This likely happens because the bird sprite collides with the wall twice. It happens very fast, so you don't see it, but it momentarily changes its direction to the left, then collides with the wall again and changes direction again. Since the bird is already in the wall, further collisions are not registered and it continues flying to the right.
You can try adjusting the origin point and collision polygons in all animation frames, make them strictly symmetrical. But the easiest solution is to add a cooldown period. After changing the direction, ignore further collisions, say for the next 1 second.
You can use Timer behavior and check that the cooldown timer is not running. Or simply save the collision time in an instance variable on the bird. And compare (lastCollisionTime>(time-1))