My Second Thought on Invasive Alien Species
'Through the Lens', Fujingaho Magazine, September 2019
Photos and text: Her Imperial Highness Princess Takamado
English Translation: Asia Club, a WBSJ Volunteer Group (YOKOYAMA Kazuko, KASE Tomoko, UENO Naohiro)
BirdLife International, an international non-governmental organization for bird conservation, where I serve as Honorary President, has designated avian species as an indicator of biodiversity and is pursuing conservation activities along the four aspects of “species, habitats, sustainability and local people”. I often feel complicated difficulties in promoting these activities, for they involve various factors. This time I would like to write about invasive alien species which cause problems in conserving the ecosystem unique to each country and region.
Invasive alien species are animals and plants which have been introduced for some reason into a certain place where they have not normally occurred. Any natural environment exists based on diverse relationships created by native biology over an extended period of time. Invasive alien species are likely to exert negative effect upon such an environment. Species which have invaded into a new environment, increased and finally threatened the biodiversity, are disquietingly called as invasive alien or introduced species.
The first photo shows the Rock Dove, Columbia Livia. It is the oldest known invasive bird in Japan, whose introduction can be found even in the literature of the Heian Era (794 to 1185). At the bottom of my heart I would like to call it a Japanese bird, if its history could date back to such an old time. However, the “Checklist of Japanese Bird, the 7th Revised Edition” clearly defines the Rock Dove as an introduced species.
The photo at the bottom is of the Mute Swan (Cygnus olor). It was confirmed to have bred at Lake Utonai in Hokkaido in 1978, more than 40 years ago. The bird swims so gracefully raising its wings that it has been depicted in a lot of paintings and illustrations of myths and fairy tales. Knowing that it originally came from Europe, I quietly chuckled when I saw the couple staying, as if for granted, on the ditch beside the rice paddies in Ibaragi Prefecture.
The other two photos of the Chinese Hwamei (Garrulax canorus) were taken for this essay to introduce to you. You may be unaccustomed to this invasive alien bird, but it is rapidly increasing in number and expanding its territory at present. This bird contributed to the decline of native species in Hawaiian Islands, and recently it was designated as a specified foreign organism by the Invasive Alien Species Act in Japan. It was first introduced into Japan as a pet, but as some people felt it too noisy, for it calls loud and endlessly, and others got bored of its somber appearance, it was let out of the cage and went wild as a so-called ‘escaped bird’, ending up to stay in Japan.
The Eurasian Collared Dove (Streptopelia decaocto) was introduced into Japan way back in the Edo Era (1603-1868) and now has been designated as the prefectural bird of Saitama Prefecture. The Chinese Bamboo Partridge (Bambusicola thoracica) was brought into Japan as a hunting bird in 1919. These species were depicted in Japanese paintings and have attracted national popularity as part of the nation’s scenery. On the contrary, birds of parakeet family, which are recently fling over the center of Tokyo, and the Chinese Hwamei do not seem to have fitted to Japanese scenery yet. I feel a sense of discomfort toward the Mute Swan, although it is so long as 40 years since it has been introduced, but to the eyes of younger people, it must be a familiar bird from birth which they have seen swimming in lakes and moats. So “whether accustomed or not” would be the key and only time might solve the situation.
Various thoughts came to my mind while I was observing the Chinese Hwamei busy in breeding chicks for 6 hours in a tent set close to the bird. After having been released according to the human convenience, it is merely striving to adapt itself to our environment to survive, It never means to destroy the ecosystem of Japan, but when it increases in number excessively, it can cause mal effects.
Any alien bird should not be regarded as harmful just because it was introduced, so we should observe it carefully. I may sound a little too greedy, but I sincerely wish such birds manage to come to terms with our native biology and enrich our ecosystem accordingly.