ELi5: How do some animals get enough nutrients out of eating hay or grass or a single variety of leaf for their entire lives?

Question

ELi5: How do some animals get enough nutrients out of eating hay or grass or a single variety of leaf for their entire lives?

In: 293

Answer 1

Most animals like deer still regularly seek out salt deposits to get minerals they lack from their diet. Even many butterflies and birds do the same. And, herbivores like deer are also known to eat meat/eggs when the opportunity is presented.