ABSTRACT The New Zealand endemic southern ant (Monomorium antarcticum) excavates subterranean nests in various soil types, with brood distributed throughout excavated cavities connected by tunnels. Because cavities are often constructed near the soil surface, variation in rainfall patterns will affect soil moisture, and potentially lead to regular flooding of cavities. We examined how M. antarcticum make colony emigration decisions as soil moisture changes over time, and investigated how colonies manage brood underground during simulated rainfall events. We show that colonies will emigrate to wetter soil and excavate a new nest when their environment becomes too dry. After we add water to the surface of the nest (i.e. simulate rainfall), workers transport brood from cavities into tunnels, and move them back into the cavities as soon as the ‘rain’ stops. Workers tend to prioritise moving brood from cavities with higher densities of brood, regardless of the depth of the cavity from the soil surface. We discuss how the ability to emigrate in response to changes in soil environment, and to effectively respond to unpredictable rainfall/flooding events, can help us understand how this species persists in a wide-range of habitat types.

中文翻译：

---

响应南方蚂蚁 Monomorium antarcticum Smith（膜翅目：蚁科）土壤湿度条件的地下筑巢行为

摘要新西兰特有的南方蚂蚁（Monomorium antarcticum）在各种土壤类型中挖掘地下巢穴，其巢穴分布在由隧道连接的挖掘空腔中。由于空洞通常建在土壤表面附近，降雨模式的变化会影响土壤湿度，并可能导致空洞定期泛滥。我们研究了 M. antarcticum 如何在土壤湿度随时间变化时做出菌落迁徙决定，并研究了在模拟降雨事件期间菌落如何管理地下育雏。我们表明，当它们的环境变得太干燥时，菌落会迁移到更潮湿的土壤中并挖掘一个新巢穴。在我们向巢表面加水（即模拟降雨）后，工人们将巢穴中的巢穴运送到隧道中，并在“雨”停止后立即将它们移回空腔中。工人倾向于优先从具有较高密度的洞穴中移动育雏，而不管该洞穴距离土壤表面的深度如何。我们讨论了响应土壤环境变化的迁徙能力以及有效应对不可预测的降雨/洪水事件的能力如何帮助我们了解该物种如何在广泛的栖息地类型中生存。