  We study the entanglement dynamics of two cavities interacting with
independent reservoirs. Expectedly, we observe that, as the cavity entanglement
is depleted, it is transferred to the reservoir degrees of freedom. We find
that when the cavity entanglement suddenly disappear, the reservoir
entanglement suddenly and necessarily appears. Surprisingly, we show that this
{\it entanglement sudden birth} can manifest before, simultaneously, or even
after {\it entanglement sudden death}. Finally, we present an explanatory study
of other entanglement partitions and of higher dimensional systems.
