The chicken is not telling the truth.
There are two possibilities:
The chicken is telling the truth.The chicken is not telling the truth.Let us take the 1st case. If the chicken is telling the truth, all chickens should be liars, which makes itself a liar. This contradicts the fact that it is telling the truth.Taking the 2nd case, if the chicken is not telling the truth, all chickens need not be liars, which is logically possible.So, the only possible answer is that the chicken is not telling the truth.An alternative answer is: Chickens cannot talk.