the imaginary quadratic field $\mathbb {Q}(\sqrt {-d}) $. Nontrivial pointwise upper bounds
are known only for $\ell= 3$; nontrivial upper bounds for averages of $ h_ {\ell}(-d) $ have
previously been known only for $\ell= 3, 5$. In this paper we prove nontrivial upper bounds
for the average of $ h_ {\ell}(-d) $ for all primes $\ell\geqslant 7$, as well as nontrivial upper
bounds for certain higher moments for all primes $\ell\geqslant 3$.