Chicken on tree

These kampong chickens settled down perched 15 feet up high on a rambutan tree for the night. Safe place away from predators I supposed. They ran around wild during the day & not trained to come home to a coop at dusk. They are very quiet as soon as everyone of them settled comfortably. But come morning they start the day very early - 5am! They wake you up with their very loud and persistence kookkooo.....!!! The rambutan tree when it fruits taste real nice and sweet, could it be due to contributions from these chickens?