and LG2 while in LG3 Pisces was the principal one. The forkbeard feeding behaviour may be characterized as presenting a shift pattern from a more generalist diet (small Crustacea, mainly Caridea) in the young adults to a more specialist strategy (teleosts) in the adults.

Conflict and Cooperation in the Group Feeding of the Social Spider Stegodyphus Mimosarum

Behaviour ◽  
1985 ◽  
Vol 94 (1-2) ◽  
pp. 167-182 ◽  
Author(s):  
Margit M. Enders ◽  
Paul I. Ward
Keyword(s):  
Group Size ◽  
Feeding Behaviour ◽  
Prey Size ◽  
The Body ◽  
Large Prey ◽  
Social Spider ◽  
Small Prey ◽  
Conflict And Cooperation ◽  
The Social ◽  
Group Feeding

Abstract1. Stegodyphus mimosarum, a social spider, lives in colonies which may contain hundreds of individuals. Feeding behaviour was examined with respect to feeding group size and prey size. 2. Prey were less likely to escape and were subdued more quickly when attacked by more than one spider. 3. During capture small prey were frequently bitten directly on the body whereas large prey were almost always bitten on an appendage. 4. Pulling struggles for subdued prey occurred. They lasted longest over medium sized prey. Small prey were easier to transport to the nest than medium prey and large prey were pulled by more spiders from a single retreat. 5. Spiders which had participated in a capture initially bit preferentially on the prey's head or thorax but others which joined later to feed bit at random. 6. Feeding became less efficient as group size increased and an experiment suggests that individuals injected less poison and digestive enzymes when feeding in groups.

scholarly journals Prey Size Decline as a Unifying Ecological Selecting Agent in Pleistocene Human Evolution

Quaternary ◽  
2021 ◽  
Vol 4 (1) ◽  
pp. 7
Author(s):  
Miki Ben-Dor ◽  
Ran Barkai
Keyword(s):  
Prey Size ◽  
Prey Availability ◽  
Stone Tool ◽  
Foraging Efficiency ◽  
Energetic Cost ◽  
Large Prey ◽  
Biomass Density ◽  
Cultural Changes ◽  
Progressive Decline ◽  
Brain Expansion

We hypothesize that megafauna extinctions throughout the Pleistocene, that led to a progressive decline in large prey availability, were a primary selecting agent in key evolutionary and cultural changes in human prehistory. The Pleistocene human past is characterized by a series of transformations that include the evolution of new physiological traits and the adoption, assimilation, and replacement of cultural and behavioral patterns. Some changes, such as brain expansion, use of fire, developments in stone-tool technologies, or the scale of resource intensification, were uncharacteristically progressive. We previously hypothesized that humans specialized in acquiring large prey because of their higher foraging efficiency, high biomass density, higher fat content, and the use of less complex tools for their acquisition. Here, we argue that the need to mitigate the additional energetic cost of acquiring progressively smaller prey may have been an ecological selecting agent in fundamental adaptive modes demonstrated in the Paleolithic archaeological record. We describe several potential associations between prey size decline and specific evolutionary and cultural changes that might have been driven by the need to adapt to increased energetic demands while hunting and processing smaller and smaller game.

Does prey abundance affect prey size selection by the Eagle Owl (Bubo bubo)?

2021 ◽  
Author(s):  
Jorge Tobajas ◽  
Carlos Rouco ◽  
Javier Fernandez-de-Simon ◽  
Francisco Díaz-Ruiz ◽  
Francisca Castro ◽  
...  
Keyword(s):  
Prey Size ◽  
Prey Abundance ◽  
Bubo Bubo ◽  
Size Selection ◽  
Eagle Owl

scholarly journals Prey-size selection by freshwater flagellated protozoa

1990 ◽  
Vol 35 (7) ◽  
pp. 1429-1436 ◽  
Author(s):  
Thomas H. Chrzanowski ◽  
Karel Šimek
Keyword(s):  
Prey Size ◽  
Size Selection
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