Аннотация:The European Common Frog (Rana temporaria) is a widespread species but spatial orientation of this frog is partial. Characteristics of spatial usage are unknown too. So, the main aim of our investigation was to study orientation abilities of the common frog after artificial displacement from the capture site at different distances and to reveal characteristics of space utilization during summer.
Our research was conducted at Zvenigorod Biological Station, Moscow region, Russia in summer 2013 and 2015. Length and weight of each captured adult frogs were measured. The main method of studying spatial behaviour was tracking with a spool and line technique. Each tracking device consists of spool with thread. Tracking devices were fixed on the frog’s body by an elastic band. General weight of device is lower than 5% of frog’s body mass. Distances of displacement were from 0 to 400 m. Capture points and releasing places were marked by GPS-navigator and by sticks. We fixed thread end on the stick. Unreeled thread marked frog’s movements. We checked frogs twice a day and map frog’s route with environmental characteristics like shelters and borders.
We found out that frogs can feel direction to capture sites after displacement to distances up to 300 m but they were confused after displacement to 400 m and can’t find the right direction (according to Rayleigh Test for circular data р<0,01 for frogs displaced to 40 (16 frogs), 100 (20) и 200 m (13), р=0,03 для 300 m (13), р=0,33 для 400 m (24)). Larger distances of displacement were correlated with longer periods needed to choose the right direction. At the same time male’s route length before choosing the certain direction was much smaller than that for female’s ones.
We measured length of the route near logs, under them and above them, movements through brushwood and on open area and calculated the part of each characteristic in the whole route for each frog. Distance of displacement were correlated with amount of movements on the open areas (according to Kruskal-Wallis test p=0,01). Frogs moved more secretly at their capture sites and less secretly after displacement to 40 and 100 m. Nondisplaced frogs mainly used logs as shelters. Displaced frogs preferred fallen trees and branches as shelters which could be observed distantly. Probably these differences could be based on bigger frog’s aspiration to coming more rapidly to their home sites if they can sense it nearness and ignore the risk to be eaten. At the same time frogs displaced to bigger distances as 200 or 300 m are more cautious and often use shelters for rest and to avoid predators.