IADIZA   20886
INSTITUTO ARGENTINO DE INVESTIGACIONES DE LAS ZONAS ARIDAS
Unidad Ejecutora - UE
artículos
Título:
Group foraging in the colonial spider Parawixia bistriata (Araneidae): effect of resource levels and prey size
Autor/es:
FLORENCIA FERNÁNDEZ CAMPÓN
Revista:
ANIMAL BEHAVIOUR
Editorial:
Elsevier, Ltd.
Referencias:
Año: 2007 vol. 74 p. 1551 - 1562
ISSN:
0003-3472
Resumen:
In animal groups whose focus is on juvenile growth, prey attributes and the way in which individuals have access to those prey influence the level of sociality. Models examining the evolution of group foraging predict that if an individual is able to monopolize a prey item, it should not permit collaboration in the capture of or feeding on that prey. If monopoly is not possible, individuals should allow others to join due to high cost of prey defensibility. Hunger stress can affect the above predictions through its effect on the perceived value of a prey item. An increase in the individual tendency to attack prey could result in more group captures when under higher hunger levels when the resident spider fails to monopolize a prey item. I conducted a study on the foraging behaviour of the colonial spider, Parawixia bistriata, in habitats with different insect availability. I offered prey items of known size to spiders at their web sites and determined frequency of group capture and feeding relative to prey size. I also recorded the number of individuals participating in capture and feeding groups and interactions between the resident and other spiders foraging. Individuals exhibited a higher tendency to capture prey and feed in a group as the size of the prey increased. In addition, spiders from habitats where there are lower prey levels (dry sites) had a higher tendency to attack collectively prey than spiders from wet sites where prey levels were higher. Although there were no between-habitat differences in tendency to feed in groups, the number of spiders in the groups was larger at dry sites. Interactions between the resident and other spiders foraging were not of a high aggression level over all trials but behavioural acts involving direct interactions were more frequent in groups from dry sites.