localscale not working

I am trying to scale a prefab after its instantiated but the scale just doesn't get changed and I don't get any errors either.

here is my code:

 IEnumerator spawnBird1()
     {
         wait = Random.Range (5f, 10f);
         yield return new WaitForSeconds (wait);
         Debug.Log ("spawn1");
         Vector3 spawnPosition = new Vector3 (-50f, Random.Range (8f, 25f) ,8f);
         Instantiate (Bird, spawnPosition , Quaternion.identity);
         Vector3 scale = Bird.transform.localScale;
         scale.x = 2f;
         scale.y = 2f;
         index = Random.Range (1,4);
 
         switch (index)
         {
         case 1:
             StartCoroutine ( spawnBird1() );
             break;
             
         case 2:
             StartCoroutine ( spawnBird2() );
             break;
             
         case 3:
             StartCoroutine ( spawnBird3() );
             break;
         }
 
     }