juveniles. They have a slight crest, which can be raised when needed. Males are not easily mistaken for other species, but the drab females may be confused with the Say's phoebe. Worn feathers are replaced by molting, which takes between 62 and 79 days and begins in July, lasting until September. Many vermilion flycatchers molt only after completing their migration to warmer regions. The molt is fairly slow compared to that of other families, as quick molting creates poor feathers and interrupts flight, which is untenable for an aerially feeding species. A 2013 study determined that monsoon rain patterns do not affect molting, as had been previously expected. Instead, latitude-based temporal effects are more important in timing the molt. Vocalizations Ornithologist David Sibley describes the perching song as a pit pit pit pidddrrrreedrr, whereas the Cornell Lab of Ornithology describes it as a ching-tink-a-le-tink, with an emphasis on the last syllable. The flight song is given by males who fly high above the canopy, and is described as a pt-pt-pre-ee-een by the Cornell Lab. The regular song may also be given as a slower chatter call. Other noises include a pees noise that is given as a call. A peent is giving while foraging, but a more aggressive variety is also used between males. As a lead-up to copulation, the female may give a tjee-tjee-tjee call. The call of the vermilion flycatcher is important in establishing its territory. Males make only a single song while perching, but can alter the song to convey different intentions. The male's song consists of a variable first part, and a second part with four elements. The first part of the song gets longer after nest construction, and before dawn. The first part encodes information regarding the quality of the male to potential mates and the level of threat to other males—which is related to the intensity with which males defend their territory. Females do not usually sing. Urban noise pollution appears to affect songs; a population in Mexico City was found to sing louder and longer songs as ambient noise increased. Singing is not heard year-round; populations in Arizona and Texas sing only from late February through July. Non-vocal sounds include snapping the beak, by males between songs and by females while watching male courtship flights. Their wings may also be used to create a whirring noise while perch hopping or during territorial displays,