Which Wood White

[Paul]

I missed the ID reasoning discussion regarding Wood Whites previously had, and really wondered what Guy, and anyone else for that matter, might make of these...

Taken Aug 2005 in the Dordogyne...


Taken July 2007 in the Haute Alpes...


Taken July 2008 in the French Pyrenees...

[Zonda]

Whatever,,, you got them good Paul.

[Paul]

Reali, you're too kind!

seriously, thanks for that!

[NickB]

Nice ones Paul. I saw both Real's and Wood White in Switzerland - and Guy gave me some tips, which seem easy to follow in the field, but not so from the photo...mainly guesswork you understand, so here goes....
1st - No idea!
2nd - Wood
3rd - Real
But most likely I'm wrong. No doubt Guy will give us the benefit of his wisdom...
N

[Padfield]

I'm with you on those, Nick! The first is ambiguous, the second a definite wood white and the third probably Réal's, though it's not as clear cut as the one I think you photographed near Geneva on the first day, Nick. In my opinion you can only be really confident when you see extreme examples from one end of the spectrum or the other.

Both Yves Gonseth (the former Swiss recorder) and I got 100% on a blind test of 7 known individuals last year, caught and prepared by Yannick, the present recorder (he didn't kill them for this blind test, but as part of his job, determining the status of reali in Switzerland, and I asked him to set up the test in the hope that we might be able to do away with the killing bit in future!). It's not statistically very significant, but it does suggest there's something in the method. I applied a different method that I had invented myself to the same 7 individuals and found it agreed with 6 of them but delivered the wrong result in one case.

See here:

http://www.pieris.ch/diagnostik/s_reali_01.html

Guy

[Paul]

Is the suggestion then the hindwing in reali is more evenly rounded than that of sinapis, and the dark hinwing mark echoes it, or is it just the mark that we look at ... my German is limited to achtung and shweinhund from old war comics.... sorry

[Padfield]

The suggestion is that in Switzerland, at least (it is probable, from other studies, that visible differences between forms of the same species in different countries and regions are greater than the differences between the two species at any single location!), the dark post-discal shadow on the hindwing of reali is curved, and parallel to the outer margin, while that of sinapis is straight and not parallel to the outer margin.

The individuals they choose as examples are not extreme, and don't really show up the differences!!

Both species are common in Switzerland, and sympatric, with a probable ratio of 3 : 1, sinapis : reali. That means, basically, once you've seen a few dozen wood whites you've definitely seen both species!!

Guy

Any chance of your posting that individual I identified in the field as 'almost certainly reali', Nick? The one you photographed in the woods near Geneva.

[Paul]

Ok, think I understand!!!

[Padfield]

Here's the most extreme curvy one I've photographed (reali):



And here's a classic sinapis:



Guy

[NickB]

...it's not as clear cut as the one I think you photographed near Geneva on the first day, Nick. In my opinion you can only be really confident when you see extreme examples from one end of the spectrum or the other. Guy

I managed to remember something, at least, Guy...

This is the one I got - fairly ragged affair, but I think it shows what you mean...