Combined effect of ambient temperature and solar radiation on maned sloths' behaviour and detectability

Changes in ambient temperature and solar radiation may affect sloths' metabolic rate and body temperature, with consequent changes in activities, postures and microhabitat selection. Although the separate effect of temperature and solar radiation on sloth's behaviour have been previously studied, the combined effect of these climatic factors on behavioural aspects of sloths has never been systematically evaluated in field conditions. Here we evaluated the influence of hourly ambient temperature variation on maned sloth (Bradypus torquatus) activities, postures and tree crown positions, under sunny and cloudy conditions; and tested if any of the animal posture and position increase their exposure to human detection. We performed 350 h of visual observation on eight maned sloths, equipped with radio-backpacks, in northern Bahia, Brazil, recording their activities, and their resting postures and positions on tree crowns. We also recorded the time taken to visualize the sloths on 58 days to analyse if sloths' detection is affected by posture and position. Higher ambient temperature, within a range of 21–33°C, increased the sloths' activity levels in cloudy conditions but reduced their activity in sunny conditions. Increasing ambient temperature also reduced the frequency of huddled posture and increased the frequency of extended posture and permanence in the inner tree crown. Lastly, the postures and positions did not influence sloths' detectability. Thus, the direction of the temperature–activity relationship depends on climatic conditions (sunny/cloudy), and individuals rely on resting postures and positions to thermoregulate. The warmer and drier future climate, expected to occur in the northern Atlantic Forest, may impose change in the diurnal activity levels and postural pattern for this threatened species, leading maned sloths to reduce its activity on sunny and warmer days and adopting an extended posture.     

Some observations on mating behaviour of several cranes in captivity

Responding to the actions of the mate and taking somewhat fixed patterns,Grus japonensis, G. vipio, G. antigone, Anthropoides paradisea andBalearica regulorum pairs are finally led to copulation by a sequence of mating behaviours. There are slight differences in pre-copulatory behaviour patterns between the species and the female's ‘wing-spreading’, being the soliciting and key posture for copulation, differs between the genera; The female's wings are spread wide inGrus, fairly wide inAnthropoides, and are almost folded inBalearica. Post-copulatory behaviours, however, have definite species-specific characters. They usually consist of ‘head-down’ (bowing) or ‘warping’, ‘arching’, etc. immediately following the dismounting of the male inGrus. But a pair ofBalearica first keep their heads high, or gaze at each other for a while, and then show remarkable ‘ruffle-bowing’. These characteristic post-copulatory behaviours are obviously correlated with the threat displays, evolved under agonistic situations, typical to each species.     

Social transmission of physiological and behavioural responses to castration in suckling Merino lambs

In social species like sheep, social context can modify both physiological and behavioural responses to stressors and normal behavioural patterns. Presence of conspecifics can ameliorate responses to noxious stimuli, an effect termed social buffering, whereas the presence of a distressed conspecific can invoke a distress response in an observer animal not receiving a noxious organic insult, an effect termed social contagion. Furthermore, synchrony of normal behaviours can occur within a group. Here a range of social contexts were created by grouping suckling lambs undergoing knife, ring or sham castration treatments either homogeneously or heterogeneously by castration treatment in pens within an animal house. The impact of social grouping on cortisol, rectal temperature, pain avoidance behaviours, postural behaviours and synchrony of behaviour in the first 12 h following castration treatment was examined. Irrespective of castration treatment, lambs grouped homogeneously by castration treatment had higher cortisol concentrations across the four time points measured than lambs grouped heterogeneously. They also spent 1.9% more of the time in restless behaviour in the first 1 h following castration, and in the 12 h following castration spent 6.7% more of their time lying ventrally, 4.9% less time standing normally, 1.6% more time walking normally, and 4.9% less time in total standing postures. Interactions between social grouping and castration treatment were not significant for physiological variables, pain related behaviours or postures with the exception of lateral lying which was decreased in knife castrated lambs grouped heterogeneously with other castration treatments from 1.9% (homogeneous grouping) to 0.4% (heterogeneous group). Synchronisation of behaviour was seen for walking in lambs grouped heterogeneously by castration treatment and for feeding at the trough in lambs grouped homogenously by ring and sham castration treatments. Lying and standing respectively, were negatively synchronised (occurred less frequently than predicted by chance alone) in ring and knife castrated lambs grouped homogeneously. The results indicate that mixing lambs that received the three castration treatments within a pen modified the activity profile of the lambs but did not substantially modify the behavioural or physiological changes that are stigmatic of responses to the specific castration treatments. The social contexts contrasted in the study did not result in marked contagion or social buffering between lambs of the measured responses and did not confound comparison of castration treatments. None-the-less, the comparability of responses observed in castration treatment groups penned homogenously or heterogeneously might not necessarily occur in other classes of sheep or in other social contexts. The absence of social transmission of behavioural and physiological responses indicates that grouping non-castrated lambs with castrated lambs did not compromise the welfare of the non-castrated lambs when their mothers were present.     

Intra-Site Variability in the Still Bay Fauna at Blombos Cave: Implications for Explanatory Models of the Middle Stone Age Cultural and Technological Evolution

To explain cultural and technological innovations in the Middle Stone Age (MSA) of southern Africa, scholars invoke several factors. A major question in this research theme is whether MSA technocomplexes are adapted to a particular set of environmental conditions and subsistence strategies or, on the contrary, to a wide range of different foraging behaviours. While faunal studies provide key information for addressing these factors, most analyses do not assess intra-technocomplex variability of faunal exploitation (i.e. variability within MSA phases). In this study, we assess the spatial variability of the Still Bay fauna in one phase (M1) of the Blombos Cave sequence. Analyses of taxonomic composition, taphonomic alterations and combustion patterns reveal important faunal variability both across space (lateral variation in the post-depositional history of the deposits, spatial organisation of combustion features) and over time (fine-scale diachronic changes throughout a single phase). Our results show how grouping material prior to zooarchaeological interpretations (e.g. by layer or phase) can induce a loss of information. Finally, we discuss how multiple independent subdivisions of archaeological sequences can improve our understanding of both the timing of different changes (for example in technology, culture, subsistence, environment) and how they may be inter-related.     

Behavioural Thermoregulation in a Small Neotropical Primate

The maintenance of body temperature in endothermic animals imposes considerable metabolic costs that vary with air temperature fluctuations. To minimise these costs, endotherms can adopt certain behaviours to adjust the pattern of heat transfer between their bodies and the environment. In this study, we evaluated whether a small Neotropical primate, the black‐fronted titi monkey (Callicebus nigrifrons), living in a seasonal environment can use behavioural mechanisms to cope with fluctuations in the air temperature. We monitored the air temperature and the titi monkeys’ behaviour over 1 yr. When the animals were inactive, we recorded the microhabitat used, the huddling between individuals and the body postures adopted. The monkeys primarily responded to air temperature fluctuations through microhabitat selection: they spent more time in sunny places and used higher strata of forest under lower temperatures. Moreover, they used sunny microhabitats during the first hour of their active period after colder nights. The monkeys did not huddle or change body postures in response to air temperature fluctuations. Huddling behaviour seemed to be primarily influenced by social interactions, and body postures were more energy conserving, regardless of temperature. Titi monkeys, however, used more energy‐conserving postures and huddling behaviour under cloudy conditions than sunny conditions, suggesting that these behaviours may be important when they are unable to thermoregulate by microhabitat selection. We concluded that fluctuations in air temperature can promote significant changes in the behaviour of titi monkeys and can impose important restrictions on mammals’ activities, even in tropical regions.     

The Good,the Bad,and the Ugly: Agonistic Behaviour in Juvenile Crocodilians

We examined agonistic behaviour in seven species of hatchling and juvenile crocodilians held in small groups (N = 4) under similar laboratory conditions. Agonistic interactions occurred in all seven species, typically involved two individuals, were short in duration (5–15 seconds), and occurred between 1600–2200 h in open water. The nature and extent of agonistic interactions, the behaviours displayed, and the level of conspecific tolerance varied among species. Discrete postures, non-contact and contact movements are described. Three of these were species-specific: push downs by C. johnstoni; inflated tail sweeping by C. novaeguineae; and, side head striking combined with tail wagging by C. porosus. The two long-snouted species (C. johnstoni and G. gangeticus) avoided contact involving the head and often raised the head up out of the way during agonistic interactions. Several behaviours not associated with aggression are also described, including snout rubbing, raising the head up high while at rest, and the use of vocalizations. The two most aggressive species (C. porosus, C. novaeguineae) appeared to form dominance hierarchies, whereas the less aggressive species did not. Interspecific differences in agonistic behaviour may reflect evolutionary divergence associated with morphology, ecology, general life history and responses to interspecific conflict in areas where multiple species have co-existed. Understanding species-specific traits in agonistic behaviour and social tolerance has implications for the controlled raising of different species of hatchlings for conservation, management or production purposes.     

Behaviour is not Reliably Inferred from End-Product Structure in Caddisflies

Many animals engage in elaborate behavioural sequences in order to build structures. The ‘end‐products’ (e.g., nests of birds, cases of caddisflies) of these behaviours have occasionally been used either to infer details of building behaviour or to infer that structures similar in appearance are constructed by similar behavioural sequences. However, behavioural information can be extrapolated from end‐products only if there is congruence between the end‐product structure and the animal's movements. Case building behaviour was studied in caddisflies (Trichoptera) to examine the relationship between end‐products and behaviour. We found examples of taxa that built similar structures using different behavioural patterns, and taxa that built different structures using similar behaviours, regardless of whether these taxa were closely or distantly related. These findings question the reliability of behavioural inferences based solely on details of their associated end‐products and suggest that end‐product structure should be removed from the definition of animal behaviour.     

Muting individual nestlings reduces parental foraging for the brood

Nestling birds use vocal and visual behaviours when soliciting food from parents. Such behaviours serve at least two discrete functions: (1) to induce parents to bring more food; and (2) to influence how food is allocated among brood members. Playback experiments have shown that vocalizations serve function 1. Do they also function to influence intrabrood allocation, as contemporary begging theory suggests, or is that governed chiefly by the nonvocal components of begging (neck stretching, gaping, jockeying for position within the nest)? We tested this hypothesis using a novel nonsurgical muting technique to decouple the vocal and visual components of begging in nestling red-winged blackbirds, Agelaius phoeniceus. Single chicks that were muted temporarily (1 h) continued to be fed at roughly the same rate as either the same individual prior to muting or sham-muted nestlings in the same brood. Parents reduced provisioning rates by increasing nest attentiveness in response to changes in the begging behaviour of the brood following treatment. These changes included less time spent begging (visual and vocal) accompanied by a reduction in the collective vocalizations of the brood. Our results suggest that vocalizations function primarily to regulate parental foraging rates, and visual begging displays function primarily to access food (competition).Copyright 2002 Published by Elsevier Science Ltd on behalf of The Association for the Study of Animal Behaviour     

Parasite-induced suppression of aggregation under predation risk in a freshwater amphipod: Sociality of infected amphipods

Recent findings suggest that grouping with conspecifics is part of the behavioural defences developed by amphipod crustaceans to face predation risk by fish. Amphipods commonly serve as intermediate hosts for trophically transmitted parasites. These parasites are known for their ability to alter intermediate host phenotype in a way that promotes predation by definitive hosts, where they reproduce. If aggregation in amphipods dilutes the risk to be preyed on by fish, then it may dilute the probability of transmission for the parasite using fish as definitive hosts. Using experimental infections, we tested whether infection with the fish acanthocephalan Pomphorhynchus laevis alters attraction to conspecifics in the amphipod intermediate host Gammarus pulex. We also measured G. pulex's activity and reaction to light to detect potential links between changes in aggregation and changes in other behaviours. The attraction to conspecifics in the presence of predator cue, a behaviour found in uninfected gammarids, was cancelled by the infection, while phototaxis was reversed and activity unchanged. We found no correlation between the three behaviours in infected amphipods, while activity and aggregation were negatively correlated in uninfected individuals after the detection of predation cue. The physiological causes and the adaptive value of aggregation suppression are discussed in the context of a multidimensional manipulation.     

Do functional demands associated with locomotor habitat,diet, and activity pattern drive skull shape evolution in musteloid carnivorans?

A major goal of evolutionary studies is to better understand how complex morphologies are related to the different functions and behaviours in which they are involved. For example, during locomotion and hunting behaviour, the head and the eyes have to stay at an appropriate level in order to reliably judge distance as well as to provide postural information. The morphology and orientation of the orbits and cranial base will have an impact on eye orientation. Consequently, variation in orbital and cranial base morphology is expected to be correlated with aspects of an animal's lifestyle. In this study, we investigate whether the shape of the skull evolves in response to the functional demands imposed by ecology and behaviour using geometric morphometric methods. We test if locomotor habitats, diet, and activity pattern influence the shape of the skull in musteloid carnivorans using (M)ANOVAs and phylogenetic (M)ANOVAs, and explore the functional correlates of morphological features in relation to locomotor habitats, diet, and activity pattern. Our results show that phylogeny, locomotion and, diet strongly influence the shape of the skull, whereas the activity pattern seems to have a weakest influence. We also show that the locomotor environment is highly integrated with foraging and feeding, which can lead to similar selective pressures and drive the evolution of skull shape in the same direction. Finally, we show similar responses to functional demands in musteloids, a super family of close related species, as are typically observed across all mammals suggesting the pervasiveness of these functional demands.     

Social interactions in kittiwake colonies: social facilitation and/or favourable social environment

A video study of social facilitation was carried out on a kittiwake, Rissa tridactyla, colony. For the analysis, the video sequences were divided into adjacent periods of 15 s. The temporal limits of each behaviour could thus be defined and its length taken into account. There were significant differences between the behaviour of neighbouring birds during the mating of a pair and that shown at other times. A comparison of the frequencies of behaviours shown by neighbouring birds during the two alternating stages of mating (Mounting and Copulation) permitted two kinds of behaviours, which differed during mating, to be distinguished. (1) The behaviours that differed between Copulation and Mounting reveal the reaction of the neighbouring birds to Copulation (but no evidence of social facilitation could be found). (2) The behaviours that differed only between Mating sequences (case sequences) and other sequences (control sequences) had probably started before the mating started. Consequently, the temporal clustering of activities in colonies may be due to the effect of particular behaviours which could favour the appearance of certain other behaviour. This mechanism (Favourable Social Environment) can act simultaneously with social facilitation. It raises the possibility that social environment may influence greatly the production of young in colonial birds.     

From Spontaneous Motor Activity to Coordinated Behaviour: A Developmental Model

In mammals, the developmental path that links the primary behaviours observed during foetal stages to the full fledged behaviours observed in adults is still beyond our understanding. Often theories of motor control try to deal with the process of incremental learning in an abstract and modular way without establishing any correspondence with the mammalian developmental stages. In this paper, we propose a computational model that links three distinct behaviours which appear at three different stages of development. In order of appearance, these behaviours are: spontaneous motor activity (SMA), reflexes, and coordinated behaviours, such as locomotion. The goal of our model is to address in silico four hypotheses that are currently hard to verify in vivo: First, the hypothesis that spinal reflex circuits can be self-organized from the sensor and motor activity induced by SMA. Second, the hypothesis that supraspinal systems can modulate reflex circuits to achieve coordinated behaviour. Third, the hypothesis that, since SMA is observed in an organism throughout its entire lifetime, it provides a mechanism suitable to maintain the reflex circuits aligned with the musculoskeletal system, and thus adapt to changes in body morphology. And fourth, the hypothesis that by changing the modulation of the reflex circuits over time, one can switch between different coordinated behaviours. Our model is tested in a simulated musculoskeletal leg actuated by six muscles arranged in a number of different ways. Hopping is used as a case study of coordinated behaviour. Our results show that reflex circuits can be self-organized from SMA, and that, once these circuits are in place, they can be modulated to achieve coordinated behaviour. In addition, our results show that our model can naturally adapt to different morphological changes and perform behavioural transitions.     

How experienced alpine-skiers cope with restrictions of ankle degrees-of-freedom when wearing ski-boots in postural exercises

The present study investigates the mechanisms underlying changes in postural strategy that occur to compensate for mechanical ankle joint restrictions induced by wearing ski-boots during postural exercises. Fourteen experienced skiers were asked to stand as still as possible in a stable (STA) posture and in 2 postures with instability in the medio/lateral and antero/posterior (ML and AP postures) direction. Postural tasks were performed with eyes open or closed and while wearing or not wearing ski-boots. The electromyographic (EMG) activity of representative lower limb muscles and positions of centre-of-foot pressure (COP) were recorded and analyzed. Our results illustrated enhanced postural performances with ski-boots in the STA posture, whereas postural performances remained unchanged when wearing ski-boots in the ML and AP postures. Analysis of COP sways in the frequency domain did not illustrate any modification in the contribution of different neuronal loops when the study subjects wore ski-boots. EMG showed that the mechanical effects of wearing ski-boots were compensated by changes in postural strategy through the reorganization of muscle coordination, made possible by inherent redundancies in the human body. The preservation of postural performances, despite restrictions of ankle degrees-of-freedom induced by ski-boots, emphasizes the subjects’ capacity to exploit the additional support provided by ski-boots by adequately adjusting muscle coordination to control posture in different balance conditions.     

Sleep in the herring gull (Larus argentatus)

Sleep postures and eye state of free-ranging herring gulls (Larus argentatus) were studied during the breeding season. Three mutually exclusive behaviours were observed, namely sleep, rest-sleep and rest postures. Arousal thresholds, eye blink rates and eye closure time were obtained during these behaviours. Significant relationships existed between eye blinking, eye closure, and a raised threshold of arousal when birds were in the sleep and rest-sleep postures. During a natural disturbance, birds in the sleep posture remained in this posture but did not blink their eyes: this is called pseudo sleep. Male gulls also exhibited a lower threshold of arousal while in the sleep posture compared with females. We conclude that rhythmic eye blinking is a good indication of sleep in herring gulls.     

Agonistic behaviour of juvenile gulls,a neuroethological study

The results relating to agonistic behaviour obtained during an exploration of the brain of juvenile herring and lesser black-backed gulls (Larus argentatus and fuscus) with electrical stimulation are reported. As an introduction the normal agonistic behaviour of immature gulls is described. While the flight and aggressive behaviour is largely unritualized the threat behaviour is more stereotyped. Three basic threat patterns are distinguished: the arched, hunched, and squat postures. The relationship of these juvenile agonistic patterns with adult courtship is considered. A large number of sites evoking fear behaviour were found, anatomically widely and incoherently distributed. It is demonstrated that the spontaneous fearfulness levels of individual subjects influences the likelihood of obtaining escape eliciting loci. Stimulation of a nubmer of these sites had an after-effect: a persistent, increased probability of escape behaviour. It seems likely that a proportion of the fear sequences elicited were secondary responses to evoked sensory hallucinations and forced small movements. None of the sites explored yielded outright attack behaviour. Thirteen sites yielded characteristic threat sequences. About half of them produced changes in ‘mood’ persisting for some 15 min. The sites were clustered in a paleostriatal-septal periventricular and an infundibular area. Histological differentiation of the neuroventricular interface at these areas is noted. Based on these it is argued that the secretion of ‘liquormones’ is responsible for the changes in ‘mood’ that followed stimulation.     

The Behaviour of Red Kangaroos (Megaleia rufa) on Hot Summer Days

To investigate the functional significance of the behaviour of large mammals in hot, arid conditions, field observations were made of the behaviour of red kangaroos. The behaviour of individual animals was recorded in detail during hot summer days and measurements of the prevailing temperature and radiation environment were made. Changes in the postures adopted by animals during the day are described in relation to environmental conditions; and the occurrence of certain postures and behaviours at periods of greatest heat stress is reported.     

Genetic composition of social groups influences male aggressive behaviour and fitness in natural genotypes of Drosophila melanogaster

Indirect genetic effects (IGEs) describe how an individual''s behaviour—which is influenced by his or her genotype—can affect the behaviours of interacting individuals. IGE research has focused on dyads. However, insights from social networks research, and other studies of group behaviour, suggest that dyadic interactions are affected by the behaviour of other individuals in the group. To extend IGE inferences to groups of three or more, IGEs must be considered from a group perspective. Here, I introduce the ‘focal interaction’ approach to study IGEs in groups. I illustrate the utility of this approach by studying aggression among natural genotypes of Drosophila melanogaster. I chose two natural genotypes as ‘focal interactants’: the behavioural interaction between them was the ‘focal interaction’. One male from each focal interactant genotype was present in every group, and I varied the genotype of the third male—the ‘treatment male’. Genetic variation in the treatment male''s aggressive behaviour influenced the focal interaction, demonstrating that IGEs in groups are not a straightforward extension of IGEs measured in dyads. Further, the focal interaction influenced male mating success, illustrating the role of IGEs in behavioural evolution. These results represent the first manipulative evidence for IGEs at the group level.     

Hunted Woolly Monkeys (Lagothrix poeppigii) Show Threat-Sensitive Responses to Human Presence

Responding only to individuals of a predator species which display threatening behaviour allows prey species to minimise energy expenditure and other costs of predator avoidance, such as disruption of feeding. The threat sensitivity hypothesis predicts such behaviour in prey species. If hunted animals are unable to distinguish dangerous humans from non-dangerous humans, human hunting is likely to have a greater effect on prey populations as all human encounters should lead to predator avoidance, increasing stress and creating opportunity costs for exploited populations. We test the threat sensitivity hypothesis in wild Poeppigi''s woolly monkeys (Lagothrix poeppigii) in Yasuní National Park, Ecuador, by presenting human models engaging in one of three behaviours “hunting”, “gathering” or “researching”. These experiments were conducted at two sites with differing hunting pressures. Visibility, movement and vocalisations were recorded and results from two sites showed that groups changed their behaviours after being exposed to humans, and did so in different ways depending on the behaviour of the human model. Results at the site with higher hunting pressure were consistent with predictions based on the threat sensitivity hypothesis. Although results at the site with lower hunting pressure were not consistent with the results at the site with higher hunting pressure, groups at this site also showed differential responses to different human behaviours. These results provide evidence of threat-sensitive predator avoidance in hunted primates, which may allow them to conserve both time and energy when encountering humans which pose no threat.