Familiarity with a partner facilitates the movement of drift foraging juvenile grayling (Thymallus thymallus) into a new habitat area
Preferring one social partner over another can enhance fitness. This paper reports that juvenile grayling were significantly more likely to enter and forage in new, upstream habitats when paired with familiar versus unfamiliar social partners. Fish paired with unfamiliar partners or when alone were more reluctant to enter the new area. The entry times for both fish in a familiar pair were significantly correlated, but uncorrelated for unfamiliar fish. These differences between familiars and unfamiliars were consistent over a 2-week period. Fish with familiar partners spent more time within three body lengths of each other than did those with unfamiliars. The results are discussed in relation to optimality models of drift foraging, which do not included sociality. It is suggested that the social dimension creates a more dynamic foraging response to variable environmental conditions and could have consequences for growth.
KeywordsSocial context Exploration Drift foraging Familiar Grayling
Paul Hart thanks the University of Leicester for granting him study leave and the University of Karlstad for inviting him to visit and for financial support. We thank Ashley Ward and Mike Webster for instructive comments on an earlier draft. The experiment was approved by Sveriges Djurförsöksetiska nämnd (Swedish Experimental Animal’s Ethical Committee, Reference Number: 278-2010).
- Frank SA (1998) Foundations of social evolution. Monographs in behavior and ecology. Princeton University Press, PrincetonGoogle Scholar
- Maitland PS, Campbell RN (1992) Freshwater fishes of the British Isles. Harper Collins, LondonGoogle Scholar
- Meddis R (1984) Statistics using ranks: a unified approach. Blackwells, OxfordGoogle Scholar
- Railsback SF, Harvey BC (2002) Analysis of habitat-selection rules using an individual-based model. Ecology 83:1817–1830Google Scholar
- Sall J, Creighton L, Lehman A (2005) JMP©start statistics. A guide to statistics and data analysis using JMP© and JMPI INC software. London: Thomson.Google Scholar
- SOFA Statistics Package v 1.1.2. http://www.sofastatistics.com/home.php (last accessed 8th May 2013)
- Webster MM, Ward AJW, Hart PJB (2007) Boldness is influenced by social context in threespine sticklebacks (Gasterosteus aculeatus) Behav 144:351–371Google Scholar