Female Calls Research Articles

The function of breeding season chip calls by female hooded warblers (Wilsonia citrina)

We document use of 'chip' vocalizations by breeding female hooded warblers (Wilsonia citrina) and propose explanations for the function of the calls. Fertile females (building or laying stage) chip differently than incubating females, via a lower chip rate, shorter bouts of chipping and more bouts per hour. Females responded to playbacks of fertile chipping and a female model on their territories by approaching and chip calling. Resident males were generally not responsive to their mate's chip calls and did not move closer when their mates chipped; however, neighbouring males often intruded onto territories in response to female chip calls. Neighbouring males did not distinguish between playbacks of fertile and incubation chip calls, but responded to both at equally low frequencies. Radio-tracked neighbouring males intruded onto territories significantly more frequently when females were chipping than when they were silent. Such intrusions likely function as extra-pair mating attempts. Finally, variation in call pattern among fertile females did not correlate with frequency of extra-pair young. Our study provides some support that chip calls of hooded warblers function in female territory defence and attraction of potential extra-pair males but further testing of these hypotheses is required.

Friendships between males and lactating females in a free-ranging group of olive baboons (Papio hamadryas anubis): evidence from playback experiments

Close association between an anoestrous female at the time of lactation and adult male(s) is relatively rare in mammals, but common in baboons (Papio hamadryas subsp.). The functional significance of these “friendships” remains unclear, however. In chacma baboons (P. h. griseipes), friendships are a counter-strategy to infanticide by immigrant males. Experimental playback of female distress calls in chacma baboons revealed that male friends are more motivated to protect females and infants than are control males. Olive baboons (P. h. anubis) also exhibit friendships, but infanticide is rare, suggesting that friendships provide females with protection from non-lethal aggression (anti-harassment hypothesis) or serve to promote male–infant bonds that later benefit the maturing juvenile (future male caretaker hypothesis). We replicated these playback experiments on a group of olive baboons to test between these hypotheses and to evaluate if the lower costs of non-lethal harassment lessens male protective responsiveness relative to protection from (more costly) infanticide. Spatial data revealed that most lactating females had one to four friend males. Relative to non-friends, friend dyads were characterized by higher rates of allogrooming and infant handling, but less agonism. Female rank was correlated with the number of male friends. Just as in chacma baboons, playback of female screams elicited stronger responses from male friends than control males in support the anti-harassment hypothesis. Compared to the chacma baboon, male olive baboons appeared to exhibit similarly high levels of protective solicitude for female friends although they protect against non-lethal harassment rather than infanticide

Effects of meteorology, astronomical variables, location and human disturbance on the singing apes: Hylobates albibarbis

Gibbons are characterized by their species-specific calls. The frequency of singing is known to be affected by rainfall, with singing occurring less in the wet season. I investigate the hypothesis that gibbon singing is also affected by the natural light-dark cycle, and by the changing light intensity and air quality resulting from the smoke haze which blankets the Indonesian island of Borneo on a yearly basis. I compare three singing variables-onset of singing, average duration of singing bout and number of female great calls produced during the dry season of 2006 when there was no smoke haze (June-August) and when there was smoke haze present (September-November). I present evidence which indicates that the changes in singing behavior are affected by changes in rainfall and smoke intensity but not by other meteorological factors (i.e. wind and light intensity) or changing astronomical cues (light intensity, month, time of sunrise, time of moonrise, nocturnal illumination index, day length and night length). The possible long-term effects of this on gibbon behavior and territoriality are discussed. The need to carry out more research on the long-term effects of the smoke haze on wildlife behavior and possible solutions to the problem are discussed.

Comparisons of calling behaviour of different geographical populations of Helicoverpa armigera

Abstract: The cotton bollworm, Helicoverpa armigera, with worldwide distribution, evolves into different geotypes for adapting to the changes of geographical climates. Comparisons of calling behaviour of the insect collected from the temperate region in northern China (Beijing), the temperate region in north‐western China (Kashi) and the tropical region in southern China (Haikou) were investigated in the laboratory as a first step to understanding the influence of reproductive behaviour on its population differentiation. There were more than 80% of virgin females of each population that showed calling behaviour. The age at which the moths of all three populations initiated calling varied significantly. The durations of calling in scotophase and the percentages of females calling also differed between populations. Only a few females of the Beijing and Haikou populations called in the first 2 h after the onset of scotophase, whereas many Kashi females called at this time. However, the main calling peak occurred during the second half of scotophase for all three populations. Females of the Beijing and Haikou populations exhibited similar calling onset times at the same age, whereas the Kashi females initiated calling significantly earlier than those of Beijing and Haikou from nights 3 to 7. The durations of each calling bout and the time spent by both Beijing and Haikou populations were similar to each other at the same age, but were significantly shorter than that of the Kashi population from nights 3 to 7. These results suggest that there are genetic variations not only in pre‐period calling but also in the calling behaviour of H. armigera.

Duet structure provides information about pair identity in the red-crowned crane (Grus japonensis)

We studied the acoustic features of the endangered red-crowned crane (Grus japonensis), and, specifically, whether or not the duets carry information about a mating pair identity. The population of this species in the wild is only approximately 2,000 individuals. In 2003–2006, we recorded 343 duets from eight captive and two wild pairs. All of the duets contained an introduction, an unordered alternation of pair mate calls, followed by the main part, representing the regular sequence of syllables, containing 1–2 male and 1–4 female calls per syllable. We subdivided the syllables into five types, by the number of male and female calls per syllable, and analyzed the occurrence of the different syllable types in the duets of the ten pairs. The analysis showed the sustainable pair-specific use of particular syllable types through the years. The discriminant analysis standard procedure, based on seven frequency and temporal parameters of male and female calls, showed 97.7% correct assignment to the pair, which is significantly higher than random values. The high pair specificity of the duet acoustic structures provides the basis for call-based censuses. This would enable the monitoring of the red-crowned crane mating pairs in their natural habitat.

Female food solicitation calling, hunger levels and habitat differences in the black-capped chickadee

During the egg-laying period, female passerines have high resource demands and are often fed by their mates. In black-capped chickadees, Poecile atricapillus, these courtship feedings can be solicited via unique calls given by females. A female's solicitation call rate may reflect her hunger level and honestly signal need to her mate. To test this, nine chickadee pairs were supplementally fed during the egg-laying period. Solicitation call rates by these experimental females decreased significantly from prefeeding rates; the same was not true for nine control pairs. As this suggested that solicitation call rate may be directly influenced by hunger, we questioned whether variation in call rates of females may reflect differences in resource availability between habitats and/or differences in provisioning levels by their mates. We measured the solicitation calls of female chickadees mated either to socially dominant or subordinate males during egg laying in 2003 and 2004 across two sites that differ in quality for chickadees: a mature forest (higher quality) versus a young forest (lower quality). There was a significant interaction between rank and habitat on female solicitation call rates: subordinate females in young forests had significantly higher calling rates compared to dominants. There was no difference in call rates of subordinates and dominants in mature forest, and these call rates did not differ from those of dominants in young forest. This result suggests that food limitation imposed by habitat may disproportionately affect subordinate pairs.

Male discrimination of receptive and unreceptive female calls by temporal features

In murky, crowded ponds in South Africa, female clawed frogs, Xenopus laevis (Daudin), vocalize to signal reproductive state. Female calls consist of acoustically similar clicks delivered in trains with characteristic rates. The rapping call of a sexually receptive female has a more rapid click rate [81 ms mean interclick interval (ICI)] than the ticking call of an unreceptive female (219 ms ICI). Rapping stimulates male advertisement calling, whereas ticking suppresses an already calling male. We examined how males label and discriminate female click rates. A labeling boundary experiment revealed that males perceive click rates between the means of rapping and ticking as lying on a continuum. They respond to 98 and 160 ms ICI as though to rapping and ticking, respectively. However, calling evoked by a click rate equally common to both calls (120 ms ICI) did not differ from the response to either rapping or ticking. A second experiment evaluated whether males discriminate click rates both labeled as ticking (180 and 219 ms ICI). Ticking suppresses advertising males, and suppressed males habituate (resume calling) to prolonged ticking. Both ticking stimuli suppressed males with equal effectiveness, and males habituated in equivalent amounts of time. When the stimulus was switched during habituation, no dishabituation occurred. We conclude that male labeling of click trains as rapping or ticking reflects an ambiguity resulting from the overlap in ICIs naturally occurring in the calls. Males do not respond differentially to click rates within the ticking category. Males thus combine discriminating and non-discriminating strategies in responding to the salient feature of female calls.

Intended Receivers and Functional Significance of Grunt and Girney Vocalizations in Free‐Ranging Female Rhesus Macaques

AbstractWe investigated the intended receivers and contexts of occurrence of grunt and girney vocalizations in rhesus macaques (Macaca mulatta) to assess whether these calls are best interpreted as signals of benign intent or as calls that may function to attract the attention of other individuals or induce arousal. We focally observed 19 free‐ranging adult female rhesus macaques. Female calls increased dramatically after infants were born, and most were directed toward mother–infant dyads. When infants were physically separated from their mothers, callers visually oriented toward infants in over 90% of the cases, suggesting that infants were the intended receivers of grunts and girneys. Approaches followed by vocalizations were more likely to lead to the caller grooming the mother, less likely to elicit a submissive response, and more likely to result in infant handling than approaches without calls. Infant handling, however, was not necessarily benign. Vocalizations were often emitted from a distance >1 m and were rarely followed by approaches or social interactions. Our results suggest that grunts and girneys are unlikely to have evolved as signals that encode information about the caller's intention or subsequent behavior. Whereas girneys may be acoustically designed to attract infants’ attention and elicit arousal, grunts may have no adaptive communicative function. Mothers, however, may have learned that other females’ grunts and girneys are unlikely to be associated with significant risk and, therefore, are generally tolerant of the caller's proximity and behavior.

In the mating system of the bat Saccopteryx bilineata, bioacoustic constraints impede male eavesdropping on female echolocation calls for their surveillance

At night, bats utter loud echolocation calls at high repetition rates that may reveal the location and current behaviour of callers to eavesdropping bats. Given the strong attenuation of echolocation calls, we predicted that territorial males of a harem-polygynous species ought to forage at close distance to females to survey their movements by social eavesdropping. We estimated a maximum detection distance of 38 m for echolocation calls of Saccopteryx bilineata (Temminck, 1838) (Chiroptera; Emballonuridae) broadcasted within the forest under the sound transmission conditions of our study site and for an assumed signal detection threshold of 20 dB SPL (50 m for a threshold of 0 dB SPL). We then simultaneously radio-tracked the nocturnal movements of eight male–female pairs that each rested in the same harem territory during the day and measured the distances at which dyads foraged. Male–female pairs foraged at a median distance of 139 m. In the case of 90% of simultaneous bearings, males foraged at distances that prevented eavesdropping on 44 kHz echolocation calls (>38 m; 87% of radio fixes >50 m). Males and females of the same daytime territory roosted, on average, 226 ± 194 m apart from each other at night. Thus, males were most likely unaware of where females foraged as a result of the strong attenuation of female echolocation calls. In general, such acoustic constraints on social eavesdropping may promote extra-harem group paternities, female choice, and sperm competition in bats, and may therefore present an important selective force in the evolution of bat mating systems.

Alternative mating behaviors of the queen polymorphic ant Temnothorax longispinosus

Mating behaviors of ants fall into two categories: female calling, in which a female alate releases pheromones that attract males, and male swarming, in which large male aggregations attract females. Female calling is common in species with queens that return to their natal nest to found colonies dependently after mating, while male swarming is common in species with queens that disperse to found independently. In some species that display both founding strategies, a queen-size polymorphism has evolved in which dependent-founding queens are smaller than independent-founding queens. Dependent founding is likely difficult if gynes (virgin queens) are mating in distant swarms. Therefore, a queen may adopt one or the other mating strategy based on its size and founding behavior. We investigated mating behaviors in the queen-polymorphic ant, Temnothorax longispinosus. Observations in laboratory mating arenas indicated that small gynes exhibited significantly lower flight activity than large gynes. Both forms mated in male swarms, and neither form exhibited female calling. The reduced flight activity of the small morph may facilitate returning to the natal nest after mating, provided the mating swarm is located nearby. Therefore, alternative colony-founding behaviors may be possible without the evolution of female-calling behavior; however, the reduced flight activity of small morphs may require that mating swarms are not distant from the natal nest.

Aspects of Male Competition in Colobus vellerosus: Preliminary Data on Male and Female Loud Calling, and Infant Deaths After a Takeover

Male Colobus vellerosus are the main participants in intergroup encounters, and lead incursions in neighboring groups during which they attack infants. Extragroup copulations, all-male groups, and male takeover occur in the species. Here, we provide additional information on behaviors associated with male reproductive competition in Colobus vellerosus. We examined 1 resident male loud calling and participation in intergroup encounters in relation to a takeover. We also report a second case of takeover that led to the death of the former resident male and the death of 2 male infants, presumably as a result of aggression from the all-male group. The new resident male wounded the third infant of the group, which apparently died after its mother abandoned it. During the period characterized by the attacks on the infant and after its disappearance, females initiated and participated in loud call bouts with the new resident male. We examine the possible functions of female loud calling, and suggest that in this context, it might force the resident male to call along to indicate his presence.

Vocal Responses of Captive Gibbon Groups to a Mate Change in a Pair of White-Cheeked Gibbons (Nomascus leucogenys)

The singing behaviour of 3 pairs of white-cheeked gibbons (Nomascus leucogenys) held at the Perth Zoo was observed for 6 months in 2005. These groups included a family (mated pair and 2 immature offspring) and a pair without offspring. During the study, the female without offspring was exchanged for an unpaired female from New Zealand. After the new pair had been released onto the island enclosure and began to duet, the duetting rate of the white-cheeked gibbon family increased. The increased singing began after the new female had started to sing solo female great calls. These observations support the hypothesis that duets have an intergroup communication function in white-cheeked gibbons. The pair that duetted most frequently also copulated most frequently but allogroomed the least. We suggest that duetting may be more important to intergroup relations than to pair bond maintenance in this species.

Dynamics of sperm transfer in the ant Leptothorax gredleri

Mating tactics differ remarkably between and within species of social Hymenoptera (bees, wasps, ants) concerning, e.g., mating frequencies, sperm competition, and the degree of male sperm limitation. Although social Hymenoptera might, therefore, potentially be ideal model systems for testing sexual selection theory, the dynamics of mating and sperm transfer have rarely been studied in species other than social bees, and basic information needed to draw conclusions about possible sperm competition and female choice is lacking. We investigated sperm transfer in the ant Leptothorax gredleri, a species in which female sexuals attract males by "female calling." The analysis of 38 female sexuals fixed immediately or up to 7 days after copulation with a single male each revealed that the sperm is transferred into the female bursa copulatrix embedded in a gelatinous mass, presumably a spermatophore. Sperm cells rapidly start to migrate from the tip of the spermatophore towards the spermatheca, but transfer is drastically slowed down by an extreme constriction of the spermathecal duct, through which sperm cells have to pass virtually one by one. This results in the spermatheca being filled only between one and several hours after mating. During this time, the posterior part of the spermatophore seals the junction between bursa copulatrix and spermathecal duct and prevents sperm loss. The prolonged duration of sperm transfer might allow female sexuals to chose between ejaculates and explain previously reported patterns of single paternity of the offspring of multiply mated queens.

Vocal mother–pup communication in guinea pigs: effects of call familiarity and female reproductive state

Vocal communication is of special importance in mother-offspring interactions in many precocial mammals, where the offspring are highly mobile. Newborn guinea pigs, Cavia aperea f. porcellus, make distinct calls when separated from their mother. Assuming that offspring separation calls are important in mother-offspring communication, we predicted guinea pig females would respond more strongly to calls of their own than to calls from unfamiliar pups or other guinea pig calls and would respond to pup calls only during lactation when responses are adaptive. In playback experiments, we tested lactating females' responses to separation calls from their own pups and from unfamiliar pups and to female contact calls. We also tested responses by females in late pregnancy (days 50-60) to separation pup calls. Lactating females responded with significantly more vocalizations to their own and to unfamiliar pup calls than to control sounds. Mothers also responded significantly more strongly to playback of calls from their own pups than to calls from unfamiliar pups, suggesting that mothers are able to use vocal cues in pup recognition. The reproductive state significantly influenced responses: lactating females always responded to pup calls, whereas pregnant females did not respond, suggesting that responsiveness is state dependent.

Reconsidering the taxomony of several Ostrinia species in the light of reproductive isolation: a tale for Ernst Mayr

We reconsider the taxonomy of a group of closely related Ostrinia spp., illustrating how useful Mayr's biological spe- cies concept remains for studying speciation patterns and processes. We review and re-analyse recent data on Ostrinia scapulalis , Ostrinia nubilalis , Ostrinia narynensis and Ostrinia orientalis , along with those obtained over > 45 years in the former Soviet Union. The ten species of the 'trilobed uncus' group in the Ostrinia genus are clas- sified into subgroups according to male mid-tibia morphology. However, none of the characters that further discrim- inate between them (female sex pheromones, male genitalia and calling time) varies together with male mid-tibia morphology, and neither do molecular markers. Moreover, male mid-tibia morphology appears to depend on only two diallelic loci and seems to be unrelated to reproductive isolation between Ostrinia taxa. By contrast, reproductive iso- lation is strongly related to host-plant type. In accordance with Mayr's species concept, we thus propose a revision of the trilobed uncus Ostrinia spp. based primarily on host-plant type. We propose that O. narynensis Mutuura & Munroe, 1970 ( syn. nov. ) and O. orientalis Mutuura & Munroe, 1970 ( syn. nov. ) be synonymized with O. scapulalis (Walker, 1859). We further demonstrate that O. nubilalis auctt. pro parte feeding on mugwort, hop, and several other dicotyledons (previously called the ' O. nubilalis mugwort-race' in France) also belongs to O. scapulalis . Consequently, we propose that only O. nubilalis specimens feeding on maize (the former French ' O. nubilalis maize- race') belong to O. nubilalis (Hubner, 1796). The implications of this revision are discussed. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 91 , 49-72. ADDITIONAL KEYWORDS: biological species concept - host-races - Ostrinia furnacalis - Ostrinia narynensis - Ostrinia nubilalis - Ostrinia orientalis - Ostrinia scapulalis - speciation - taxonomy.

Sex Pheromone of Lonomia obliqua: Daily Rhythm of Production, Identification, and Synthesis

The sex pheromone of Lonomia obliqua Walker (Lepidoptera: Saturniidae) was studied in the laboratory. All female calling occurred during the scotophase. Most females (70.6%) called first within 24 hr of eclosion. Calling varied with age of female, with older (5- to 6-day-old) females calling earlier in the scotophase and for longer durations than younger (0- to 1-day-old) females. The sex pheromone gland of 1- to 3-day-old virgin females was extracted during the calling peak. A Y-olfactometer bioassay showed significant attraction of males to a filter paper containing the female gland extract. Gas chromatographic-electroantennogram detection (GC-EAD) analysis of the extract indicated the presence of at least two possible pheromone components. Gas chromatographic-mass spectrometric analysis of the major GC-EAD-active peak indicated a hexadecenyl acetate; chemical derivatization indicated delta11 unsaturation. Synthetic samples of (E)- and (Z)-11-hexadecenyl acetate were obtained by coupling 10-bromo-1-decanol and 1-hexyne, utilizing lithium chemistry. The comparison of the retention time of dimethyl disulfide derivatives of the natural compound, to those of synthetic chemicals, confirmed the natural compound as (E)-11-hexadecenyl acetate. The minor component was identified as the related alcohol, (E)-11-hexadecenol. The ratio of the two components in female extract was 100:35. Preliminary tests of males in a Y-olfactometer showed that their response to a mixture of the two compounds was not significantly different from that to gland extract.

Vibrational Communication of <I>Metcalfa pruinosa</I> (Hemiptera: Fulgoroidea: Flatidae)

Vibrational communication of the Nearctic flatid planthopper Metcalfa pruinosa (Say) (Hemiptera: Flatidae) was investigated to determine the role of substrate-borne vibrational signals in mating behavior. Signaling activity changes throughout the day and vibrational communication in this planthopper begins at night. All recorded male and female signals consisted of a series of single pulses. Most of these signals were classified as calling signals. They were emitted spontaneously or were evoked by playback stimulation with prerecorded conspecific signals. Male calling signals are simple, and the main difference between male and female calls was in the pulse repetition time. Pulse repetition time in the middle section of the calling signal was the least variable property of the vibrational signals. During later stages of pair formation, males emit a phrase that is a sequence of pulse trains that has a distinct time and amplitude pattern, whereas females produce continuing monotonous substrate vibrations that could last for several hours. Males participated in continued exchange of vibrational signals. Signals exchanged during male–male interaction did not differ structurally from male calling signals and males never overlapped their signals.

Provisioning calls of the cooperatively breeding bell miner Manorina melanophrys encode sufficient information for individual discrimination

Acoustically‐mediated individual discrimination has been the focus of much investigation in ornithology. For cooperatively breeding species, strong selection pressure favouring individual recognition during acts of altruism is predicted under many of the most interesting hypotheses proposed to account for helping behaviour. We investigated differences in 157 calls given by 12 different individuals as they provisioned nestlings, including both breeding and helper bell miners Manorina melanophrys (Meliphagidae), a cooperatively breeding honeyeater endemic to south‐eastern Australia. Individual differences were apparent in all 15 call parameters analysed, many with a high level of repeatability. Moreover, the information capacity of mew calls allows as many as 515 different signatures to exist in the system. As many parameters showed strong sex differences, separate discriminant functions were used to predict individual identity within each sex. Five parameters were used in a function that correctly identified over 90% of female calls in both a training (n=35) and test dataset (n=11) not used to generate the function. Among males, a separate function used six parameters to correctly assign individual identity in 89.3% (n=84; training) and 77.8% (n=27; test) of cases. Three original parameters, including spectral and spatial characteristics, were highly correlated with functions predicting identity in both sexes. The accuracy of functions was not influenced by a signaller's sex, breeding status, or by sampling period which was spread over as much as two breeding seasons within individuals. Significant potential therefore exists for bell miners to use these simple provisioning calls in individual discrimination. If this is the case, call information also has the potential to be used by receivers as predicted by signalling hypotheses proposed to account for cooperative helping behaviour, such as the pay‐to‐stay and social prestige hypotheses.

NORTH AMERICAN ELK BUGLE VOCALIZATIONS: MALE AND FEMALE BUGLE CALL STRUCTURE AND CONTEXT

Bugle calls of male North American elk (Cervus elaphus) are common sounds during fall in the Canadian and United States Rocky Mountains. In contrast, bugle calls of female elk are rarely heard. We quantified the acoustic structure of elk bugle calls, which is an essential 1st step to understanding of the function of the call. We also investigated whether motivation‐structural rules apply to these long-distance calls. We measured male elk bugle calls in Rocky Mountain National Park, Colorado, during autumn of 1998 and 1999 and we measured female elk bugle calls on 2 Colorado elk ranches (private establishments that raise elk for commercial purposes) during spring of 2001 and 2002. All bugle calls had 3 segments: on-glide, whistle, and off-glide. Male bugle calls were longer in duration than female bugle calls (P , 0.01). Bugle calls emitted in aggressive interactions had 4 or 5 low-frequency formants, resulting in harsher, wider bandwidth bugles (P , 0.001) compared to the tonal calls emitted in nonaggressive contexts, which lacked formants. Thus, elk bugle calls appear to conform to motivation‐structural rules.

Sexual behavior of the navel OrangeWorm, Amyelois transitella (Walker) (Lepidoptera: Pyralidae)

To get a better understanding of the mating behavior of the navel orangeworm, Amyelois transitella (Walker), we developed a robust laboratory colony derived from larvae collected in Bakersfield, California and fed on dried, roasted pistachio. In the lab at 25 degrees C, most of the mating activity was observed during the last hour of the scotophase and for the first 30 min of the photophase. Female calling was characterized by the abdomen being protruded between the wings with the distal segments perpendicular to the body and exposing a pheromone gland, as well as by continuous antennation. Males approached calling females from a short distance by displaying wing fanning and antennation. When a male antennated on a calling female's abdomen, she either accepted the male and lowered the abdomen, or walked away. The accepted male made a final approach parallel to the female's body, but after coupling he rotated 180 masculine with male and female remaining in a linear, abdomen-to-abdomen position for over 3 h in average. In a possible strategy to maximize the chances of mating, the sex ratio was significantly skewed towards males in the first two days of emergence. Almost 80% of mating took place in the first two days after adult emergence, with females mating only once. About 55% of males mated only once and approximately 40% of the observed males mated twice and 5% tree times.