Which species was most notably crossed with the Père David's deer in documented hybridization studies?

Answer

Red deer (Cervus elaphus)

The scientific literature documents attempts to cross the Père David's deer with others, most notably the Red deer (*Cervus elaphus*), leading to documented hybrids.

Which species was most notably crossed with the Père David's deer in documented hybridization studies?
speciesanimaldeerhybrid