Donkeys have a unique "bray" (hee-haw) that is different from a horse's whinny. Jacks also have a slower, more deliberate courtship than stallions. Sometimes, a mare will reject a Jack because she finds his vocalizations or behavior "wrong." Similarly, a Jenny (female donkey) will often violently reject a stallion, which is why Hinnies are rare.
Horses and donkeys are closely related enough to reproduce, but their genetic mismatch creates specific challenges: Horse Mating Donkey
often inherit the body shape and smooth coat of a horse but have the long ears, small sturdy hooves, and thick heads characteristic of a donkey. Donkeys have a unique "bray" (hee-haw) that is