Walters J. (1957) Über den Balzruf des Flussregenpfeifers, Charadrius dubius Scop. ARDEA 45 (1-2): 62-72

On the song-note of the Little Ringed Plover, Charadrius dubius.a. The song-rhythm in the Little Ringed Plover was studied in the surroundings of Amsterdam in 1954, 1955 and 1956. b. On an average and on the whole this rhythm is quicker in the beginning of the display-flight: during the first 10 seconds 15.0 in 10 sec.during the second 10 seconds 14.3 in 10 sec.during the third 10 seconds 13.8 in 10 sec.during the fourth 10 seconds 13.8 in 10 sec.during the fifth 10 seconds 13.5 in 10 sec.during the sixth 10 seconds 13.4 in 10 sec.c. The rhythm is quicker at the end of the reproductive-cycle than in the beginning of the season (April). d. In 1954 the average rhythm was 14.1 in 10 sec. and in 1955/1956 14.0 in 10 sec. (Maximum 20, Minimum 11 in 10 sec.). e. Comparisons were made with the rhythms of the song-notes in some other waders: Tringa totanus average frequency 25.0 in 10 sec. Haematopus ostralegus average frequency 20.4 in 10 sec.Limosa limosa average frequency 14.4 in 10 sec.The song-flight of the Black-tailed Godwit shows a great similarity with that of dubius, not only with regard to the song-rhythm, but also to the execution of the flight itself and to the similarity of the introductory flights ('introductory-flight' of Limosa limosa (Huxley & Montague 1926) and 'hostility-flight' of Charadrius dubius (Sluiters 1938)). f. Some causes of the fluctuations in song-rhythm could be found in studying: 1. the influences of the climate and especially of the temperature; 2. the influence of the density of the breeding-population; 3. the influence of the age of the singing males; 4. a possible difference between the rhythms before the first clutches and before the second ones or replaced sets; 5. a possible connection with the history of the settlement of the species; 6. a possible connection with the shyness of the birds. g. A small part of the behaviour of the breeding-population near Amsterdam has been laid down in figures and thus gives us a base for an objective comparison with other breeding-populations of Charadrius dubius curonicus and with these of the other subspecies.