Two‐component calls in short‐finned pilot whales (Globicephala macrorhynchus)

Short‐finned pilot whales (Globicephala macrorhynchus) have complex vocal repertoires that include calls with two time‐frequency contours known as two‐component calls. We attached digital acoustic recording tags (DTAGs) to 23 short‐finned pilot whales off Cape Hatteras, North Carolina, and assessed the similarity of two‐component calls within and among tags. Two‐component calls made up <3% of the total number of calls on 19 of the 23 tag records. For the remaining four tags, two‐component calls comprised 9%, 23%, 24%, and 57% of the total calls recorded. Measurements of six acoustic parameters for both the low and high frequency components of all two‐component calls from the five tags were compared using a generalized linear model. There were significant differences in the acoustic parameters of two‐component calls between tags, verifying that acoustic parameters were more similar for two‐component calls recorded on the same tag than for calls between tags. Spectrograms of all two‐component calls from the five tags were visually graded and independently categorized by five observers. A test of inter‐rater reliability showed substantial agreement, suggesting that each tag contained a predominant two‐component call type that was not shared across tags.     

BEHAVIOURAL RESPONSE TO SONG PLAYBACK BY MALE AND FEMALE WHITE-CROWNED SPARROWS OF TWO SUBSPECIES

ABSTRACT

Nuttall's white-crowned sparrow Zonotrichia leucophrys nuttalli and the Puget Sound white-crowned sparrow Z. i. pugetensis intergrade through a zone of hybridization in northern California. The songs of the two differ in the sequence of syllable types and in the phonology of the complex syllables. We did a playback experiment to males of both subspecies in the field and to females of both subspecies in the laboratory to determine their response to the two subspecies songs. By making alterations of features of the songs, we also attempted to identify characteristics that account for subspecific recognition. Males of both subspecies were more responsive to their own subspecies song than to that of the other subspecies. Substitution of Puget Sound complex syllables into the Nuttall's song caused a reduction in response by male Nuttall's, but alteration of a Nuttall's song to a Puget Sound sequence of syllables had no effect. Females of both subspecies gave more sexual displays when played a song of their own subspecies than when played that of the other subspecies. Female Nuttall's gave an intermediate response when played Nuttall's songs with Puget Sound complex syllables or when played Nuttall's songs altered to a Puget Sound sequence. Puget Sound females did not discriminate between their own subspecies song and either of the altered stimulus songs separately. They did respond less to a song that combined both alterations than to their own subspecies song.     

Bull bellows and bugles: a remarkable convergence of low and high-frequency vocalizations between male domestic cattle Bos taurus and the rutting calls of Siberian and North American wapiti

Whereas low-frequency bellows (below 200 Hz) have been investigated in detail in both male and female domestic cattle (Bos taurus), male high-frequency bugle calls (over 800 Hz) have not been described so far in any large bovid species. In this study, high-frequency bugles and low-frequency bellows were recorded from three crossbred free-ranging domestic cattle bulls and analysed spectrographically. The maximum fundamental frequency of bellows was 113.6 Hz, whereas the maximum fundamental frequency of bugles was 958.4 Hz, ranging from 801 to 1125 Hz in different males. These amazingly high fundamental frequencies of bull bugles are comparable with those reported for Siberian wapiti Cervus elaphus sibiricus, but lower than reported values for some subspecies of North American wapiti Cervus canadensis. The similarity with both Siberian and North American wapiti was also observed in the production of bull biphonic bugles with two fundamental frequencies: the low and the high one. We suggest that bugles of domestic cattle bulls provide an excellent model for comparative research with cervid bugles concerning the mechanism of vocal production and the underlying anatomical and behavioural adaptations.     

BIPHONATION AS A PROMINENT FEATURE OF DHOLE CUON ALPINUS SOUNDS

ABSTRACT

Spectrographic analysis showed that dholes produce sounds with two fundamental frequencies (components): the high-frequency and the low-frequency, which may occur simultaneously or separately. The fundamental frequency of the low-frequency component varied from 0.52 to 1.44 kHz, and that of the high-frequency component from 5.51 to 10.77 kHz. In calls where both the frequencies occurred simultaneously, they were not integer multiples of each other. They also had different frequency modulations and had additional combinative frequency bands. These are features of biphonation. Our data showed biphonation occurs in a lot of dhole calls (20 to 92% of the calls, depending on the individual (n=14); average occurrence 44.3%, n=1317 sounds). The occurrence of biphonation did not differ between sexes and ages; however, occurrence of the high component only was significantly higher in subadult animals, whereas the occurrence of the low component only was significantly higher in adults. Based on the sound structures, we discuss probable mechanisms of sound production for both the components in the dhole. For the low component, the normal vocal folds oscillation mechanism is suggested. For the high component, four possible mechanisms of sound production are discussed. We conclude that the vortex-shedding mechanism is the most probable.