Are any mammals that breed only once in their life and then die?

While there are many species of animals that reproduce only once in their lifetime (often called semelparous), no mammals exhibit this behavior.

Semelparity is more common in insects, plants, and some fish, where the energy and resources dedicated to reproduction are significant, often leading to the death of the parent.

Mammals, by contrast, tend to be iteroparous, meaning they reproduce multiple times throughout their lives. This is likely due to the high investment mammals have in their offspring, including long gestation periods, nurturing, and extended parental care.

Therefore, while there are many semelparous animals, mammals are not included in this category.