The main differencies are (as can be seen in the attached tables):
1. Length of the unison call (UC);
in average, the UC of J-RC is 22 sec long, ranging between 3 and 50 sec; the length of UC of the K-RC is12 sec; taking only the winter calls of the J-RC, the difference is 15 (J) to 12 (K), still significant (J-RC maximum length in winter 99 observed was 32 sec, in Korea 20 sec);
2. Number of female (f) answer calls per male (m) tact;
in Japan, 10% of the f answer with 3 short calls, 30% varying between 1 to 3 calls, 60% with 2; in average 2.26; the K-RC f answer: 4% with 3 - 4 (!) calls, 43%: 2 - 3, 17% with 1 - 2 or 1 - 3; 30% with 2 answer calls, average 2.15; although this difference does not seem significant, the distribution of the variety seems indicative; J-RC f sometimes displays a very short introduction before their 2 short answer calls.