A study of Choughs'' vocal repertoire: variability related to individuals, sexes and ages

Summary The calls uttered by Choughs (Pyrrhocorax pyrrhocorax) on Islay (S-W Scotland) were recorded during the breeding season. We analysed the vocal repertoire and the degree of call variation, among and within individuals. Eight structurally different calls were identified in Choughs' vocal repertoire. Significant differences in temporal and frequency variables of calls were found between fledglings and adults, whereas females' and males' calls turned out to differ only in two parameters of the commonest call type (chwee-ow). Despite sex-related differences in this call, partners appeared to utter similar versions of it, which suggests that mate vocal mimicry might occur. A certain degree of individuality, i.e. a greater among than within individuals variability, was found in three call types, but the reverse was found in the commonest call of the species. Accordingly, we hypothesise that this call might promote effective species recognition, whereas the other call types would be involved in individual recognition.

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Das stimmliche Repertoire der Alpenkrähe: individuelle, geschlechtliche und altersabhängige Variabilität

Zusammenfassung Während der Brutzeit 1996 wurde das Rufinventar von Alpenkrähen (Pyrrhocorax pyrrhocorax) auf der Insel Islay (SW Schottland) aufgenommen und hinsichtlich individueller Variation und Unterschieden zwischen verschiedenen Individuen analysiert. Acht grundsätzlich verschiedene Rufe wurden unterschieden. Signifikante Unterschiede bestanden zwischen flüggen Jungvögeln und Altvögeln in der Ruffrequenz und der zeitlichen Abfolge der Rufe. Männchen und Weibchen unterschieden sich dagegen nur geringfügig in dem am häufigsten vorgetragenen Ruf. Ungeachtet dieser geringen sexuellen Unterschiede riefen Paarpartner sehr ähnlich, was als Hinweise auf eine Stimmenmimikrie angesehen wird. In drei Ruftypen fand sich eine gewisse Individualität mit größerer Variablität zwischen verschiedenen als innerhalb eines Rufers, wogegen der häufigste Ruf von allen Individuen sehr ähnlich vorgetragen wurde. Es wird geschlossen, daß dieser Ruf der Arterkennung dient, die anderen dagegen mehr der individuellen Erkennung.

     

Sex Differences in Infant Rhesus Macaque Separation–Rejection Vocalizations and Effects of Prenatal Androgens

Infant and juvenile rhesus macaques exhibit many sexually dimorphic behaviors, including rough and tumble play, mounting, and time spent with nonmother females. This study investigated sex differences in infant rhesus monkey separation–rejection vocalizations (SRVs), and the effects of altering the prenatal hormone environment on these differences. Pregnant females received exogenous androgen (testosterone enanthate), an androgen antagonist (flutamide), or vehicle injections for 30 or 35 days during the second (early) or third (late) trimester of pregnancy. Control females used a greater percentage of coos and arched screams than did control males. In contrast, males used a greater percentage of geckers and noisy screams than did females. Females also had longer SRV bouts, used more calls, and used more types of vocalizations than did males. Mothers were more likely to respond to the SRVs of male infants than to the SRVs of female infants. Prenatal flutamide treatment early in gestation reduced the likelihood that mothers would respond to their male offspring, but prenatal androgen treatment had no effect on response rates of mothers to female offspring. Early, but not late, androgen treatment produced females who vocalized in a male-typical manner. Similarly, early flutamide treatment produced males who displayed more female-typical SRVs. Late flutamide treatments of females produced as much masculinization of SRVs as did early androgen treatment in females. These results demonstrate sex differences in highly emotional vocalizations in infant rhesus macaques and provide evidence that the timing and form of prenatal hormonal exposure influence such vocalizations.     

Vox alouattinae: A preliminary survey of the acoustic characteristics of long-distance calls of howling monkeys

This survey of the acoustic characteristics of howling monkey loud calls, covering six of the seven members of the genus Alouattaand presenting audiospectrograms of roars from two species for the first time, suggests that the genus consists of at least two groups: a monotypic palliatagroup, including all subspecies, and a non-palliatagroup, including belzebul, caraya, fusca, pigra,and seniculus.The non-palliatagroup vocalizes continuously for sustained periods of time;their loud calls exhibit a wide bandwidth relative to the calls of the palliatagroup, with emphasized frequencies generally in the range 300- 2000 Hz. The palliatagroup does not vocalize continuously, their vocal bouts being significantly shorter than those of the non-palliataforms. The emphasized frequencies are normally restricted to 300- 1000 Hz, with little acoustic energy in higher frequencies. This bipartite classification places pigrawithin the non-palliatagroup father than with parapatric palliata,which may have important phylogenetic implications. Further, the classification suggests two modes of employing the highly derived howler vocal tract to produce loud calls within the portion of the ambient noise spectrum favorable to long- distance transmission of sound. Finally, I discuss the constraints placed by environmental acoustics on strategies for long- distance communication, hypothesized modes of vocal production, and the use of acoustic studies for phylogenetic reconstruction. Each discussion suggests projects, some already under way, that could elucidate the determinants of variations in communicative patterns within specific social and physical environments.     

Circadian Variation with a Diurnal Bimodal Profile on Scent-Marking Behavior in Captive Common Marmosets (Callitrhix jacchus)

Scent-marking behavior is associated with different behavioral contexts in callitrichids, including signalizing a territory, location of feeding resources, and social rank. In marmosets and tamarins it is also associated with intersexual communication. Though it appears very important for the daily routine of the individuals, very few researchers have investigated distribution through the 24-h cycle. In a preliminary report, we described a preferential incidence of this behavior 2 h before nocturnal rest in families of common marmosets. We expand the data using 8 family groups (28 subjects), 8 fathers, 6 mothers, 8 nonreproductive adults (4 sons and 4 daughters), and 6 juvenile (3 sons and 3 daughters) offspring that we kept in outdoor cages under natural environmental conditions. We recorded the frequency of anogenital scent marking for each group during the light phase, twice a wk, for 4 consecutive wks, from March 1998 to September 1999. Cosinor test detected 24- and 8-h variations in 89.3% and 85.7% of the subjects, respectively, regardless of sex or reproductive status. The 8-h component is a consequence of the 2 peaks for the behavior, at the beginning and end of the light phase. Daily distribution of scent marking is similar to that others described previously for motor activity in marmosets. The coincident rhythmical patterns for both behaviors seem to be associated with feeding behavior, as described for callitrichids in free-ranging conditions, involving an increase in foraging activities early in the morning and shortly before nocturnal rest.     

Vocal behavior of captive Sichuan golden monkeys (Rhinopithecus r. roxellana)

Vocal behavior of four pairs of adult Sichuan golden monkeys was studied at the San Diego, Seattle, Los Angeles, and San Francisco zoos between November 1984 and October 1986. Four call types made up 86% (1,357/ 1,578) of vocalizations that occurred during 45 h of tape-recording. All four major vocalization types were made by both sexes. There was, however, significant sexual asymmetry in their production: 82% to 99% of each type was produced by one sex or the other. Frequently, duets developed when an individual male or female responded to the vocalizations of its cagemate. Males vocalized more than did females in each of the four pairs, and males responded vocally to female calls more than twice as frequently.