Whether it's legal to shoot or kill trespassers is one of our most common property law questions. Short answer: generally only in self-defense and in fear of bodily harm or death. And while we normally don't think of animal trespassers in this light, perhaps we should.
An unidentified Texas man was recently hospitalized and had his jaw wired shot after a bullet he fired at an armadillo in his yard at 3 a.m. ricocheted off the animal's armor and struck him in the face. The status of the armadillo is unknown, but the man's unfortunate fate raises an interesting legal question: When can you legally kill animals on your property?
Most jurisdictions have animal cruelty laws that prohibit people from intentionally killing animals (with the obvious exception of licensed hunting). In California, for example, a person who "maliciously and intentionally maims, mutilates, tortures, or wounds a living animal, or maliciously and intentionally kills an animal" can be charged with a felony.
New York's animal cruelty law is even more comprehensive:
A person who overdrives, overloads, tortures or cruelly beats or unjustifiably injures, maims, mutilates or kills any animal, whether wild or tame, and whether belonging to himself or to another, or deprives any animal of necessary sustenance, food or drink, or neglects or refuses to furnish it such sustenance or drink, or causes, procures or permits any animal to be overdriven, overloaded, tortured, cruelly beaten, or unjustifiably injured, maimed, mutilated or killed, or to be deprived of necessary food or drink, or who willfully sets on foot, instigates, engages in, or in any way furthers any act of cruelty to any animal, or any act tending to produce such cruelty, is guilty of a class A misdemeanor.
Neither California's nor New York's animal cruelty laws are specific to location, so they would presumably apply equally to your property as to someone else's.
There are important exceptions to most animal cruelty laws. For instance, it is permissible to kill an animal under California law if the animal is a danger to life, limb, or property. And the important qualifier in New York's statute is "unjustifiably injured, maimed, mutilated or killed." Most courts have interpreted animal cruelty statutes, to allow killing a dangerous animal so long as the killing wasn't malicious.
Most of us wouldn't see a wandering armadillo at three in the morning as dangerous to anything but our gardens flowerbeds -- and even then, some diced cayenne peppers can keep the armored trespassers away. But, as one Texas man found out, that armor might be more dangerous than we think.