Lie grouopoid up to Morita equivalence are a model for differentiable stacks. Geometrical structures that are invariant under Morita equivalence are then well defined on the corresponding stack. Quasi symplectic groupoids have been shown to be Morita invariant and thus represent the right notion of 1-shifted symplectic structure. Here we show that quasi Poisson groupoids represent the correct notion of 1-shifted Poisson structure. The result follows from the Morita invariance of the graded 2-Lie algebra of polyvector fields. Based on joint work with N.Ciccoli, C.Laurent-Gengoux and P.Xu.