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Die Unfallopfer der Seidenschwanz-Invasion Bombycilla garrulus von 2004/05: Alter, Geschlecht, Mauser und Schädelpneumatisation.
(von 1994 bis 2006 vergeben)
Bombycilla garrulus, ageing, sexing, moult, pneumatization
Altersbestimmung, Geschlechtsbestimmung, Merkmale, Mauser, Schädelpneumatisation
Casualties of the Bohemian Waxwing Bombycilla garrulus invasion 2004/05 in Switzerland: age, sex, moult and skull pneumatization. Among the examined 123 Bohemian Waxwings found between January and March 2005 35 % were first-year females, 30 % first-year males, 22 % adult females and 13 % adult males. 88 % of these birds with known mortality cause were victims of collisions with windows. Ageing by the presence or absence of «angles» at the primary tips was in most cases straightforward. However I found two adult females with nearly no «angles» at their primary tips (Fig. 2) and one first-year male with slight «angles» (Fig. 4).
Among the examined 43 adults 5 showed arrested moult of the secondaries (S; Fig. 1). The maximum was 4 unmoulted S (S 3–6). All of the 80 first-year birds had completely renewed their body plumage. Within the wing coverts (only upper wing) postjuvenile moult was not extensive. 43 % moulted no Greater Coverts (GC), at most (only 2 % of the birds) the innermost 4 GC were moulted (GC 8–11). If no GC were replaced, the moult of the Marginal and Medium Coverts, too, could be suppressed. In most cases, however, part of the Marginal and the innermost Medium Coverts were renewed. When two or more GC were replaced, the renewal of the Marginal and Medium Coverts was complete. Moult limits within the wing coverts were very hard to detect (Fig. 3).
The time needed to complete the pneumatization of the skull roof in Bohemian Waxwings was estimated to lie between 6 and 8 months. 57 % of the examined first-year Waxwings had completed their skull pneumatization. Of the others, 70 % showed last remnants of unpneumatized bone, a further 24 % had three quarters and two individuals only half of the skull roof pneumatized. All the examined adults had a fully pneumatized skull roof.
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