  Supergravity models with spontaneously broken supersymmetry have been widely
investigated over the years, together with some notable non-linear limits.
Although in these models the gravitino becomes naturally massive absorbing the
degrees of freedom of a Nambu-Goldstone fermion, there are cases in which the
naive counting of degrees of freedom does not apply, in particular because of
the absence of explicit gravitino mass terms in unitary gauge. The
corresponding models require non-trivial de Sitter-like backgrounds, and it
becomes of interest to clarify the fate of their Nambu-Goldstone modes. We
elaborate on the fact that these non-trivial backgrounds can accommodate,
consistently, gravitino fields carrying a number of degrees of freedom that is
intermediate between those of massless and massive fields in a flat spacetime.
For instance, in a simple supergravity model of this type with de Sitter
background, the overall degrees of freedom of gravitino are as many as for a
massive spin-3/2 field in flat spacetime, while the gravitino remains massless
in the sense that it undergoes null-cone propagation in the stereographic
picture. On the other hand, in the ten-dimensional USp(32) Type I Sugimoto
model with "brane SUSY breaking", which requires a more complicated background,
the degrees of freedom of gravitino are half as many of those of a massive one,
and yet it somehow behaves again as a massless one.
