Playback Of Calls Research Articles

Vocal behaviour of Crested Francolin Dendroperdix sephaena in response to playback calls

The Crested Francolin Dendroperdix sephaena is a common gamebird in sub-Saharan Africa but its vocal behaviour is poorly recorded. A fixed area (24 km2) in the Borakalalo National Park (North West province, South Africa) was traversed during December 2007 to January 2009 and 140 Crested Francolin groups were enticed with playback calls and their calls recorded. The coveys were recorded to identify different calls and to capture statistics on call characteristics during the breeding and non-breeding seasons. Sonograms were produced to analyse and compare the structural characteristics of calls. The Crested Francolin possesses a basic communication system of eight distinctive calls that is similar to the repertoire size of other non-passerines. The duet is a cooperative call by a male and female to advertise, among other functions, territorial occupancy. Males produce a call similar to but different from the duet that advertises reproductive neutrality to avoid physical clashes. Male and female calls could be mate selection tools in dense bush that optimise the chance of fit males and females that roam in the population to pair.

Comparing responses of four ungulate species to playbacks of baboon alarm calls

A growing body of evidence suggests that a wide range of animals can recognize and respond appropriately to calls produced by other species. Social learning has been implicated as a possible mechanism by which heterospecific call recognition might develop. To examine whether familiarity and/or shared vulnerability with the calling species might influence the ability of sympatric species to distinguish heterospecific alarm calls, we tested whether four ungulate species (impala: Aepyceros melampus; tsessebe: Damaliscus lunatus; zebra: Equus burchelli; wildebeest: Connochaetes taurinus) could distinguish baboon (Papio hamadryas ursinus) alarm calls from other loud baboon calls produced during intra-specific aggressive interactions ('contest' calls). Overall, subjects' responses were stronger following playback of alarm calls than contest calls. Of the species tested, impala showed the strongest responses and the greatest difference in composite response scores, suggesting they were best able to differentiate call types. Compared with the other ungulate species, impala are the most frequent associates of baboons. Moreover, like baboons, they are susceptible to both lion and leopard attacks, whereas leopards rarely take the larger ungulates. Although it seems possible that high rates of association and/or shared vulnerability may influence impala's greater ability to distinguish among baboon call types, our results point to a stronger influence of familiarity. Ours is the first study to compare such abilities among several community members with variable natural histories, and we discuss future experiments that would more systematically examine development of these skills in young ungulates.

A novel female call incites male–female interaction and male–male competition in the Emei music frog, Babina daunchina

In anurans, females generally remain silent during mating or only produce calls of very low intensity before mating. Consequently the functions of female calls are not as well understood as those produced by males. We investigated a novel female call produced during mating in the Emei music frog. The functions of the female call during reproductive behaviours were evaluated by field and seminatural playback experiments. During mating, low-intensity female calls (approximately 3.2 s in duration) alternated with male sexual movements (approximately 1.34 s in duration). Female calling was sometimes prolonged when we interrupted male movements, which is consistent with the idea that female calls may stimulate male sexual activity and perhaps facilitate ovulation. In their natural environment, Babina males vocalize and mate in well-hidden underground nests. Field playback experiments showed that female calls significantly increased the rate of male advertisement calling which may help females locate males. Males also showed significant positive phonotactic responses to playback of female calls, and increased aggressive call production and other aggressive behaviours which females may use as cues for mate selection.

Vocal competition in male Xenopus laevis frogs

Male Xenopus laevis frogs produce underwater advertisement calls that attract gravid females and suppress calling by male competitors. Here we explore whether groups of males establish vocal ranks and whether auditory cues alone suffice for vocal suppression. Tests of male-male pairs within assigned groups reveal linear vocal dominance relations, in which each male has a defined rank. Both the duration over which males interact, as well as the number of competitive opportunities, affect linearity. Linear dominance across the group is stable for about 2 weeks; rank is dynamic. Males engage in physical interactions (clasping) while paired but clasping and vocal rank are not correlated. Playbacks of advertisement calls suppress calling and calls from high- and low-ranking males are equally effective. Thus, auditory cues alone suffice to suppress vocal behavior. Playback intensities equivalent to a nearby male advertising effectively suppress calling while low-intensity playbacks are either ineffective or stimulate vocal behavior. X. laevis advertisement calls are biphasic, composed of alternating fast and slow click trills. Approximately half the males tested are more vocally suppressed by all slow than by all fast trills; thus, these males can distinguish between the two phases. The fully aquatic family Pipidae diverged from terrestrial ancestors approximately 170 mya. Vocal suppression in the X. laevis mating system may represent the translation of an ancient anuran social strategy to underwater life.

Experimental evidence that sentinel behaviour is affected by risk

Sentinels are a conspicuous feature of some cooperative societies and are often assumed to provide benefits in terms of increased predator detection. Similar to other cooperative behaviours, variation in investment in sentinel behaviour should reflect variation in the benefits of such behaviour. However, evidence for this is inconclusive: to date experiments have manipulated the cost of sentinel behaviour, and considerations of changes in the benefits of sentinel activity on investment patterns are lacking. Here, we experimentally manipulated the benefits of sentinel behaviour in the cooperatively breeding pied babbler (Turdoides bicolor) to assess whether this had any impact on sentinel activity. We simulated the presence of an unseen predator using playbacks of heterospecific alarm calls, and the presence of an actual predator using a model snake. In both cases, the increase in perceived predation risk caused an increase in sentinel activity, demonstrating that investment in sentinel activity increases when the benefits are greater.

Eavesdropping and Risk Assessment Between Lions, Spotted Hyenas and African Wild Dogs

AbstractVocalizing allows rapid transmission of detailed information beyond line of sight. However, the risk of eavesdropping by unintended receivers means there is also a potential cost to any vocalization. For fugitive species such as African wild dogs the potential cost of attracting dangerous competitors as eavesdroppers is especially significant. Experiments presented here demonstrate that eavesdropping lions Panthera leo were highly motivated to approach playbacks of wild dog Lycaon pictus vocalizations. As lions will kill any wild dogs they can catch, wild dogs risk paying high costs should their calls be detected. Lions were less likely to approach playbacks of spotted hyena Crocuta crocuta whoops, with responses split according to gender: male lions remained quick to approach hyena whoops, but females without accompanying males typically did not approach. Although hyenas seemed at least as capable as lions of detecting playbacks of wild dog calls, they were significantly less likely to subsequently approach them. Analogous to female lions faced with hyenas, the reluctance of hyenas to approach wild dogs may well derive from an assessment of the potential risks involved. We consider the hypothesis that wild dog twitters display counter‐adaptations against eavesdropping, but suggest that this species may best limit the risk of detection by avoiding areas where they are most likely to be overheard by lions.

Alarm calls of tufted titmice convey information about predator size and threat

Many birds utter alarm calls when they encounter predators, and previous work has revealed that variation in the characteristics of the alarm, or ‘‘chick-a-dee,’’ calls of black-capped (Poecile atricapilla) and Carolina (P. carolinensis) chickadees conveys information about predator size and threat. Little is known, however, about possible information conveyed by the similar ‘‘chick-a-dee’’ alarm call of tufted titmice (Baeolophus bicolor). During the winters of 2008 and 2009, free-ranging flocks (N ¼ 8) of tufted titmice were presented with models of several species of raptors that varied in size, and titmice responses were monitored. Smaller, higher threat predators (e.g., eastern screech-owl, Megascops asio) elicited longer mobbing bouts and alarm calls with more notes (D-notes) than larger lower threat predators (e.g., red-tailed hawk, Buteo jamaicensis). During playback experiments, titmice took longer to return to feeding after playbacks of alarm calls given in response to a small owl than to playbacks given in response to a large hawk or a robin (control). Like chickadees, titmice appear to utter alarm calls that convey information about predator size and threat. Titmice, however, appear to cue in on the total number of D-notes given per unit time instead of the number of D-notes per alarm call. The broadband alarm calls of titmice, containing D-notes uttered in an unpredictable manner that may make it difficult for predators to determine the number of titmice calling, may be particularly well suited for deterring predators.

Population density and habitat use of the threatened Balsas screech owl in the Sierra de Huautla Biosphere Reserve, Mexico

The Balsas screech owl Megascops seductus is a threatened species that is endemic to Mexico. We estimated the population density of the Balsas screech owl and evaluated habitat use during the dry season in the Sierra de Huautla Biosphere Reserve, Mexico. We estimated a total of 6.7 owls km -2 during the dry season (October 2001 to April 2002) by recording spontaneous calling and responses to playback of owl calls. October showed the highest density (12.2 owls km -2 ) and Feb- ruary the lowest (2.8 owls km -2 ); differences between months most likely were due to calling activity rather than density. Balsas screech owls used all 5 vegetation types identified in the Sierra de Huautla Biosphere Reserve; 4 were used in proportion with their availability, and Gliricidia-Caesalpina forest was used significantly less than its availability. There was significant variation in the number of owls recorded across different vegetation types. Conserved dry forest had the highest number of owl records, followed by thorn forest, disturbed forest, agricultural systems, and the fewest records in Gli- ricidia-Caesalpina forest. In order to design effective conservation plans for this threatened endemic owl, future research should prioritize population trends in various parts of its range and gather life history information.

Mother is not like mother: Concurrent pregnancy reduces lactating guinea pigs’ responsiveness to pup calls

Offspring signalling can serve to communicate need to the parents and thus influence parental readiness to provide care. Offspring stimuli that affect parental care have been investigated extensively. Yet much less is known about the mechanisms leading to a decline in maternal motivation when conflicts of provisioning current and future offspring may arise. Here we tested responses by pregnant and non-pregnant female guinea pigs (Cavia aperea f. porcellus) to playback of pup calls during their period of lactation for dependent offspring. Most concurrently pregnant and lactating females did not respond to pup calls, whereas non-pregnant lactating females responded strongly. Our findings expand on previous studies by showing that female behavioural responsiveness to pup stimuli is strongly reduced by concurrent pregnancy and lactation. These instantaneous measurements of female responsiveness to young show more directly than standard measures like nursing performance or time to weaning how female motivation to care for current offspring is diminished by simultaneous gestation.

‘Chick-a-dee’ calls of Carolina chickadees convey information about degree of threat posed by avian predators

Individuals of many group-living species of birds respond to potential predators by giving alarm calls, and some species give different, spatially referential alarm calls in response to aerial predators (raptors in flight) and terrestrial predators (including perched raptors). In black-capped chickadees, Poecile atricapillus, characteristics of alarm calls also vary with predator size and level of perceived threat (Templeton et al. 2005, Science, 308, 1934–1937). We examined whether the terrestrial alarm calls of Carolina chickadees, P. carolinensis, show similar variation. In 2007 and 2008, we monitored responses of eight flocks of Carolina chickadees in Madison County, Kentucky, U.S.A. to mounts of different species of raptors that varied in size. Chickadees responded to the raptors by uttering ‘chick-a-dee’ calls with different numbers and types of notes. Larger, lower-threat predators (e.g. red-tailed hawk, Buteo jamaicensis) elicited calls with significantly more introductory ‘chick’ notes and fewer ‘dee’ notes, whereas smaller, higher-threat predators (e.g. eastern screech-owl, Megascops asio) elicited calls with few or no ‘chick’ notes and significantly more ‘dee’ notes. In addition, playback experiments revealed that a greater percentage of Carolina chickadees responded to playback of ‘chick-a-dee’ calls previously given in response to a small predator than during playback of calls given in response to a large predator. These results suggest that the ‘chick-a-dee’ alarm call is a graded signal that informs conspecifics about the presence and behaviour (i.e. perched) of a predator and the degree of threat posed by that predator.

Detection probability of vocalizing dugongs during playback of conspecific calls

Dugongs (Dugong dugon) were monitored using simultaneous passive acoustic methods and visual observations in Thai waters during January 2008. Chirp and trill calls were detected by a towed stereo hydrophone array system. Two teams of experienced observers conducted standard visual observations on the same boat. Comparisons of detection probabilities of acoustic and visual monitoring between two independent observers were calculated. Acoustic and visual detection probabilities were 15.1% and 15.7%, respectively, employing a 300 s matching time interval. When conspecific chirp calls were broadcast from an underwater speaker deployed on the side of the observation boat, the detection probability of acoustic monitoring rose to 19.2%. The visual detection probability was 12.5%. Vocal hot spots characterized by frequent acoustic detection of calls were suggested by dispersion analysis, while dugongs were visually observed constantly throughout the focal area (p<0.001). Passive acoustic monitoring assisted the survey since detection performance similar to that of experienced visual observers was shown. Playback of conspecific chirps appeared to increase the detection probability, which could be beneficial for future field surveys using passive acoustics in order to ensure the attendance of dugongs in the focal area.

Ultrasonic communication in rats: Effects of morphine and naloxone on vocal and behavioral responses to playback of 50-kHz vocalizations

Rats emit ultrasonic vocalizations and it was hypothesized that these vocalizations have an important role in intra-specific communication. Recently, we demonstrated that playback of 50-kHz ultrasonic vocalizations can induce social approach, indicating that 50-kHz calls can serve to (re)establish or to maintain social contact. It is known that endogenous opioids are implicated in the regulation of social behavior, particularly in rough and tumble play. Here, we tested whether administration of opioid ligands can affect social approach in response to playback of 50-kHz calls in juvenile and adult rats. Rats were either treated with 1 mg/kg naloxone, 1 mg/kg morphine, or with saline vehicle. Administration of opioid ligands affected social approach at both ages. Specifically, in juvenile and adult rats, social approach displayed in response to playback of 50-kHz calls was reduced in case of naloxone treatment, but enhanced with morphine. Furthermore, juvenile rats treated with saline or morphine emitted a substantial amount of ultrasonic vocalizations in response to the playback of 50-kHz calls. Such ultrasonic calling was not seen in naloxone treated rats. Importantly, these drug-dependent differences were stimulus-specific, i.e. seen only in response to playback of 50-kHz calls and not in response to playback of background noise. The present finding that opioid ligands can affect social approach and ultrasonic vocalizations induced by playback of 50-kHz calls, indicates that an important feature of social interaction in rats, namely ultrasonic communication, is at least partially regulated by endogenous opioids.

Eavesdropping on the Neighbourhood: Collared Pika (Ochotona collaris) Responses to Playback Calls of Conspecifics and Heterospecifics

AbstractThe acoustic environment, composed in part by the vocalizations of sympatric animals, is a major source of information and can be used to fine‐tune behavioural decisions. Active assessment of alarm calls within and between mammal species is not fully understood. We explored the behavioural responses of collared pikas to con‐ and heterospecific vocalizations, in order to determine whether they selectively attend to these calls. Pikas increased their vigilance after playback of alarm calls of heterospecific mammals (marmots and ground squirrels), but responded most strongly to conspecific calls. While responses to playback calls of their own, of neighbours and of a stranger did not differ, pikas did discriminate between individual callers in a habituation‐discrimination experiment. The ability to make use of information from different sources in their acoustic environment likely facilitates pikas’ behavioural decisions that affect foraging, predator avoidance and nepotism.

Call Playbacks Increase Detection Rates of Northern Hawk Owls in Recent Burns

Call Playbacks Increase Detection Rates of Northern Hawk Owls in Recent Burns

Calling Patterns in Male Responses to Conspecific Playbacks in the Johnstone’s Whistling FrogEleutherodactylus johnstonei

Vocal interactions are common in chorusing frogs. Changes in the calling patterns of Eleutherodactylus johnstonei males were analyzed by recording their responses to playbacks of conspecific calls repeated at fixed periods (long: 1.7 s, short: 0.98 s). The call period and timing, estimated through the onset response time, were determined for each male. Males reduced and regularized the period of their calls in response to both stimuli, regardless of their absolute and relative period (i.e., the difference between the male’s period and the stimulus period). Males avoided initiating their calls during ongoing stimuli, but did not time their calls in the silent gap between successive stimuli in ways that reduced the probability of overlap: the proportion of calls without overlap did not depart from random expectations when the silent gap was long, and was smaller than expected when the gap was short. This result indicated that males react to the presence of the virtual competitor but not to its particular characteristics. Fixed responses have been described in other anurans, and often relate to trade-offs between female attraction, male competition, predator attraction, and depletion of energy reserves. Lack of coordination with the stimuli, beyond inhibition of calling during an ongoing stimulus, also indicates somewhat rigid vocal strategies, at least under the experimental conditions. Results from the short period trials suggested a compromise between maintaining a call period and avoiding call overlap. Whether female behavior is influenced by call interference and whether males pay selective attention to distant males instead of to close neighbors must be investigated to better understand the vocal behavior of E. johnstonei.

Banded mongoose recruitment calls convey information about risk and not stimulus type

Many species use specific vocalizations that attract conspecifics to food sources or that recruit other group members to inspect secondary predator cues or to mob predators. However, little is known regarding the variation in the acoustic structure of such calls and the associated meaning. In the cooperatively breeding banded mongoose, Mungos mungo, we investigated calls produced in the context of group recruitment to three different stimulus types: (1) secondary predator cues; (2) snakes; and (3) members of rival groups. Calls produced in response to predator faeces differed from the harsher variants elicited by snakes and rival groups, but the latter two elicited similar calls. Only a few calls of intermediate acoustic structure were produced in response to the different stimulus categories. Playbacks of calls elicited by the different stimuli caused individuals to approach the speaker in the same way. However, calls elicited specifically by snakes and rival mongooses resulted in a higher proportion of receivers responding and a faster receiver response than calls elicited by faeces. This suggests a graded rather than a discrete recruitment call system. Thus, despite obvious differences in stimulus type and the purpose of recruitment, the acoustic structure of calls conveys information about the risk of the encountered stimulus and not the stimulus type itself, allowing receivers to adjust their response according to the urgency. Since calling continued for prolonged periods after all group members had gathered around the callers, these calls may also function to deter rivals and to coordinate the subsequent group response.

A predator-elicited song in the splendid fairy-wren: warning signal or intraspecific display?

Predator-elicited vocalizations are typically thought to function as alarms to conspecifics or as deterrents to predators. In splendid fairy-wrens, Malurus splendens , ‘Type II song’ is commonly elicited in response to vocalizations of the grey butcherbird, Cracticus torquatus , a potential predator of both nestlings and adults. We examined the context of Type II songs and investigated possible antipredator functions of this vocalization using mount presentations of predators at nests, playbacks of Type II songs to females in the field and playbacks of Type II songs to nestlings. Males did not give Type II songs in response to silent mount presentations of predators at the nest, females ignored Type II songs played in the field and nestlings ignored Type II songs played at the nest. Using playbacks of butcherbird calls to males in the presence of predator and nonpredator mounts, we found that males were not more likely to give Type II songs when a predator was near the nest. Despite being commonly uttered in response to predator calls, this vocalization does not appear to be an alarm or predator deterrent. We suggest that the song is a form of male advertisement.

Marmoset (Callithrix geoffroyi) Food‐Associated Calls are Functionally Referential

AbstractSignals that are functionally referential provide listeners with information about a signaler’s external environment, such as the presence of a nearby predator. Just as alarm calls may signal the presence of a predator, food‐associated calls may signal the presence of food. To date, however, the only conclusive evidence that conspecifics perceive information about food from food‐associated calls comes from a single species, the domestic chicken. Geoffroy’s marmosets, small, arboreal New World primates, often emit food‐associated calls when finding or consuming food. We presented playbacks of food calls and control sounds to two groups of naturalistically housed marmosets and observed the frequency of food‐related behaviors (FRBs) during the 20‐min post‐playback period. Relative to the control playbacks, food call playbacks elicited an increase in the frequency of two FRBs (foraging and feeding), lasting throughout the post‐playback observations. Moreover, the effect of food call playbacks was robust, occurring without regard to the type of food eliciting the food calls, the rate of food calling, or whether the signaler was a member of the receiver’s group. To our knowledge, this research is the first to demonstrate that the food‐associated calls of a primate species, like the food‐associated calls of domestic chickens, meet the perception criterion for functionally referential communication. The results are discussed in light of the affective and cognitive mechanisms that may underlie the responses of receivers to hearing food‐associated calls given by marmoset conspecifics.

Group Territoriality as a Form of Cooperative Breeding in the Flightless Kagu (Rhynochetos jubatus) of New Caledonia

ABSTRACT. Birds that live in family groups and cooperatively defend the family's territory are currently recognized as cooperative breeders only if helpers assist with chick rearing. We observed breeding Kagus (Rhynochetos jubatus) and video-monitored nests to determine whether help with feeding or family size affected their reproductive success. During >5,500 h of nest monitoring, helpers never provided parents or chicks with food. The reproductive success of families increased with group size nonetheless. Family size affected breeding success more than habitat-related parameters. Nonbreeding Kagus reacted to playback calls as often as breeding birds did. Observations of territorial fights gave additional evidence that nonbreeding group members help defend the family's territory and can, therefore, improve reproductive success. Our results suggest that cooperative territory-defense was the most important factor that increased the breeding success of Kagus. We propose that group territoriality should be c...

The response of American robins (Turdus migratorius) to aerial alarms

AbstractAlarm calls are important signals that allow individuals to convey information about both predator type and risk level. How individuals respond to these calls may depend on both the intensity of the call as well as the age of the responder. We investigated an aerial alarm call of the American robin and specifically examined how call rate (reflecting intensity) and age affect the anti-predator behaviors of responders. Both juveniles and adults significantly altered their behavior upon hearing playbacks of seet calls; they foraged less and increased vigilance and other anti-predator behaviors. Adult robins were also able to distinguish between low intensity and high intensity calls; skygazing, an important behaviour that allows robins to scan for raptors, increased with call rate. Juveniles, on the other hand, skygazed less and there was a trend for juveniles to spend more time alert than adults suggesting that some learning may be involved.