FIELD RECORDINGS OF ECHOLOCATION AND SOCIAL SIGNALS FROM THE GLEANING BAT MYOTIS SEPTENTRIONALIS

ABSTRACT

We recorded echolocation and ultrasonic social signals of the bat Myotis septentrionalis. The bats foraged for insects resting on or fluttering about an outdoor screen to which they were attracted by a ‘backlight’. The bats used nearly linearly modulated echolocation signals of high frequency (117 to 49 kHz, see Tables) with a weak second harmonic. The orientational signals from patrolling bats were about 2.4 ms in duration and occurred at a repetition rate of about 18 Hz (see Figure 3). The signals used by bats as they approached the screen were of shorter duration (0.72 ms) and occurred at higher rates (33.8 Hz) (Table 2 and Figure 4). We registered one feeding ‘buzz’ (Figure 5). We recorded social signals when two bats patrolled the hunting area. The social signals were characterized by their longer durations (6 ms, see Table 1), lower frequencies (70 to 30 kHz), and curvilinear sweeps (Figures 7 and 8). We calculated the source levels of orientational and social signals using the differences in arrival times at three microphones in a linear array (Figures 1 and 2). The source levels were on average 102 dB peSPL at 10 cm (Table 1). We could not calculate source levels of the signals used by bats as they approached the screen at close range, but these signals were much weaker (about 65 dB peSPL at the microphone).     

A NEW ACOUSTIC SIGNAL OF THE FRUIT-FLIES DROSOPHILA SIMULANS AND D. MELANOGASTER

ABSTRACT

We found a new acoustic signal in Drosophila simulans (si) and D. melanogaster (me). It is a ‘rejection signal’ (RS) produced by adult males and young males and females in response to the courting behaviour of mature males who emit ‘pulse songs’ (i.e. love song: LS). It occurs most frequently in si, less in adults me except if the interacting males belong to different chemical morphs (i.e. temperate or equatorial population). There are no differences in the LS characteristics directed to various sexes and ages. The RSs produced by adult males or by young animals do not differ significantly either. They are emitted by neither virgin nor fecundated adult me females but a few times by virgin adult si females. The RS (like the LS) is a multipulse signal but intervals between pulses are about twice those of LS, around 90 ms for si and 80 ms for me. They are very irregular, as is the distribution of energy along the bandwidth mainly between 300 and 800 Hz for si and 200 and 600 Hz for me. The sound level of the RS is from 10 to 20 dB less than the LS. The RS seems to be linked to the ‘flicking’ behaviour produced by both wings, while the LS always corresponds to the so-called ‘wing vibration’.     

Sex‐dependent effects of Cacna1c haploinsufficiency on juvenile social play behavior and pro‐social 50‐kHz ultrasonic communication in rats

As cross‐disorder risk gene, CACNA1C is implicated in the etiology of all major neuropsychiatric disorders characterized by deficits in social behavior and communication and there is evidence for sex‐dependent influences of single‐nucleotide polymorphisms within CACNA1C on diagnosis, course, and recovery in humans. In this study, we aimed, therefore, at further exploring the role of Cacna1c in regulating behavioral phenotypes, focusing on sex‐specific differences in social behavior and communication during the critical developmental period of adolescence in rats. Specifically, we compared rough‐and‐tumble play, concomitant emission of pro‐social 50‐kHz ultrasonic vocalizations, and social approach behavior in response to playback of 50‐kHz ultrasonic vocalizations between constitutive heterozygous Cacna1c ^+/? females and wildtype Cacna1c ^+/+ littermate controls, and contrasted present female findings to data previously reported in males. Our results show for the first time that partial depletion of Cacna1c leads to sex‐dependent alterations in social behavior and communication in rats. In females, Cacna1c haploinsufficiency led to hypermasculinization, with rough‐and‐tumble play behavior, in general, and pinning behavior, in particular, being even higher than in males without affecting concomitant 50‐kHz ultrasonic vocalizations. In males, in contrast, rough‐and‐tumble play behavior was not altered, yet emission of 50‐kHz ultrasonic vocalizations was diminished following partial Cacna1c depletion. The behavioral responses elicited by playback of 50‐kHz ultrasonic vocalizations were reduced upon partial Cacna1c depletion in both sexes. It thus can be concluded that Cacna1c plays a prominent sex‐dependent role in regulating juvenile rat social play behavior and pro‐social 50‐kHz ultrasonic communication with relevance to sex‐specific effects seen in neuropsychiatric disorders.     

Non-song acoustic communication in migrating humpback whales (Megaptera novaeangliae)

Humpback whales are renowned for the complex structured songs produced by males. A second, relatively understudied area of humpback acoustic communication concerns un-patterned sounds known as "social sounds," produced by both males and females. These include vocalizations as well as sounds produced at the surface of the water as a result of surface behaviors ( e.g. , breaching, pectoral slapping). This study describes a portion of the non-song social sound repertoire of southward migrating humpbacks in Australian waters, and explores the social relevance of these sounds. On migration, humpback whales travel in social groups of varying compositions. These social groups are not stable in that humpback whales continually change group composition by splitting from, or joining with, other groups. The results of this study suggest that "breaching" and "slapping" have a communicative function. Other sounds such as "underwater blows" and "cries" were heard mainly in competitive groups while other low-frequency sounds such as "grumbles,""snorts,""thwops," and "wops" may function in intra- or inter-group communication. Particular sounds ("grunts,""groans," and "barks") were almost exclusive to joining pods suggesting a role in social integration. Social sounds in humpbacks may have specific social and behavioral functions relating to social group composition, and the mediation of interactions between these social groups.     

Incubation feeding by male Scarlet Tanagers: a mate removal experiment

ABSTRACT Incubation feeding, where males feed their mates, is a common behavior in birds and may improve female condition, nest attentiveness, and nesting success. We used behavioral observations and a temporary mate removal experiment to test the female nutrition hypothesis for incubation feeding by male Scarlet Tanagers (Piranga olivacea). All males (N= 20) were observed incubation feeding and fed females both at the nest (x? 1.36 trips/h) and away from the nest (x? 20.1 trips/h). Male feeding rate off‐nest was negatively correlated with the duration of female foraging bouts and positively correlated with the total time females spent incubating per hour. Eggs were predated at seven of 19 (37%) nests, but nest survival during incubation was not related to either female incubation behavior or male feeding rate. During temporary removal experiments (N= 12), female Scarlet Tanagers remained on the nest significantly longer and did not have longer foraging bouts. An unexpected outcome of the removal experiments was a dramatic change in female vocal behavior. All 12 experimental females gave chik‐burr calls during the male‐removal experiments (x? bout length = 11.7 min), but during normal observation periods only six of 20 females at the incubation stage gave chik‐burr calls (x? bout length = 0.7 min, N= 20). Our results suggest that female tanagers likely gain nutritional benefits from incubation feeding, but male feeding may not improve immediate reproductive success. Nine of 54 (17%) nestlings in five of 17 broods (29%) were extra‐pair young (EPY), indicating that males could potentially benefit from incubation feeding via mate retention and fidelity as well as, or instead of, through immediate gains in reproductive success. Our study indicates that females benefit from incubation feeding and do not simply passively accept food from their mates, but instead may influence male feeding rates through direct (e.g., mate following and vocalizing) and indirect (the threat of mate abandonment or cuckoldry) means.     

Human cerebral response to animal affective vocalizations

It is presently unknown whether our response to affective vocalizations is specific to those generated by humans or more universal, triggered by emotionally matched vocalizations generated by other species. Here, we used functional magnetic resonance imaging in normal participants to measure cerebral activity during auditory stimulation with affectively valenced animal vocalizations, some familiar (cats) and others not (rhesus monkeys). Positively versus negatively valenced vocalizations from cats and monkeys elicited different cerebral responses despite the participants' inability to differentiate the valence of these animal vocalizations by overt behavioural responses. Moreover, the comparison with human non-speech affective vocalizations revealed a common response to the valence in orbitofrontal cortex, a key component on the limbic system. These findings suggest that the neural mechanisms involved in processing human affective vocalizations may be recruited by heterospecific affective vocalizations at an unconscious level, supporting claims of shared emotional systems across species.     

A glandular neckpatch secretion and vocalizations act as signals of territorial status in male puku (Kobus vardoni)

Territorial male puku ( Kobus vardoni ) have thicker necks than bachelors, develop a glandular secretion on their necks and utter bouts of whistles. The neckpatch develops at the time when bachelor males move into the territorial areas and when most conceptions occur. Interactions between two territorial males usually result in a face-off, whilst interactions between a bachelor male and a territorial male usually result in a chase. In both cases, the neckpatch may act as a territorial 'badge' which prevents escalation of the interaction.

Résumé

Le cob de Vardon mâle territorial a un cou plus épais que les mâles célibataires, développe une sécrétion glandulaire au niveau du cou et pousse de brefs siffle-ments. La glande du cou se développe à 1'époque ou les mâles célibataires pénètrent dans les espaces territoriaux, en saison de reproduction. Les interactions entre deux mâles territoriaux débouchent généralement sur un retrait tandis qu'entre un mâle célibataire et un mile territorial, elle aboutit d'habitude à une poursuite. Dans les deux cas, la glande du cou joue le rôle d'un 'badge' territorial qui empêche l'escalade de la confrontation.     

Fruit sharing between wild adult chimpanzees (Pan troglodytes schweinfurthii): a socially significant event?

Although food sharing is a habitual aspect of chimpanzee (Pan troglodytes) life, sharing of plant foods between unrelated adults is rare. Observations of such behavior have typically been interpreted as the outcome of a process by which individuals that are otherwise unable to gain access to the food manage to obtain a nutritional benefit. Here we present behavioral details and an acoustic analysis regarding an observation of food sharing between unrelated adult wild chimpanzees that we suggest cannot be explained using traditional nutrition-based models. Instead we propose that the exchange is only understandable as a socially important event, and we cite two further observations in the same population that support this suggestion.     

A comparative approach to the organization of vocal signals in noctural prosimians

Vocalizations and corresponding behavior patterns were recorded inGalago demidovii (Lorisidae), Microcebus murinus, andCheirogaleus medius (Cheirogaleidae). Physical characteristics of the calls were analyzed and calls correlated with their behavioral context. Based on these correlations an «advertisement» call can be identified in all three species. Interspecific comparison suggest that within the Prosimian suborder there are at least two different evolutionary pathways in the organization of this call and of the vocal repertoires in general. The Lorisid speciesG. demidovii conveys acoustic information mainly in pulsed calls, leading to an extreme amplitude-modulation. Individual characteristics are in temporal patterns of calls.C. medius andM. murinus, the Cheirogaleid species, use tonal calls and encode individual characteristics in frequency patterns. Despite the fundamental similarity in the call-structure of the two Cheirogaleid species different adaptations can be found to meet different ecological needs.     

Behavioral phenotypes of genetic mouse models of autism

More than a hundred de novo single gene mutations and copy‐number variants have been implicated in autism, each occurring in a small subset of cases. Mutant mouse models with syntenic mutations offer research tools to gain an understanding of the role of each gene in modulating biological and behavioral phenotypes relevant to autism. Knockout, knockin and transgenic mice incorporating risk gene mutations detected in autism spectrum disorder and comorbid neurodevelopmental disorders are now widely available. At present, autism spectrum disorder is diagnosed solely by behavioral criteria. We developed a constellation of mouse behavioral assays designed to maximize face validity to the types of social deficits and repetitive behaviors that are central to an autism diagnosis. Mouse behavioral assays for associated symptoms of autism, which include cognitive inflexibility, anxiety, hyperactivity, and unusual reactivity to sensory stimuli, are frequently included in the phenotypic analyses. Over the past 10 years, we and many other laboratories around the world have employed these and additional behavioral tests to phenotype a large number of mutant mouse models of autism. In this review, we highlight mouse models with mutations in genes that have been identified as risk genes for autism, which work through synaptic mechanisms and through the mTOR signaling pathway. Robust, replicated autism‐relevant behavioral outcomes in a genetic mouse model lend credence to a causal role for specific gene contributions and downstream biological mechanisms in the etiology of autism.