That's a great plan. Try again, and try different spots with vantage points looking to the areas where you could hear them. If you can get to where they were feeding, see if that food source is reducing and look where they might move up or down slope to a ripening source. If they don't feel threatened, then they'll return to the same area. If the calling hasn't gotten any out of the brush, then change to a different offering.
-Steve
