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Shakhparonov V.V., Ogurtsov S.V., 2008. Short and long distance homing in the marsh frog, Rana ridibunda Pallas // RIN08: Orientation & Navigation. Birds, Humans & Other Animals. University of Reading, UK. 2-4 April, 2008. Royal Institute of Navigation. RIN08 CD-ROM. Paper No.039.
We investigated pond search orientation of the Marsh frog (Rana ridibunda Pall.) in the populations of the west of Moscow region near Zvenigorod Biological station of Moscow State University, near the town of Kharabali in Astrakhan region and near the village Maliy Utrish in Krasnadar region. During  our experiments we displaced frogs at different distances from their ponds and tracked their movements with the use of mechanical tracking device. The device consisted of a 'rucksack' and a sewing machine bobbin with 60m of thread, which was mounted on the frog's back. We found that in summer the marsh frogs from Utrish (110 ind.) and Moscow population (43 ind.) after displacement up to 250m from their breeding pond tended to return to that pond. They showed the best results at the distance less than 70m. We suppose that this effect associated not only with small distance to the water source, but also with a good familiarity of the some area near the pond. We tested our hypothesis at the Utrish, where frogs live in one big lake, about 150 m long. We supposed that frogs from one end of the lake should orient better and move more rapidly near their familiar bank, than frogs from the opposite end of this lake released in the same place. The experiment proved our hypothesis.
Frogs from Kharabali population (40 ind.) didn't show such a fidelity to their ponds and moved to the nearest water. We explain the difference in their behaviour by the threat of dehydration in warm and dry southern climate of Astrachan region unlike other two populations. At the distance of 500m and more from all ponds frogs moved in random manner in all populations. We conducted the same experiments in autumn (September) with the frogs from Moscow population (15 ind.). In this case frogs caught in the pool and displaced from the pond moved to the river from the distance up to 450m as the river serves as a hibernation site for these frogs. At the distance more then a kilometer from the river they went in a stereotyped compass direction that corresponded with the direction of their autumn migration to the hibernation site.
 The analysis of tracks showed that frogs had some 'starting loop' in the initial phase of their movement, after that they chose some direction and held it. The length of this 'starting loop' was minimal (6-9m) in the familiar zone (up to 70m) as frogs presumably quickly detected their position with the use of short distance cues. This loop was also small at the time of autumn migration when frogs went in a stereotyped compass direction that implies the use of global cues. In other situations, the length of the 'starting loop' was larger (15-20m).
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