Female Calls Research Articles

Herbivore-Induced Changes in Cotton Modulates Reproductive Behavior in the Moth Spodoptera littoralis

Plants produce chemical defense compounds to resist herbivore attack either by repelling the herbivores or attracting natural enemies of the herbivores. We have previously shown that volatile compounds from cotton released in response to herbivory by conspecifics reduce oviposition in cotton leafworm moth Spodoptera littoralis. It remained, however, unclear whether herbivore-induced changes also affect moth pre-mating and mating behaviours. In this study we examined the effect of herbivore-induced changes in cotton on reproductive behaviours i.e., female calling, male attraction and investment, and mating behaviour in S. littoralis. We found a reduction in the number of females calling i.e., females releasing pheromone, in the presence of cotton plants damaged by larvae of S. littoralis compared to undamaged plants. Females also spent significantly less time calling and showed a delay in calling in the presence of damaged plants. Furthermore, males exhibited significantly delayed activation and reduced attraction towards female sex pheromone in the presence of damaged plants. We also found that mating success and the number of matings were significantly reduced in the presence of damaged plants whereas male investment i.e., spermatophore weight, was not affected. Thus, our study provides evidence that herbivory by conspecifics on host plants affect pre-mating and mating behaviours in an insect herbivore.

Calling behavior of males and females of a Bornean frog with male parental care and possible sex-role reversal

In many species that use acoustic signals for mate attraction, males are usually the most vocal sex. In frogs, females typically remain silent, while males produce advertisement calls to attract mates. In some species, females vocalize, but usually as a response to an initial male advertisement call. The smooth guardian frog (Limnonectes palavanensis), found on Borneo, has exclusive paternal care while the females mate and desert after laying the clutch. Males provide care to the eggs until hatching and then they transport the tadpoles to small bodies of water. The vocal repertoire of this species has never been described. Males have a distinctive advertisement call to attract females, but produce the call very infrequently. We found that females of L. palavanensis not only respond to male advertisement calls but also vocalize spontaneously, forming lek-like aggregations around a single male. Males may or may not respond to a particular female with a short courtship call, which is elicited only by the female call and not the male advertisement call. The calling rate of females is consistently higher throughout the night compared with the calling rate of males. These observations suggest that this species exhibits a reversal in calling behavior and possibly a sex-role-reversed mating system. Exceptional cases of species with a sex-role reversed mating system have been observed in fishes and birds, but not in frogs. For sex-role reversal to occur, there must be intense parental care by the males and a surplus of females. Additionally, females should exhibit characteristics that are usually observed in males in species with conventional sex roles. We found that in L. palavanensis, females are highly vocal, exhibiting higher calling rates compared with the calling rates of the males. This behavior, where females out-signal males has not been observed in anurans. This female calling behavior coupled with observations of several females approaching a male provides evidence of a female-biased operational sex ratio, a characteristic of a sex-role-reversed mating system. Thus, this study provides quantitative evidence that L. palavanensis exhibits various aspects consistent with a sex-role reversed mating system.

Using dual-sex calls improves the playback census method for a nocturnal burrow-nesting seabird, the Manx Shearwater Puffinus puffinus

ABSTRACTCapsule: Playback with dual-sex calls increases the response rate of Manx Shearwaters Puffinus puffinus by 40–60% and reduces its daily variability, which would improve the precision of population estimates.Aims: To test whether playing male and female calls would elicit more responses to playback than male-only calls, reduce daily variability and the length of response rate calibration trials, and give more precise estimates. We also measured response times to playback and assessed the reliability of visual signs of occupancy at burrow entrances.Methods: Responses to four playback call-types (male-only and three variants of dual-sex calls) were compared in repeated trials at two colonies (Ramsey and Rum, UK) during May–June 2014.Results: Dual-sex calls gave higher response rates with lower variance than male-only calls, because females frequently replied to female calls but rarely to male calls. In simulated 3–5-day calibration trials, response rates and correction factors were up to 50% more precise with dual-sex calls. Visual signs of burrow occupancy were unreliable.Conclusion: Playback for Manx Shearwaters should use a 25 seconds recording of male and female calls intermixed, with 10 seconds listening time for delayed responses. Census-specific calibration trials are essential for accurate estimates of daily response rates.

Vocalizations of female frogs contain nonlinear characteristics and individual signatures.

Anuran vocalization is sexually dimorphic, with males doing the bulk of vocalizing. Female vocalization is rare and has been observed in a handful of species, including the concave-eared torrent frog (Odorrana tormota). Females O. tormota have been reported to emit moderate-level calls to attract males. In contrast to males, female’s vocal signals show no evidence of nonlinear phenomena (NLP). However, with females emitting calls so infrequently that this conclusion must be considered tentative in light of the limited supporting data. The present study was undertaken to test the hypotheses that their vocalizations: 1. may not be purely linear, 2. may contain individual signatures, similar to their male counterparts. We recorded 671 calls from six captive gravid females and found that their vocalizations are as complex as male calls, with numerous calls exhibiting complex upward/downward frequency modulations, and 39% of female calls containing at least one component of the NLP, i.e., subharmonics, deterministic chaos, frequency jump, or biphonation. Furthermore, females in captivity tend to call in bouts throughout the day and night, and the call rate varies hourly with a maximum of >10 calls per minute matching the maximum call rate in males. Similar to males, female vocalizations carry individual signatures, and all sound parameters analyzed differ significantly between individuals. This represents the first report ever showing that vocalizations of female anurans: 1. contain NLP, 2. carry individual signatures. Presence of signatures in both the male and female vocalizations opens up the possibility for males (and females) to distinguish individual frogs in both sexes acoustically, and thus their sound communication ability may be more advanced than previously thought.

Dwarf mongooses use sex and identity cues in isolation calls to discriminate between callers

The information transmitted by acoustic signals has attracted much scientific interest in recent years. However, isolation calls, which are long-distance vocalizations used by lost group members to reunite with their social group, have been surprisingly neglected. These calls assist in maintaining group cohesion and are thus particularly important in species that depend on the group for survival or reproduction such as cooperative breeders. Our study therefore examined the information transmitted by the isolation vocalization in a wild cooperatively breeding carnivore: the dwarf mongoose, Helogale parvula. We ran an acoustic analysis for informative cues within isolation calls, and conducted a series of playback experiments to identify whether mongooses could discriminate between callers based on these cues. The acoustic structure of dwarf mongoose isolation vocalizations contained information concerning the caller's identity, sex and potentially also group membership. Target mongooses discriminated between callers of their own and other groups and biased their response based on the sex of the caller. They responded more quickly and for longer, and approached more closely, for calls of foreign females than calls of female group mates. This is the first time that sex specificity has been demonstrated in the vocalization of an herpestid, and we suggest that dwarf mongooses eavesdrop on the calls of isolated foreigners and may use isolation calls to attract and identify potential mates.

Sex, Fashion, Work: James Joyce and the Late-Victorian Actress

AbstractThis article considers the presence of three late-Victorian actresses (Mrs Patrick Campbell, Eleonora Duse, and Sarah Bernhardt) in the work of James Joyce. The first appears in Joyce’s short story ‘A Mother’ (Dubliners). The strong influence of the other two is also detectable in the characterization of Ulysses’ heroines, Gerty MacDowell and Molly Bloom, and in a seminal text of late modernism, Finnegans Wake. In ‘A Mother’, Joyce’s attention to the importance of fashion on the stage and to poor working conditions for female performers calls to mind the career of Mrs Patrick Campbell. In Ulysses, Gerty’s performance in ‘Nausicaa’ recalls the techniques of the Ibsenian actress Eleonora Duse, known especially for her blushing; I argue that, given this famous skill and Joyce’s fascination with her, Duse directly informs Gerty’s characterization. Finally, Molly Bloom’s repertoire of dramatic references, including Trilby, Lillie Langtry, Sarah Bernhardt, publicity photographs, and Pineroticism, sugges...

Sex pheromone titre in the glands of Spodoptera litura females: circadian rhythm and the effects of age and mating

AbstractThe present study investigates the effects of age and mating status on the circadian variations of gland sex pheromone titre in female Spodoptera litura Fabricius. Similar to other nocturnal moths, S. litura females exhibit circadian variations of gland sex pheromone contents, with higher levels during scotophase and lower levels during photophase. The sex pheromone titre in the glands peaks during the first scotophase after eclosion and sharply declines afterwards. Higher pheromone contents during scotophase may facilitate female reproductive activities, and the negative relationship between pheromone titre and female calling is likely the result of pheromone release during female calling. Interestingly, the present study demonstrates that mated S. litura females have significantly higher sex pheromone titre in their pheromone glands (PGs) than virgin females. This finding contrasts with all previous studies of other insect species, in which mating generally reduces the sex pheromone titre in female PGs. In S. litura, mating and male accessory gland fluids can suppress female calling behaviours and re‐matings. These results suggest that the suppression of female calling behaviours by mating and male accessory gland fluids may significantly reduce the release of sex pheromones and thus result in higher sex pheromone titre in the PGs of mated females.

Lerneca inalata beripocone subsp. nov. (Orthoptera: Phalangopsidae;Luzarinae): a new taxon for the northern Pantanal of Brazil.

The first record of the Orthoptera species Lerneca inalata for Brazil is presented here. The taxon is represented by a new subspecies Lerneca inalata beripocone subsp. nov. (Phalangopsidae, Luzarinae), collected in the Pantanal of Poconé, Mato Grosso, Brazil. This work includes morphological and morphometric data as well as descriptions of female genitalia and calling song. The new subspecies has as diagnostic features the male genitalia with six ventral spines on the B sclerite, the first spine having a subtle bifurcation; the mid-region of the strongly sclerotized pseudepiphallus; inclination of C sclerite with slightly concave curvature; tegmina-length ratio and the speculum (syn. mirror) width approximately three times the length of the apical area. The description of the female genitalia and the calling song is presented for the first time for the species Lerneca inalata. A distribution map covers the local occurrence of its subspecies.

Experimental evolution reveals that population density does not affect moth signalling behaviour and antennal morphology

Population density can play a vital role in determining investment in reproductive behaviours and morphologies of invertebrates. Males reared in high-density environments, where competition is high but difficulties in locating mates are low, may invest more in reproductive structures associated with sperm competition such as testes, at the expense of those traits associated with mate location, such as antennae. In species where females advertise for mates, such as most moths, a high-density environment may also lead to a reduction in pheromonal signalling (calling) length and frequency as a result of high mate abundance. While such responses have been shown at the phenotypically plastic level in moths, heritable evolutionary adaptations have seldom been tested, and studies of how population density influences pheromone signalling strategies are scarce. Here we use behavioural assays and scanning electron microscopic measurements to test whether larval population density influences, at the genetic level, the ability of males to locate females and male investment into antennal morphology, in addition to its effect on the frequency and duration of female calling. We used two replicated populations of the Indian meal moth Plodia interpunctella that had experimentally evolved under high or low population densities for 35 generations. We found no significant divergence in antennal morphology or mate acquisition behaviours between the two density populations. These findings suggest that although population density has the ability to create plastic changes in both morphological and behavioural traits, this factor alone is unlikely to be causing evolutionary change in male and female signalling in this species.

Substrate-borne vibrations of male psyllids vary with body size and age but females are indifferent

During sexual selection members of the opposite sex utilize a variety of signal modalities to acquire information about potential mates. As a prerequisite, signal modalities must exhibit intraspecific variation and correlate with desirable traits that reflect the fitness of the signaller. Anecdotal accounts suggest that female psyllids (Hemiptera: Sternorrhyncha) utilize substrate-borne vibrations (SBVs) to choose between males. However, comprehensive studies investigating the role of SBVs in Psylloidea are lacking. We used laser vibrometry and playback experiments to study the mating and calling behaviours of a psyllid, Aacanthocnema dobsoni (Triozidae). Specifically, we quantified call parameters and asked whether they vary intraspecifically and correlate with male body size and age. We also tested whether female responsiveness is influenced by the body size and age of calling males. Calls were sex-specific: male calls were more complex and comprised long and short syllables while female calls comprised only short syllables. Temporal and spectral parameters of male calls differed significantly from those of female calls. Calls of both sexes exhibited a high level of intraspecific variation. Larger males produced calls with a lower dominant frequency and older males produced calls of higher intensity and pulse rate. We used playback to test female responsiveness to calls recorded from males of contrasting sizes and ages. Surprisingly, female responsiveness was not influenced by body size or the age of calling males. Interestingly, females are polyandrous but only virgins called or responded to male calls. Conversely, males called frequently and attempted (and often succeeded) to mate with unresponsive females. These results demonstrate that A. dobsoni utilizes SBVs for mate attraction but not for precopulatory mate selection. We suggest that polyandry in A. dobsoni potentially evolved in response to male harassment and, as a consequence of polyandry, sexual selection is probably achieved via postcopulatory sexual selection mechanisms.

An investigation of sex differences in acoustic features in black-capped chickadee (Poecile atricapillus) chick-a-dee calls.

Sex differences have been identified in a number of black-capped chickadee vocalizations and in the chick-a-dee calls of other chickadee species [i.e., Carolina chickadees (Poecile carolinensis)]. In the current study, 12 acoustic features in black-capped chickadee chick-a-dee calls were investigated, including both frequency and duration measurements. Using permuted discriminant function analyses, these features were examined to determine if any features could be used to identify the sex of the caller. Only one note type (A notes) classified male and female calls at levels approaching significance. In particular, a permuted discriminant function analysis revealed that the start frequency of A notes best allowed for categorization between the sexes compared to any other acoustic parameter. This finding is consistent with previous research on Carolina chickadee chick-a-dee calls that found that the starting frequency differed between male- and female-produced A notes [Freeberg, Lucas, and Clucas (2003). J. Acoust. Soc. Am. 113, 2127-2136]. Taken together, these results and the results of studies with other chickadee species suggest that sex differences likely exist in the chick-a-dee call, specifically acoustic features in A notes, but that more complex features than those addressed here may be associated with the sex of the caller.

The Lombard effect in male ultrasonic frogs: Regulating antiphonal signal frequency and amplitude in noise.

Acoustic communication in noisy environments presents a significant challenge for vocal animals because noise can interfere with animal acoustic signals by decreasing signal-to-noise ratios and masking signals. Birds and mammals increase call intensity or frequency as noise levels increase, but it is unclear to what extend this behavior is shared by frogs. Concave-eared torrent frogs (Odorrana tormota) have evolved the capacity to produce various calls containing ultrasonic harmonics and to communicate beside noisy streams. However, it is largely unclear how frogs regulate vocalization in response to increasing noise levels. We exposed male frogs to various levels of noise with playback of conspecific female courtship calls and recorded antiphonal signals and spontaneous short calls. Males were capable of rapidly adjusting fundamental frequency and amplitude of antiphonal signals as noise levels increased. The increment in fundamental frequency and amplitude was approximately 0.5 kHz and 3 dB with every 10 dB increase in noise level, indicating the presence of noise-dependent signal characteristics. Males showed the noise-tolerant adaption in response to female calls in noise level from 40 to 90 dB SPL. The results suggest that the noise-dependent signal characteristics in O. tormota have evolved as a strategy to cope with varying torrent noise.

Conspecific females promote calling behavior in the noctuid moth, Pseudaletia adultera

AbstractChanges in female calling behavior in response to the presence of conspecific pheromones (pheromone autodetection) have been demonstrated in a number of moth species. However, the observed changes vary between species, and several ecological and adaptive explanations for autodetection have been proposed. We studied the effect of conspecific females on the calling behavior of the noctuid moth Pseudaletia adultera (Schaus) (Lepidoptera: Noctuidae, Hadenini), by comparing the age of first calling, as well as the onset and pattern of calling, when females were held individually or in the presence of conspecifics. Grouped females started calling at a lower age, a higher percentage of females called during the scotophase, and they called longer compared to females held in isolation. We also demonstrated that female antennae respond to each of the three main components of the sex pheromone – (Z)‐11‐hexadecen‐1‐ol, (Z)‐11‐hexadecen‐1‐yl acetate, and (Z)‐11‐hexadecenal – and that the response patterns differed from those of male antennae. By calling more and extending her calling window in presence of conspecific females, a female may increase her chances of accessing males. However, the potential benefits need to be considered within an ecological context, considering factors such as migration, oviposition, and foraging.

HVC contributes toward conspecific contact call responding in male Bengalese finches.

The processes of producing and acquiring birdsong, like human speech, utilize interdependent neural systems for vocal learning and production. In addition to song, these brain areas are undoubtedly used for other affiliative behaviors. Oscine sound production is lateralized because their vocal organ contains two independently controlled sound sources. Therefore, songbirds offer a unique opportunity to study the biological relevance of lateralized behavioral control. Bengalese finches (Lonchura striata domestica) produce different types of sound with each sound source: the left sound generator produces tonal frequencies from 1 to 4 kHz and the right sound source produces the lower frequency (<2 kHz) tonal and broadband sounds. We sought to investigate whether the premotor nucleus HVC contributes toward lateralized auditory processing of conspecific vocalizations. We ablated either the left or the right HVC and tested birds with the callback paradigm using female contact calls that were filtered to accentuate particular frequency ranges. The results show that (a) the acoustic frequency of call stimuli drives different patterns of calling behavior and that (b) both HVC nuclei contribute toward contact call production, but HVC ablation does not alter the number of short calls produced upon hearing a female contact call. These data are consistent with the emerging view that the motor production and auditory processing are linked and suggest that HVC may contribute toward affiliative behaviors by promoting the production of contact call responses.

Songbird mates change their call structure and intrapair communication at the nest in response to environmental noise

The coordination of behaviours between mates is a central aspect of the biology of the monogamous pair bonding in birds. This coordination may rely on intrapair acoustic communication, which is surprisingly poorly understood. Here we examined the impact of an increased level of background noise on intrapair acoustic communication at the nest in the zebra finch, Taeniopygia guttata. We monitored how partners adapted their acoustic interactions in response to a playback of wind noise inside the nestbox during incubation. Both zebra finch parents incubate and use coordinated call duets when they meet at the nest. The incubating parent can vocalize to its partner either outside the nestbox (sentinel duets) or inside the nestbox (relief and visit duets), depending on the context of the meeting. Pairs use these duets to communicate on predation threats (sentinel duets), incubation duties (relief) and other nesting activities (visit duets). Each of these duets probably represents a critical component of pair coordination. In response to the noise playback, partners called less and more rapidly during visit and relief duets. Female and male calls were more regularly and precisely alternated during relief duets. Mates increased the number of visit duets and their spatial proximity during sentinel duets. Furthermore, both females and males produced louder, higher-frequency and less broadband calls. Taken together our results show that birds use several strategies to adjust to noise during incubation, underlining the importance of effective intrapair communication for breeding pairs.

Sequential Filtering Processes Shape Feature Detection in Crickets: A Framework for Song Pattern Recognition.

Intraspecific acoustic communication requires filtering processes and feature detectors in the auditory pathway of the receiver for the recognition of species-specific signals. Insects like acoustically communicating crickets allow describing and analysing the mechanisms underlying auditory processing at the behavioral and neural level. Female crickets approach male calling song, their phonotactic behavior is tuned to the characteristic features of the song, such as the carrier frequency and the temporal pattern of sound pulses. Data from behavioral experiments and from neural recordings at different stages of processing in the auditory pathway lead to a concept of serially arranged filtering mechanisms. These encompass a filter for the carrier frequency at the level of the hearing organ, and the pulse duration through phasic onset responses of afferents and reciprocal inhibition of thoracic interneurons. Further, processing by a delay line and coincidence detector circuit in the brain leads to feature detecting neurons that specifically respond to the species-specific pulse rate, and match the characteristics of the phonotactic response. This same circuit may also control the response to the species-specific chirp pattern. Based on these serial filters and the feature detecting mechanism, female phonotactic behavior is shaped and tuned to the characteristic properties of male calling song.

Age related decline in female lar gibbon great call performance suggests that call features correlate with physical condition.

BackgroundWhite-handed gibbons (Hylobates lar) are small Asian apes known for living in stable territories and producing loud, elaborate vocalizations (songs), often in well-coordinated male/female duets. The female great call, the most conspicuous phrase of the repertoire, has been hypothesized to function in intra-sexual territorial defense. We therefore predicted that characteristics of the great call would correlate with a caller’s physical condition, and thus might honestly reflect resource holding potential (RHP). Because measurement of RHP is virtually impossible for wild animals, we used age as a proxy, hypothesizing that great call climaxes are difficult to produce and maintain over time, and that older adults will therefore perform lower quality great calls than young adults. To test this we analyzed the great call climaxes of 15 wild lar gibbon females at Khao Yai National Park, Thailand and 2 captive females at Leo Conservation Center, Greenwich, CT.ResultsFindings show that call climaxes correlate with female age, as young animals (n = 8, mean age: 12.9 years) produced climaxes with a higher frequency range (delta F0), maximum F0 frequency and duty cycle than old animals (n = 9, mean age: 29.6 years). A permuted discriminant function analysis also correctly classified calls by age group. During long song bouts the maximum F0 frequency of great call climaxes’ also decreased. Additional data support the hypothesis that short high notes, associated with rapid inhalation as an individual catches its breath, reflect increased caller effort. Older females produced more high notes than younger females, but the difference only approached statistical significance, suggesting that calling effort may be similar across different ages. Finally, for the first time in this species, we measured peak intensity of calls in captive females. They were capable of producing climaxes in excess of 100 dB at close range (2.7 m).ConclusionsAge and within-bout differences in the lar gibbon great call climax suggest that call features correlate with physical condition and thus the call may have evolved as an honest signal in the context of intra-sexual territorial defense and possibly also in male mate choice via sexual selection, although further testing of these hypotheses is necessary.

Seroprevalence of Hepatitis B Infection among Pregnant Women in One of the Institute of Northern India

Hepatitis B Virus (HBV) occurs worldwide with more than 2 billion people being infected with HBV at some time in their lives. Transmission of HBV from carrier mothers to babies can occur during perinatal period and is important factor in determining the prevalence of infection in highly endemic areas. To assess the prevalence of hepatitis B infection, among otherwise healthy pregnant females. This retrospective study analysed records of antenatal care registry from 1(st) April 2013 to 30(th) March 2014 at our institution. Details of a total of 3686 pregnant women subjected to screening of Hepatitis B surface antigen (HBsAg) using Enzyme Linked Immunosorbent Assay (ELISA) was recorded into a preset proforma. Data thus obtained has been analysed using SPSS version 13 and presented. Seroprevalence of HBsAg positive antenatal females was 1.11%. The mean age of HBsAg positive pregnant women was 24.98±4.16 years. Thirty one (75.61%) subjects hailed form a rural area. 4 (09.75%) and 3 (07.31%) subjects had HBV-HCV co-infection and HBV-HIV co-infection respectively. Mean parity of women with HBV infection was 1.83±0.87. Most common age group with HBV infection was 25-30 years. Around 130 countries in the world are currently covered by routine hepatitis B immunization. High prevalence of seropositivity of HBsAg among antenatal female calls for routine vaccination against HBV infection. Universal free screening for HBV infection needs to be offered to all antenatal females on an opt-out basis to prevent the next generation from being grappled by chronic hepatitis, cirrhosis and hepatocellular carcinoma.

Female Sexual Preferences Toward Conspecific and Hybrid Male Mating Calls in Two Species of Polygynous Deer, Cervus elaphus and C. nippon.

The behavioral processes at the basis of hybridization and introgression are understudied in terrestrial mammals. We use a unique model to test the role of sexual signals as a reproductive barrier to introgression by investigating behavioral responses to male sexual calls in estrous females of two naturally allopatric but reproductively compatible deer species, red deer and sika deer. Previous studies demonstrated asymmetries in acoustic species discrimination between these species: most but not all female red deer prefer conspecific over sika deer male calls while female sika deer exhibit no preference differences. Here, we extend this examination of acoustic species discrimination to the role of male sexual calls in introgression between parent species and hybrids. Using two-speaker playback experiments, we compared the preference responses of estrous female red and sika deer to male sexual calls from conspecifics versus red × sika hybrids. These playbacks simulate early secondary contact between previously allopatric species after hybridization has occurred. Based on previous conspecific versus heterospecific playbacks, we predicted that most female red deer would prefer conspecific calls while female sika deer would show no difference in their preference behaviors toward conspecific and hybrid calls. However, results show that previous asymmetries did not persist as neither species exhibited more preferences for conspecific over hybrid calls. Thus, vocal behavior is not likely to deter introgression between these species during the early stages of sympatry. On a wider scale, weak discrimination against hybrid sexual signals could substantially contribute to this important evolutionary process in mammals and other taxa.Electronic supplementary materialThe online version of this article (doi:10.1007/s11692-015-9357-0) contains supplementary material, which is available to authorized users.

Sex and species recognition by wild male southern white rhinoceros using contact pant calls

Recognition of information from acoustic signals is crucial in many animals, and individuals are under selection pressure to discriminate between the signals of conspecifics and heterospecifics or males and females. Here, we first report that rhinos use information encoded in their calls to assess conspecifics and individuals of closely related species. The southern (Ceratotherium simum) and critically endangered northern (C. cottoni) white rhinos are the most social out of all the rhinoceros species and use a contact call pant. We found that southern white rhino pant calls provide reliable information about the caller's sex, age class and social situation. Playback experiments on wild territorial southern white rhinoceros males revealed that they responded more strongly to the pant calls of conspecific females compared to the calls of other territorial males. This suggests that pant calls are more important form of communication between males and females than between territorial males. Territorial southern males also discriminated between female and territorial male calls of northern species and reacted more intensively to the calls of northern than southern males. This might be caused by a novelty effect since both species naturally live in allopatry. We conclude that white rhinos can directly benefit from assessing individuals at long distances using vocal cues especially because their eyesight is poor. Pant calls thus likely play a significant role in their social relationships and spatial organization. In addition, better understanding of vocal communication in white rhinos might be helpful in conservation management particularly because of their low reproduction in captivity.