Predation: Prey plumage adaptation against falcon attack.

Several plumage types are found in feral pigeons (Columba livia), but one type imparts a clear survival advantage during attacks by the swiftest of all predators--the peregrine falcon (Falco peregrinus). Here we use quantitative field observations and experiments to demonstrate both the selective nature of the falcon's choice of prey and the effect of plumage coloration on the survival of feral pigeons. This plumage colour is an independently heritable trait that is likely to be an antipredator adaptation against high-speed attacks in open air space.

Issues in the classification of multimodal communication signals.

Communication involves complex behavior in multiple sensory channels, or "modalities." We provide an overview of multimodal communication and its costs and benefits, place examples of signals and displays from an array of taxa, sensory systems, and functions into our signal classification system, and consider issues surrounding the categorization of multimodal signals. The broadest level of classification is between signals with redundant and nonredundant components, with finer distinctions in each category. We recommend that researchers gather information on responses to each component of a multimodal signal as well as the response to the signal as a whole. We discuss the choice of categories, whether to categorize signals on the basis of the signal or the response, and how to classify signals if data are missing. The choice of behavioral assay may influence the outcome, as may the context of the communicative event. We also consider similarities and differences between multimodal and unimodal composite signals and signals that are sequentially, rather than simultaneously, multimodal.

Bird calls: their potential for behavioral neurobiology.

Birdsongs are always part of larger set of sound signals. Every bird uses a repertoire of calls for communication. Calls are shorter and simpler than songs, with a much larger range of functions. Whereas songs are specialized for application in reproduction and territoriality, calls also serve such functions as signaling about food, maintaining social cohesion, contact calls, synchronizing and coordinating flight, and the resolution of aggressive and sexual conflicts. Alarm calls of various kinds are a major component, including distress, mobbing, and hawk alarm calls. Call repertoires vary greatly in size, up to 20 or so distinct call types. Rough estimates for songbirds range between 5 and 10, but some birds, especially galliforms, may have twice as many. Call usage is often sexually dimorphic and commonly varies seasonally and with physiological state. Most calls appear to be innate, but more and more examples of developmental plasticity in bird calls are emerging. Some display well-defined local dialects. A case is made for the value to avian behavioral neurobiology of including bird calls in studies of the psychophysics and sensory physiology of signal perception. They may also help to extend the range of neurobiological investigations of the song system to include circuitry controlling such functionally related behaviors as aggression and reproduction.

The Umwelt and its relevance to animal communication: introduction to special issue.

This introduction applies J. von Uexküll's (1934/1957) concept of the Umwelt to the study of animal communication, particularly as it pertains to studies presented at a recent workshop on animal communication in the context of the environment. The environment is conceived broadly in the articles that follow, including the many physical and social environments in which an animal may find itself. The Umwelt concept is briefly expanded here to include also the personal microenvironment of the signaler in which the signal is embedded into the suite of concurrent nonsignaling behaviors of the individual. Other animals may even infer aspects of the signaler's own immediate Umwelt by noticing accompanying attentional cues such as the direction of eye gaze. In this way, part of the Umwelt can be accessible to companions, facilitating the communication process.

Dialects in wild chimpanzees?

Chimpanzees emit a loud, species-typical long distance call known as the pant hoot. Geographic variation between the pant hoots of chimpanzees living in two neighboring populations, the Mahale Mountains and Gombe Stream National Parks, Tanzania, was examined. Analysis of six acoustic features revealed subtle differences in the way chimpanzees from the two populations called. Individuals from the Mahale study site uttered one section of their pant hoots at a faster rate and with shorter elements than animals from Gombe Stream. In addition, individuals at Mahale delivered broader-band, higher pitched "climax" elements than males from Gombe. While genetic factors, anatomical differences, variations in the use of calls at the two sites, and changes in calling over time may account for the variability between populations, we suggest the additional possibility that differences in pant hooting may be due to learning. © 1992 Wiley-Liss, Inc.

Ethology and the origins of behavioral endocrinology.

The neurosciences embrace many disciplines, some long established, others of more recent origin. Behavioral endocrinology has only recently been fully acknowledged as a branch of neuroscience, distinctive for the determination of some of its exponents to remain integrative in the face of the many pressures towards reductionism that so dominate modern biology. One of its most characteristic features is a commitment to research at the whole-animal level on the physiological basis of complex behaviors, with a particular but by no means exclusive focus on reproductive behavior in all its aspects. The search for rigorously defined principles of behavioral organization that apply across species and the hormonal and neural mechanisms that sustain them underlies much of the research. Their aims are much like those put forth in the classical ethology of Lorenz and Tinbergen, one of the roots from which behavioral endocrinology has sprung. But there are others that can be traced back a century or more. Antecedents can be found in the work of such pioneers as Jakob von Uexküll, Jacques Loeb, Herbert Spencer Jennings, and particularly Charles Otis Whitman who launched a tradition that culminated in the classical contributions of Robert Hinde and Daniel Lehrman. William C. Young was another pioneer. His studies revolutionized thinking about the physiological mechanisms by which hormones influence behavior. An earlier potent influence was Karl Lashley who helped to shape the career of Frank Ambrose Beach who, more than anyone, has played a leading role in launching this new field.

Do responses of galliform birds vary adaptively with predator size?

Past studies of galliform anti-predator behavior show that they discriminate between aerial and ground predators, producing distinctive, functionally referential vocalizations to each class. Within the category of aerial predators, however, studies using overhead models, video images and observations of natural encounters with birds of prey report little evidence that galliforms discriminate between different raptor species. This pattern suggests that the aerial alarm response may be triggered by general features of objects moving in the air. To test whether these birds are also sensitive to more detailed differences between raptor species, adult chickens with young were presented with variously sized trained raptors (small, intermediate, large) under controlled conditions. In response to the small hawk, there was a decline in anti-predator aggression and in aerial alarm calling as the young grew older and less vulnerable to attack by a hawk of this size. During the same developmental period, responses to the largest hawk, which posed the smallest threat to the young at all stages, did not change; there were intermediate changes at this time in response to the middle-sized hawk. Thus the anti-predator behavior of the adult birds varied in an adaptive fashion, changing as a function of both chick age and risk. We discuss these results in light of current issues concerning the cognitive mechanisms underlying alarm calling behavior in animals.

Innateness and the instinct to learn.

Concepts of innateness were at the heart of Darwin's approach to behavior and central to the ethological theorizing of Lorenz and, at least to start with, of Tinbergen. Then Tinbergen did an about face, and for some twenty years the term 'innate' became highly suspect. He attributed the change to Lehrman's famous 1953 critique in which he asserted that classifying behaviors as innate tells us nothing about how they develop. Although Lehrman made many valid points, I will argue that this exchange also led to profound misunderstandings that were ultimately damaging to progress in research on the development of behavior. The concept of 'instincts to learn', receiving renewed support from current theorizing among geneticists about phenotypic plasticity, provides a potential resolution of some of the controversies that Lehrman created. Bioacoustical studies, particularly on song learning in birds, serve both to confirm some of Lehrman's anxieties about the term 'innate', but also to make a case that he threw out the genetic baby with the bathwater. The breathtaking progress in molecular and developmental genetics has prepared the way for a fuller understanding of the complexities underlying even the simplest notions of innate behavior, necessary before we can begin to comprehend the ontogeny of behavior.

Innateness and the instinct to learn

O conceito de inato estava no cerne da abordagem de Darwin ao comportamento assim como no das teorias etológicas de Lorenz e, pelo menos inicialmente, de Tinbergen. Depois, Tinbergen deu uma reviravolta e, durante mais ou menos vinte anos, o termo "inato" tornou-se altamente suspeito. Tinbergen atribuiu sua mudança à famosa crítica de Lehrman, em 1953, segundo a qual classificar comportamentos como inatos não traz informação alguma a respeito de seu desenvolvimento. Embora muitas das críticas de Lehrman sejam relevantes, tentarei mostrar que a mudança de enfoque também gerou sérios equívocos que acabaram prejudicando o progresso da pesquisa sobre o desenvolvimento do comportamento. O conceito de "instintos para aprender", reforçado por teorias recentes de geneticistas a respeito da plasticidade fenotípica, abre um caminho para a superação de algumas das controvérsias que Lehrman originou. Estudos em bioacústica, em particular sobre a aprendizagem do canto em aves, confirmam alguns dos temores de Lehrman a respeito do termo "inato", mas também mostram que ele restringiu, sem discernimento, a relevância da determinação genética. O progresso espetacular da genética molecular e da genética do desenvolvimento fornece a base para uma melhor apreensão da complexidade existente até nas noçäes mais simples de comportamento inato, o que é necessário para que possamos entender a ontogênese do comportamento.