P. Dall'Antonia et U. Sinsch, In search of water: orientation behaviour of dehydrated natterjack toads, Bufo calamita, ANIM BEHAV, 61, 2001, pp. 617-629
We analysed the water-finding ability of 12 natterjack toads, after mild de
hydration, in an experimental environment (octagonal arena) which provided
geo- and hydrotactic, magnetic, olfactory and visual cues for orientation.
We tested the hypotheses that the water-finding ability is based on pilotag
e, using gradients of waterborne cues, and that the cues used for water ori
entation differ between individuals. Random search behaviour of naive toads
released in the arena showed that goal-oriented movements towards the exit
leading to water required previous experience of the position of the water
source. Thus, the water-finding ability of natterjacks is restricted to fa
miliar areas. Physiological and behavioural responses to training and testi
ng varied considerably between individuals: six toads became oedomatous and
learned how to locate water, whereas the remaining six did not. We analyse
d the orientation behaviour of successfully trained toads in the training a
rena, when directional cues were removed or provided conflicting informatio
n, and present evidence for individuality in the use of orientation cues: t
hree toads relied mainly on geotactic cues and olfactory pilotage, another
mainly on visual landmarks and geomagnetic information, and another used al
l cues available without clear preference. In conclusion, to detect water,
dehydrated toads rely on a multisensory orientation system, which is basica
lly the same as that used during breeding migrations and includes several r
edundancies. (C) 2001 The Association for the Study of Animal Behaviour.