Tod's mother is seen in the beginning of the film, running through the woods holding baby Tod in her mouth, while trying to run from an off-screen hunting dog and hunter. Finally, she comes to a fence by Big Mama's tree, which Big Mama watches as Tod's mother puts him in some large grass underneath the fence post and then runs away, hearing the dog and hunter coming. Then gunshots are heard, and she is killed off-screen. She had sacrificed herself to save her son.
Tod's mother's death resembles that of Bambi's, as they were both shot by hunters off-screen.
Many fans believe that Amos Slade was presumably the hunter off-screen who killed Tod's mother, and that Chief was the dog chasing her. However, this is most likely impossible, because Amos returned home from getting Copper shorty after, while Chief was resting at home.
Another possibility is that Man from Bambi killed her, implying that the film possibly takes place during the events of Bambi.