Frog doesn't disappear after bird eats it

private bool gameStarted = false;

[SerializeField]
private Text gameStateText;
[SerializeField]
private GameObject player;
[SerializeField]
private BirdMovement birdMovement;
[SerializeField]
private FollowCamera followCamera;
private float restartDelay = 3f;
private float restartTimer;
private PlayerMovement playerMovement;
private PlayerHealth playerHealth;

// Use this for initialization
void Start () {
    Cursor.visible = false;

    playerMovement = GetComponent<PlayerMovement> ();
    playerHealth = GetComponent<PlayerHealth> ();

    // Prevent player from moving before start of game
    playerMovement.enabled = false;

    // Prevent bird from moving before start of game
    birdMovement.enabled = false;

    // Prevent follow camera from moving before start of game
    followCamera.enabled = false;
}

// Update is called once per frame
void Update () {

    // if game is not started and player presses space bar or touches screen, start game
    if (gameStarted == false && Input.GetKeyUp(KeyCode.Space)) {
        StartGame();
    }

    // if player is no longer alive then...
    if (playerHealth.alive == false) {

        //end the game
        EndGame();

        //Increment timer to count up to restarting
        restartTimer = restartTimer + Time.deltaTime;

        //...and if it reaches restart delay
        if(restartTimer >= restartDelay) {

            //...then reload currently loaded level
            SceneManager.LoadScene(SceneManager.GetActiveScene().buildIndex);
        }
    }
}

private void StartGame() {
    // Set game state
    gameStarted = true;

    // Hide Text
    gameStateText.color = Color.clear;

    // Allow player to move
    playerMovement.enabled = true;

    //Allow bird to move
    birdMovement.enabled = true;

    // Allow camera to move
    followCamera.enabled = true;
}

private void EndGame() {
    // Set game state
    gameStarted = false;

    //Set Game Over text
    gameStateText.text = "Game Over";
    gameStateText.color = Color.white;

    //Remove player from game
    player.SetActive(false);
}