It is narrated from Sayyiduna Khallad bin al-Sa'ib (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever plants a crop, and then a bird or some animal eats from it, it will be a charity (sadaqah) for him."
Hadith Referenceالمعجم الكبير للطبراني / باب الخاء / 4119