This is deplorable and the guy deserves to be punished, but six months in prison and 3-5 years probation for killing an over-sized chicken seems a bit harsh, considering some of the penalties I've seen for much more serious offenses. I think 30 days in jail or a $1000 fine would be more appropriate. Of course, the penalty might make more sense if the article identified what the "two other felony counts" were.
Yes, I know that helmeted guineafowl are not chickens, but they are close enough. In the U.S., they are commonly found on farms (my sister's next door neighbor has them), and I've even seen them walking down the middle of the street here in Texas. They are "exotic" in the sense that they are not native to the U.S., but they are domesticated farm animals.
I know I will get slammed for this opinion, so keep in mind that I am not saying what they did was not bad. It was bad. But it wasn't an endangered species or something much more important, like a human.