  The hosts of long duration gamma-ray bursts are predominantly starburst
galaxies at subsolar metallicity. At redshifts z<1, this implies that most of
them are low-mass galaxies similar to the populations of blue compact dwarfs
and dwarf irregulars. What triggers the massive star-formation (SF) needed for
producing a GRB progenitor is still largely unknown, as are the resolved gas
properties and kinematics of these galaxies and their formation history. Here
we present a sample of six spatially resolved GRB hosts at z<0.3 observed with
3D spectroscopy at high spectral resolution (R=8,000-13,000) using FLAMES/VLT.
We analyzed the resolved gas kinematics of the full sample and the abundances
in a subsample. Only two galaxies show a regular disk-like rotation field,
another two are dispersion-dominated, the remaining two have a double emission
component associated with different parts of the galaxy, which might indicate a
recent merger. All galaxies show evidence for broad components underlying the
main emission peak (sigma = 50-110 km/s). This broad component is more
metal-rich than the narrow components, it is blueshifted in most cases, and it
follows a different velocity structure. We find a weak correlation between the
SF rate and the width of the broad component, its flux compared to the narrow
component, and the maximum outflow velocity of the gas, but we do not find any
correlation with the SF density, metallicity or stellar mass. We associate this
broad component with a metal-rich outflow from star-forming regions. The GRB is
not located in the brightest region of the host, but is always associated with
some star-forming region showing a clear wind component. Our study shows the
potential of 3D spectroscopy to study the SF processes in galaxies hosting
extreme transients, the need for high S/N, and the perils using unresolved or
only partially resolved data for these kinds of studies.
