Bopapodamus

Bopapodamuses are a tree-climbing hippopotamus-like species that appear in Donkey Kong Country Returns and Donkey Kong Country Returns 3D. They only appear in the Forest world where they appear in many of its levels.

During the levels, the Kongs must jump on the Bopapodamuses to get across large gaps. The Kongs can only jump on a Bopapodamus four times: after that it falls into the abyss, leaving the Kongs vulnerable to also falling down. If the Kongs do not directly jump on a Bopapodamus's head, it swats them down into the pit, causing them to lose a life.

Trivia

 * Bopapodamuses were planned to reappear in Donkey Kong Country: Tropical Freeze but never made it in the final game. According to concept art they were supposed to float on water surfaces instead of being on poles.

Reference
Pogopotamus