Abstract:
Since the beginning of the sixties I have systematically recorded wader voices in many countries - but mostly in Denmark. Because the redshank Tringa totanus is a noisy and common bird, my collection of recordings of this species in particular is comprehensive, with recordings from many countries and from all seasons of the year. In all I have about two hours' recording of redshank calls in my collection. From these I have selected several hundred calls for sonographic analyses. In this way they represent the birds' different "call types'' from different areas. All the sonograms have been measured (in time and frequency) and described. The conclusions from the results of the redshank voice analyses are the following:
- It is possible to describe the variation in the different call types from different areas.
- Occurrence of the different call types correlates with different kinds of the birds' behaviour, breeding conditions etc.
- The call types and the sonographic analyses from breeding areas with Tringa totanus and Tringa totanus robusta (from Iceland) are compared. The calls from the larger Icelandic subspecies are on average of lower frequency than those of birds from Denmark, and in the sonograms there are some minor differences.
- As a conclusion from the spectrographic analyses I put forward a hypothesis about the composition of the redshank vocal repertoire. It consists of four simple voice elements-and all the different calls are compositions from these elements in such a way that the elements vary in time. These elements are hereditary but can vary in time and some details from population to population-and from individual to individual.