  The $\gamma$-process in core-collapse and/or type Ia supernova explosions is
thought to explain the origin of the majority of the so-called $p$ nuclei (the
35 proton-rich isotopes between Se and Hg). Reaction rates for $\gamma$-process
reaction network studies have to be predicted using Hauser-Feshbach statistical
model calculations. Recent investigations have shown problems in the prediction
of $\alpha$-widths at astrophysical energies which are an essential input for
the statistical model. It has an impact on the reliability of abundance
predictions in the upper mass range of the $p$ nuclei. With the measurement of
the $^{164,166}$Er($\alpha$,n)$^{167,169}$Yb reaction cross sections at
energies close to the astrophysically relevant energy range we tested the
recently suggested low energy modification of the $\alpha$+nucleus optical
potential in a mass region where $\gamma$-process calculations exhibit an
underproduction of the $p$ nuclei. Using the same optical potential for the
$\alpha$-width which was derived from combined $^{162}$Er($\alpha$,n) and
$^{162}$Er($\alpha$,$\gamma$) measurement makes it plausible that a low-energy
modification of the optical $\alpha$+nucleus potential is needed.
