Japanese speakers also feel a huge affinity with Chinese because of the use of Chinese characters. All Chinese characters, except some which were 'made in Japan', have on readings. The effect of this was to provide a kind of gloss on the meaning of the Japanese word. Although this kind of usage is no longer common in Japanese it is still shown in dictionaries. Thus, a Chinese speaker would totally miss any cognate words in Vietnamese.
Chinese characters form a channel for mutual linguistic influence.
The system of Vietnamese bird names is totally different from both the Chinese and Japanese names. While it may be far-fetched to claim that this is a result of discarding the Chinese writing system, it is definitely a background cause. By ditching Chinese characters, the Vietnamese basically lost whatever obligation they may have felt to refer to Chinese precedents in choosing and developing bird names. Vietnamese ornithologists were free to develop bird names completely on their own terms. On the other hand, the shared use of Chinese characters facilitated ornithological interchange between China and Japan over a long period of time before WWII, an interchange that still continues in Taiwan.