Laurence Henry

Song Sharing Reflects the Social-Organization in a Captive Group of European Starlings (sturnus-Vulgaris)

The social organization of captive groups of adult male and female starlings caught in different localities was studied to understand the possible social basis of song sharing. In the nonbreeding season, the social organization was based on within-sex groups or pairs and a few intersexual pairs. The pattern of song sharing clearly reflected the social organization. Members of the social pairs of females shared most of their songs, whereas males shared songs with other males to an extent that depended on their degree of social association. Song sharing was mostly restricted to birds of the same sex. The ability for adult vocal plasticity in both males and females may reflect the variety of possible social situations in this species.

Direct social contacts override auditory information in the song-learning process in starlings (Sturnus vulgaris).

Social influence on song acquisition was studied in 3 groups of young European starlings raised under different social conditions but with the same auditory experience of adult song. Attentional focusing on preferred partners appears the most likely explanation for differences found in song acquisition in relation to experience, sex, and song categories. Thus, pair-isolated birds learned from each other and not from broadcast live songs, females did not learn from the adult male tutors, and sharing occurred more between socially associated peers. On the contrary, single-isolated birds clearly copied the adult songs that may have been the only source of attention stimulation. Therefore, social preference appears as both a motor for song learning and a potential obstacle for acquisition from nonpreferred partners, including adults.

Experience-dependent neuronal specialization and functional organization in the central auditory area of a songbird

The effect of early experience on brain development was investigated in the central auditory area of a songbird, the field L complex, which is analogous to the mammalian auditory cortex. Multi‐unit recordings of auditory responses in the field L complex of adult starlings raised without any experience of adult song during development provide strong evidence of developmental plasticity both in the neuronal responses and in the functional organization of this area. Across the entire area, experimental birds, separated from adults from the age of 1 week old until they were 2 years old, had a much larger number of neurons that responded to all the stimuli than did control birds. The well‐known tonotopy demonstrated in adult wild birds using the same procedure was altered. This study is the first to bring evidence of developmental plasticity in the organization of the central auditory areas in songbirds. These results are discussed in relation to other reports on effects of early experience on brain development.

Social experience influences the development of a central auditory area

Vocal communication develops under social influences that can enhance attention, an important factor in memory formation and perceptual tuning. In songbirds, social conditions can delay sensitive periods of development, overcome learning inhibitions and enable exceptional learning or induce selective learning. However, we do not know how social conditions influence auditory processing in the brain. In the present study, we raised young naive starlings under different social conditions but with the same auditory experience of adult songs, and we compared the effects of these different conditions on the development of the auditory cortex analogue. Several features appeared to be influenced by the social experience, among which the proportion of auditory neuronal sites and the neuronal selectivity. Both physical and social isolation from adult models altered the development of the auditory area in parallel to alterations in vocal development. To our knowledge, this is the first evidence that social deprivation has as much influence on neuronal responsiveness as sensory deprivation.

The use of song repertoire changes with pairing status in male European starling

The experimental removal of the females from 5 breeding pairs of starlings caused the males to change both the quantity and quality of song when compared with 6 unmanipulated control pairs. The increase in the duration and commonness of warbling song after mate removal supports the idea that this type of song functions as mate attraction and stimulation. In contrast, the species-specific whistled songs are more important after pairing, which supports the idea that they are more involved in male-male interactions.

Linking social and vocal brains: could social segregation prevent a proper development of a central auditory area in a female songbird?

Direct social contact and social interaction affect speech development in human infants and are required in order to maintain perceptual abilities; however the processes involved are still poorly known. In the present study, we tested the hypothesis that social segregation during development would prevent the proper development of a central auditory area, using a “classical” animal model of vocal development, a songbird. Based on our knowledge of European starling, we raised young female starlings with peers and only adult male tutors. This ensured that female would show neither social bond with nor vocal copying from males. Electrophysiological recordings performed when these females were adult revealed perceptual abnormalities: they presented a larger auditory area, a lower proportion of specialized neurons and a larger proportion of generalist sites than wild-caught females, whereas these characteristics were similar to those observed in socially deprived (physically separated) females. These results confirmed and added to earlier results for males, suggesting that the degree of perceptual deficiency reflects the degree of social separation. To our knowledge, this report constitutes the first evidence that social segregation can, as much as physical separation, alter the development of a central auditory area.

Adult: young ratio influences song acquisition in female European starlings (Sturnus vulgaris).

One parallel between humans and most songbirds is the fact that young require social interactions with an adult to acquire specific vocalizations. Songbirds are considered good models for comparative studies, although reports to date concern almost exclusively male songbirds. In addition, adult influence on vocal communication is generally investigated only in restricted social contexts (usually dyads). Here, the authors analyzed song learning and spatial associations among young female starlings that were maintained for 1 year in dyads (1 adult, 1 young), triads (2 adults, 1 young) or a larger group (7 young, 2 adults). Segregation by age was seen in the triads and in the larger group. The influence of adults (proportion of songs copied from adults) decreased as the young adult ratio increased. Unusual temporal features were observed in young maintained in triads and young neglected copying adult songs in the presence of peers. These results are among the first to explore the circumstances under which females learn and from whom they learn. They also add new insight to a wide range of questions about social influences on learning.

Dialects in Animals: Evidence, Development and Potential Functions

Dialects are one of the parallels that have long been established between human language and animal communication. Here we will describe the different forms of “dialects” discovered in animals and discuss some potential functional parallels between human and animal dialects, arguing that in both cases different mechanisms and functions may be at stake where large geographical versus very localized (e.g. social) variations are concerned. Birdsong studies in particular, but also recent studies of mammal vocalizations, show that the use of the term “dialect” to refer to within-species vocal variations in animal species is more than a metaphor and that animal dialects offer a possibility to explore the causes and functions of linguistic variation and change. We present here an original view, as our approach is not “primate-centered”, and takes into consideration “homoplasy” (analogy) as a potential mechanism to explain that different taxa have evolved the same functional response to social constraints. We will develop an integrative view of animal dialects through birdsong studies where ontogeny, causality (brain processes), functions and evolution are considered in a common framework.

Sexing Adult Pale-Winged Starlings Using Morphometric and Discriminant Function Analysis.

Accurate sexing of birds is vital for behavioral studies but can be a real problem in the field, especially for monomorphic species. Our goal here was to characterize the morphology of male and female monomorphic pale-winged starlings (Onychognathus nabouroup), a South African sturnid whose plumage is sexually monomorphic. Morphological measurements of genetically sexed animals indicated that males were statistically larger than females for five measurements: Mass, tail length, tarsus length and wing length. By using a Discriminant Function Analysis based on the measurements taken by one ringer, we were able to predict correctly the sex of 81.10% of the birds of data collected in the field and 77.9% of museum skins independently of year of capture and ringer. The model developed here should be useful for further field studies of this species.

The timing of moult in males and females of the monomorphic Pale-winged Starling Onychognathus nabouroup

Pale-winged Starlings Onychognathus nabouroup inhabit the arid western interior of southern Africa and moult—breeding overlap may occur. We collected field data in two successive years on the moult of individual birds, whose sex was confirmed by genetic techniques. Small samples revealed a non-significant tendency for the moult of females in the early stages of wing moult to be more advanced than that of males in both years, but also clear evidence that the starting date of moult differed in the two years. In this species the moult schedule may thus be variable at both the individual and the population levels.