Our strategy for Angry Birds Birdday Party (Birthday Party) level 19-13 is to loft a Yellow bird nearly straight up, speeding through the two hanging pigs and into the base of the rightmost tower. Loft the Pink bird, landing her between the two peaks of the left structure. Trigger the bubbles about half way down the structures, clearing the level. If needed, you have some room to spare with the 3-star score. The score in the video below is 100,890.