  In this paper we discuss the entanglement properties of a thermal
non-relativistic free bosonic field. We demonstrate how to formally construct
spatial modes in order to use a continuous variable separability criterion and
show that the construction of the modes plays a significant role in the way the
entanglement manifests itself. For instance the presence of entanglement
depends on the shape of the modes and their separation. The temperature of the
gas is another crucial factor and for one choice of modes we show that
entanglement can be found at arbitrarily high temperatures as long as we can
zoom in on suitably small regions in space. Moreover, we show that the
entanglement here is useful as it can be extracted to a pair of localised
systems.
