Sibling Recognition in Bank Swallows (Riparia riparia)

Observations of the behavior of newly-fledged bank swallows suggest that sibling recognition may be a mechanism promoting location of the home burrow in their large, dense colonies and of cohesion of family groups following departure from the burrow. We tested for sibling recognition in the field by comparing the antiphonal response of sibling groups to the recorded calls of own vs. unrelated sibling groups. Birds responded more to the calls of their own groups. In a laboratory experiment we raised chicks in isolation from 8–10 to 20 days of age and exposed them to a call of an unrelated chick. When tested in a choice situation at 15–20 days, chicks approached the familiar call in preference to a different call which they had not previously heard. We suggest that sibling recognition is based on familiarity, i.e., that it requires a period in which the calls of siblings are learned.     

Individual voice recognition in a territorial frog (Rana catesbeiana)

Some territorial animals display low levels of aggression towards a familiar territorial neighbour in its usual territory, but exhibit high levels of aggression towards neighbours in novel locations and unfamiliar individuals. Here, we report results from a field playback study that investigated whether territorial males of the North American bullfrog (Rana catesbeiana) could discriminate between the acoustic signals of simulated neighbours and strangers in the absence of contextual cues associated with a specific location. Following repeated exposures to synthetic bullfrog calls from a particular location, subjects responded significantly less aggressively to a familiar call, compared with an unfamiliar one, when both calls were broadcast from familiar and novel locations, indicating that bullfrogs could recognize a neighbour's calls independently of the contextual cues provided by the direction of the neighbour's territory. Subjects responded equally aggressively to unfamiliar calls broadcast from either a familiar or a novel location, which indicates that they could perceive unfamiliar calls as those of a stranger, regardless of where the stranger was encountered. Together, these two results provide evidence that a frog possesses a capacity for individual voice recognition.     

Does Gray Squirrel (Sciurus carolinensis) Response to Heterospecific Alarm Calls Depend on Familiarity or Acoustic Similarity?

In habitats in which multiple species are prey to the same predators, individuals can greatly benefit from recognizing information regarding predators that is provided by other species. Past studies have demonstrated that various mammals respond to familiar heterospecific alarm calls, but whether acoustic similarity to a familiar call can prompt a mammal's recognition of an unfamiliar call has yet to be shown. We presented alarm calls to free‐ranging eastern gray squirrels (Sciurus carolinensis) and recorded behavioral changes in vigilance and antipredatory response. Playbacks included alarm calls of a sympatric bird (American robin, Turdus migratorius), an allopatric bird with a call structure similar to that of the robin (common blackbird, Turdus merula), and an allopatric bird with a distinct call structure (New Holland honeyeater, Phylidonyris novaehollandiae). Squirrels responded significantly more frequently to squirrel alarm calls (positive control) than to robin song (negative control) or honeyeater calls. Squirrel response to robin and blackbird alarm calls was statistically similar to their response to squirrel alarm calls, indicating that squirrels responded to those alarm calls as if they provided information about the presence of predators. However, squirrel response to robin song was not statistically different from response to any of the other avian calls, including the robin and blackbird alarms, suggesting that squirrels neither respond to blackbird alarms as if they clearly signify danger, nor as if they clearly do not signify danger, perhaps reflecting some ambiguity in interpretation of the calls. These results suggest that squirrel responses to alarm calls are generally based on call familiarity, but that acoustic similarity of an unfamiliar allopatric call to a familiar call also can elicit antipredator behavior. The lack of response to honeyeater alarm calls also supports the hypothesis that call recognition by gray squirrels is dependent on familiarity, rather than simply detection of an acoustic feature common to alarm calls across a variety of avian species.     

Social recognition and approach in the chick: lateralization and effect of visual experience

Chicks, Gallus gallus domesticus, tested monocularly on day 3 after hatching recognize familiar versus unfamiliar conspecifics and choose to approach one or other when they use the left eye, whereas they approach familiar and unfamiliar chicks at random when they use the right eye. In experiment 1 we investigated the effects of light exposure of embryos prior to hatching on this particular form of lateralization. Irrespective of whether they hatched from eggs incubated in the dark or from eggs exposed to light during the final days of incubation, chicks using the left eye had higher choice scores (meaning they chose to approach either a familiar or an unfamiliar chick) than chicks using the right eye or both eyes. Therefore, light experience prior to hatching did not influence the lateralization of individual recognition or choice behaviour, although it did affect latency to move out of, and time spent in, the centre of the runway. Experiment 2 showed that visual/social experience posthatching influences choice behaviour: chicks housed in a group in the light for 12 h on day 1 posthatching made a clear choice between familiar and unfamiliar chicks when tested on day 3, but chicks kept in a group in the dark on day 1 did not make a choice, instead alternating between the two stimuli. In experiment 3 we found that posthatching visual/social experience increased the choice scores of chicks using the right eye and thereby removed any lateralization of choice behaviour. The results suggest that visual experience of a social group is required before chicks using their right eye (and left hemisphere) will pay attention to the cues that distinguish one chick from another. Chicks using their left eye (and right hemisphere) recognize the difference between individuals without requiring visual experience with other chicks. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.     

Individuality,kin similarity and experimental playback of contact calls in cooperatively breeding riflemen

Riflemen/tītipounamu (Acanthisitta chloris) are kin-based cooperatively breeding birds, which appear able to recognise their relatives. Here, we investigate the potential for vocalisations to act as recognition cues in riflemen. We identified an appropriate contact call and recorded it at the nest from 19 adult riflemen. Measurements of call characteristics were individually repeatable. In addition, call similarity was significantly correlated with relatedness among all birds and among males. Thus, in principle, these contact calls contain sufficient information for individual recognition of familiar kin, and some assessment of relatedness between unfamiliar birds. To test whether riflemen responded differently to calls of kin, we broadcast calls of relatives and non-relatives as separate treatments in a playback experiment. Focal birds rarely responded aggressively or affiliatively, and their tendency to do so was unrelated to treatment. We conclude that zip calls are suitable kin recognition cues, but whether they are used as such remains unknown.     

Reliable Information Content and Ontogenetic Shift in Begging Calls of Grey Warbler Nestlings

The most critical assumption of communication models regarding parent–offspring conflict is that food solicitation displays of genetic offspring are honest signals to elicit beneficial parental care. A critical requirement of honesty is the reliable change of perceivable aspects of begging calls with physiological needs. We experimentally tested whether and how the acoustic structure and begging call rate of individual Grey Warbler Gerygone igata nestlings change with hunger level and age. We also examined a rarely documented component of chick begging calls, namely the temporal dynamics of acoustic modulation after nestlings heard parental feeding calls. Begging call structure narrowed in frequency range and, surprisingly, decreased in amplitude as chick hunger levels increased. We also found that begging calls changed with chick age, with the frequency increasing and the duration decreasing for older chicks. These results indicate that the acoustic properties of nestling Grey Warbler begging calls are complex and may be used to signal several aspects of nestling traits, including hunger level and age (or size, a correlate of age). Overall, begging calls of Grey Warbler chicks appear to be honest, implying that parents are likely to benefit from relying on the acoustic features of their progeny’s calls which predict chick need. Our results have important implications regarding the reliability and information content of nestling solicitation signals for the brood parasite shining cuckoo Chrysococcyx lucidus exploiting Grey Warbler parental care, in that these begging‐call mimetic specialist cuckoos might also need to match closely the dynamics of acoustic features of their host chicks’ calls.     

不同背景的同伴强化及催产素处理对雌性棕色田鼠可卡因条件位置偏爱的影响

同伴间的社会互作是一种天然奖赏,能够影响成瘾药物使用的敏感性。催产素（Oxytocin,OT)能够调节社会行为,并提高社会互作的奖赏价值。然而不同背景的同伴互作以及与OT合并使用是否对可卡因的奖赏效应有不同的影响尚不清楚。棕色田鼠(Microtus mandarinus)是一种单配制田鼠,个体间具有较复杂的社会行为。利用雌性棕色田鼠,我们首先检测了可卡因(20 mg/kg)单独强化以及与不同背景关系的同伴（熟性雌性、陌生雌性和陌生雄性）同时强化诱导的条件位置偏爱（conditioned place preference, CPP）及持续时间;其次检测了实验鼠外周注射OT (1 mg /kg)并给予不同背景同伴强化对可卡因CPP的影响。结果表明,可卡因单独强化时,实验鼠能够形成可卡因CPP并能持续至3周;用熟悉的雌性同伴强化时,实验鼠对可卡因CPP的维持时间缩短;用陌生的雌性或雄性同伴强化时可抑制可卡因CPP的形成。实验鼠注射OT后,用熟悉雌性或陌生雄性同伴分别强化时会抑制或反转可卡因CPP。这些结果表明不同背景关系的同伴强化对可卡因奖赏效应的影响不同。OT可促进同伴强化的奖赏价值,降低动物对可卡因的偏爱,且该效应因强化同伴的背景而不同。     

Individual variation in pup vocalizations and absence of behavioral signs of maternal vocal recognition in Weddell seals (Leptonychotes weddellii)

Individually stereotyped vocalizations often play an important role in relocation of offspring in gregarious breeders. In phocids, mothers often alternate between foraging at sea and attending their pup. Pup calls are individually distinctive in various phocid species. However, experimental evidence for maternal recognition is rare. In this study, we recorded Weddell seal (Leptonychotes weddellii) pup vocalizations at two whelping patches in Atka Bay, Antarctica, and explored individual vocal variation based on eight vocal parameters. Overall, 58% of calls were correctly classified according to individual. For males (n= 12) and females (n= 9), respectively, nine and seven individuals were correctly identified based on vocal parameters. To investigate whether mothers respond differently to calls of familiar vs. unfamiliar pups, we conducted playback experiments with 21 mothers. Maternal responses did not differ between playbacks of own, familiar, and unfamiliar pup calls. We suggest that Weddell seal pup calls may need to contain only a critical amount of individually distinct information because mothers and pups use a combination of sensory modalities for identification. However, it cannot be excluded that pup developmental factors and differing environmental factors between colonies affect pup acoustic behavior and the role of acoustic cues in the relocation process.     

Acoustic systems are adapted to breeding ecologies: individual recognition in nesting penguins

In all species of penguins studied to date, the display call, or parental call, has been demonstrated experimentally to facilitate identification between mates and between chicks and parents. We investigated parent-chick recognition in two nesting species, the Adélie penguin, Pygoscelis adeliae, and the gentoo penguin, P. papua. Through playback experiments, we tested the capacity of chicks to recognize the parental call at varying levels of background noise. By using modified calls, we found that chicks of neither species used temporal characteristics of the parental call (variations in frequency or amplitude with time) for individual recognition, but that both species used a simpler parameter, the pitch of the call. This finding contrasts with the more sophisticated use of acoustic cues by chicks of two non-nesting species, identified in earlier work. These differences in auditory processing of parental calls may have evolved because of different ecological constraints, particularly whether recognition of a nest site supports mutual identification of parent and offspring. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.     

Kin recognition in Bufo scaber tadpoles: ontogenetic changes and mechanism

Ontogenetic changes in kin-recognition behavior, effect of social environment on kin-recognition ability, and use of visual and chemical cues in kin recognition have been studied in tadpoles of Bufo scaber after rearing them with kin, in mixed groups, or in isolation from Gosner stage 12 (gastrula). By use of a rectangular choice tank the tadpoles were tested for their ability to choose between (a) familiar siblings and unfamiliar non-siblings, (b) unfamiliar siblings and familiar non-siblings, and (c) unfamiliar siblings and unfamiliar non-siblings. When tested without any stimulus groups in the end compartments of the tank, random distribution was observed for the tadpoles and no bias for the apparatus or the procedure. In the presence of kin and non-kin in the end compartments, significantly more tadpoles spent most of their time near kin (familiar or unfamiliar) rather than near non-kin during early larval stages, up to stage 37. After stage 37 (characterized by the differentiation of toes), test tadpoles showed no preference to associate with kin, suggesting an ontogenetic shift in the kin-recognition ability in B. scaber. In experiments involving selective blockade of visual or chemical cues the test tadpoles preferentially associated near their kin on the basis of chemical rather than visual cues. These findings suggest that familiarity with siblings is not necessary for kin recognition and that kin-recognition ability is not modified after exposure to non-kin by mixed rearing. The findings for B. scaber indicate a self referent phenotype matching mechanism of kin recognition which is predominantly aided by chemical rather than visual cues.     

Experience with adults shapes multisensory representation of social familiarity in the brain of a songbird

Social animals learn to perceive their social environment, and their social skills and preferences are thought to emerge from greater exposure to and hence familiarity with some social signals rather than others. Familiarity appears to be tightly linked to multisensory integration. The ability to differentiate and categorize familiar and unfamiliar individuals and to build a multisensory representation of known individuals emerges from successive social interactions, in particular with adult, experienced models. In different species, adults have been shown to shape the social behavior of young by promoting selective attention to multisensory cues. The question of what representation of known conspecifics adult-deprived animals may build therefore arises. Here we show that starlings raised with no experience with adults fail to develop a multisensory representation of familiar and unfamiliar starlings. Electrophysiological recordings of neuronal activity throughout the primary auditory area of these birds, while they were exposed to audio-only or audiovisual familiar and unfamiliar cues, showed that visual stimuli did, as in wild-caught starlings, modulate auditory responses but that, unlike what was observed in wild-caught birds, this modulation was not influenced by familiarity. Thus, adult-deprived starlings seem to fail to discriminate between familiar and unfamiliar individuals. This suggests that adults may shape multisensory representation of known individuals in the brain, possibly by focusing the young's attention on relevant, multisensory cues. Multisensory stimulation by experienced, adult models may thus be ubiquitously important for the development of social skills (and of the neural properties underlying such skills) in a variety of species.     

Individual Variation in Advertisement Calls of Territorial Male Green Frogs, Rana clamitans: Implications for Individual Discrimination

Individuals of many territorial species discriminate between familiar territorial neighbors and unfamiliar strangers based on individual differences in acoustic signals. Many anuran amphibians are territorial and use primarily acoustic communication during social interactions, but evidence for acoustically mediated individual discrimination is available only for one species. As a first step in research designed to investigate individual discrimination in a second species of territorial frog, we examined patterns of within-male and among-male variability in 198 advertisement calls of 20 male green frogs, Rana clamitans . The aim was to determine which acoustic properties could be used by males to recognize their territorial neighbors and to estimate limits of reliability afforded by these properties for identifying different neighbors. All of the call properties that we examined exhibited significant inter-individual variation. Discriminant function analyses assigned between 52% and 100% of calls to the correct individual, depending on sample size and the call properties included in the model. This suggests that there is sufficient among-male variability to statistically identify individuals by their advertisement calls. The call properties of fundamental frequency and dominant frequency contributed the most towards discrimination among individuals. Based on their natural history and behavior and the results reported here, we suggest that male green frogs likely discriminate between strangers and adjacently territorial neighbors based on individual variation in advertisement calls.     

Parent-offspring recognition in bank swallows (Riparia riparia): II. Development and acoustic basis

In study 1, bank swallow (Riparia riparia) chicks were exchanged with like-aged chicks from other broods. Parents accepted chicks that were transferred into their nests at age 15 days or younger; rejection began to occur at 16 to 17 days. In study 2, chicks' vocalizations were recorded in the burrow. We found that an immature begging call given by young chicks is replaced by a ‘signature’ call at 15 to 17 days of age. An acoustic analysis suggested that these calls are individually distinctive. Study 3 was a playback experiment designed to test whether the chicks' signature calls are a sufficient cue for parental recognition. We found that parents would approach a speaker broadcasting the calls of their chicks in preference to one simultaneously broadcasting the calls of alien chicks. The pattern of results suggests that parental recognition is based on the chicks' signature calls and that development of recognition is dependent on the development of the call.     

Experience Based Use of Landmark and Vector Based Orientation During Homing by the Ant Formica cunicularia (Hymenoptera: Formicidae)

Homing paths of Formica cunicularia foragers from an artificial food reward were analyzed on a familiar terrain and in displacement experiments on a familiar and an unfamiliar terrain. Foragers were tested either when relatively new to a foraging route (untrained group) or after a day’s experience with it (trained group). Untrained foragers followed direct homing paths to the nest site when tested in the familiar terrain but followed tortuous paths when displaced to the unfamiliar terrain. Trained foragers behaved similarly to untrained ones when tested from the food reward to the nest site in the familiar terrain but their behavior changed in displacements. Irrespective of the familiarity of the displacement site, these foragers followed paths taking them to the expected nest sites. The results showed that foragers did not rely on chemical cues for homing and revealed that untrained foragers disregarded path integration and were directed to the nest site when it is in their visual panorama. On the contrary, trained foragers may have relied on path integration on familiar and unfamiliar terrain. The results also demonstrated that experience greatly affected the preferential use of visual and vector based cues by foragers during homing.     

The effects of habitat‐ and diet‐based cues on association preferences in the three‐spined stickleback (Gasterosteus aculeatus)

A number of recent papers have investigated the potential of familiarity to organize the distributions of free‐ranging animals. It is not clear, however, to which extent individual recognition or a more general recognition of a group odour is responsible for familiarity preferences. First, we tested the sensory basis of the recognition of familiars in three‐spined stickleback ( Gasterosteus aculeatus ). When allowed to choose between a familiar and an unfamiliar stimulus shoal on the basis of both visual and chemical communication, visual communication only and chemical communication only, the preference of focal fish for familiars was shown to be dependent on the presence of chemical cues. We subsequently investigated the mechanisms underlying such association preferences, specifically the effects of recent habitat and diet on preferences. Experimental fish were divided into four treatment groups consisting of two environment treatments (saline and freshwater) and two diet treatments ( Daphnia spp. and chironimid larvae). Focal fish subsequently showed significant association preferences for groups of unfamiliar fish that had undergone the same environment or diet treatment as themselves, suggesting self‐referent matching. These data indicate that individual recognition is not a pre‐requisite for the expression of familiarity preferences.     

Prenatal light exposure affects early feather-pecking behaviour in the domestic chick

Recently we proposed that early feather pecking is a form of social exploration. Social recognition, important for exploration, is a lateralized function in the domestic chick. Lateralization of functions can be influenced by light exposure late in embryonic development. Therefore, we investigated whether this light exposure affected early posthatching feather-pecking behaviour in domestic chicks, Gallus gallus domesticus. White leghorn embryos either were exposed to light or remained in darkness in the last week of incubation. After hatching, they were housed in groups of two light-exposed and two dark-incubated chicks. Light-exposed chicks showed more feather pecking than did their dark-incubated cagemates. Dark-incubated chicks preferred to direct feather pecks to unfamiliar peers than to familiar peers; light-exposed chicks showed no preference. These effects were present in the first week after hatching and remained at least another 3 weeks. These results support the hypothesis that early gentle feather pecking is part of the normal behavioural repertoire of young chicks and influences social exploration. We discuss a possible mechanism underlying these results. We also suggest that it may be worthwhile not to expose embryos to light during the last week of incubation when housing hatchlings in commercial conditions, where feather pecking is a serious problem.     

Kin recognition by tadpoles and froglets of the wood frog Rana sylvatica

Summary We investigated kin recognition by the wood frog Rana sylvatica in blind laboratory experiments using spatial proximity as a recognition assay. Tadpoles were tested for the ability to discriminate between: 1) familiar full-sibs and unfamiliar non-kin, 2) unfamiliar paternal half-sibs and unfamiliar non-kin, and 3) familiar and unfamiliar full-sibs. Tadpoles discriminated full- and paternal half-sibs from unrelated conspecifics, but did not discriminate between familiar and unfamiliar full-sibs. Froglets from the same laboratory population were tested for the ability to discriminate between 1) familiar full-sibs and unfamiliar non-kin, and 2) unfamiliar paternal half-sibs and unfamiliar non-kin. Froglets preferentially associated with full- and half-sibs over unrelated conspecifics. Our results show that familiarity, i.e., prior association, is not necessary for kin recognition in tadpoles and froglets. The ability of tadpoles and froglets to recognize unfamiliar paternal half-sibs demonstrates that a common maternal factor is not necessary for kin recognition, and indicates that the recognition cue has a genetic component. Our results add to the increasing evidence that a variety of vertebrate and invertebrate animals have the ability to recognize unfamiliar kin by using genetically specified recognition cues.     

Temporal Limitations on Social Learning of Novel Predators by Indian Mynahs, Acridotheres tristis

Antipredator vocalizations of social companions are important for facilitating long-term changes in the responses of prey to novel predator stimuli. However, dynamic variation in the time course of acoustic communication has important implications for learning of predator cues associated with auditory signals. While animals often experience acoustic signals simultaneously with predator cues, they may also at times experience signals and predator stimuli in succession. The ability to learn about stimuli that are perceived not only together, but also after, acoustic signals has the potential to expand the range of opportunities for learning about novel events. Earlier work in Indian mynahs ( Acridotheres tristis ) has revealed that subjects acquire a visual exploratory response to a novel avian mount after they have experienced it together with conspecific distress vocalizations, a call produced in response to seizure by a predator. The present study explored to what extent such learning occurred if the avian mount was experienced after, rather than simultaneously with, distress calls, such as might happen if call production is interrupted by prey death. Results showed that mynahs that experienced a novel avian mount simultaneously with the sound of distress calls exhibited a sustained exploratory response to the mount after training relative to before that was not apparent in birds that received distress calls and mount in succession. This finding suggests that vocal antipredator signals may only trigger learning of environmental stimuli with which they share some temporal overlap. Recipients may need to access complementary non-vocal cues from the prey victim to learn about predator stimuli that are perceived after vocal behaviour.     

Individual recognition of parental calls by bank swallow chicks (Riparia riparia)

Antiphonal responses of newly fledged bank swallows (Riparia riparia) to the calls of their parents during the joined flights to and from the home burrow suggest that recognition of parents by offspring is a mechanism promoting family cohesion, a necessary condition for the adequate provisioning of chicks in this highly colonial species. Paternal and maternal calls used while leading chicks revealed higher inter-than intra-individual variability in temporal and frequency parameters, indicating that these calls could reliably identify individuals. When tested in the field at the onset of the fledging period, chicks answered significantly more playbacks of parent calls than of alien adult calls. Quantified observations of the rearing activity of the parents suggest that chick-parent recognition is based on familiarity, because of the chicks' differential exposure to the parental calls prior to fledging. During the development of the chicks in the burrow, both parents (which share the rearing activities equally) often call before feeding the chicks.     

Independent effects of familiarity and mating preferences for ornamental traits on mating decisions in guppies

The avoidance of familiar individuals as mates can act to maximizethe benefits of polyandry or might help to minimize inbreedingin small or highly philopatric populations. As previous matesare also familiar, the effects of familiarity and mating historycan often be confounded. Here, we disentangle these effectson mating decisions in the guppy, Poecilia reticulata, and examinetheir influence on sexual selection. In 3 experiments, malesand females were 1) able to mate, 2) had visual and olfactorycontact, or 3) had visual contact only. Familiarity was successfullyacquired via visual cues, and females were in all cases morelikely to mate with unfamiliar than with familiar males, indicatingthat familiarity is a more important determinant of mating outcomethan mating history. Males did not court unfamiliar femalesany more than familiar females and did not differentially allocatesperm. Familiarity did not alter the strength of sexual selectionon male coloration: we found overall positive selection forbright, large males. Female preferences for unfamiliar malesand ornamental traits may therefore be largely independent.