All you wanted to know about house geckos

Soon after I arrived in Townsville I learned that two species of gecko lived in the houses here, one native and the other a recent arrival from Asia. They looked almost exactly the same and had the same lifestyle, and no-one I knew could reliably tell the difference between them except that the Asian geckos chirped.

That’s where my knowledge stopped until I decided recently that it was time I sorted them out. Here goes:

pinkish gecko on wall
Asian House Gecko, Hemidactylus frenatus, aka Pacific house gecko, spiny-tailed house gecko and bridled house gecko (click for larger image, as usual)
pinkish native gecko on ceiling
Native gecko, Gehyra dubia, aka Dtella, Dubious gecko or tree gecko

Both of them are genrally known simply as ‘gecko’ and I have also heard ‘jelly lizard’ as a common name from an older resident.

They are both about the same size, growing to approximately 15cm overall. Both of them change colour according to their surroundings and are usually dark with a distinct pattern by day but pale and almost patternless at night.

dark gecko
Asian gecko in a shady spot under the house during the day

Both of them are primarily nocturnal and their hunting strategies are very similar: both are “ambush” hunters in that they sit and wait for prey rather than actively roam in search of it.

The most reliable way of distinguishing them is that the Asian gecko has a series of small spines along the top and edges of the tail (in its original state); the top row extends onto the lower back as small bumps. If you catch one, you can check its toes: all toes of the Asian gecko have claws, but the inner toes of the Dtella are clawless. Also, the native gecko generally has paired white spots along the spine, as in my second photo on this page, though they may not be at all obvious in darker colour modes.

The two species can also be distinguished, more easily though not so reliably, by their calls. The Asian gecko calls more often and more loudly than the native species; its loud “chuck-chuck-chuck” is obviously the origin of its Indonesian common name, Chichak or Cheechak. The native gecko’s call is a softer chattering.

brown gecko with grey tail
This native gecko’s tail has regrown with strangely contrasted colouring

There are slight behavioral differences between the species. It appears* that the Asian geckos are willing to tolerate brighter lights while hunting than the native species, which means that native geckos are more likely to lurk in the shade of curtains or picture frames and dart out at nearby prey whereas Asian geckos often rest in brightly lit open spaces, relying on immobility to remain unnoticed by their prey. It probably gives Asian geckos a competitive advantage in our houses, too.

The Department of Agriculture, Fisheries and Forestry information sheet on Asian geckos (pdf here) doesn’t give quite the same reasons but comes to similar conclusions:

H. frenatus is an aggressive and territorial species, features that allow it to successfully compete with native species. … Male and female H. frenatus are known to eat juveniles of other gecko species as well as their own progeny (Bolger and Case, 1992).

The ability of H. frenatus to replace locally native gecko species seems most pronounced in urban areas. Artificial lighting on buildings attracts large numbers of insects and H. frenatus is well adapted to utilise this food resource, perhaps more so than native gecko species, which may be better adapted to hunting more dispersed insect populations.

I walked around my house with a camera one evening to see whether I could identify the species we had here and the results lined up very neatly with that light tolerance. (For the record, I saw three or four geckos in each room and there are probably just as many in each bedroom. We don’t bother them, since they eat lots of insects and they don’t bother us at all except by leaving neat little black and white droppings.) I found only Asian geckos in the kitchen (most brightly lit and fewest shady hiding spots), only native geckos in the lounge/TV room (dimmest lighting) and both species in the study-cum-reading-room (mid-level lighting and plenty of hiding places).

Asian gecko pale brown
An Asian gecko on a window at night

Sources:

*Information from Professor Lin Schwarzkopf of James Cook University’s School of Marine and Tropical Biology, which confirmed and explained a vague memory I had of being told, years ago, about a difference in hunting styles.

24 thoughts on “All you wanted to know about house geckos”

  1. Great post! I always just thought the light coloured ones were Asian geckos but you have set me straight…I’ll check tails from now on.
    I hope it’s ok that I linked back to this post from one of your photos? If not I will remove it immediately; of course just when I needed a photo of our own resident gecko he is nowhere to be found!

    1. Hi, Michelle,
      I’m glad to have helped you with ID and I enjoyed your post about your domestic wildlife. It sounds like you have more reptiles than we do, but then again, we have a cat which is a very active hunter.
      I looked to see where you were writing from and couldn’t see any indication. It might be worth adding “Brisbane” or “SE Queensland” or whatever to your “About” page.
      As for using my photos – I’m generally happy for people to do that but I like to be acknowledged for them, with “photo by Malcolm Tattersall” or words to that effect and (preferably) a link back to the source. That goes for my Flickr photostream, too, which has more geckos and frogs and lots of insects.

  2. Thank you for explaining , :) , one of the things you always like to know , we seem to only have the whitish smooth ones here ( Redlands, Qld) haven’t really seen the spiny tailed ones around and I was having a discussion ( disagreement really) about which were which .. Luckily I was right so I am going to show your article to them :))

    1. I’m glad my article was helpful, but I do hope you weren’t too mean to the person you were discussing the geckos with, because they really are very hard to tell apart.
      I was talking to someone from Brisbane a couple of weeks ago and they said that the Asian ones have almost completely displaced the natives down there but I wouldn’t be surprised if it varies a lot, with houses near bushland still having (more) natives than fully urbanised areas and a lot of places having a mixture as we do here.

  3. Got at least one of the asian species running around my flat (in Gympie, Qld). I leave him (or her) alone and he leaves me alone. We co-exist in harmony, but if he keeps the insects down, he’s earning a roof over his head.
    It annoys me when I see people regarding these harmless (unless you’re a mozzie) creatures as “creepy-crawlies”, taking any steps they can to eradicate them from their home.
    Great post. I didn’t know how to identify each species, before reading this.

    1. I live completely surrounded by bush and have several species of native gekos here. Recently one or more Asian gekos have moved in. As they threaten to displace the native gekos I would like to remove them before their population increases too much. Has any one heard of an effective trapping method?

      1. Hello, Di,
        I’m having trouble imagining any trapping method which would discriminate between species which are so similar in size, prey and behaviour. My only suggestion would be to encourage the natives by minimising artificial light around the house – turning off lights when you’re not in the room, reducing exterior lighting, etc – since it seems that the Asian geckos do better in brightly lit places. I know it’s not a solution, but it may tilt the balance just enough in the natives’ direction. And after all, such small environmental differences around my own house do seem to make a difference to which species dominates each room.
        Good luck!

  4. Great information…thank you! We have recently moved to Townsville and have not seen so many Gecko’s before. They are cute little things. I was also curious about whether they were poisonous to cats, but if your cat hunts them (and I am sure eats them), I will not have to worry about our cat now. It will keep her busy trying to catch them!

    1. Welcome to Townsville, Tracy!
      I’m happy to help, but a bit ambivalent about your cat (and a bit ambivalent about my own, I must admit, for similar reasons).
      Firstly, cats are responsible for killing far too much native wildlife. On the the other hand, they are hunters, and we can’t ignore their nature altogether. We compromise by keeping our cat indoors at night, which is peak hunting time, but he still kills lots of skinks and occasional tree snakes and birds, as well as the geckos.
      Secondly, many wild animals do carry parasites which can affect predators, and if the predators are our pets we can pick up the parasites ourselves. I’m no expert but http://cairnsvet.com.au/cairns-pet-health-problems/ seems to cover them fairly adequately and not too technically. There’s no need to panic but it’s good to know the risks.

  5. Wonderful post, but may I please add that Asian House Gecko’s tails will not be scaly if they fallen off and grown back. Therefore you should check the lower back when you see a gecko with no scales because the indigenous gecko will not have a scaly lower back

  6. Yeah sure it’s all love, love, love till they start pooping on everything you own! I use to think they were cute too. Now they have out competed all our native ones and I think of them as larger cockroaches. They are a pest do not be fooled.

  7. Good info but if they are not native they shouldn’t be here all they do is take food from native species and crap everywhere crawley cruncher sorts them out

  8. I find them a pest. They bark at night and crap all over the walls and am happy to get rid of them do I don’t have to constantly clean up the mess they leave. Peter

    1. G’day, Peter,
      What you say about them is absolutely correct and your response to them isn’t unusual. Our choices, what ever they are, always affect the world around us. Most obviously, we go into the garden and kill what we call weeds for the sake of what we call flowers and vegetables. Is that fair to the weeds? Not really. They were only doing what the flowers and vegetables were doing, growing as well as they could.

  9. Hi Malcom,
    Thanks for the info. I’m newly arrived in Brizzy and find we have a few popping up in the house, and a couple outside living near the front door light. Your info will help us tell them apart. Although it’s only the outside ones that ‘cluck’.

    I do have a question though – do they eat fruit ? This morning one of our lady finger bananas was nibbled. It sat in a fruit bowl, 1.5 meters up on shelves. No poop, so did not think it was nice or rats. Would it have been our inside geckos?

    Many thanks
    Maree

    1. Yes, they will eat fruit. They seem to have difficulty with tough skins but will nibble a banana, especially if its stem has been broken off to expose the fruit, or a mango if its skin has been nicked.

  10. Does anyone know if the Asian geckos (or the native ones) eat bees? I’ve seen them hanging around my hive but I’ve never seen them take a bee, yet.

    1. Hi, Alan,
      I’ve seen them take adult cockroaches, which are comparable in size and toughness, but I don’t know about bees. Maybe someone else can help?
      There’s also a possibility that they sneak a bit of pollen or honey when can get away with it, since we know they eat fruit.

  11. Thanks great post, most grateful. I worry about expensive electrical appliances, they wrecked my brother’s air con in Brisbane, the outside bit. I am sad that maybe our natives will disappear soon. Re air conditioning, I live in Buderim, and I was told by bro, RP 7 spray, they don’t like it (so electrician said). I sprayed the external bit and now I can’t hear them at night. Thanks for your informative article, you have helped to save the natives, regards veronica

Leave a Reply