Tag Archives: turtles

Invasion of the Turtles

27 Apr

Hi blog.

We’ve had some glorious weather, perfect for cycling to work.  The home trip is not quite as satisfying, mostly because of the tiny flying insects that swarm under the trees in the late afternoon and collide with my face.

I’ve spotted pheasants, both male and female, a masked palm civet, seen the feeding habits of crows, heard the cries of thrushes and bush warblers… pity that the ride ends at work!

I’ve seen the Mississippi red-eared sliders (Trachemys scripta elegans) too.  I’ve mentioned them in an older post, and have often wondered why the local governments don’t seem to be doing anything about them.

Alien invasion! Walk for you lives!

Then this article from the Japan Times made its way into my news feed:



Alien red-ear sliders greatly outnumber Japan’s own turtles



APR 26, 2016

Invasive red-ear slider turtles now vastly outnumber endemic Japanese turtles and are causing significant stress to the ecosystem, the Environment Ministry said Friday.

A study has put the number of red-ear sliders at 8 million, eight times the total population of endemic species.

Originally from the United States, the animals are widely kept as pets. However, they can grow to a considerable size and are often dumped in ponds and rivers when they outgrow their lodgings.

The species is known in Japan as midorigame and in some other countries as the red-ear terrapin.

“The growing population of red-ear slider turtles would mean the depopulation of insects, fish and other turtles that live on water weeds,” Masato Morikawa, an official in charge of monitoring alien species, told The Japan Times on Monday. “The population has gradually but continuously been increasing over the years.”

The species is believed to have been introduced after World War II. From the 1970s, the animals were widely sold at matsuri (festivals) and pet shops.

It is only one of several invasive turtle species now displacing local species.

The ministry said red-ear slider turtles have mainly colonized waterways in Kanto, Chubu and the Inland Sea areas. The entire population is estimated to consume up to 320 tons of water weeds each week.

Morikawa conceded that the need to control other alien species is more pressing as they can cause harm to humans: the poisonous red-back spider and the snapping turtle, which can bite off a finger, are among the priorities.

“At this point, the red-ear slider turtles are exterminated only in areas that are extremely overpopulated, but we are strengthening measures against them,” he said.

The ministry plans to restrict imports, crack down on the abandoning of pets and step up culls.

Article ends.

The writer did make a noticeable mistake in the article – baby red-eared sliders are known as midorigame whereas the species is known as akamimigame or, more correctly, mishishippi akamimigame.

Many people are unaware that it is not a native species.  Others simply take the dichotomal view that it is “foreign” as opposed to “Japanese” – rather than the infinitely more accurate and helpful “introduced” or “feral” as opposed to “native”- and therefore has some natural advantage.  (Much the same way foreign-born sumo wrestlers somehow have an unfair natural advantage… because…  er… reasons)

Red-eared sliders do have certain advantages in this case.  Firstly, they mature at an earlier age than the native turtles they compete with.  They also grow larger, enabling them to successfully compete for basking and nesting space, plus acting as a deterrent against would-be predators.  Thirdly, they are omnivores – the young have a tendency towards carnivorous habits while older turtles prefer plant material – and will feed on either plant or animal matter as need dictates.  Finally, the Japanese suburban and semi-rural environments lack predators that significantly impact their population.  The Mississippi red-eared slider’s natural enemies include alligators, raccoons, and skunks, all missing from the Japanese ecosystem.  Foxes and badgers may prey upon young turtles, but these are noticeably absent from most suburban environments.

My take: The reason for these turtles damaging the environment can be put down to human irresponsibility.  No kind of permit is required to buy the babies sold at shops or even stalls.  A lack of understanding of the responsibilities involved (“What?  I’m supposed to look after this for the next 30 years?”) plus a complete absence of any understanding of the biology of the sliders – like that they don’t remain babies forever.

They start off small, cute and green… but grow to be not small, not cute and not green.

I really have a disdain for killing reptiles, but I feel that culling will be the only way to control their numbers, in addition to banning further imports and restricting ownership.

On the good news front…

4 Nov

Hi blog.

A new post is long overdue, and I’m lucky to have stumbled onto some good news for a change.


Sea turtles seen laying more eggs

The Yomiuri Shimbun

4:37 am, October 31, 2014

The Yomiuri Shimbun More sea turtles have been coming ashore in Japan to lay eggs in recent years, according to a survey finding by the Environment Ministry. Loggerhead musk turtles, one of the species seen in the nation, were spotted laying eggs on 9,661 occasions in fiscal 2012, compared with less than 2,000 in 2006.

The findings were based on data collected by local volunteers, who surveyed the egg-laying habits of sea turtles at 41 sandy beaches, including those in Chichijima island in a remote part of Tokyo, in Omaezaki, Shizuoka Prefecture, and on Iriomote Island in Okinawa Prefecture.

“Sea turtles who were born after the nation’s sand beaches were markedly rejuvenated in the 1970s or later across the country may have returned to the beaches upon maturing,” said an official at the ministry.

The sea turtles that lay eggs on sandy beaches in Japan are mainly green turtles, loggerhead musk turtles and hawksbill sea turtles, all of which are registered on the ministry’s red list of endangered species.

Of them, loggerhead musk turtles, which can be seen on beaches ranging from Ibaraki Prefecture to Okinawa Prefecture, were seen to have laid their eggs on 3,562 occasions in fiscal 2004. There were only 1,919 such occasions in fiscal 2006. In the following years, however, the number started rising to reach 9,661 in fiscal 2012.

Green turtles, which are often spotted on beaches in the Ogasawara islands, were recorded to have laid their eggs on 265 occasions in fiscal 2012, up from around 100 times a year up until fiscal 2009.

Meanwhile, hawksbill sea turtles, which were spotted laying eggs no more than four times a year — and sometimes not at all — until fiscal 2009, laid their eggs nine times in fiscal 2011.

Sea turtles are said to become mature at ages ranging from 30 to 40, laying eggs once every two to four years.

Sandy beaches in Japan have been steadily renewed since the 1970s thanks to relocating wave-dissipating tetrapods closer to land and introducing sand, according to the ministry.

The latest survey results also showed that since fiscal 2008, the predation of eggs by such animals as wild boars and raccoon dogs was reported on many occasions. On Iriomote Island, as many as 60 percent of the egg-laying spots were attacked by predators in one year.

The ministry will also expedite its efforts to implement countermeasures such as setting up protective fences.

I’m hoping that the up-beat mood of the article is justified and not just another feel-good piece of journalism.  I guess we’ll just have to wait and see.

Good luck, turtles.

Splitting hairs? An adventure in Cross-Linguistic Naming

6 Nov

One of the interesting aspects of doing any anything nature-related in Japan is the difference in nomenclature between the English and Japanese languages.

Most non-linguists tend to think in very absolute terms – generally along the lines that their language’s interpretation of the world is the only one.  They are usually also guilty of believing that every word has an exact counterpart in other languages.


Let’s take a simple example, like “caterpillar”.

Simple, right?


Are you talking about a smooth-skinned caterpillar (further divided into “green” and “not green”!), a not-green looper or inchworm, or a hairy larval form of a moth or butterfly?  The Japanese language makes distinctions between all of these.

The smooth-skinned caterpillars come under the term “imomushi” (芋虫).  This group has two more sub-divisions: loopers or inchworms, called “shakutorimushi” (尺取り虫) – “measuring insect”, and the green-coloured varieties or “aomushi” (青虫) – “green insect”.

It’s green! The caterpillar of the swallowtail on a mandarin tree.

It bears mentioning here that the Japanese word “mushi”, while often translated as “insect”, is closer in meaning to the American generic “bug”, or the “creepy-crawly” of my childhood.  Thus, insects, spiders, centipedes, snails and worms can all come under the vernacular “mushi”

And if that’s not confusing enough, “ao” is usually translated as “blue”, but in reality covers a whole range of colours from blue to the light greens.  Green vegetables are “blue vegetables”, the green traffic light is also “blue”.  Translation work sometimes leaves me feeling blue (or is that green?)


The other group of caterpillars is the one whose members possess hair or spines as defensive mechanisms.  These are collectively known as “kemushi” (毛虫) – “hair insects”.  Most of these are the larval forms of moths, but some butterfly larvae are also in this group.


To complicate the issue further, there are also common names given to specific caterpillars.  An example of this is the moth Monema flavescens, known locally as iraga (刺蛾), although at least a dozen regional names also exist.  The larval form is called iramushi (刺虫), and loves persimmon leaves.  I can tell you from personal experience, you DON’T want to touch one of these!!  Just brushing against it produced more pain than a bee sting, and a rash which lasted all day.


Twenty milimetres of pain – the larval form of the iraga moth. Photo courtesy of Wikipedia.

I’ve just mentioned regional names, and these can cause confusion too.  Freshwater fish often have several different regional names, making it difficult to be sure which fish is being discussed.  Furthermore, the regional name for one fish may be the same as another regional name for a different fish.

Another example of identity crisis of is the raccoon dog, or tanuki (), with the badger, or anaguma (穴熊).  Both these animals are superficially similar, but are not closely related at all.  In some parts of the country, a dish known as tanukijiru (“tanuki soup”) is known, but it more likely contains the meat of the badger – assuming it contains meat at all.  Another dish bearing the same name is a vegetarian dish, the meat being substituted with konyaku.

Confusion arises because both these animals have been known as mujina () in different areas.  The soup in question was often known as mujinajiru.  Ascertaining which animal “mujina” refers to is difficult at best.


Spot the differences. Tanuki (top) and Japanese badger (bottom). Photos courtesy of Wikipedia.

The tanuki is a fascinating animal and deserves its own blog entry.


Now to the flipside – distinctions made in the English language but not in Japanese.


I recently learned that there are no rabbits on mainland Japan.  Japan’s only true rabbit is the Amami rabbit, Amamikurousagi (奄美黒兎) of Amamioshima and Tokunoshima islands.  The “rabbit” of Japanese folk tales is actually a hare – Nihon nousagi (日本野兎) or just nousagi (野兎).  The generic word usagi in Japanese can be either a rabbit or a hare – the language doesn’t make the distinction.  (It doesn’t split hares?)


A translation of “Kachi-Kachi Yama”. The hare has been translated as “rabbit”, and the tanuki described as “a kind of badger” – it’s actually a member of the dog family. Scanned from “Once Upon a Time in Japan”, Kodansha, 1985

Another generic word is hachi ().  Most Japanese (and their Japanese-English dictionaries) translate this word as “bee”.  In fact, the insect in question is more likely to be a wasp or hornet.  There are specific names for different bees and wasps, but the bee/wasp distinction is not made.


Bees and wasps. Clocwise from top left: Japanese hornet, Japanese honey bee, large carpenter bee, paper wasp. All “hachi” in Japanese.  Images courtesy of Wikipedia.

And finally, turtles and tortoises.

Growing up in Australia in the 1980’s, we (or rather, herpetologists) had three turtle/tortoise distinctions – turtles (specifically flippered sea animals), tortoises (club-footed or clawed animals that spend most of their time on land) and freshwater tortoises (animals with webbed feet and living in lakes and rivers) – also known as terrapins in the UK.  In the ‘90s, this changed to just turtles (aquatic or marine animals) and tortoises (terrestrial animals).

In Japanese, these animals are known collectively as kame ().  But then, the Japanese language has a separate word for soft-shelled turtles – suppon ().


This is just a small selection of some of the challenges of cross-linguistic wildlife watching.  There is no “right” or “superior” language for dealing with nature – one needs only an open and inquisitive mind.

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