Yes, it is illegal to kill a feral cat in Texas unless it is done in a humane way which can only mean in the conventional way that a domestic cat is euthanised i.e. by veterinarian or veterinary technician. There are some rare exceptions and a defense (see base of page). You’ll also have to distinguish between feral and stray (a stray might be someone’s pet). This last point is important as killing someone’s pet is criminal damage (a crime under a different law). Also feral cats are not (and cannot be) listed as game items to be hunted.
The law is stated under Texas’ Animal Anti-Cruelty Law: Texas Penal Code 42.09 and 42.092.
To quote: “It is a crime to intentionally, knowingly, or recklessly: torture, cruelly kill, or cause serious injury to any dog or cat, including strays and ferals;
Kill, poison, or cause bodily injury to any animal without the owner’s consent;
Abandon or fail to provide food, water, care, or shelter to any animal in your custody; or
Transport or confine an animal in a cruel manner.”
The law is very clear as you can see. This statute does not list any exceptions, such as exceptions regarding invasive species or pests or nuisance animals.
In point of fact, the feral cat is not listed as an invasive species in Texas. Neither is the feral cat listed as a nuisance animal in Texas.
Neither is the feral cat listed as an animal that can be trapped in Texas. The furbearing animals which can be trapped in Texas are: badgers, beavers, fox, mink, muskrat, nutria, opossum, otter, raccoon, ring-tailed cat, skunk and civet cat.
There would appear to be some rare exceptions:
A landowner or his agent may kill a nuisance fur-bearing animal on his land. The animal can be killed in any way. Clearly this must happen on the landowner’s property. And the animal must be a nuisance. I don’t see a definition of “nuisance” in this instance. Obviously a feral cat doing nothing on someone’s land would not be a nuisance and therefore a landowner’s actions could be challenged if he/she killed a feral cat on his land without complying with the rules of this exception.
It is a defense to kill an animal on a person’s property that has injured or is injuring livestock.
My conclusion is quite clear, which is that it is illegal to kill a feral cat in Texas unless it is done in an entirely humane way. This must exclude by shooting unless it occurs under a law regarding the destruction of a ‘dangerous animal’ in which case the health authority or police officer may destroy such an animal if a police officer believes that the animal presents a threat to a person’s life or the health official regards the animal’s capture to be hazardous due to the nature, disposition or diseased condition of the animal (Source: 1992 Code Section 3-1-3(C); Ord. 031009-9; Ord. 031211-11.)
Clearly a feral cat might be considered to be a dangerous animal but I am not sure if it falls under this description. But note that the only person who could kill a feral animal under these circumstances would be someone in authority and not a member of the general public.