Like many other small gecko species, the Hemidactylus turcicus is one of those species that we tend to take for granted. The type that most people will see on the walls of the house they rented for their holidays but never really stop to think about.

Growing up in Brazil, I would often see other species of the same genus such as the H. mabouia and the H. frenatus around the house. Unfortunately, I am ashamed to say that when I was around 6 years old, I did capture one and tried to keep it as my pet whilst "feeding" it vegetables. However, as I grew, I became more interested in their behaviour and started to study their biology more closely.

Most Brazilians will look at these small geckos and call them by the exact same common name - lagartixa. It doesn't matter what type of gecko it is. If it is on the wall and small, it's a lagartixa. This sort of 'non-reaction' is what drove me to write about the H. turcicus in the first place. When people think about reptiles they will often imagine big snakes and lizards. They will say things like 'I don't like reptiles' but wouldn't bat an eyelash at the little geckos on the wall. These tiny little creatures are reptiles too - and they are fascinating!

I encountered my first H. turcicus during a trip to Ikaria, one of the Greek islands. In my head, I immediately started comparing their colouration, size and behaviour to the tropical species with which I am familiar. The similarities, as expected, are many - they are insectivores, active during the evening or night and can be found near human dwellings on dry stone walls. They tend to hide under rocks during the day or inside cracks on the walls. Like many other geckos, they tend to sit near light sources that attract moths and other insects. You can sometimes find a small group of the H. turcicus banded together near light bulbs appraising potential prey. Hayley & Blackshaw (2015) had a research article published in The Herpetological Bulletin on how habitat structure may affect the foraging behaviour of the H. turcicus that is definitely worth a read. 

Although they have adhesive toes that help them cling to walls and rocks whilst maintaining even an upside down position, the adhesive pads don't extend to the end of the toes. Instead, they stop short of the tip of the toe where a small claw helps the geckos grip to rougher surfaces. This is illustrated in Figure 1 (Arnold & Ovenden, 2002, plate 20) where the diagram clearly shows where the adhesive pads end and a little claw sticks out from the tip of the gecko's toe. The photograph in Figure 2 gives us a better idea of what this looks like in real life.

It is no secret that instances of cannibalism occur in many reptile and amphibian species worldwide. Geckos are no exception to the rule. For instance, David Soulsby noted evidence of cannibalism in one of H. turcicus' most similar species - the Common House Gecko (H. frenatus) in his book 'Animal Cannibalism: The Dark Side of Evolution'. Although he did not mention H. turcicus specifically in his book, it is not a stretch to imagine that such a successive invasive species would display instances of cannibalism. Other gecko species have been reported to prey on smaller gecko species as well as smaller individuals of their own species. Parves & Alam (2015) highlight this occurrence in their paper published in The Herpetological Bulletin with H. flaviviridis as an example. As they noted, however, an individual's size would greatly affect its ability to predate on other individuals.

As some types of geckos are commonly kept as pets nowadays, it may come as no surprise that some species can produce a high pitched sound similar to a squeak when they feel threatened. Males of the H. turcicus species are known to be fairly territorial and warn-off competitors through a series of clicks and squeaks. It's important to note that these squeaky sounds are also used in a range of other social situations such as calling and attracting potential mates.

Females tend to lay a couple of eggs 2-3 times a year. They usually hide their clutches under rocks or in cracks where the eggs stay for 6-12 weeks before hatching. Younglings tend to be translucent pink in colour with a banded tail.

Next time you spot a gecko on the wall, try to get a good look at it - maybe take a couple of photos if you can. This will help you identify the gecko species and will make these encounters all the more interesting!

References:

• Arnold, N. & Ovenden, D. (2002). A Field Guide to the Reptiles and Amphibians of Britain and Europe. London, Harper Collins Publisher.

• Soulsby, D. (2013). Animal Cannibalism: The Dark Side of Evolution. Sheffield, 5m Publishing.

• Mattison, C. (2014). Nature Guide: Snakes and Other Reptiles and Amphibians. London, Dorling Kindersley.

• Haley, T. & Blackshaw, R. (2015). Does Habitat Structure Affect Foraging Success in the Mediterranean House Gecko, Hemidactylus turcicus?. The Herpetological Bulletin 133: 10-12.

• Parves, N. & Alam, S.M.I. (2015). Hemidactylus flaviviridis: Predation on Congeneric Hemidactylus frenatus in Dhaka, Bangladesh. The Herpetological Bulletin 132: 28-29.