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Grote Vale Spotvogel

Hippolais languida · Upcher's Warbler

id	68324
datum	12 t/m 14 oktober 2019: 3 dagen
gemeente	Wormerland (NH)
locatie	Wormerland - Polder Wijde Wormer (NH)
coördinaten	N 52.48358 O 4.8871
aantal, kleed	1, 1e kj
soort waarneming	veldwaarneming
status	Aanvaard, gepubliceerd in jaarverslag CDNA
waarnemer(s)	K Vaartjes, D Kok et al
opmerkingen	mtDNA analyses (based on faeces samples) stored in GenBank, photographed, sound-recorded, videoed (Dutch Birding 41: 449, plate 629, 2019). This bird was photographed in a garden in the middle of a ‘random’ Dutch polder. The images immediately stirred a discussion about its identity. Though definitely not settled, the general consensus went towards the long-expected first Eastern Olivaceous Warbler Iduna pallida. The following day, it was still present when Upcher’s Warbler was suggested as an unexpected but better option by a few keen birders. Despite the perhaps not very typical length of the first primary (a bit on the long side for Upcher’s but too short for Eastern Olivaceous), they showed its plumage features, structure and behaviour (it often swinged its tail sideways, and fanned it) better fitted Upcher’s. Unfortunately, no permission from the landowners was granted to trap the bird. Although measurements would have been valuable, in hindsight this proved to be unnecessary for the identification. A few recorded calls on the second day fitted Upcher’s and seemed to rule out Eastern Olivaceous. Moreover, out of 15 faecal samples randomly collected on leaves of its favourite bush the day after it departed, two belonged to the bird (others belonged to Common Blackbird Turdus merula, Song Thrush T philomelos and House Sparrow Passer domesticus). The mtDNA analysis confirmed the identity as Upcher’s (Peter de Knijff in litt), the first for western Europe. The committee identified it as a first calendar-year bird (see plate 549).