About Motacila flava (1 Viewer)

Hello friends
It's the first time for me in the forum
I would need information on the species Motacila flava, in particular on the Iberian subspecies, feldeg and thunbergi; that would help me to distinguish them well, in various parts of the year and according to age.
Distinguish, for example:
- one female of M. flava flava and one male of M. flava iberian
- feldeg and thunbergi

There is information, but good and with illuminating images there is little.

Thanks

Sorry for my English, I only speak Portuguese.

This is not easy!

Apart from the males in summer, they can be very difficult or impossible to separate by plumage. So if you are starting to learn to identify them, best wait for spring.

In Portugal, concentrate on iberiae, flava, flavissima and thunbergi.
The last two are quite easy, but iberiae and flava are similar: the colour of the throat is different for adult males: white for iberiae, yellow for flava.
Unfortunately, young males of flava have a white throat so they look more like iberiae.
http://i.picmoo.com/photos/187/2016/3/9bacbabcf93a5a6e3f69261de0bd4e54946cb28e.jpg?1458454505

You can differentiate the various forms by call, which may help with birds that are unidentiable by plumage. The call of northern birds usually sounds like "chiip", of southern birds (like iberiae) more like "chrriip". It is best to record the calls and compare the spectrograms with software...

Thank you
I am birdwatcher experienced so it is that I have doubts of these.
There is some information on the subject, some reasonable, but it is far from being clear and elucidative in the most difficult cases.
Even this one "Pipits and Wagtails of Europe... - Per Alstrom and Krister Mild" has gaps.

Thanks again.