Beobachtungen zu Biologie und Verhalten des Großen Kragenlaubenvogels (Chlamydera nuchalis)

Zusammenfassung

Von Mai bis Juli 1969 wurde im Gebiet von Darwin und Arnhemland (Northern Territory, Australien) Biologie und Verhalten vonChlamydera nuchalis studiert.

28 Lauben wurden gefunden. Einzelheiten des Laubenbaues und der hierzu verwendeten Materialien werden beschrieben. Das ♂ muß etwa 4–5000 Zweige zum Laubenplatz schaffen; die Wände der Laube bestehen aus etwa 1400 bis 1840 Zweigen.

Die zur Ausschmückung der Laube verwendeten Gegenstände umfaßten Molluskenschalen, Knochen, Glasstückchen, Steine und kleine glänzende Metallobjekte. Das Gesamtgewicht des Laubenschmuckes betrug 6,6 bis 12,1 kg. Größe und Gewicht der Einzelobjekte schwankten zwischen 4–10 mm und 0,2–1,2 g bzw. 73 × 36 mm und 40 g. Ihre Gesamtzahl liegt zwischen 5000 und 12 000. Bevorzugt werden weiße und graue Objekte; auch grüne Glasstückchen wurden gefunden.

Die Technik des Laubenbaus, die ausschließlich das ♂ ausführt, wird beschrieben. Der Rohbau nimmt etwa 3 Wochen in Anspruch, doch werden im Anschluß daran dauernd neue Objekte eingetragen. Anzeichen für das „Ausmalen“ der Laube wurden nicht gefunden. Während der Balz singt das ♂ intensiv auf Bäumen oder am Boden. Die einzelnen Balzphasen werden beschrieben. Während des Höhepunktes versucht das ♂ durch Sprünge im Kreis das ♀ an der Laube zu halten. Begattung wurde außerhalb der Laube nahe dem Ausgang beobachtet. Offensichtlich hat ein ♂ mehrere ♀ während einer Balzperiode. Während der Balz wird die Laube dauernd ausgebessert und ihr Schmuck neu arrangiert.

Summary

From May to July, 1969 the author observed in the region of Darwin and Arnhem Land (Northern Territory, Australia) the biology and behaviour of the Great Grey Bower Bird.

28 bowers were found, in three cases the building process was observed. Bower-building starts with cleaning up an area of 210 to 95 cm and with forming a 7.5 cm thick mat of small twigs intertwined in all directions. The walls are made of uniform twigs the measurements of which are on an average 29.2 mm in length and 2.4 mm in thickness at the lower end. A wall consists of 700 to 920 twigs placed parallel to each other (1400 to 1840 twigs on the two walls). The ♂ carries 4000 to 5000 twigs to the site of the bower. The paper gives the measurements of the bower and its orientation towards cardinal points.

The bower is completed by a collection of ornaments which consists of land and sea shells of the generaXanthomelon, Venus andTelescopium, bone and glass fragments, stones (almost exclusively quartzite and limestone), and small pieces of glossy metal objects, tin seals etc. The lowest total weight of all objects collected was 6.2 kg, the highest was 12.1 kg. The size and weight of the objects varies between 4 to 10 mm and 0.2 to 1.2 g and 73 by 36 mm and 40 g respectively.

Their total number was established at 5000 to 12000.Chlamydera nuchalis prefers white and grey objects with the exception of glass of which also green fragments were found. Some objects were experimentally painted blue, red, black, yellow and green. The ♂ discarded them successively and threw them out of the bower.

The paper describes the technique of bower-building which is carried out solely by the ♂. It takes the bird three weeks to finish the construction in the rough, but even afterwards the ♂ systematically continues to complete the bower, adding a growing number of ornamental objects. During the display period, however, a ♂ rebuilt a bower, which had been destroyed, within 2.5 days. The activities observed are shown in the table. Bower Birds may carry, on an average, 90 twigs and 28 glass fragments per hour to the bower. The bower wall painting behaviour ofChlamydera maculata andPtilonorhynchus violacaeus was not observed inChlamydera nuchalis. No traces of painting were found in any of the bowers observed. The author found an interesting behaviour pattern in two ♂ who stuck pieces of food into the cracks in the walls. This behaviour strikingly resembles that of passerines feeding their young.

During the display period the ♂ sings ardently either on trees or on the ground. Display consists of alluring manifestations of the ♂, including nape-crest presentation and bounds. At the bower, the ♂ shows the ♀ some objects on the opposite side of the passage, and after bowing and raising his head, he turns it so that the nape is directed toward the ♀, and presents to her its lilac crest. During the culminating phase of display the ♂ attempts, by circling in leaps, to keep the ♀ at the bower. Mating was observed outside the bower, next to its exit. A ♂ apparently has several females during the display period. Also during display the ♂ rearranges and completes the bower.