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A new and comparatively inexpensive system for producing sonograms - The Stortfield Sonogram System - is introduced with the assistance of the designer Ian Anderson. It comprises an 8 bit analog-to-digital converter on an IBM PC compatible card and sound analysis software supplied on a floppy disk. A continuous real time display of amplitude or frequency is provided, and print-outs can be obtained in conventional or 3-D format. Sound samples may be saved on disk for repeated analysis. 1ts potential is illustrated with sounds of European and African birds.

During social interactions, Mongolian gerbils Meriones unguiculatus emit sexually dimorphic, ultrasonic vocalisations. The calls can be broadly classified into physical structures of three types: frequency upsweep, modulated and unmodulated vocalisations. In the present laboratory study characterising ultrasound production in prepubertal gerbils of different ages, we found that: a) a wider range of structural types of sound are made by juvenile groups than adults: b) juvenile females show greater range and rate of emission than males; and c) androgen treatment of neonatal females defeminizes the range and rate of calling. We suggest that during male development androgen influences the speed of maturation of the vocal system.

Emperor Penguins Aptendodytes forsteri are able to add a sequence of syllables into their song. The proportion of songs having an additional sequence varies through the breeding season. The proportion of songs having an additional sequence increases because the percentage of one-sequence songs decreases and the percentage of three-sequence songs increases. Short songs were more inclined to be lengthened by an additional sequence: at the minimal percentage of one-sequence songs is more quickly attained than the maximal percentage of three-sequence songs; b) the proportion of lengthened one-sequence songs is three times higher than the proportion of lengthened two-sequence songs; e) twenty-one birds singing short and long variants have been recorded: 20 of them sang short variants whose duration was shorter than the mean measured for the population. The sound pressure level varies through the breeding season. Conclusion: Redundancy by an additional sequence found in songs of emperor penguins may be the result of the increase of the ambient noise level of the colony.

Sounds are captured using a sampling interface operating on 8 bits at a frequency from 3 to 48 kiloHertz. During sampling, the signal - as an amplitude envelope - scrolls across the screen in real time so that you can choose exactly the part you want. A signal processor would be needed to obtain a scrolling sonogram. The programme is written in Assembler language and operates with the user interface of the Amiga (commands by icons and menus). Thus it is rapid and very easy to use. The sonograms are obtained using a Fast Fourier Transform in which the number of significant points and the unit of scrolling can be changed. The width to length relationship is similar to that of the Kay analyser. Sections across the sonogram can be made, measured and stored, as can be whole sonograms, with a view to statistical analysis.

Temporally coded acoustic signals of rejection and attraction have been studied in various zoological groups from Insects to Mammals. For a given species, the comparison between the two types of signals shows that the rhythm of the "rejection signals'' is slower and more irregular than that of the "attraction signals''. In addition, in related species the signals of attraction are more differentiated than the signals of rejection. An interpretation of a functional nature has been suggested.

Kent (1987) has shown that the chick can discriminate between its own mother and an alien hen on the basis of the hen's maternal cluck vocalization. When the cluck of the hen was examined using a sonograph it was found that there was considerable variation in the clucks produced by different hens. However the clucks remained constant in structure over time (Kent 1989). Thus the cluck is ideal for individual recognition of the mother hen by the chick. References: Kent, J.P. (1987). Behaviour, 102, 1-14; Kent, J.P. (1989). Behaviour, 108, 1-19.

British bat species show a wide range of echolocation behaviour and foraging tactics. Some species, like those of the genus Rhinolophus, use long constant-frequency (CF) components in their calls and hunt among clutter. Myotis daubentoni uses steep frequency-modulated (FM) cries and frequently gaffs prey from the water surface. Nyctalus noctula uses different calls containing both CF and FM segments according to the ecological situation. By using direct observation, multiple-flash stereophotogrammetry and recording of echolocation calls, some of the link: between flight morphology, foraging behaviour and echolocation in British bats have been elucidated.

Part 1: Organisation. Starlings have two categories of song: whistled and warbling song. We describe first the structure and organisation of the warbling song of individual birds from widely separated geographic origins. In all of these the warbling category is seen to be an extremely complex performance which includes strongly contrasting note types and even simultaneous production of very different notes. In the next level of organisation the notes are grouped into units, the motifs, each of which is sung from 1 to 12 times before the bird goes on to the next. Finally these motif groups are arranged in a definite sequence, although not every motif is present in each song. Songs are long, ranging from 30 to 50 seconds in duration. Warbling is an essentially individual performance in that, except for 2 or 3 species-specific motif types, the others are all characteristic of an individual bird. The beginnings and endings of the songs are clearly defined, the sequences opening usually with an individual motif type and closing with a species-specific one. There are large differences between individuals in the size of the repertoire which may extend from about 20 to more than 35 motif types. Part 2: Year to year changes. Further to these general studies, birds in a starling colony have been observed over a period of two years to determine whether the song structure of a given individual changes with time. The age and reproductive status were taken into account. The changes observed differed according to whether they were songs characteristic of an individual bird that were considered or whether they were of the species-specific type. No modifications in the structure of the species-specific whistles were observed from one year to the next, whereas each bird totally renewed its repertoire of individual whistle types. The changes in the warbling song depended on the age of the bird: a very young individual totally renewed its repertoire from one year to the next, whereas others added only new motif types to their repertoire. These results show that even o1d individuals can acquire new song elements.

Four types of vocalizations uttered by the nocturnal Lizard Gekko gecko (the "Tokay'') are described. A bark of intimidation, distress calls, a short not very intense call, apparently related to sexual inter-action, and a long, complex sequence. This "long sequence'' is considered as a territorial proclamation which functions also as a mating-call. This call has been analysed in detail with special emphasis on the intra-individual variations. The mean duration of this sequence is 22.3 s, the intensity is 70 do at lm and the maximum of energy is between 300 and 400 Hz. This sequence is composed of three phases. The first one consists of several "roulades'', the second, of bi-motifs which sound like two syllables tok-kay, and the third, not always present, is a kind of "rattle''. The number of motifs and the occurrence of the 3rd phase vary in the sequence of an individual, but the duration of the motifs is relatively stable.

After a short description of the repertoire of the species (including the purr-call, the chatter-call and the distress-call of both males and females), the paper focuses on the behavioural significance and functions of the vocalizations. These were deduced from play-back experiments (some data comes from the literature). The purr-call appears to be principally a sexual signal (given only by males), acting as a pre-mating isolating mechanism; the chatter-call, given by both sexes, acts mostly as a territorial signal (including also individual recognition, an aspect which is not detailed in the present study). Particular attention is given to variations between and within populations (Mediterranean and Atlantic colonies). There are both micro- and macro-geographic variations (on the purr-call only). Play-back tests show that birds do recognize calls from their own geographic origin. It is suggested that there is a biological function of the macro-geographic variation in calls (although morphometric studies did not reveal this fact) and that it may have consequences on species-specific recognition. The potential importance of such a mechanism is stressed for speciation process.