The porcupine falls into the nuisance category. This animal lives on the bark of trees, and trees are scarce around here. Trees also aid in erosion control, are an important component of our ecosystem and provide shade, to name a few benefits. Once a porcupine eats a trees bark, the tree dies, so as you may imagine they aren't overly welcome, and are eliminated when located.
Then there are their quills, which many an animal has found painfully lodged in themselves when attempting to tangle with a porcupine. In severe cases these quills can lodge in the tongue and throat, causing extreme pain and possibly death.
The curious will also get stabbed with quills, usually in the nose as they walk along sniffing the porcupine, who will eventually get mad and whack them with his tail. When we weaned last week we spotted this cow of my brothers, who most likely got her quills as a result of being curious.
We hauled her home so that we could remove the quills. In this location, the quills would eventually get broken and/or worn off. They aren't life threatening, and more of a discomfort to her than anything. But, we didn't want her to have to suffer, so we readily took the time to remove this poky problem from her face.