Shahparonov V.V., Ogurtsov S.V., 2003. The role of the native pond odour in orientation of the green toad (Bufo viridis) youngs-of-the-year // 12th Ordinary General Meeting of Societas Europaea Herpetologica. Programme & Abstracts, Zoological Institute of the Russian Academy of Sciences, Saint-Petersburg, Russia, 12-16 August, 2003, p.146.
According to field observations conducted in the north-west of Moscow region green toad B. viridis remains at least several days near the native pond after metamorphosis. Youngs-of-the-year with rudiments of tail keep within 1 m from the water body of the native pond and when disturbed escape to the pond. These toadlets tested in pair-choice conditions prefer water from the native pond compared with water from the strange one. At the onset of metamorphosis tailless toadlets could occupy the area up to 5 m from the native pond. Being disturbed they prefer to escape to surrounding vegetation. Tailless toadlets caught within 1 m from the water edge as well as toadlets caught between 1 to 5 m from the pond demonstrate indifference to water from the native pond compared with water from a strange one.
Toadlets exposed to artificial chemical marker - morpholine, 10-7 mole/l – on Gosner larval stages 19-21, i.e. during 4 days between hatching and the beginning of active feeding, show preference to morpholine (10-8 mole/l) after metamorphosis. Toadlets fail to form preference to morpholine when exposed to it during the same time period after metamorphosis. They remain indifferent as do the control toadlets that are not acquainted with morpholine.
These results show that native pond odour could mediate orientation of B. viridis youngs-of-the-year after metamorphosis. Chemical stimuli could be learnt during a sensitive period in larval development.