Minecraft wiki entry for Chicken, associated text: 0–2 feathers. The maximum is increased by 1 per level of Looting, for a maximum of 0–5 with Looting III.
1 raw chicken (1 cooked chicken if killed while on fire). The maximum is increased by 1 per level of Looting, for a maximum of 1–4 with Looting III.
1–3 when killed by a player or tamed wolf; (10 if it was part of a chicken jockey).