  We report on temperature dependent scanning tunneling microscopy and
spectroscopy studies of undoped SrFe$_{2}$As$_{2}$ single crystals from 6 K to
292 K. Resistivity data show spin density wave (SDW) transition at T$_{SDW}$
$\approx$ 205 K and the superconducting transition at $\sim$ 21 K while
magnetic susceptibility does not show any superconductivity. Conductance maps
and local tunneling spectra show an electronically homogeneous surface at all
studied temperatures. Tunnel spectra correlate well with the SDW transition
with a depression in the density of states near the Fermi energy below
T$_{SDW}$. On further lowering the temperature, the width of this partial
energy gap associated with the SDW decreases. Using the anti-correlation of
superconducting phase with SDW, we interpret this gap weakening as a precursor
to superconductivity. This may give rise to a facile nucleation of
superconductivity near defects.
