TsukuBlog

A Local Perspective on Life in Tsukuba, Ibaraki, Japan.

Japan`s House Bats- Watch Them Flit about the Evening Sky in Most Residential Areas

 

A bat

An ABURA KO-MORI (Japanese house bat), the only one of Japan`s 30 or so bat species to live almost exclusively in residential areas

By Avi Landau

 

As a nature lover, I was really spoiled during my first years in Tsukuba. After a few weeks of enduring (what I remember as) the prison-cell-like rooms of Tsukuba University`s Oikoshi Dormitory Complex, I was fortunate enough to have found a nice house to live in right smack in the middle of one of the city`s wildest areas-  Konda-Dai , which though conveniently located only about 2.5 Kilometers from the Tsukuba Express`s Terminal Station, had  remained almost completely undeveloped- because of the presence of numerous archaeological sites and rare protected birds. There I could observe the area`s abundant wildlife without even having to leave the the comfort of my home! From the wide upstairs windows I could spy pheasants, weasels, goshawks, hares, quail, very long Japanese rat snakes, and even once- a fox.

Abura Ko-mori (Japanese house bats) live under the eaves of people`s houses, in chimneys, attics, or in any tiny space they can find. They eat plenty of mosquito and other bugs while they are out feeding for a two hour period after dusk sets in.

Abura Ko-mori (Japanese house bats) live under the eaves of people`s houses, in chimneys, attics, or in any tiny space they can find. They eat plenty of mosquito and other bugs while they are out feeding for a two hour period after dusk sets in.

.At night my yard would be visited by badgers, racoon-dogs and palm-civets. The loud hooting of owls was my bedtime music- and the croaking of frogs in summer was often so loud that I could not hold a telephone conversation. It was a happy life.

 

Then came the big earthquake of March 11th- and it all ended. The old place became unsafe, and the unthinkable (for me at that time) happened- I had to pack up and move somewhere else. It was truly traumatic. Fortunately, with the help of very kind people, I was able to move into a beautiful reconstructed old Japanese farmhouse near the foot of Mt. Tsukuba in the old town of Hojo. Right in front of this house ran a river- well to be more specific, an irrigation trench- which was full of creatures- fish, crabs, frogs, and very often the most beautiful bird which can be seen in Tsukuba (or perhaps in all of Japan)- the kingfisher (KAWASEMI). So that house also turned out to be great for a nature lover………….. but then a tornado hit the town………….. and it was time to move again!

 

The next house that I found was in one of Tsukuba`s new residential neighborhoods. It had been created in the 1970`s by bulldozing and paving over what had been (as some older Tsukuba natives have told me) an impassable woods and marshland. Though it still does have nice parks and is VERY convenient- it consists mostly of  rows and rows of houses closely packed together. I was more than a bit depressed about what moving there would mean for my around- the-house wildlife viewing.

An abura ko-mori clinging onto the wall of a house. These tiny bats find roosting spaces in any cracks or holes they can find. They thrive in palces that are well lit at night because the lights attract the insects upon which they feed

An abura ko-mori clinging onto the wall of a house. These tiny bats (between 3.4 and 4.8 cm in length) find roosting spaces in any cracks or holes they can find. They thrive in palces that are well lit at night because the lights attract the insects upon which they feed

JAPANESE HOUSE BATS (ABURA KO-MORI, 油蝙蝠)*

But when I took my first evening walk in Matsushiro ( the name of my new neighborhood) after having moved in, I noticed little black creatures darting about in the twilight. Because of their size and color, I immediately tagged them as swallows (TSUBAME), which spend the summer in Japan, flying about like little fighter jets, picking mosquitos and other insects out of the air.

Then I stopped for a better look. Something was strange. While swallows fly sleekly and gracefully, what I was watching flitted about in strange zigzags patterns- as if they were drunk.

But then, as my eyes adjusted to the dim twilight, I realized that what I was looking at were bats- and there were lots of them!

And since like swallow bats also grab insects out of the sky- after detecting them by echo-location with their built-in sonar system- I decided to have a bit of fun by tossing  tiny pebbles into the air. The trick worked- as nearby bats quicky sped towards the rising stones- though they gave up on them as they started to drop, probably realizing by this motion that these objects were not insects.

So  now I knew that there were bats in my new neighborhood- but what species were they?

Well, identifying them might not seem like an easy task when you find out that there are about 30 bat species that live within the Japanese archipelgo.

The fact is, however, that there is only one of these species, and a very common one at that, that prefers to live in, or should I say almost exclusively lives in, populated areas, usually roosting in houses, store-houses or other man-made structures- the ABURA KO-MORI (or IE KO-MORI), the Japanese house bat.

A few weeks later, a zoologist who lives down the block from me confirmed this identification (one interesting thing about Matsushiro is that most of its residents are scientists or professors!).

The Japanese house bat lives not only on Japan`s main islands (from southern Hokkaido on down) and many of its outer islands, but also in eastern Siberia, China, Korea, Taiwan and Vietnam.

While most of Japan`s wild mammals have been decreasing in number, housebats are one of the species which have been increasing- and in some places, including Tokyo- dramatically so.

This is because the so-called Heat Island Phenomenon which has been responsible for rising average annual temperatures in all of Japan`s concrete jungles has meant more insects for the bats to feed on- as well as more warmth, which has decreased the bats period of hibernation (traditionally from November through March).Many house bats in Tokyo (or even Tsukuba for that matter), do not hibernate at all anymore.

While you can see bats every evening in Matsushiro (near Matsushiro Park) and around Doho Park (among other places) one of the best places to see large numbers of housebats at dusk is along the Meguro River, near Meguro Station in Tokyo.

Though bats eat LOTS of harmful insects and have traditionally been considered a LUCKY animal- modern Japanese who value convenience and cleanliness over all things do not like bats living on their property. Any hardware store or homesupply center has bat repellant on its shelves.

Though bats eat LOTS of harmful insects and have traditionally been considered a LUCKY animal- modern Japanese who value convenience and cleanliness over all things do not like bats living on their property. Any hardware store or homesupply center has bat repellant on its shelves. This product is apparently effective in keeping away both bats and moles!

Bats and Swallows Have Lost Traditional Respect Given Them

I have described above how I first thought that the bats flying in my neighborhood were swallows. The similarity lies not only in their size and the fact that they fly about quickly.

Swallows and housebats both eat harmfull insects during Japan`s hotter months, and both nest or roost in or on man-made structures- very often private homes.

Though they are mammals and not birds,bats could be said to be nocturnal swallows, who like swallow live in people`s houses  and hunt insects in the dark instead of daylight, using echo-location instead of their eyes.

The two species , share one other characteristic: they were both long considered by the Japanese to be lucky creatures, and houses which were selected by either or both as a place to live were considered to be fortunate.

In recent years, however, people have been forgetting these traditional attitudes, as convenience and cleanliness have grown more important in people`s lives than kindness.

People don`t want swallows nests on their homes anymore as the birds are noisy and soil the area beneath them.

Bats nesting in or on people`s homes can be noisy and dirty. Their droppings are smelly and they also carry fleas. While male bats live on their own, the females and shildren roost together. Sometimes as many as 200 bats take up residence at one house. That means a lot of droppings.

So while in past ages families happilly tolerated (or even celebrated) the presence of these creatures- now many families knock down swallows nests and call the exterminator or put in bat repellent when they realize bats are roosting in or around their homes.

PERSONAL MEMORIES OF BATS

Though I definitely do not find bats cute, I do find them AMAZING- especially how agile they are and how accurately and quickly they can navigate using their echo-location system.

My first experience with these strange creatures (they sleep, mate, and raise their young UPSIDE-DOWN!) was when I was 18 years old. I was travelling around Egypt for about one month and  was sailing for a few days along the Nile in a feluka- the traditional Egyptian river boat. Every evening MILLIONS of bats would fly along the great river`s banks. My first time to approach and then become encircled in such a swarm while walking on the banks of the Nile, I froze thinking I would be hit by one (or many) of them.memories from my chidhood- I was perhaps 6 or 7 years old- and my mother telling me of how bats got tangled up in your hair flooded my brain. ( its strange how certain memories stick with you, while others don`t). I soon realized, though, that the bats would never hit me, no matter how quickly I moved or no matter how full the air around me was with them- their radar was too sensitive and their reactions too quick for that. Well I guess that should have been obvious since they can detect and snatch flying insect in the night air!

There was also the time on Borneo, along the Kinabitangan River in Sabah whern I was standing uder a tree trying to get a better look at a fruit large bat which was munching on some fruit. Suddenly something came plummeting towards me- and I didnt get out of the way on time……SPLAT…… my t-shirt was covered in an interesting purple pattern created by the impact of bat poop (by the way, some of you might remember my post about an ice-cream shop in Ibaraki Prefecture which sold two products: ice-cream and bags of bat guano (poop) for use as fertilizer).

A bag of bat poop being sold as fertilzer at an ice cream shop (now unfortunately closed down) in Kasumigaura City

A bag of bat poop being sold as fertilzer at an ice cream shop (now unfortunately closed down) in Kasumigaura City

Other  places I have been to which were great for observing large fruit bats (and when I say large I DO mean large!) were Sydney Australia (at the park near the Opera House) and along the Ganges River in Bagladesh- from the River Rocket ferry.

Surprisngly, it was near Tsukuba (in Ina Machi, now part of Tsukuba Mirai City), that I got my closest look at one of these fruit bats. Apparently someone had been keeping one of these cat-sized critters (they are also called flying foxes) as a pet- but could not take care of it anymore. It was then adopted by a friend of mine, a veterenarian, Dr. Koyano. It was at his office that I had a flying fox try to climb up my leg- upside-down, of course. Creepy!

 

Then is is what is probably the most dramatic story of all- sitting at a restaurant on Saipan and having a bowl of soup set down on my table containing broth…….and one whole boiled bat !

 

Anyway, just as I used to take guests out for shorts nature walks when I lived in Konda-Dai and Hojo, I now take visitors to my place in Matsushiro out as well- at dusk- to see the bats !

* The scientific name of the Japanese house bat is pipistrellus abramus. When I first saw this name I assumed that a scientist named Abrams or Abram had been involved in introducing the species to the west. Well this is a good example of the old adage: when you assume, you make an ASS of yourself ! This is because abramus does not derive from the name Abrams but from the Japanese word ABURAMUSHI which means oil bug. This is what the people of Nagasaki called the house bat when none other than Philipp Franz von Seibolt, the German doctor and naturalist stationed at the Dutch trading post of Dejima (an artificial island built for the foreigners in Nagasaki Harbour) was living there (in the early 19th century). It was Siebolt who first introduced this bat to Europeans and it was he who transcribed ABURAMUSHI as aburamus.