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Orientation of the smooth newt (Triturus vulgaris) foraging on zooplankton
Esa Ranta, Mari Saloheimo and Visa Nuutinen
Annales Zoologici Fennici
Vol. 23, No. 3 (1986), pp. 281-287
Published by: Finnish Zoological and Botanical Publishing Board
Stable URL: http://www.jstor.org/stable/23736008
Page Count: 7
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The behaviour of smooth newt adult females foraging on Daphnia was analysed. Newts were given different-sized Daphnia (1.5, 2.3 and 3.8 mm), either as one-sized or two-sized prey in different densities and size ratios. The frequency distribution of angles of turns mede by newts between discrete moves during foraging bouts is a normal function peaking at approx. 0°. Increasing prey abundance or size of prey made newts turn more widely during their foraging bouts. The movements of newts during foraging bouts are directional (i.e., moving straight ahead dominates) with the exception that the first turn made after ingestion of a prey tends to be a wider arc than subsequent turns. In other words, newts move straight ahead before capturing a prey, but make random turns just after capturing the prey. A computer simulation with aggregated prey suggests that a "directional-random' turning rule (observed newt behaviour) gives the highest prey capture rate when compared to "directional-directional' (second best) or "random-random' turning rules.
Annales Zoologici Fennici © 1986 Finnish Zoological and Botanical Publishing Board