Yes. Mongooses eat young black mambas, secretary birds and large species of eagle eat adult mambas.
Eagles and Vultures rarely.
As Geoff Lawton says in his Permaculture Food Forest DVD, "If you have a plague of grasshoppers you ACTUALLY have a deficiency of turkeys". A 1kg turkey will eat 3kg of grasshoppers in a season....
No animals eat a Blak widow their too dangerous