this owl is most active, when they can often be heard calling to one another in a high-pitched whinny or chuckle. These songs often consist of 5–7 notes that repeat in short duration, similar to the sound of a young puppy. The distinctive vocalizations of elf owls vary according to sex, with males exhibiting a wider repertoire of complex notes as opposed to females of the same species. Males have two primary classifications of songs, each of which share similar characteristics of structure and function. Most avian observers refer to "Class A" songs to describe those that vary in length (generally 5–15 notes), and are used as both territorial proclamation and to herald the arrival of males to females in the area. While Class A tones reflect changes in environmental factors — wind, precipitation, moonlight, and temperature — Class B songs have significantly less variation among individuals. Class B functions as the primary mating call, stimulating females and encouraging them to accept male sexual advances. As the season goes on and mating begins, Class A songs are observed with lower frequency than Class B. There are also a handful of locational, so-called "scolding", and territorial songs belonging to both male and female birds of the elf owl species. Distribution and habitat The elf owl is known to migrate in large groups, with patterns of migration varying depending on flock and habitat location. Some broods of elf owl migrate to the southwest United States (California, Arizona, New Mexico, and Texas) in the spring and summer for breeding. In the winter, it is found in central and southern Mexico. Migrant elf owls return north in mid-April to early May. Resident populations occur in a couple of places in south central Mexico and along the Baja peninsula. Behaviour and ecology Elf owls feign death when handled, an adaption that encourages a predator to relax its grip so that the owl can escape. Elf owls are also notoriously territorial. Territories are established by the male and are defended by both the male and the female, and males also tend to view their chosen female mate as a territory to be defended, as well. This defense is often accomplished through the use of song. During the breeding season, elf owls are monogamous and stay in breeding pairs, but can be found in small groups during migration and when mobbing predators. Adults as well as young