Alien Invaders!

I come in peace. I will leave your ecosystem in pieces.

Aliens???

Well, when it comes to wildlife, the term ‘alien species’ basically refers to any species found in a habitat outside of its native range. Basically, species that are here that aren’t supposed to be thanks to humans, be it accidental (eg. stowaways) or intentional (eg. releases).

You may have heard of the term ‘Invasive species’. Broadly speaking, these are aliens which have adapted so well to their new environments that they have begun to harm the habitat.

These will be the kinds of species we’ll be talking about today. Some of you might be surprised at some of the entries – without further ado let’s dive into it!

Content Warning: This post features images of injured and dead animals. If you are squeamish, eating or whatever, just bear that in mind when reading about our second animal here.

Alien Invader #1 – White-vented Myna

The bane of Orchard Road, Shenton Way, native wildlife, and me, every single morning trying to sleep in.

Many of us may know of this one. Also known as the Javan Myna, this super common bird is native to, well, Java in Indonesia. It was introduced to Singapore as a part of the cagebird trade, but subsequent escapees/releases had established a wild population by 1925.

A flock of roosting Javan Myna (Acridotheres javanicus).
Credit to Low Choon How.

As most of us can attest to after a meal in the hawker centre, the Javan Mynas aren’t picky eaters at all. While they do have their natural preferences, they’ll eat just about anything they can get their hands (or I guess, beaks) on.

They aren’t too fussy about nesting sites either. Almost any small space – gaps in overhead train lines, spaces in HDB shelters and holes in trees is fine with them.

These guys are pretty bold and intelligent, too. They’ve been observed coming up close to humans (unfortunately still an excellent source of food) going so far as following grass cutters to catch exposed insects. In one instance a lone individual was seen picking a fight with a monitor lizard!

Juvenile Oriental Magpie-robin. This once-common native has become much rarer in recent times. Taken at Gardens by the Bay.

All of these factors combined are the reason why they’re now the most common bird in Singapore. Being so adaptable to the environment forces native species to compete in order to survive.

The Oriental Magpie-robin is one such species. In addition to illegal trapping for sale as a prized songbird (more on that in a future post), this species has faced stiff competition from Javan Mynas. It’s gotten to a point where most locals can’t really recognize this bird anymore!

(Un) Common Myna (Acridotheres tristis).
Credit to Hobbyfotowiki.

Another severely affected species, the Common Myna, has been forced to change its name the to Uncommon Myna instead to more accurately reflect its status locally. (I should stress that this is a joke and not meant to be taken literally).

In all seriousness, the populations of our native birds have suffered greatly. As you’ll see later on, many invasive aliens are able to freely multiply because the ecosystem cannot change quickly enough to adapt to a new addition. Most of our common urban birds for example, like the Rock Pigeon or House Crow, are invasive aliens as well.

Many of these birds have multiplied to the point where they’re not just a nuisance to the ecosystem, but to people as well. There are some things we can do to address this problem, and I’ll be covering that in a future post discussing our interactions with our urban birdlife.

Alien Invader #2 – Red Eared Slider

Sometimes cute, but often a two-faced parasite who pretends to like you for food. Wait. Nevermind. All pets are like that.

Most people know these as simply “terrapins”, and they are pretty common around Singapore. Chances are, if there’s a pond or a lake in a park, there’s a couple of these guys there too. They are native to North America though, so why are they seemingly everywhere here?

Well, many people have released them into the wild over the years. Some, out of goodwill or religious beliefs, believe that release would be for the animal’s own good (returning it to nature), while others simply cannot care for them anymore.

Red-eared Slider hatchlings commonly sold in pet stores. Credit to Tadpole667

A big issue is that they are easily found in many pet stores, at really cheap prices and small sizes. Gives the impression that it’s a cute, unique and low-maintenance pet but that could not be farther from the truth.

As an owner of one of these myself I can confidently say that providing proper care for a terrapin is not very easy or cheap. These guys are a commitment, too, being able to grow up to 30 cm on average, and live well over 20 years.

A terrapin which was attacked by another one. It had to be euthanised due to its severe injuries. Credit to ACRES.

So when they realise this, many owners release them into the wild, thinking they belong there and may do better in the wild instead.

Unfortunately, according to NParks 80-90% of released animals in Singapore do not survive their first day in the wild. Having lived under human care, they often lack the skills needed to survive in the wilderness. Many find themselves disoriented in a completely new environment, now needing to deal with predators and having to look for food on their own.

The ones that do survive on the other hand, have the potential to be invasive species.

It’s believed that native species like the Malayan Box Turtle have dwindled greatly for reasons similar to the Common Myna – competition with the invasive aliens. Red Eared Sliders are hardier, larger, bolder, more aggressive and reproduce much more efficiently.

Malayan Box Turtles (Cuora amboinensis) are among the species directly impacted by Red eared Sliders. Photo was taken at Singapore Quarry.

They can also be rather damaging to the environment. As any terrapin owner can tell you, these guys devour pretty much anything and everything, and their voracious appetites can be quite destructive to native plants. Hence, other animals which depend on these plants for food are also affected by the presence of this species.

What can we do, then? Well, for those of us who already own one, just don’t release them into the wild. There’s a good chance your terrapin will be much happier staying in your home than in the wild. If you can no longer care for it, consider rehoming them instead. That’s how I got my terrapin, actually! What’s important is they are not released into the wild.

Operation No Release, an initiative started by NParks to advocate for, well, no release of animals into the wild.

For the rest who may be considering getting a terrapin as a pet, do your research first and make sure you’re fully committed to owning one. Owning a pet is a wonderful experience but it is a lifetime commitment, and if you’re not prepared for that, don’t get a pet.

All right, back to the alien invasion – who’s up next?

Alien Invader #3 – Dioscorea sansibarensis aka “the Batman plant”

Bat you didn’t see that coming.

Yep, you saw that right. plants can be invasive species too! Dioscorea sansibarensis, also known as the Zanzibar yam, is often called the “Batman plant” locally because the shape of its leaf so closely resembles the Batman symbol.

The Batman Plant growing on trees. Credit to Kwan.

Originally from Africa, this weed can be found everywhere in our forests. And I mean EVERYWHERE. Next time you head to our nature reserves, keep a lookout for these guys on the forest floor where they’re especially visible. You’ll see what I mean.

So, what’s the problem with these aliens?

Well, these guys grow extremely quickly and cling on to growing trees to soak up more sunlight. This blocks light from reaching younger saplings and hinders their growth. In the long run, this can be really detrimental to the growth of forests.

Understandably, NParks has been actively attempting to remove this species from our forests, but it’s proving a lot more difficult than you’d expect.

The huge underground bulbs of Dioscorea. Credit to NParks.

For one, these plants are incredibly resilient. I’ve personally taken part in one of NParks’ removal attempts, and wow, it truly is an intense workout.

Not only do you have to struggle against the tangled mess the weeds, but you have to remove their huge, underground bulbs as well. as you can see on the left, some of them can be quite huge. The biggest ones I’ve seen personally were around 10-12kg!

And here’s the kicker: These bulbs have to be completely removed. If even the smallest shards or shreds are left behind, the plant is still able to regrow and establish itself once again. A truly fearsome opponent indeed.

Operation “Die Dioscorea”, as it’s called, involves repeated, continuous removal of this invasive plant from our forests. It’s not easy, as cleared areas constantly need to be rechecked and re-pruned accordingly. From my research, it seems the operation has been happening since at least 2009 till now. That’s how amazingly formidable and impressive this plant really is!

Many volunteers (myself included) have found that while tiring, the experience still is pretty fulfilling. Even if the plants aren’t fully eradicated, keeping their growth to a minimum can really work wonders for the sake of the ecosystem. If you’re interested to try it out yourself, check this link out for more details.

Conclusions

This is by no means an exhaustive list. There’s plenty of flora and fauna here that don’t belong, but for better or for worse, they are mostly here to stay. I have to say though, many of these species we see all the time everywhere to the extent they’re mostly overlooked – they do command some level of respect. Their tenacity and fearsome natures have enabled them to be some of the most common examples of nature many of us frequently encounter.

While their presence should not be something we actively encourage, animal cruelty or killing these animals is really not the solution. It is not the animals’ fault that they are invasive – they are merely fulfilling their biological instincts. It is instead our responsibility to manage and ethically keep their negative ecological impacts to a minimum.

With the plants though. Yeah, plant murder is fine. Well. That’s a whole other can of worms.

Maybe I’ll open it one day. Until next time, seeya 🙂

References/Additional Reading

Non-native Residents https://www.nparks.gov.sg/mygreenspace/issue-27-vol-4-2015/conservation/non-native-wildlife-in-singapore

Invasive trees?! https://journals.sagepub.com/doi/10.1177/194008291500800116

White-vented Mynas https://lkcnhm.nus.edu.sg/dna/organisms/details/470

Red Eared Sliders http://www.reptilesmagazine.com/Red-Eared-Slider-Care-Sheet/

https://lkcnhm.nus.edu.sg/dna/organisms/details/819

Dioscorea https://www.nparks.gov.sg/mygreenspace/issue-06-vol-3-2010/conservation/freeing-the-forest-from-weeds

Image Credits

“Batman plant”: http://www.natureloveyou.sg/Dioscorea%20sansibarensis/Main.html

Javan Myna: https://en.wikipedia.org/wiki/File:Acridotheres_javanicus_-_Kent_Ridge_Park.jpg

https://singaporebirdgroup.wordpress.com/2015/06/05/the-javan-myna-mixed-fortunes-of-a-familiar-stranger/

Common Myna: https://commons.wikimedia.org/wiki/File:Common_myna,_(Acridotheres_tristis).jpg

Red Eared Sliders: https://commons.wikimedia.org/wiki/File:Baby_Red_Eared_Sliders.JPG

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