Pied or White wagtail

Hi-

Svensson has been used for detailed ID  help in the field since the 70's by Field birders-  personally recommended to me back then by a former BBRC chairman- very useful. Van Duivendijk is a really great  accessible field resource too.

S

Unknown said:

The birds I am referring to are from a sewage works in Wiltshire, which is ringed between January and March and the leader of the group has extensive experience of the bird both in the UK and on the mainland of Europe.  There are numerous criteria used: rump colour, great coverts, tail length, wing length, crown etc.  These are easier to identify when you have the bird in the hand and identification is never done on only one criterion: it has to be a combination.

Just to be clear, I haven't said that I have any good reason to think that this is inaccurate in any way - just that a previous report of large numbers of White Wagtails in Scotland in autumn and early winter (which involved birds identified in the hand, using many criteria) has been questioned. As far as I am aware there are no other published studies that have suggested that M. a. alba winters anywhere in the UK in any sort of significant numbers - so I hope that details of this Wiltshire study are published at some point (they may already have been published locally?). It would be interesting to know when the White Wagtails are being recorded (ie. is it throughout  January through to March, or are they mainly trapped during the second part of this period?). It is certainly possible that they are being overlooked in the UK during the winter, and I would think that south-western parts of the UK would be a likely area if they are wintering here (which could perhaps be a recent thing).

Unknown said:

Svensson: Identification of European Passerines is the ringer's bible.  Also, Van Duivendijk: Advanced Bird ID Handbook - The Western Palearctic both have excellent descriptions for separating the sub-species.

There is also a paper that was published in Dutch Birding magazine a few years ago which is well worth a read: White Wagtail and Pied Wagtail - A New Look

Unknown said:

What I did note and can't quite understand is that in or around 2008 a ringers conference was held in the Cotswold Water Park area (a very short wagtail flight from where Simon is talking about and I do know the ringer he is referring to).  At that time I.D papers on white / pied wagtail were circulating including a ringers guide by Iain Livingstone.  Shortly after there was an increase in white wagtails being reported to the website I manage for the CWP area.  I asked why and was sent the I.D guide.   This continued for a year or 2 but I no longer get records of white wagtail.   They can't have stopped passing through so I do wonder whether this I.D puzzle is a bit of a fashion that comes and goes.

There is definitely an element of "fads" when it comes to things like subspecies identification (and also things like aging, and the identification of hybrids). On the other hand though, it is quite possible that there actually were far larger numbers of White Wagtails passing through your area a few years ago. It is not unusual for there to be runs of 'good' years for some species, followed by periods with lower numbers before the numbers potentially pick up again.

However, it will usually be the case that when new identification criteria are published birders (and ringers) will try them out. The Iain Livingstone ID paper is now considered flawed by many (the first photo in the 'Dutch Birding' paper I linked in my first post shows one example of a wagtail incorrectly identified using the criteria in that paper.

Hi Roy - unfortunately, as much as I would like the data to be published, the owner of the data and the site has a problem with writing stuff up.  

For example, he has more data on Tree Sparrows than anybody else in this country, having ringed over 1,400 pulli in 2012 alone, and having been involved in the Tree Sparow project for over 10 years with a similar level of involvement, has been instrumental in the re-establishment of the population over large parts of north Wiltshire and into Oxford.  He has exported his methods into Oxford, and the people he helped have been in the media with their success story but he is too busy ringing, nest checking and managing habitat to write it up.