Your Dexterity score increases by 2, and your Wisdom score increases by 1, and your Strength score is decreased by 4

Most Chickens are neutral and rarely choose sides when it comes to law and chaos. Pack leaders and warriors might be lawful, while explorers and adventurers might tend toward chaotic.

Chickens are about 1 foot tall. They have thin, lightweight bodies that weigh between 5 and 10 pounds. Your size is Tiny.

Your base walking speed is 25 feet.

You have a flying speed of 15 feet. Chickens are clumsy flyers and can't sustain flight for more then one turn 

Your beak is your natural weapon, which you can use to make an unarmed strike. If you hit with it, you deal piercing damage equal to 1d4 + your Dexterity modifier, instead of the bludgeoning damage normal for an unarmed strike.

You can speak, read, and write Common.

As a chicken you have no arms or hands making somatic components of spells impossible to cast and holding weapons impossible. 

You are not a humanoid, you tiny chicken body is not normal to be seen in any land. Most tailors and smiths are not used to making armour or clothes for you.

Any armour or clothes you intend on buying will often cost more despite the materials needed being less and don't expect to walk into any shop and buy off the shelf, most places will need time to tailor make any equipment to fit your unique frame.

Your kind are not uncommon in town as livestock, as such people are not surprised to see you walking around and will largely ignore you until you display your sentience assuming you to be a common dumb creature.

some benefits include having Advantage and Expertise on Stealth rolls in any town where your sentience isn't known, and also being low on the list of opponents for larger features to attack.