I often see this explanation on foreign websites:
There are two subspecies, South and North. The biggest difference between the south and the north is that the ear line in the south is not connected, while the ear line in the north is connected. As can be seen from the following distribution map, there is actually only one subspecies of storks distributed in China or neighboring countries. Hainan and Vietnam are probably the phenotypes of the same subspecies in different regions. From the pictures below, we can see that the ears of Vietnam are connected with those of Hainan or Yunnan, while Gracula religiosa is the representative of the south, and their ears are connected.
Look at the three different forms of myna that can be bought in China, and their ear cords, all of which are connected together.
The representative subspecies of southern myna, a subspecies of Borneo myna, has a broken ear line. This subspecies of myna is distributed in southern Vietnam and southern Thailand.
Another subspecies of southern myna: Indian myna with yellow ears is also broken.
The characteristics of Yunnan emu's ear line are like a big hat or cloak hanging on its head. It is said that the speaking ability of Yunnan EMU is no worse than that of Vietnam EMU. Many people regard Yunnan EMU as Hainan EMU, but there are obvious differences in earphone lines.
There are obvious differences between Hainan and Yunnan. The earlobes and ear lines in Hainan are not as coherent and beautiful as those in Yunnan, and the earlobes look abrupt.
Hainan stork's oral ability is very poor, and few people can learn 5-6 sentences.
Vietnamese myna, it has no earlobe and its learning ability is comparable to that of Yunnan myna.
Vietnamese myna is the most common myna on the market at present, with the best learning ability. If you want to buy Vietnamese myna, there is the simplest way, so you must hurry early rather than late, because the estrus of Vietnamese myna is in February, and the first nest of myna I saw in China is in March. At this time, I basically bought Vietnamese myna.
Hainan myna usually enters the breeding season in mid-April, and many profiteers will mix Hainan myna with Vietnamese myna and sell it together in the later period, so the later they buy it, the higher the probability of buying Hainan myna.
If you must buy storks after mid-April, you must choose the one with the smallest nest size, because even experts can hardly tell whether the chicks are from Vietnam or Hainan, but the storks in Vietnam are smaller than those in Hainan, so if your city can only buy late storks, you must choose the one with the smallest nest size.
Yunnan stork is very rare, which is basically untraceable in the domestic market. If you are lucky enough to meet them, the probability of buying lottery tickets is similar. This stork has a strong ability to speak, but because of its small number, it is impossible to analyze its time to market and the characteristics of its chicks.