Specialization in building tasks in the mound-building mouse, Mus spicilegus

Specialization can be defined as when specific individuals perform a specific task for a relatively long period of time. The mound-building mouse is a suitable species to study specialization during a collective construction task, as juveniles build imposing mounds in which to overwinter. The process includes several successive phases involving the transport and piling up of different kinds of materials along with covering up the mound with dirt and digging galleries. Laboratory studies revealed that within a group of six individuals, two individuals transported most of the material provided for building. We tested whether this behavioural differentiation corresponded to a real specialization. Mice were given two different transport tasks corresponding to different phases of the building process. Experimental groups received two different building materials in two consecutive periods while control groups received the same building material for both periods. As predicted, in experimental groups, carriers of one material were not the same individuals as the carriers of the second material. This shift in the identity of the carrier according to the material we provided indicates a specialization for a different transport task. By contrast, in control groups, mice tended to keep their carrier status during the two periods. We concluded that, at least under controlled laboratory conditions, a task-related specialization occurred during the collective construction of the mound. This specialization could be explained as part of a division of labour in the mound-building mouse.