H i spectra of the GRB hosts (histograms) with the Gaussian fit overplotted (red lines). These fits are presented only for illustration, as the total fluxes were determined from the direct integration of the spectra (Sect. 3.1). Vertical dotted lines show the frequency range used to measure the total H I emission and to produce the integrated H I maps (Fig. 1). The spectrum marked “060505comp” corresponds to the companion object north-west of the GRB 060505 position (Fig. 1).