The Barry White of Citrine Wags.
This morning (8th November) Phil (who gave it the Barry moniker) and I went to check out Danes Dyke South- to look for the Citrine Wagtail. Last seen two days ago, the tidewrack at South Landing which had provided food for pipits and wagtails including the Citrine had been almost nearly washed away in the windy/ stormy conditions of two days ago. South Dykes, one mile to the west can keep the higher level tide wrack. It had, and there was the Citrine Wagtail.
There are some curious things about this bird as already covered. In a nutshell it is:
1) Exceptionally late- about the 4th November record in Britain ever
2) It has a distinct orangey bill base- more usually associated with flava wagtails
3) The call seemed odd, deeper and ‘fuller’ than typical Citrine
Late birds often come from further east… There are several potential explanations. The plumage and call are too close to Citrine to me to invoke the hybrid explanation. Normal variation, say a young bird with pale bill base may explain it (though have no data on such young birds)? However my preferred working hypothesis is that it’s from a less well-known breeding population- perhaps further east than our usual records. Intriguingly this record of Citrine Wagtail on Vancouver Island (2nd record for North America) was coincidentally (or not) a vagrant in mid November with similar orangey bill base pattern.
The call really is also definitely unusual. Following the field impression of three of us Flamborough regulars that it sounded a little odd for Citrine (and some friends commenting here on the blog), the sonogram seemed to bear that out. So I asked some Dutch guys who have been looking into the calls of Citrine and eastern flavas for some time. Thanks to Nils van Duivendijk, Sander Bot and especially Dick Groenendijk
I just looked through the recording of the Flamborough Citrine Wagtail. I looked at the recording where eight calls can be heard and these calls are all rather low pitched. I compared the calls with some of my own recordings and after some measurements it seems that the Flamborough wagtail called more than 1 kHz lower compared with other recordings of Citrine Wagtail. The average maximum frequency of the Flamborough bird is 6.6 kHz, whereas I am used to see recordings of Citrine Wagtail with maximum frequencies well above 7.5 kHz.
When looking to sonogram structure, this looks OK for me for Citrine. The first ascending part with two very close parallel lines, the length of both legs roughly similar and for most of the eight calls in the recording the rather blunt-tipped ‘n’ shape. Note that the descending second part of the call looks rather solid and that the modulations are only proper visible at the maximum frequency, which also suits Citrine much better compared with an eastern yellow wagtail. The first and to a lesser extend also the fifth flight call looks a bit more pointed (like in Eastern Yellow Wagtail), but I have found some more flight calls of Citrine showing this feature and I think this is best explained by variation.
Although (very) low pitched, structure of the sonograms looks to me pretty good for Citrine Wagtail.
Have another listen to the call: