frog song also plays a prominent role in courtship. in túngara frogs ("engystomops pustulosus"), male frogs increase the complexity of their calls, adding additional note types when greater numbers of competitor males are present, which has been found to attract greater numbers of female frogs. some species change their courtship calls when females are especially nearby. in male glass frogs ("hyalinobatachium fleichmanni"), a long frequency-modulated vocalization is produced upon noticing another nearby frog, but is changed to a short chirping song when a female approaches. several species (e.g. dendrobatid frogs ("mannophryne trinitatis"), ornate frogs ("cophixalus ornatus"), splendid poison frogs ("dendrobates speciosus")), switch from long-range loud trilling sounds to short-range quieter chirps when females move closer, which is thought to allow mate attraction without alerting competitor males to female locations.