Time In Close Proximity Research Articles

Female koalas prefer bellows in which lower formants indicate larger males

Despite an extensive literature on the role of acoustic cues in mate choice little is known about the specific vocal traits that female mammals prefer. We used resynthesis techniques and playback experiments to examine the behavioural responses of oestrous female koalas, Phascolarctos cinereus, to male bellows in which a specific acoustic cue to body size, the formants, were modified to simulate callers of different body size. Oestrous females looked longer towards, and spent more time in close proximity to, loudspeakers broadcasting bellows simulating larger male koalas. These findings suggest that female koalas use formants (key components of human speech) to select larger males as mating partners, and represent the first evidence of a marsupial mating preference based on a vocal signal. More generally, these results indicate that intersexual selection pressures to lower formants and exaggerate size are present in a marsupial species, raising interesting questions about the evolutionary origins of formant perception.

Finding Your Friends at Densely Populated Roosting Places: Male Egyptian Fruit Bats (Rousettus aegyptiacus) Distinguish between Familiar and Unfamiliar Conspecifics

Individual recognition via olfactory, auditory, or visual cues is crucial for animals to form and maintain stable social groups, particularly in large colonies such as those of Egyptian fruit bats (Rousettus aegyptiacus). We tested whether Egyptian fruit bats are able to distinguish between familiar and unfamiliar conspecifics, using two captive groups of male bats. We recorded the behavioural and auditory responses of focal animals in a binary choice experiment in which they could approach either members of their own social group or unfamiliar individuals. In general, bats preferred to stay close to other bats, familiar or unfamiliar, over resting alone and spent more time in close proximity to members of their own group than to unfamiliar conspecifics. The majority of bats interacted more with the unfamiliar individuals, although this result did not reach significance. We conclude that Egyptian fruit bats are able to distinguish between familiar and unfamiliar conspecifics. Since only one individual emitted social calls and bats never produced echolocation calls during the experiment, we infer that individual recognition was most likely mediated via olfactory and/or visual cues. The ability to identify familiar individuals may indicate that males of Egyptian fruit bats form stable groups within their large colonies.

Variability of Female Responses to Conspecific vs. Heterospecific Male Mating Calls in Polygynous Deer: An Open Door to Hybridization?

Males of all polygynous deer species (Cervinae) give conspicuous calls during the reproductive season. The extreme interspecific diversity that characterizes these vocalizations suggests that they play a strong role in species discrimination. However, interbreeding between several species of Cervinae indicates permeable interspecific reproductive barriers. This study examines the contribution of vocal behavior to female species discrimination and mating preferences in two closely related polygynous deer species known to hybridize in the wild after introductions. Specifically, we investigate the reaction of estrous female red deer (Cervus elaphus) to playbacks of red deer vs. sika deer (Cervus nippon) male mating calls, with the prediction that females will prefer conspecific calls. While on average female red deer preferred male red deer roars, two out of twenty females spent more time in close proximity to the speaker broadcasting male sika deer moans. We suggest that this absence of strict vocal preference for species-specific mating calls may contribute to the permeability of pre-zygotic reproductive barriers observed between these species. Our results also highlight the importance of examining inter-individual variation when studying the role of female preferences in species discrimination and intraspecific mate selection.

Aggression, grooming and group‐level cooperation in white‐faced capuchins (Cebus capucinus): insights from social networks

The form of animal social systems depends on the nature of agonistic and affiliative interactions. Social network theory provides tools for characterizing social structure that go beyond simple dyadic interactions and consider the group as a whole. We show three groups of capuchin monkeys from Barro Colorado Island, Panama, where there are strong connections between key aspects of aggression, grooming, and proximity networks, and, at least among females, those who incur risk to defend their group have particular "social personalities." Although there is no significant correlation for any of the network measures between giving and receiving aggression, suggesting that dominance relationships do not follow a simple hierarchy, strong correlations emerge for many measures between the aggression and grooming networks. At the local, but not global, scale, receiving aggression and giving grooming are strongly linked in all groups. Proximity shows no correlation with aggression at either the local or the global scale, suggesting that individuals neither seek out nor avoid aggressors. Yet, grooming has a global but not local connection to proximity. Extensive groomers who tend to direct their efforts at other extensive groomers also spend time in close proximity to many other individuals. These results indicate the important role that prosociality plays in shaping female social relationships. We also show that females who receive the least aggression, and thus pay low costs for group living, are most likely to participate in group defense. No consistent "social personality" traits characterize the males who invest in group defense.

The impact of moving to a novel environment on social networks, activity and wellbeing in two new world primates

Among the stressors that can affect animal welfare in zoos, the immediate effect of relocation to a novel environment is one that has received little attention in the literature. Here, we compare the social network, daily activity and the expression of stress-related behavior in capuchins (Cebus apella) and squirrel monkeys (Saimiri sciureus) before and just after they were relocated to a new enriched enclosure. Results showed similar immediate responses to the move in the two species. Both showed a substantial increase in the time spent resting and spent more time in the highest and "safest" part of their enclosure after relocation. Both capuchins and squirrel monkeys spent significantly more time in close proximity to other group members after relocation, compared to before. In squirrel monkeys, the structure of the social network, which was initially correlated to affiliation, was no longer so after the move. In capuchins, the network analysis showed that individuals regrouped by age, with the youngsters who were potentially more affected by stress being in the center of the network. Social network analysis helped to achieve a more complete picture of how individuals were affected by relocation. We suggest that this type of analysis should be used alongside traditional methods of observation and analysis to encompass the most complex aspects of animal behavior in times of stress and to improve welfare.

Insights into social relationships among female black howler monkeys Alouatta pigra at Palenque National Park, Mexico

Abstract We investigated the social relationships among adult females in two multimale-multifemale groups of black howler monkeys Alouatta pigra during a 14-month study in Palenque National Park, Mexico. Based on over 900 focal hours and over 5400 scan samples recording neighboring group members, we found that females very rarely engaged in agonistic interactions and no dominance hierarchy could be discerned. Relationships among resident females were primarily affiliative, but females of one study group spent a higher proportion of time in close proximity and engaged in affiliative interactions with one another at higher rates than females in the other study group. The strength of female relationships increased with the birth of an infant. Although no females immigrated during the study period, the temporary association of three extragroup females with our study groups implies that the social system of black howler monkeys is more dynamic than previously suggested. These findings suggest that female black howler monkeys behave more similarly to female red howler monkeys A. seniculus than to female mantled howler monkeys A. palliata.

Normal social seeking behavior, hypoactivity and reduced exploratory range in a mouse model of Angelman syndrome

BackgroundAngelman syndrome (AS) is a neurogenetic disorder characterized by severe developmental delay with mental retardation, a generally happy disposition, ataxia and characteristic behaviors such as inappropriate laughter, social-seeking behavior and hyperactivity. The majority of AS cases are due to loss of the maternal copy of the UBE3A gene. Maternal Ube3a deficiency (Ube3am-/p+), as well as complete loss of Ube3a expression (Ube3am-/p-), have been reproduced in the mouse model used here.ResultsHere we asked if two characteristic AS phenotypes - social-seeking behavior and hyperactivity - are reproduced in the Ube3a deficient mouse model of AS. We quantified social-seeking behavior as time spent in close proximity to a stranger mouse and activity as total time spent moving during exploration, movement speed and total length of the exploratory path. Mice of all three genotypes (Ube3am+/p+, Ube3am-/p+, Ube3am-/p-) were tested and found to spend the same amount of time in close proximity to the stranger, indicating that Ube3a deficiency in mice does not result in increased social seeking behavior or social dis-inhibition. Also, Ube3a deficient mice were hypoactive compared to their wild-type littermates as shown by significantly lower levels of activity, slower movement velocities, shorter exploratory paths and a reduced exploratory range.ConclusionsAlthough hyperactivity and social-seeking behavior are characteristic phenotypes of Angelman Syndrome in humans, the Ube3a deficient mouse model does not reproduce these phenotypes in comparison to their wild-type littermates. These phenotypic differences may be explained by differences in the size of the genetic defect as ~70% of AS patients have a deletion that includes several other genes surrounding the UBE3A locus.

Space to choose: network analysis of social preferences in a captive chimpanzee community, and implications for management

Social network analysis (SNA) is rapidly gaining popularity in primatology, but its application to the management of zoo-housed primates has been largely overlooked. Here I use SNA techniques to explore the social structure of chimpanzees (Pan troglodytes) housed in the new "Budongo Trail" exhibit at Edinburgh Zoo, UK. Given that individuals have extensive space (2332 m(2)), and access to several interconnected exhibit sections, I test the hypothesis that individuals are able to choose to interact with specific social partners. Spatial association and social interaction data were recorded from 400 focal watches on 11 individuals, and association, affiliative, and agonistic networks were constructed. Matrix correlations showed that individuals who spent time in close proximity were likely to affiliate with one another, but spatial association did not predict the frequency of agonistic encounters. Cluster analysis revealed significantly distinct sub-groups in the affiliative network (but not association or agonistic networks) in line with maternal kinship. Overall my findings support the hypothesis that the Budongo Trail exhibit facilitates the expression of social preferences, and suggests that SNA can be a useful tool to study zoo primates when proximity between individuals is not forced (i.e. in large, modern exhibits). Now that I have validated a set of SNA methods for this community, they can be used to trace changes in social dynamics over a longer time period, and ultimately assist zoo staff in their management decisions.

Effect of the density of conspecifics on runway social reinstatement behavior of male Japanese quail genetically selected for contrasting adrenocortical responsiveness to stress

Runway tests are considered indicative of underlying sociality in birds and their ability to make social discriminations and establish interactions among conspecifics. Herein, social reinstatement behavior in male juvenile Japanese quail selected for a reduced (LS, low stress) or exaggerated (HS, high stress) adrenocortical response to brief mechanical restraint was evaluated. Individual males were given the choice to reinstate with either 2 (low density, LD) or 8 (high density, HD) unfamiliar randombred conspecifics placed in goal boxes at opposite ends of a two-choice runway (TCRW). Then, the same males were individually retested in a single goal box runway wherein they were exposed to a goal box containing either a LD or a HD of males. In the TCRW, a higher (P < 0.01) number of HS males started their ambulation toward the goal box containing the HD as opposed to LD of conspecifics. The HS males also spent more (P < 0.01) time in close proximity (within a 10-cm close zone; CZ) to the HD (218 s) rather than LD (57 s) of conspecifics. In contrast, the LS males did not differ in their initial direction of travel and they spent similar average amounts of times in the CZ of their stimulus LD (141 s) and HD (124 s) conspecifics. Similar to the TCRW results, in the single goal box runway, HS males spent more (P < 0.01) time in the CZ of HD rather than LD conspecifics, whereas LS quail spent similar amounts of time in the CZ of LD and HD males. Considering that runways are novel (and therefore frightening) environments, our findings suggest that HS quail may find better shelter (i.e., more comfort) in close proximity to a larger rather than smaller group of conspecifics, whereas LS birds find groups of varying conspecific density equally attractive. The results suggest that LS quail possess favorable social adaptive qualities because they appear to be better suited to cope with situations where the density of conspecifics is variable.

The effects of alternative weaning methods on behaviour in beef calves

The aim of this experiment was to compare the behavioural responses and weight change of beef calves weaned using three weaning methods. Forty-eight primiparous Hereford or Hereford × Angus nursing beef calves (180.7 ± 1.3 days old; mean ± SEM) were assigned to one of three treatments: 1) CON: weaned abruptly on day 0; 2) FEN: calves were separated by fence line from dams on day − 17 but remained in visual sight of one another; or 3) NF: cows and calves remained together but suckling was prevented on day − 17 by inserting a nose-flap anti-suckling device. In all treatments remote physical separation of the cow and calf took place on day 0. Behaviours were recorded by instantaneous sampling from day − 20 to day − 13, and from day − 3 to day 5, except on day 0. Distance between cows and calves and the fence line in FEN calves and between the dyads in NF calves were recorded from day − 17 to day − 13. Body weights of calves were recorded on days − 24, − 11, 0, 7 and 21. There was a day and treatment by day interaction for all behaviours. Behavioural responses were strongest during the first 2 days after fence line separation in the FEN calves and after remote separation in the CON calves. For the NF calves, behavioural effects were observed immediately after insertion of the nose-flaps, including numerous unrewarded suckling events, and again when remote physical separation took place. Overall the FEN calves vocalized ( P < 0.03) more than CON and NF calves. CON calves played ( P < 0.02) and ruminated ( P < 0.04) more often than FEN and NF calves, and walked ( P = 0.01) more than NF. On day − 17 and day − 16, FEN calves (and their dams) spent more time within 30 m of the fence line than on day − 15 to day − 13 ( P < 0.02). NF calves spent more time in close proximity of their dams on day − 17 and day − 16 ( P < 0.001). Calves of the CON treatment had a greater average daily gain (ADG) than FEN and NF calves ( P < 0.008); ADG was greater in FEN than in NF calves ( P = 0.02). Two-stage weaning with nose-flaps resulted in a second distress response after remote physical separation from the dam, and a drop in ADG in both periods indicating that the response was distributed between the two stages. In calves weaned using the fence line method, the response was more prolonged and more intense, with no advantages for weight gain compared to abrupt weaning. In conclusion, the two alternative weaning methods did not appear to provide any clear benefits in reducing weaning distress in beef calves compared to abrupt weaning in the conditions used in this experiment. However, the use of nose-flaps seems to reduce distress better than fence line separation.

Gender differences in aggressive behaviour in convict cichlids

Males and females of many species engage in agonistic encounters. However, differing selection pressures on each sex are predicted to result in sex differences in aggressive behaviour during contests. Comparing male and female intrasexual contests can yield intriguing differences, shedding light on the forces shaping the use of particular aggressive tactics. We investigated whether fundamental gender-related differences in aggression, not explained by current parental role, are present in convict cichlids, Amatitlania nigrofasciata. Intrasexual agonistic encounters between isolated males and between isolated females not previously paired to a breeding partner were staged. Using this approach we first tested for behavioural differences between the sexes. Second, using a novel startle technique aimed at probing motivation to fight, we tested for gender-related differences in aggressive motivation. Third, we examined whether size, rather than gender, plays a role in determining the tactics used during contests. In addressing these aims we found: (1) females used more frontal display and biting, and spent more time in close proximity to their opponent, whereas males used more lateral display and tail beating than females during agonistic encounters; (2) there was no difference in the response of male or female convict cichlids to a startling stimulus aimed at probing motivation to fight; and (3) the addition of focal weight and length as possible covariates had no significant effect on the analyses. Possible causal and functional reasons for these gender-related differences in fight tactics are discussed.

Caregivers recognize and bias response towards individual young in a cooperative breeding mammal, the banded mongoose

AbstractIn research on parental care and cooperative breeding an issue is whether caregivers recognize individual young and therefore preferentially care for those young that will maximize inclusive fitness gains. This field study experimentally evaluates whether caregivers within groups of the cooperative breeding banded mongoose (a communal breeding species that produces litters of mixed parentage) exhibit individual recognition and increased responsiveness to the pup to which they are normally associated within a stable escort–pup pairing. A focal pup was presented to its group under controlled circumstances following temporary removal. The focal escort of a specific pup was more responsive to controlled presentation of that pup than other adults (a control escort, other escorts and non‐escorts), spending a greater amount of time in close proximity. This study therefore demonstrates individual recognition and increased responsiveness by adult caregivers to associated pups in the banded mongoose. Thus, caregivers may selectively provide care for specific young within a litter, potentially increasing their inclusive fitness.

Enhanced social learning between siblings in common ravens, Corvus corax

It has been suggested that social dynamics affect social learning but empirical support for this idea is scarce. Here we show that affiliate relationships among kin indeed enhance the performance of common ravens, Corvus corax, in a social learning task. Via daily behavioural protocols we first monitored social dynamics in our group of captive young ravens. Siblings spent significantly more time in close proximity to each other than did nonsiblings. We subsequently tested birds on a stimulus enhancement task in model-observer dyads composed of both siblings and nonsiblings. During demonstration the observer could watch the model manipulating one particular object (target object) in an adjacent room. After removing the model, the observer was confronted with five different objects including the former target object. Observers from sibling dyads handled the target object for significantly longer periods of time as compared with the other four available objects, whereas observers from nonsibling dyads did not show a preference for the target object. Also, siblings matched the model's decision to cache or not to cache objects significantly more often than did nonsiblings. Hence, siblings were likely to attend to both, the behaviour of the model (caching or noncaching) and object-specific details. Our results support the hypothesis that affiliate relations between individuals affect the transmission of information and may lead to directed social learning even when spatial proximity has been experimentally controlled for.

The Genetic Basis of Individual-Recognition Signals in the Mouse

The major histocompatibility complex (MHC) is widely assumed to be a primary determinant of individual-recognition scents in many vertebrates [1-6], but there has been no functional test of this in animals with normal levels of genetic variation. Mice have evolved another polygenic and highly polymorphic set of proteins for scent communication, the major urinary proteins (MUPs) [7-12], which may provide a more reliable identity signature ([13, 14] and A.L. Sherborne, M.D.T., S. Paterson, F.J., W.E.R.O., P. Stockley, R.J.B., and J.L.H., unpublished data). We used female preference for males that countermark competitor male scents [15-17] to test the ability of wild-derived mice to recognize individual males differing in MHC or MUP type on a variable genetic background. Differences in MHC type were not used for individual recognition. Instead, recognition depended on a difference in MUP type, regardless of other genetic differences between individuals. Recognition also required scent contact, consistent with detection of involatile components through the vomeronasal system [6, 18]. Other differences in individual scent stimulated investigation but did not result in individual recognition. Contrary to untested assumptions of a vertebrate-wide mechanism based largely on MHC variation, mice use a species-specific [12] individual identity signature that can be recognized reliably despite the complex internal and external factors that influence scents [2]. Specific signals for genetic identity recognition in other species now need to be investigated.

Nocturnal Male Sex Drive in Drosophila

Many behaviors and physiological processes including locomotor activity, feeding, sleep, mating, and migration are dependent on daily or seasonally reoccurring, external stimuli. In D. melanogaster, one of the best-studied circadian behaviors is locomotion. The fruit fly is considered a diurnal (day active/night inactive) insect, based on locomotor-activity recordings of single, socially naive flies. We developed a new circadian paradigm that can simultaneously monitor two flies in simple social contexts. We find that heterosexual couples exhibit a drastically different locomotor-activity pattern than individual males, females, or homosexual couples. Specifically, male-female couples exhibit a brief rest phase around dusk but are highly active throughout the night and early morning. This distinct locomotor-activity rhythm is dependent on the clock genes and synchronized with close-proximity encounters, which reflect courtship, between the male and female. The close-proximity rhythm is dependent on the male and not the female and requires circadian oscillators in the brain and the antenna. Taken together, our data show that constant exposure to stimuli emanating from the female and received by the male olfactory and other sensory systems is responsible for the significant shift in intrinsic locomotor output of socially interacting flies.

Can redirected aggression explain interspecific attacks by Australian magpies on other birds?

AbstractAttacks by participants of conflicts against a third party are referred to as redirected aggression. Usually the third party is a conspecific — few documented cases of redirected aggression against other species exist. The Australian magpie (Gymnorhina tibicen), however, often attacks other species; the reasons for attacks are largely unknown. Some attacks occur after territorial disputes with conspecifics, suggesting that attacks are the result of redirected aggression. We subjected eight Australian magpie groups to simulated territorial intrusions. In one treatment an Australian magpie and rock dove (Columba livia) were presented in cages next to one another (5 m apart) on the territory for 30 min; the Australian magpie decoy was then covered and aggressive responses toward the rock dove by residents were recorded for a further 30 min (Treatment 1). Two additional treatments were presented in an identical manner on each territory where both decoys were either Australian magpies (Treatment 2) or rock doves (Treatment 3). We predicted that if Australian magpies regularly redirect aggression onto benign species after conspecific territorial intrusions, attack rates on the rock dove decoy in Treatment 1 would be higher than attack rates on the rock dove decoy in Treatment 3. Residents were seldom recorded close (&lt;1 m) and not seen attacking rock dove decoys during tests. In contrast, Australian magpie decoys were often approached and attacked by residents. After a decoy was covered (following the first 30 min phase), residents spent little time in close proximity (on cage, &lt;0.3 m, or 0.3-1 m) to the rock dove decoy in either Treatment 1 or Treatment 3; in contrast, residents were often recorded close to the Australian magpie decoy in Treatment 2. We found no evidence that Australian magpies redirect aggression onto other birds after territorial intrusions. The true proportion of territorial disputes leading to redirected attacks may be small, or only occur under highly specific contexts.

Familiarity modulates social tolerance between male lizards, Lacerta monticola, with size asymmetry

Theoretical and field studies suggest that inferior competitors may be able to avoid costly agonistic interactions, although the mechanisms involved are poorly understood in lizards. The “Dear enemy recognition” theory proposes that higher tolerance among familiar than among unfamiliar conspecifics may reduce costly interactions. Male lizards Lacerta monticola are able to discriminate between familiar and unfamiliar conspecific males through chemical signals alone. To better understand the implications of this discrimination ability, we performed a laboratory experiment on the role of familiarity in social tolerance estimated as the degree of spatial proximity with no sign of aggressiveness between males with a size asymmetry. In natural conditions the outcome of neighbour-stranger interactions might be the result of asymmetries in residence. Therefore, we staged pairwise encounters between familiar and unfamiliar males in neutral terraria to avoid an interacting effect of residency asymmetry. The latency to the first time in close proximity was significantly longer when small males were faced with unfamiliar males. The time that unfamiliar lizards spent in close proximity was significantly lower than that with familiar males. Our design allowed us to conclude that there was a higher social tolerance among familiar individuals with a size asymmetry that was independent of residency asymmetry.

Antiphonal exchanges in female African elephants

Female African elephants (Loxodonta africana) engage in antiphonal exchanges of rumble vocalizations. In this study, female African elephants (N=7) housed at Disney’s Animal Kingdom were outfitted with audio-recording collars and videotaped during 50 1-hour observation sessions (conducted in 2002). We found that production of the antiphonal response rumble reflected changes in herd affiliation that had taken place since our previous study (2000). Second, we examined response latency and found that females responded more quickly to the rumbles of affiliated partners than to those of a nonaffiliated female. Since affiliated partners spend more time in close proximity by definition, they may engage in higher rates of temporally associated calling simply because nearby stimuli impact them simultaneously or due to a social facilitation effect, not because they are true vocal exchanges. Therefore, we examined antiphonal rumble responses when female pairs were more than 25 m apart. We found that at these distances, affiliated females still exchanged rumbles more frequently, and responded at a decreased latency, than nonaffiliated pairs. Our results provide support for functional hypotheses of African elephant rumble vocalizations that require instances of temporally associated calling in order to be true communicative events. [Work supported by Grant No. NSF-IIS-0326395.]

Health &amp; safety: what every IT professional should know

Information professionals are mostly employed in offices, but their working environment is often quite unlike that of colleagues in other departments. IT staff whose job role requires them to spend a lot of time in close proximity to densities of computer kit are likely to find themselves spending much of their working day in surroundings configured to meet the needs of machine, rather than man. IT staff are more exposed to HS and they are prone to putting themselves at risk by ignoring the rules of safe practice.

Helpers benefit offspring in both the short and long-term in the cooperatively breeding banded mongoose

Helpers in cooperative and communal breeding species are thought to accrue fitness benefits through improving the condition and survival of the offspring that they care for, yet few studies have shown conclusively that helpers benefit the offspring they rear. Using a novel approach to control for potentially confounding group-specific variables, I compare banded mongoose (Mungos mungo) offspring within the same litter that differ in the amount of time they spend with a helper, and hence the amount of care they receive. I show that pups that spend more time in close proximity to a helper are fed more, grow faster and have a higher probability of survival to independence than their littermates. Moreover, high growth rates during development reduce the age at which females breed for the first time, suggesting that helpers can improve the future fecundity of the offspring for which they care. These results provide strong evidence that it is the amount of investment per se that benefits offspring, rather than some correlate such as territory quality, and validate the assumption that helpers improve the reproductive success of breeders, and hence may gain fitness benefits from their actions. Furthermore, the finding that helpers may benefit offspring in the long-term suggests that current studies underestimate the fitness benefits that helpers gain from rearing the offspring of others.