Cygnus columbianus  ·  Whistling Swan

id 4149
datum 9 december 1992
gemeente Het Hogeland (GR)
locatie Eenrum
coördinaten N 53.36348  O 6.4597
aantal, kleed 1, adult
soort waarneming veldwaarneming
status Niet aanvaard, gepubliceerd in jaarverslag CDNA
waarnemer(s) H.A. Diephuis, J.W. de Jong
opmerkingen Based on newly described identification features other than the amount of black on the bill (Visscher & van Duivendijk 2015), all five records were reassessed. According to Evans & Sladen (1980), only a small minority (4.3%) show more than 10% yellow on the bill. This minority type however seems to be over-represented in Dutch records. This was, eg, the case for a widely twitched bird in Drenthe, Friesland and Groningen in the winters of 1997/98 and 1998/99. ‘Hybrigades’ with Bewick’s Swan C bewickii are a realistic option, and Bewick’s with aberrant bills are not unheard of (Evans & Sladen 1980). Identification based on a single feature is therefore tricky, especially in birds with a relatively large amount of yellow on the bill. The presence of the new features could not be determined in the records. It was therefore decided that all records are no longer proven and, as a consequence, Whistling Swan was removed from the Dutch list. Annual Report 2018.

Beschik je over foto's of andere extra informatie of heb je opmerkingen over dit geval? Neem dan contact met ons op.