Male Calls Research Articles

Acoustic parameters of courtship and human-directed friendly vocalisations in seven species of Neotropical deer in captivity

Context Polygynous deer rut vocalisations have been found to be highly conspicuous, typical of the species and important in sexual selection. Information about vocalisations is not available for Neotropical species (subfamily Odocoileinae). Aims The objective was to record courtship vocalisations from all Neotropical deer available, looking for differences among species useful for taxonomic identification, characterise the vocalisations according to acoustic parameters and to try to determine functions. Methods Four species of brocket deer (red, Mazama americana (n = 9); grey, M. gouazoubira (n = 7); Amazonian brown, M. nemorivaga (n = 3); Brazilian dwarf, M. nana (n = 1)), and one individual each of marsh (Blastocerus dichotomus), white-tailed (Odocoileus virginianus) and taruca (Hippocamellus antisensis) deer were recorded in captivity at two institutions, in conditions of courtship or human interaction. The acoustic analysis was performed with Praat. Data from the first three species of Mazama were analysed statistically with a multilevel model with two layers. Key results In the context of courting either females or humans, male deer produced low-intensity, short-duration (0.1–0.3 s) bleats with fundamental frequencies (F0) between 100 and 400 Hz; calls were similar among species. The duration of these calls for Amazonian brown brocket males was significantly longer than for males of the other two species. Females of two species had longer-duration calls than did males, in friendly interactions with humans. F0 differences among species for both friendly and courtship calls were almost significant for males of M. gouazoubira. Individual differences were highly significant for both duration and mean F0. Mean F0 for courtship calls of adult males was not correlated with body size in six of the seven species, in contrast to the theory of acoustic allometry. Conclusions The production of male courtship bleats is probably a basic feature of Odocoiline deer and is probably important in sexual selection and female choice. The differences from one species to another are not sufficient for taxonomic use but may be incipient isolating mechanisms between grey and Amazonian brown brocket deer. Implications Studies of deer vocalisations have shown their importance in sexual selection and their incredible variety in closely related species and subspecies, but they have dealt mainly with Old World deer. This study fills a gap in our knowledge, as the first on Neotropical deer, which constitute six genera and 17 species and are widely distributed in the Americas. These data are important for future studies on the function and phylogeny of deer vocalisations.

Complex sensory environments alter mate choice outcomes.

Noise is a common problem in animal communication. We know little, however, about how animals communicate in the presence of noise using multimodal signals. Multimodal signals are hypothesised to be favoured by evolution because they increase the efficacy of detection and discrimination in noisy environments. We tested the hypothesis that female túngara frogs' responses to attractive male advertisement calls are improved in noise when a visual signal component is added to the available choices. We tested this at two levels of decision complexity (two and three choices). In a two-choice test, the presence of noise did not reduce female preferences for attractive calls. The visual component of a calling male, associated with an unattractive call, also did not reduce preference for attractive calls in the absence of noise. In the presence of noise, however, females were more likely to choose an unattractive call coupled with the visual component. In three-choice tests, the presence of noise alone reduced female responses to attractive calls and this was not strongly affected by the presence or absence of visual components. The responses in these experiments fail to support the multimodal signal efficacy hypothesis. Instead, the data suggest that audio-visual perception and cognitive processing, related to mate choice decisions, are dependent on the complexity of the sensory scene.

Acoustic Experience Interacts with Perceived Risk of Predation in Shaping Female Response in Crickets

Female response to male sexual signals is context dependent and influenced by a variety of environmental factors. For instance, females often adjust mating preferences in response to predation risk. Social experiences as a juvenile, such as exposure to conspecific sexual signals, have also been shown to influence female mating preferences as adults. Experiments that examine the influence of both environmental factors and early social experiences on female preferences are needed to understand female mating behaviors in the wild. In Pacific field crickets (Teleogryllus oceanicus), males produce a calling song that females evaluate during mate choice. We examined the influence of both risk perception and juvenile exposure to calling song in shaping adult T. oceanicus female phonotaxis to either a high- or low-quality calling song. We predicted that females raised in song-less conditions would be more responsive to calling song to maximize mating opportunities, and that females would show reduced response to calling in a risky, open area. Females raised in a song-deprived environment were much more responsive to calling song compared to those reared with song. In contrast to our predictions, females raised in song-less conditions were more responsive to the high-quality song in the risky, open arena. These results suggest that juvenile acoustic rearing influences female responsiveness to male calling song, but it has less influence on strength of preference for signal quality.

The influence of long-term cadmium exposure on the male advertisement call of Xenopus laevis

Cadmium (Cd) is a non-essential environmental endocrine-disrupting compound found in water and a potential threat to aquatic habitats. Cd has been shown to have various short-term effects on aquatic animals; however, evidence for long-term effects of Cd on vocal communications in amphibians is lacking. To better understand the long-term effects of low-dose Cd on acoustic communication in amphibians, male Xenopus laevis individuals were treated with low Cd concentrations (0.1, 1, and 10μg/L) via aqueous exposure for 24months. At the end of the exposure, the acoustic spectrum characteristics of male advertisement calls and male movement behaviors in response to female calls were recorded. The gene and protein expressions of the androgen receptor (AR) were determined using Western blot and RT-PCR. The results showed that long-term Cd treatment affected the spectrogram and formant of the advertisement call. Compared with the control group, 10μg/L Cd significantly decreased the first and second formant frequency, and the fundamental and main frequency, and increased the third formant frequency. One and 10-μg/L Cd treatments significantly reduced the proportion of individuals responding to female calls and prolonged the time of first movement of the male. Long-term Cd treatment induced a downregulation in the AR protein. Treatments of 0.1, 1, and 10μg/L Cd significantly decreased the expression of AR mRNA in the brain. These findings indicate that long-term exposure of Cd has negative effects on advertisement calls in male X. laevis.

Estimating abundance of the Stripeless tree-frog Hyla meridionalis by means of replicated call counts

The Stripeless tree-frog Hyla meridionalis reaches its eastern-most European distributional limit in NW Italy, and specifically in the Cinque Terre National Park. Here for two consecutive years, we estimated tree-frog population abundance by call surveys at 24 sites. Data were analysed in the framework of N-mixture open population models based on repeated counts of calling males. The results obtained by this statistical approach were effective in estimating population size together with annual recruitment and survival. The tree-frog male population size remained constant between years and site abundance was inversely related with altitude. On the bases of these findings, our application of N-mixture models to tree-frog calling males was successful and is a promising cost-effective method to obtain long-term monitoring data on this species over large geographic areas.

Potential effect of the global warming to the subfamily Lipotactinae (Orthoptera: Tettigoniidae) in China and acoustics data of Lipotactes truncatus Shi & Li, 2009

Abstract Species in the subfamily Lipotactinae are brachypterous with a small body and have limited dispersal ability. In this study, it’s the first time to describe the male calling song of Lipotactes truncatus Shi & Li, 2009. MaxEnt was used to predict the potential geographic distribution of Lipotactinae in present-day and year 2070, in order to explore responses to global warming of this subfamily in China. As for L. truncatus, two types of calling songs are observed with the peak frequencies in the ultrasound range. With the trend of global warming, the suitable habitats of the subfamily Lipotactinae will change in three ways: i) migrate to high latitude area; ii) migrate to the coastal region of south China; iii) migrate along altitude gradients in mountains. Some species will be locked into the “sky islands”, which will accelerate speciation process, with global warming.

Males’ calls carry information about individual identity and morphological characteristics of the caller in burrowing petrels

Acoustic communication in burrowing petrels has been poorly studied. However, as for many other bird species, acoustic communication seems to play an essential role in social interactions during the breeding season of these seabirds. Bachelor males call from their burrow, likely to attract females, but also when vocally challenged by other males. Calling in the breeding colony exposes petrels to high predation risks and thus it should provide an important benefit. The present study focuses on the informative content of males’ calls in the blue petrel Halobaena caerulea and the Antarctic prion Pachyptila desolata, two monogamous petrel species producing a single egg per year. We tested the hypotheses that acoustic parameters of a male's calls 1) reflect phenotypic characteristics, and 2) bear an individual vocal signature. To do so, we first tested on both species the relationships between seven morphometric measurements and 11 acoustic parameters using multivariate analyses. Second, we performed a between‐class analysis and calculated the potential of individuality coding (i.e. the ratio between intra‐ and inter‐individual variabilities) for acoustic parameters in both spectral and temporal domains. Results show acoustic parameters (especially energy quartiles, call duration, and syllable or phrase rate) reflect the caller's body size, bill morphology and wing morphology in both species. Considering the seeming pertinence of wing morphology, we suggest wing area may be a more relevant trait to consider than wing length when studying soaring birds. The results support the idea that energy quartiles, phrase rate and call duration also code for individual identity. Information carried by males’ calls might play a role in social interactions, such as burrow defence (e.g. male‐male competition, neighbour‐stranger discrimination) and/or female mate choice.

Stink Bug Communication with Multimodal Signals Transmitted through Air and Substrate

This review represents complex mechanisms and processes of multimodal communication in stink bugs. During reproductive behavior the airborne and substrate-borne signals enable mate recognition, mediate directionality of movement, eliminate rivals and motivate partners for copulation. Species specific characteristics prevent hybridization at various levels of mating behavior. Male sex and/or aggregation pheromones as uni- or multicomponent signals attract mates to land on the same plant and there, trigger females to call males by vibratory signals, transmitted through the plant. Communication during courtship runs at short distance with visual, airborne, substrate-borne and contact chemical and mechanical signals. Abdomen vibrations produce the main repertoire of female and male calling, courtship and rival vibratory signals. To increase their informational value, stink bugs tune signal frequency, amplitude and temporal characteristics with mechanical properties of plants. The airborne component of species non-specific and high amplitude signals, produced by body tremulation and wing buzzing enables communication contact between mates standing on mechanically isolated plants. Female vibratory signals increase the amount of male emitted pheromone and the latter keeps female calling. Interaction, synergy and characteristics of visual, contact chemical and vibratory signals, exchanged during courtship remain under-investigated. Female and male competition for access to copulation in imbalanced sex conditions is characterized by duetting with rival song vibratory signals. Different receptors in and on different parts of the body are able to detect with high sensitivity multimodal airborne and substrate-borne communication signals. The relevance of the multimodal communication for the reproductive success of stink bugs is discussed.

Spatial Mixing between Calling Males of Two Closely Related, Sympatric Crickets Suggests Beneficial Heterospecific Interactions in a NonAdaptive Radiation.

Sympatry among closely related species occurs in both adaptive and nonadaptive radiations. Among closely related, sympatric species of a nonadaptive radiation, the lack of ecological differentiation brings species into continual contact where individuals are exposed to the risk of reproductive interference. Selection thus should cause divergence in multiple components mediating the reproductive boundary. Besides differentiation of reproductive signals per se, spatial segregation is a commonly proposed mechanism that can mitigate reproductive interference. Studying a pair of broadly sympatric, closely related cricket species from a nonadaptive radiation in Hawaii, we 1) quantified acoustic divergence of male songs and 2) tested alternative hypotheses of spatial distribution of calling males of the 2 species. Acoustic analyses of the recorded songs showed that, while the 2 species differed substantially in pulse rate, no spectral or fine temporal segregation of the pulse structure was evident, indicating the potential for acoustic masking. Moreover, we found that calling males of the 2 species are highly mixed both vertically and horizontally and showed the same preference for calling sites. More surprisingly, calling males were found to form mixed-species calling clusters where heterospecific males are closer to each other than conspecific males. Such an individual spacing pattern suggests low heterospecific aggression and/or high conspecific competition. Because females prefer higher sound intensity, heterospecific males may benefit, rather than interfere, with each other in attracting females. These findings offer a potential mechanism enabling species coexistence in sympatry.

Genetic monogamy despite frequent extrapair copulations in "strictly monogamous" wild jackdaws.

“Monogamy” refers to different components of pair exclusiveness: the social pair, sexual partners, and the genetic outcome of sexual encounters. Avian monogamy is usually defined socially or genetically, whereas quantifications of sexual behavior remain scarce. Jackdaws (Corvus monedula) are considered a rare example of strict monogamy in songbirds, with lifelong pair bonds and little genetic evidence for extrapair (EP) offspring. Yet jackdaw copulations, although accompanied by loud copulation calls, are rarely observed because they occur visually concealed inside nest cavities. Using full-day nest-box video surveillance and on-bird acoustic bio-logging, we directly observed jackdaw sexual behavior and compared it to the corresponding genetic outcome obtained via molecular parentage analysis. In the video-observed nests, we found genetic monogamy but frequently detected forced EP sexual behavior, accompanied by characteristic male copulation calls. We, thus, challenge the long-held notion of strict jackdaw monogamy at the sexual level. Our data suggest that male mate guarding and frequent intrapair copulations during the female fertile phase, as well as the forced nature of the copulations, could explain the absence of EP offspring. Because EP copulation behavior appeared to be costly for both sexes, we suggest that immediate fitness benefits are an unlikely explanation for its prevalence. Instead, sexual conflict and dominance effects could interact to shape the spatiotemporal pattern of EP sexual behavior in this species. Our results call for larger-scale investigations of jackdaw sexual behavior and parentage and highlight the importance of combining social, sexual, and genetic data sets for a more complete understanding of mating systems.

Effects of artificial light at night and male calling on movement patterns and mate location in field crickets

Anthropogenic factors, such as artificial light at night (ALAN), are increasingly linked to significant modifications in animal behaviours, such as foraging or migration. However, few studies have investigated directly whether the presence of ALAN affects the ability to find a mate (mate location). One direct effect of the presence of ALAN is that it can create a light barrier in an otherwise dark environment. This may have significant behavioural implications for nocturnally active species if it affects their ability to respond to potential mates. Our study, using the acoustically orienting Australian black field cricket, Teleogryllus commodus, determined experimentally whether the presence of a fragmented light environment influenced movement patterns of virgin females and males. Moreover, given the importance of male song for reproductive outcomes in this species, we assessed simultaneously whether such behaviours were modified by the presence of a male attraction call. We found that while initiation of movement was slower in the presence of ALAN, the behavioural shifts associated with its presence were relatively small compared to the influence of a broadcast male attraction call. The response to the male attraction call was typically stronger for females than for males, but both males and females modified aspects of behaviour when it was present regardless of whether their immediate environment was fragmented by artificial light at night or not. Artificial light at night may alter subtle aspects of movement and mating behaviour in this species, but ultimately does not provide a barrier to movement or mate location.

Lower levels of human disturbance correspond with longer-term persistence of Endangered Green Peafowl Pavo muticus populations

SummaryGalliformes are one of the most threatened groups of birds in South-East Asia, with 27% of the species threatened with extinction. Long term population viability and extinction probability studies, at different levels of threat and management, are lacking due to weak life history data. This study aimed to define the long-term viability and extinction risk of two populations of the endangered Green Peafowl Pavo muticus, facing different threat and protection levels, using Bayesian Population Viability Analysis (BPVA), which requires less data than traditional methods. The results showed an increasing trend in the Green Peafowl population in HuaiKhaKhaeng Wildlife Sanctuary (western Thailand), with a high protection level and low disturbance and high probability of assuring persistence for the next 100 years. By contrast, the population in YokDon National Park (south-central Vietnam), with a high habitat disturbance level and significant hunting pressure, is predicted to decline and has a high probability (99%) of extinction by 2097. Also, the BPVA showed minimum viable population (MVP) estimates of 250 and 450 calling males for the HuaiKhaKhaeng and YokDon populations respectively, assuring high probabilities of long-term persistence if the minimum numbers of males are available. The population size of 219 calling males at YokDon during the 2013 survey is lower than the MVP threshold of 450 calling males, which suggests the species has a low probability of long-term persistence in the area. Despite limited life history and population data, BPVA predicted the future of this population under site-specific conditions, and the results could be used to promote better management and population restoration.

Escape behaviour of female field crickets is not affected by male attractiveness, but shows consistent patterns within individuals

Predator avoidance is one of the most important fitness components because predation success is directly linked to prey death. Decision making regarding predator avoidance is influenced by many abiotic and biotic factors because of the trade-off between predator avoidance and other contextual behaviours. Attractive sexual signals may elicit responses not only from potential mates, but also from predators. Therefore, female escape behaviour will be affected by the attractiveness of male signals. I examined the effect of attractiveness of male calling songs on the components of female escape behaviour [i.e., responsiveness to artificial predatory stimuli, alternative escape tactics (jumping or forward locomotion), and locomotor distance] in the field cricket Teleogryllus occipitalis. Although song attractiveness did not affect female escape behaviour, behavioural components showed high inter-individual variation. The results showed that escape behaviour exhibited high repeatability, and the consistency affects decision-making in terms of escape behaviour in field crickets.

Females prefer the calls of better fathers in a Neotropical frog with biparental care

AbstractMale secondary sexual traits potentially function as indicators of direct or indirect fitness benefits to females. Direct benefits, such as paternal care, may be especially important to females in species with biparental care. In an experimental field study of the golden rocket frog (Anomaloglossus beebei), a Neotropical species with biparental care, we tested predictions from four hypotheses proposed to explain the evolutionary relationship between male secondary sexual traits and paternal care quality (the “good parent,” “differential allocation,” “trade-off,” and “essential male care” hypotheses). We examined: 1) the influence of paternal care on offspring survival, 2) the relationships between male calls and paternal care, maternal care, and opportunities for males to acquire multiple mates, and 3) female preferences for three acoustic properties of male advertisement calls. Our results reveal that paternal care positively impacts offspring survival, that males producing longer calls also provide higher-quality paternal care in the form of greater egg attendance and territory defense, and that females prefer longer calls. Females did not discriminate among potential mates based on differences in dominant frequency or call rate. These findings, which suggest male advertisement calls are indicators of potential direct benefits to females in the form of paternal care, are consistent with the good parent hypothesis and inconsistent with the trade-off, differential allocation, and essential male care hypotheses.

High and dry: Trade-off in arboreal calling in a treefrog mediated by local environment

AbstractTrade-offs shaping behavioral variation are often influenced by the environment. We investigated the role that the environment plays in mediating trade-offs using a widespread frog with a conspicuous mating display, Pseudacris crucifer. We first demonstrated, using playback and desiccation experiments, that calling site selection involves a trade-off between sound transmission and desiccation. We then determined the influence of local environmental conditions on the intensity of the trade-off by examining range-wide behavioral and environmental data. We showed that the benefit of improved call transmission is positively influenced by vegetation density and ground cover. Behavioral data are consistent with this relationship: sites with a greater transmission benefit have increased prevalence of arboreally calling males. We also found that the prevalence of arboreal calling behavior increases with relative humidity and air temperature, suggesting an influence of these environmental variables on the desiccation cost of arboreal calling. This study provides a clear example of the role of the environment in mediating trade-off intensities and shaping critical behavioral traits.Local environment mediates the intensity of a trade-off associated with arboreal calling behavior in a treefrog. Combining observational and experimental approaches, we show that arboreal calling behavior increases the transmission of a mating call while potentially subjecting individuals to a rate of desiccation six times greater than terrestrial calling. Local environmental conditions influence both the benefit and the cost of this trade-off, subjecting different populations to varying trade-off intensities and shaping arboreal calling behavior.

Molecular biogeography and host relations of a parasitoid fly.

Successful geographic range expansion by parasites and parasitoids may also require host range expansion. Thus, the evolutionary advantages of host specialization may trade off against the ability to exploit new host species encountered in new geographic regions. Here, we use molecular techniques and confirmed host records to examine biogeography, population divergence, and host flexibility of the parasitoid fly, Ormia ochracea (Bigot). Gravid females of this fly find their cricket hosts acoustically by eavesdropping on male cricket calling songs; these songs vary greatly among the known host species of crickets. Using both nuclear and mitochondrial genetic markers, we (a) describe the geographical distribution and subdivision of genetic variation in O. ochracea from across the continental United States, the Mexican states of Sonora and Oaxaca, and populations introduced to Hawaii; (b) demonstrate that the distribution of genetic variation among fly populations is consistent with a single widespread species with regional host specialization, rather than locally differentiated cryptic species; (c) identify the more‐probable source populations for the flies introduced to the Hawaiian islands; (d) examine genetic variation and substructure within Hawaii; (e) show that among‐population geographic, genetic, and host song distances are all correlated; and (f) discuss specialization and lability in host‐finding behavior in light of the diversity of cricket songs serving as host cues in different geographically separate populations.

Testosterone and Corticosterone Profiles and Body Condition of Calling and Non-calling Lithobates grylio

Anuran vocalization is one of the most energetically expensive behaviors recorded in vertebrates. To sustain this behavior, circulating hormones in male frogs must act to promote calling behavior while mobilizing energy reserves. We hypothesize that this is accomplished through the actions of testosterone (T) and corticosterone (CORT). T is thought to elicit calling, while CORT mobilizes energy reserves. Eventually, high CORT concentrations and low energy reserves suppress calling behavior. We evaluated this hypothesis in light of the reproductive ecology of the Pig Frog, Lithobates grylio. Plasma samples from calling and non-calling males were collected during four months of the reproductive season. Calling males were shown to have significantly higher concentrations of circulating T and high body conditions. Conversely, non-callers exhibited elevated CORT and low body conditions. There was no correlation between the two hormones, but circulating T concentrations did decrease over the season. Lastly, we found that CORT is positively correlated with circulating glucose (in non-callers); this finding is supported by CORT's known role in gluconeogenesis. Taken together, these data indicate that circulating hormones and available energy reserves likely influence calling behavior in L. grylio.

Background noise disrupts host-parasitoid interactions.

The soundscape serves as a backdrop for acoustic signals dispatched within and among species, spanning mate attraction to parasite host detection. Elevated background sound levels from human-made and natural sources may interfere with the reception of acoustic signals and alter species interactions and whole ecological communities. We investigated whether background noise influences the ability of the obligate parasitoid Ormia ochracea to locate its host, the variable field cricket (Gryllus lineaticeps). As O. ochracea use auditory cues to locate their hosts, we hypothesized that higher background noise levels would mask or distract flies from cricket calls and result in a decreased ability to detect and navigate to hosts. We used a field manipulation where fly traps baited with playback of male cricket advertisement calls were exposed to a gradient of experimental traffic and ocean surf noise. We found that increases in noise amplitude caused a significant decline in O. ochracea caught, suggesting that background noise can influence parasitoid–host interactions and potentially benefit hosts. As human-caused sensory pollution increases globally, soundscapes may influence the evolution of tightly co-evolved host–parasitoid relationships. Future work should investigate whether female cricket phonotaxis towards males is similarly affected by noise levels.

Calling behaviour of Elachistocleis matogrosso (Anura, Microhylidae) is associated with habitat temperature and rainfall

ABSTRACT Anuran calling behaviour is determined by environmental, endogenous, and social factors. The effect of these factors usually differs among and within species. We used acoustic monitoring to evaluate the effects of environmental predictors on the daily occurrence and call production of Elachistocleis matogrosso (Microhylidae) in the northeastern Brazilian Pantanal. We monitored the calling behaviour of the species over a complete annual cycle at four acoustic monitoring stations. Daily occurrence was positively associated with high minimum air temperature at all sites, and was also related to days with high abundant rainfall at two sites. This result suggests that the minimum temperature acts as the main trigger initiating calling activity in this species. In contrast, call production was positively related to rainfall and accumulated rainfall over the previous three days, with no effect of air temperature. This observation could be related to a high abundance of calling males after some rainy periods, when more water bodies are available for reproduction. Our findings reveal the importance of performing studies at different spatial-temporal and calling scales because the effects of environmental predictors on anuran calling behaviour may differ among sites, and this factor is also important when analysing daily occurrence or call production.

Social calls of Myotis nattereri during swarming: Call structure mirrors the different behavioral context.

Swarming is a characteristic behavior of bats that occurs in different social contexts. We studied the swarming behavior of Myotis nattereri at a maternity colony and at an autumn swarming site in South-West Germany by using synchronized sound and video recordings. Swarming was always associated with social vocalizations consisting of four frequently occurring call types. Call type A was a short call with a broadband steep-shallow-steep downward frequency modulation. Call type B consisted of two elements beginning with a broadband upward hooked element followed by a steep frequency modulated element. Call type C showed a characteristic rapid downward-upward-downward frequency modulation. Call type D was a long sinusoidal trill-like call with high variability in signal structure. All call types were recorded at the maternity colony, as well as at the autumn swarming site, but the incidence of each call type differed distinctly between the study sites. At the maternity roost, type A calls were most commonly produced. We found evidence for an individual signature in this call type and suggest that this social call has the function of a contact call in Natterer’s bats. At the autumn swarming site, type D calls were the most common social calls; in contrast, this call type was recorded only twice at the maternity roost. The occurrence of trills mainly at the autumn swarming site and their high variability suggests that trills function as male advertisement calls in M. nattereri.