birds

Shelduck calls are sexually dimorphic. Calls of males are high-pitched and whistling, whereas female calls sound deep and croaking. Males have different call types; in females 7 call types are known. According to preliminary observations, both males and females react specifically to calls of their partners. Individual call differences can be heard also by man. This paper aims at finding parameters of individuality, as revealed by sonograms, in the male trill-call. 1. Candidate cues for individual recognition should be (a) variable between individuals and (b) constant within individuals. 'lndividuality Index' we call the relation between average individual variation coefficient and total variation coefficient of one character in the population under study. 2. For individual recognition, the receiver could make use of several parameters. Sheldrake trill calls are individually different. Different parameters are the form of the first element and presence/absence of secondary elements. Duration and highest frequency of the calls have not been demonstrated to be reliable individual cues.

In Shelducks, as in all Anatidae species, duckling calls are uniform in both sexes. However, adults show great sexual dimorphism in vocalizations. The objective of this study is to discover how differences in male and female repertoire develop. Are duckllng vocalisations used for metamorphosis or are new calls introduced? 29 ducklings were hand-reared in different groups, and additional data from wild and captive families was also sampled. Sound recordings were analysed by sonograph. Duckling repertoire consists of 5 call types in both sexes. In females call pitch is rising until day 6, then continually falls to a minimum around day 70. The amount of noise structures in the calls increases remarkably from day 40 onwards ('voice break'). Duckling element structures partly remain recognizable. Adult calls are fully developed at 80 days of age. Female repertoire consists of low-pitched rolling or quacking sounds. ' In males call pitch rises and falls as in females. Some noise structures appear but voice break is hidden behind a 'mute phase'. In the course of further development juvenile type elements reappear. New notes are inserted between them to form the 'tyu-tyu' call. At 5 months of age, 2 different types of trills are created by high speed repetition of 'tyu' calls. Adult male repertoire is fully developed at 8 months of age and consists entirely of pure tonal whistles. To summarise: Female calls are developed straight from juvenile repertoire by lowering of pitch and an increasing amount of noise structures. Male call development first follows the female path. Later new elements appear and new call types (trills) are created. Male calls undergo a longer lasting secondary development.

Der Schilfrohrsänger zählt zu den Rohrsängerarten, bei denen gesangsaktive Männchen ihren Gesang nicht nur von Singwarten sondern auch in auffälligen Singflugen vortragen. Das Gesangsverhalten wurde untersucht sowie eine akustische Analyse des Gesangs durchgefuhrt. Grunde fur die Entwicklung eines Singfluges werden aufgrund der akustischen Befunde diskutiert.

Canary Islands blue tits are currently subdivided into four subspecies by means of morphological characters: P.c. degener (Lanzarote, Fuerteventura), P.c. teneriffae (Gran Canaria, Tenerife, Gomera), P.c.. ombriosus (Hierro), and P.c. palmensis (La Palma). The territorial songs differ between the various island populations. Those differences do not always parallel the recent division into the four subspecies as shown by play-back experiments. Songs of all subspecies have been played to most of different island populations. The experiments indicate that there have been two major colonization waves of blue tits to the Canarian Archipelago. The easternmost island Lanzarote and Fuerteventura seem to be colonized independently from each other. Starting from Lanzarote, two colonization waves can be recognized: one directly to La Palma, the other via Gran Canaria, Tenerife, and Gomera to El Hierro. It is still open to question if La Palma might have been colonized directly from the African mainland.

Since 1977 a new population of the scarlet rosefinch Carpodacus erythrinus was established in typical alpine bog habitat in southern Bavaria near Garmisch-Partenkirchen. Research on phenology, ecology and breeding biology was done by the Institute of Ornithology, Garmish-Partenkirchen. In addition, we studied the acoustic behaviour of this population. During the whole season of 1989 we controlled the complete population in three adjacent bogs. Nearly 30 males-most of them individually colour-ringed-were tape-recorded on several days and times of day in various behavioural contexts. Also playback experiments were made. We found 12 different types of the short and loud advertising song (Germ. 'Kurzstrophe'). The long and low-voiced song (Germ. 'Langstrophe') was used only in excitement. Each male, with one exception, used only one song-type. The song quality of red (adult) and green (juvenile) males was compared. Phenomena such as song-matching, changing of song-type during the breeding season and microgenesis were described.

The heart rate of unrestrained blackbirds Turdus merula was measured in the laboratory by means of radiotelemetry. Tape playback of seven different conspecific song strophes was presented to male and female birds. In addition the plasma titers of testosterone and 7ß-oestradiole were measured in both one male and one female. The heart rate responses (amount of acceleration) varied throughout the year. The males responded most strongly in spring, the females did so in winter. The seasonal response patterns of the males were similar to the pattern of the testosterone titer. The results indicate that conspecific song strophes have different meanings to male and female blackbirds in different seasons.

The sound pressure level in the songs of several individuals of six Acrocephalus species was measured in the natural environment and recorded on tape for various acoustic analyses. Sound propagation experiments carried out in spring and summer reed and urtica beds as well as grasslands were compared to measurements in a 'free' sound situation. Their purpose was to measure the attenuation of a sine wave of continuously increasing frequency and of played-back warbler songs over a certain distance. Further, they were to show a possible adaptiveness of the songs to the acoustic properties of the habitat as regards their frequency spectra. Additionally, vibration measurements on plant stalks were carried out, which revealed a correspondence of favourably used song frequencies with resonance optima of the plant stalks.

The vocal repertoire of adult Antarctic terns consists of 13 different call-types with typical functions, situation specific occurrence and partly individual specificity. I consider the simple calls as possible sources of other vocal signals in away that the most complex signals are derived in a sequence of ritualizations. Most call-types occur in special situations (context specificity) and therefore have special functions. An example for communication by vocal signals (without any optical signal) is given. The fish call series is a typical distance call, which is uttered by Antarctic terns in territorial and mate contexts. That is why this signal is qualified for investigation of species' isolating mechanisms, i.e. for interspecific comparisons. I found differences in the phonetic structure and in the frequency of fish call series between Sterna vittata and other tern species. The allopatric tern species Sterna vittata and S. paradisaea resemble each other in their behaviour about as closely as two distinct species are capable of doing. The innate acoustic signals especially, which are very effective isolating mechanisms, are quite different. That is why the hypothesis that the Antarctic tern is only a subspecies of (Moynihan 1959) or conspecific with (Wolters 1975-82) S. paradisaea can no longer be supported.

We compared the Long Call of coastal breeding yellow-legged herring gulls in the Gulf of Finland and those breeding inland in Teichu raised bog (E Latvia) and contrasted them with Larus cachinnans from S Ukraine. Principal component analyses of 10 Long Call parameters showed that L. cachinnans and Eastern Baltic yellow-legged herring gulls are essentially distinct in multivariate space with no overlap. Differences occur primarily in structural organization, element configurations and number, in the form, number and spread of harmonic bands within elements and intervals between elements. The Long Call of coastal gulls is the shortest, having 8 to 14 elements, the Long Call of Teichu gulls consists of 12 to 18 elements and cachinnans Long Call comprises 14 to 24 elements. A more obvious difference was observed in basic harmonic band frequency. Differences between samples from the Gulf of Finland and from Teichu are not of such major importance. They occur only in the duration of the Long Call, in element number, harmonic band form, element duration, in intervals between elements and amplitude modulation of separate elements. On the basis of our own investigations we maintain that yellow-legged herring gulls from Teichu bog breeding in the same geographical area as coastal gulls are a rather different group in relation to L. a. argentatus. We are not quite confident to state that inland gulls from Teichu bog can be a separate herring gull subspecies L. a. omissus. Partial interbreeding between these forms cause difficulties in recognizing that. The existence of omissus as a subspecies will possibly be proved later.

Song variability of passerine birds is a result of the interaction of space and time. Analysis of the syntax and the structure of the song of different Palearctic passerines revealed variations at some hierarchical levels. This is the consequence of learned and innate song components. The high capability of learning finds expression on the one hand in mixed-singers (for example genera Sylvia and Phylloscopus). On the other hand we know genera (for example genus Emberiza s. str.), in which species differ distinctly in (innate) size and plumage and have similar (predominantly learned) songs. Cultural transmission of the vocalizations is in this case more conservative than the inheritable plumage. We found some species (Fringilla coelebs, Carpodacus erythrinus) which demonstrate the possibility of learning different song types not only during the so called 'critical period' but also over some years. On the basis of lifelong learning, and sometimes reinforced by geographical isolation, an intensive element and song-type sharing between individuals and populations exist. In this way local dialects ('regiolects') arise. Dependent on the actual behaviour, spontaneous changes of song patterns appear, including progressive and regressive genesis (for example Fringilla coelebs and Carpodacus erythrinus).