Brood parasitism by cowbirds: risks and effects on reproductive success and survival in indigo buntings

We observed brood parasitism by brown-beaded cowbirds (Molothrusater) on indigo buntings (Passerina cyanea) and estimated dieimpact of parasitism on the success of the individual buntingsin their current nests and in their future survival and reproduction.Rates of parasitism over 8 years were 26.6% in 1040 nests and19.8% in 693 nests in two areas in southern Michigan. Risk ofparasitism was high early in the season; half the bunting nestswere begun after the end of the cowbird season. Risk was independentof female age, plant containing the nest, or habitat The immediatecost of parasitism was 1.19 and 1.26 fewer buntings fledgedper nest. Bunting success was lower in parasitized nests withcowbird eggs (nests were more likely to be deserted or predated),lower when the cowbird nestling failed (nests were more likelyto be predated), and lower when the cowbird fledged (fewer buntingsfledged) compared to nonparasitized nests. Costs were due toremoval of a bunting egg when die cowbird laid its own egg andto competition for parental care of the cowbird and buntingnestlings. Buntings that fledged from nests where a cowbirdalso fledged were only 18% as likely to survive and return totheir natal area in the next year as buntings from nests wherea cowbird did not fledge. Long-term effects of cowbird parasitismon adult breeding later in the season, survival to the nextseason, and reproductive success in the next season were negligiblewhen compared between birds that reared a cowbird and birdsthat reared only a bunting brood, or between birds that wereparasitized and birds that escaped parasitism. The results indicatelittle long-term cost of brood parasitism on individual fitnessof adult buntings beyond the impact on the current nest andthe survival of buntings that fledge from it; nearly all costis to the parasitized brood.     

Song learning and deceptive mimicry

Payne, 1978, Payne, 1981a, Payne, 1981b has suggested that young males of some bird species copy the songs of the previous occupant or the songs of local established males when setting up a territory and thereby increase their likelihood of success. According to this view, song copying is a form of deceptive mimicry. We show that first-year great tits do not share more songs than expected with the previous occupants of their territories, nor are shared songs used more often than other songs in their repertoires. Songs are shared with neighbours but not selectively with established neighbours and there is no difference in reproductive success between great tits sharing with established neighbours and with first-year neighbours. We discuss the general applicability of the deceptive mimicry hypothesis and suggest that song sharing between neighbours may be advantageous for reasons other than deceptive mimicry.     

Sensitive phases for song learning: Effects of social interaction and individual variation

Male marsh wrens (Cistothorus palustris) do not ordinarily learn songs from tutor tapes during their first spring, but in two experiments all five males given an opportunity to learn from a live the timing and significance of events in nature. There was marked individual variation in the responses of subjects to seemingly identical laboratory conditions; such differences among individuals are unexplainable but intriguing and warrant further study as more than mere ‘experimental noise’.     

Age-dependent social learning in a lizard

Evidence of social learning, whereby the actions of an animal facilitate the acquisition of new information by another, is taxonomically biased towards mammals, especially primates, and birds. However, social learning need not be limited to group-living animals because species with less interaction can still benefit from learning about potential predators, food sources, rivals and mates. We trained male skinks (Eulamprus quoyii), a mostly solitary lizard from eastern Australia, in a two-step foraging task. Lizards belonging to ‘young’ and ‘old’ age classes were presented with a novel instrumental task (displacing a lid) and an association task (reward under blue lid). We did not find evidence for age-dependent learning of the instrumental task; however, young males in the presence of a demonstrator learnt the association task faster than young males without a demonstrator, whereas old males in both treatments had similar success rates. We present the first evidence of age-dependent social learning in a lizard and suggest that the use of social information for learning may be more widespread than previously believed.     

Threshold learning dynamics in social networks

Social learning is defined as the ability of a population to aggregate information, a process which must crucially depend on the mechanisms of social interaction. Consumers choosing which product to buy, or voters deciding which option to take with respect to an important issue, typically confront external signals to the information gathered from their contacts. Economic models typically predict that correct social learning occurs in large populations unless some individuals display unbounded influence. We challenge this conclusion by showing that an intuitive threshold process of individual adjustment does not always lead to such social learning. We find, specifically, that three generic regimes exist separated by sharp discontinuous transitions. And only in one of them, where the threshold is within a suitable intermediate range, the population learns the correct information. In the other two, where the threshold is either too high or too low, the system either freezes or enters into persistent flux, respectively. These regimes are generally observed in different social networks (both complex or regular), but limited interaction is found to promote correct learning by enlarging the parameter region where it occurs.     

Song learning: the interface between behaviour and neuroethology

The high degree of developmental plasticity displayed by the songs of oscine birds makes them appropriate subjects for research on the etiology and neurobiology of vocal learning. Strong individual differences and learned local dialects are common. The readiness to acquire new songs appears to persist throughout life in some species and is restricted to relatively short sensitive periods in others. Learning can occur with remarkably few exposures to song. Mimicry of other species occurs but, given a choice, there is a tendency to favour conspecific songs. Evidence is presented for two kinds of vocal learning, one 'memory-based', the other 'action-based.' Subsong and 'plastic song' phases of motor development appear to be obligatory steps in the ontogeny of learned songs. A case is made that acquisition and production should be viewed as distinct phenomena with different physiological correlates. Research on behavioural development is closely associated with studies of the physiology of development. The two are mutually synergistic, and the synergism is well displayed in research on song learning in birds. This review of some of the characteristics of avian vocal learning as derived from behavioural studies, indicates lacunae in our knowledge about the ethology of song learning, and suggests how the comparative study of vocal development can pave the way for new insights into the underlying neurobiology.     

鸣禽前脑基底神经节X区与语言学习

成年鸣禽鸣唱语句的形成和维持依赖于听觉反馈。X区是鸣禽前脑回路的一个重要核团,对鸣禽的发声学习和语言结构的稳定有重要作用。X区在解剖结构、电生理学以及神经化学等方面的特性与哺乳类基底神经节极为相似。对鸣禽前脑X区的研究有助于揭示人类语言学习的中枢机制。本文对近年来鸣禽X区的相关研究进展,包括鸣禽X区的结构特征、电生理特性及神经化学特征予以阐述。     

Song learning in birds: the relation between perception and production

The vocal control system of oscine songbirds has some perplexing properties--e.g. laterality, adult neurogenesis, neuronal replacement--that are not predicted by common views of how vocal learning takes place. Similarly, we do not understand the relation between the direct pathway for the control of learned song and the recursive pathway necessary for song learning. Some of the paradoxes of the vocal system of birds may disappear once the relation between the perception and production of learned vocalizations is better understood. To some extent, perception and production may be two closely related states of a same system.     

Beyond learning fixed rules and social cues: abstraction in the social arena

Abstraction is a central idea in many areas of physical comparative cognition such as categorization, numerical competence or problem solving. This idea, however, has rarely been applied to comparative social cognition. In this paper, I propose that the notion of abstraction can be applied to the social arena and become an important tool to investigate the social cognition and behaviour processes in animals. To make this point, I present recent evidence showing that chimpanzees know about what others can see and about what others intend. These data do not fit either low-level mechanisms based on stimulus-response associations or high-level explanations based on metarepresentational mechanisms such as false belief attribution. Instead, I argue that social abstraction, in particular the development of concepts such as seeing in others, is key to explaining the behaviour of our closest relative in a variety of situations.     

Rapid evolution of social learning

Culture is widely thought to be beneficial when social learning is less costly than individual learning and thus may explain the enormous ecological success of humans. Rogers (1988. Does biology constrain culture. Am. Anthropol.  90 : 819–831) contradicted this common view by showing that the evolution of social learning does not necessarily increase the net benefits of learned behaviours in a variable environment. Using simulation experiments, we re‐analysed extensions of Rogers’ model after relaxing the assumption that genetic evolution is much slower than cultural evolution. Our results show that this assumption is crucial for Rogers’ finding. For many parameter settings, genetic and cultural evolution occur on the same time scale, and feedback effects between genetic and cultural dynamics increase the net benefits. Thus, by avoiding the costs of individual learning, social learning can increase ecological success. Furthermore, we found that rapid evolution can limit the evolution of complex social learning strategies, which have been proposed to be widespread in animals.     

Song learning in domesticated canaries in a restricted acoustic environment

Many songbirds learn their songs early in life from a song model. In the absence of such a model, they develop an improvised song that often lacks the species-typical song structure. Open-ended learners, such as the domesticated canary, are able to modify their songs in adulthood, although the mechanisms that guide and time the song-learning process are still not fully understood. In a previous study, we showed that male domesticated canaries lacking an adult song model in their first year substantially change their song repertoire and composition when exposed to normally reared conspecifics in their second year. Here, we investigate song development in descendants of canaries that were raised and kept as a peer group without a song model. Such males represent tutors with abnormal song characteristics. Interestingly, the F₁ generation developed quite normal song structure, and when brought into an environment with normally raised canaries in their second year, they did not modify their songs substantially. These results suggest that contact with an adult song model early in life is crucial for song crystallization, but also that song development is at least partly guided by innate rules. They also question the existing classification of canaries as open-ended learners.     

Neural mechanisms of social learning and decision-making

One of the hallmarks of human society is the ubiquitous interactions among individuals. Indeed, a significant portion of human daily routine decision making is socially related. Normative economic theory, namely game theory, has prescribed the canonical decision strategy when "rational" social agents have full information about the decision environment. In reality, however, social decision is often influenced by the trait and state parameters of selves and others. Therefore, understanding the cognitive and neural processes of inferring the decision parameters is pivotal for social decision making. Recently, both correlational and causal non-invasive neuroimaging studies have started to reveal the critical neural computations underlying social learning and decision-making, and highlighted the unique roles of "social" brain structures such as temporal-parietal junction(TPJ) and dorsomedial prefrontal cortex(dmPFC). Here we review recent advances in social decision neuroscience and maintain the focus on how the inference about others is dynamically acquired during social learning, as well as how the prosocial(altruistic)behavior results from orchestrated interactions of different brain regions specified under the social utility framework. We conclude by emphasizing the importance of combining computational decision theory with the identification of neural mechanisms that represent, evaluate and integrate value related social information and generate decision variables guiding behavioral output in the complex social environment.     

Interaction between individual experience and social learning in dogs

We investigated the interaction between individual experience and social learning in domestic dogs,Canis familiaris . We conducted two experiments using detour tests, where an object or food was placed behind a transparent, V-shaped wire-mesh fence, such that the dogs could get the reward by going around the fence. In some groups, two open doors were offered as an alternative, easier way to reach the reward. In experiment 1 we opened the doors only in trial 1, then closed them for trials 2 and 3. In experiment 2 other dogs were first taught to detour the fence with closed doors after they had observed a detouring human demonstrator, then we opened the doors for three subsequent trials. In experiment 1 all dogs reached the reward by going through the doors in trial 1, but their detouring performance was poor after the doors had been closed, if they had to solve the task on their own. However, dogs in the experimental group that were allowed to watch a detouring human demonstrator after the doors had been closed showed improved detouring ability compared with those that did not receive a demonstration of detouring. In experiment 2 the dogs tended to keep on detouring along the fence even if the doors had been opened, giving up a chance to get behind the fence by a shorter route. These results show that dogs can use information gained by observing a human demonstrator to overcome their own mistakenly preferred solution in a problem situation. In a reversed situation social learning can also contribute to a preference for a less adaptive behaviour. However, only repeated individual and social experience leads to a durable manifestation of maladaptive behaviour. Copyright 2003 Published by Elsevier Science Ltd on behalf of The Association for the Study of Animal Behaviour.      

Operant cycles and imitational learning in a social setting

The provisioning of a communally-maintained group of rhesus monkeys with operant procedures reveals the following: (1) the temporal interaction of the daily work cycles for several discrete reinforcers; (2) the interaction of these cycles with other patterns of social activity; (3) the independent acquisition of operant schedules by animals recently born to the group and of new schedules by all members of the group.     

Mate familiarity and social learning in a monogamous lizard

Oecologia - Social learning is thought to be advantageous as it allows an animal to gather information quickly without engaging in costly trial-and-error learning. However, animals should be...