Sounds and Vocal Behavior

Song

Males (and apparently not females) are highly vocal, singing from exposed perches on their territories. Males turn their head from side to side as they sing. The song is produced over most of the day, probably for the entire duration of the breeding season, which is prolonged (see breeding, below). The song is complex, consisting of several syllables (see figures 1, 2; also, XC 30511) which are sung in rapid succession within a song bout.  Individual males may repeat the same syllable within a given song bout.  Extensive recordings of a single male indicate song bouts are somewhat indeterminate in length, lasting 12.0 ± 6.4 (n ± s.d.) seconds (Clark 2006). Within a song bout, the syllables do not appear to be entirely random in order, but it is not possible to determine if there is a set song syntax without additional sound recordings. Clark (2006) indicates that, while on his territory, one male spent 33% of the time actually engaged in singing.  Comparison of recordings from 2005 (figure 1; CJC) and 1992 (figure 2; British Library recording #34377), both from Jamaica, suggest few shared syllables, indicating strong geographic, year-to-year, or individual variation in song structure.

In addition to perched song, males will sing on the wing when approaching or departing their territory, and also sing during aerial displays to other birds (see below). The function of song appears to be related to territoriality, potentially to announce territory ownership to other males and/or females, and thus it is likely to be sexually selected. It is unknown if the song is innate or learned. It is possible there are undocumented, subtle daily patterns of song production, but generally, males sing over the entire day.

Of note, recordings of songs of the Vervain Hummingbird in the Macaulay Library from the Dominican Republic (#35315, #35319) and Jamaica (#35356) sound subtly different (perhaps more nasal and squeaky) from those for M. minima minima presented in the figures below.  It is not clear whether this variation could be due to cultural evolution, individual differences, sub-specific variation, geographic variation, or different recording conditions or equipment.

Other vocalizations
A dry “chittering” scolding sound is produced by both sexes during agonistic interactions (see below). This scolding call is higher-pitched but otherwise similar (both in social context and in acoustic form) to the scolding call produced by the Anna’s Hummingbird (Calypte anna Lesson).  Below is a spectrogram of this sound, generated by a female.

Unlike close relatives within the ‘bee’ clade (McGuire et al. 2007), Vervains apparently do not produce sonations or specialized flight sounds with either their wings or tail-feathers (Bostwick & Prum 2003; Clark 2006; Clark 2008). Closely related species (including members of Archilochus, Calypte, and Selasphorus) produce sounds with their tail-feathers during courtship displays (Clark & Feo 2008), but spectrograms of the Vervain’s dive-sound indicated that their dive-sound was identical to a portion of their song (Clark 2006), and also the frequency sweeps present in the spectrograms are inconsistent with the physical mechanism by which the tail-feathers are proposed to produce sound (Clark and Feo 2008). Therefore, all of the existing evidence suggests that the sounds produced during the display-dive of this species are vocal in origin.

A humming sound is produced during flight that is similar to the flight sounds produced by all hummingbirds. Many liken it to the sound of a large bee.