It is not a chicken.

Leptodactylus fallax, commonly (and deceptively) known as the mountain chicken or giant ditch frog, is a species of frog that is native to the Caribbean islands of Dominica and Montserrat. The mountain chicken is nicknamed such after being preyed upon as a local delicacy on the islands of Montserrat and Dominica where it is found. It supposedly tastes like chicken^[ and the islands are mountainous regions in the Caribbean Sea.

Everything tastes like chicken, except chicken according to this article.