Within the hierarchical framework for galaxy formation, merging and tidal interactions are expected to shape large galaxies up to the present day. While major mergers are quite rare at present, minor mergers and satellite disruptions - that result in stellar streams - should be common, and are indeed seen in the Milky Way and the Andromeda galaxy. In the last years, the Stellar Tidal Stream Survey (PI. Martinez-Delgado) has obtained ultra-deep, wide-field imaging of some nearby spiral galaxies, based on data taken with small robotic telescopes (0.1-0.5-meter). These images have revealed for first time external views of such stellar tidal streams at unprecedented sensitivity and detail. In this talk, I present the recent results of our systematic survey of stellar tidal streams in a sample of nearby galaxies with the ultimate aim of estimating the frequency, morphology and stellar luminosity/mass distribution of the detected stellar streams in the Local Volume. I also discuss how the comparison of these observations with state-of-the-art L-CDM and W-CDM cosmological simulations of this phenomenon can provide a direct and stringent test of hierarchical structure formation on this small scale.Joint Colloquium Departament d’Astronomia i Meteorologia -IEEC.