Testing measures of boldness and exploratory activity in native versus invasive species: geckos as a model system

Abstract

Invasive species often possess a suite of behaviours that increase their likelihood of establishing populations in novel environments. These suites often include combinations of high motility, exploration, aggression, boldness or plasticity in resource use. In Australia, invasive house geckos, <i>Hemidactylus frenatus</i>, have continued to expand their range since the 1960s, spreading from predominantly human-disturbed areas to peri-urban regions. Here, we used open-field tests to investigate whether invasive house geckos showed greater exploratory activity and boldness than native Australian house geckos, <i>Gehyra dubia</i>. We expected that, like many other successful invasive species, invasive house geckos would be bolder and show greater exploratory activity than native house geckos. Consistent with our expectations, invasive house geckos showed significantly higher levels of exploratory activity, travelling on average 1.6 times further than native house geckos. However, none of our boldness tests indicated that invasive house geckos were bolder than native house geckos. In addition, we found no influence of sex on exploratory activity or boldness in either species. While invasive house geckos were not bolder than native house geckos, their increased exploratory activity may have contributed to their successful expansion into the natural environments surrounding urbanized areas.