Combination of :
* red ring with a white two alpha-numeric code.
* 1 c-ring (on right leg)
* metal ring (on left leg).
note 1 : the aim of this research is only to study the local urban population.
note 2 : details of the scheme are :
* left leg : metal ring from the Ukrainian ringing center (seria E).
* right leg : red ring with a white two alpha code over a c-ring (plain blue, green, yellow, white). This ring means the distance from the center of the city to periphery of the Lviv city along urban gradient.
note 3 :
