Species correlation

[Jack Harrison]

Different species often share very similar habitat requirements, for example our two "Purples", Hairstreak and Emperor. It does not follow that if the commoner species occurs then the less common one will automatically occur. But I suspect that the reverse is true.

So, while the presence of the relatively common Purple Hairstreak does not guarantee Purple Emperor, if Purple Hairstreak does NOT occur, then Purple Emperor certainly will not either. I offer some pairs based on MY EXPERIENCE only.

Duke of Burgundy sites always have Dingy Skipper
(but of course not all Dingy Skipper sites have the Duke)

Purple Emperor sites always have White Admiral
(but not all White Admiral sites have Purple Emperor).

Adonis Blue sites always have Chalkhill Blue but not necessarily vice-versa.

Silver Spotted Skipper sites always have Chalkhill Blue (but not vice versa)

The point I am making is that unless the commoner indicator species is present at a locality, the rarer correlation species cannot be expected so it could be a waste of time searching.

Comments? Other "pairs"?

Jack Harrison

[Dave McCormick]

I noticed this at 2-3 sites not far from where I lived, but nearly everywhere I have seen a common blue, there has been six spot burnet moths nearby, in the same area. But I have seen areas with six spot burnet that may not have common blues in it. Think it may be to do with their foodplant

[Padfield]

In England and Wales, how about grayling and silver-studded blue, with grayling being the commoner indicator species?

This pairing brings out the further point that some species have quite disjunctive habitat requirements across their range. It works for British silver-studs because they are restricted to heathland. On much of the continent, however, this species is not associated with heathland and so frequently flies in the absence of graylings (but I have noticed the link in Britanny, for example).

I have purple emperors in my local woods here in Switzerland but no purple hairstreaks (at least, I haven't seen any here yet). Nevertheless, purple hairstreaks do fly in Switzerland, sometimes commonly. So I think that pairing too may have only local force.

Guy

[Danny]

How's about Silver Washed Frits and White Admiral, they always seem to hang out together, party shall we say.

They ever appear at the same time.

Danny

[Jack Harrison]

How's about Silver Washed Frits and White Admiral

Generally true - certainly in central southern England - but in East Anglia White Admirals are found in many woods but SW Frits are virtually absent in the east. And although I have no personal experience , I believe that SW Frits occur in parts of SW England where the more-open habitat is definitely not suitable for White Admiral.

In England and Wales, how about grayling and silver-studded blue, with grayling being the commoner indicator species?

That's pretty well correct and I think in most S.S.Blue localities Grayling are also present as the commoner indicator species. Not sure though if that holds for some of the Norfolk SS Blue localities (those to north of Norwich for example). Graylings of course have another habitat where SS Blues certainly do NOT occur, that being coastal dunes.

However,in spite of the exceptions, I still think that the idea that I suggested at the beginning of this thread of commoner indicator species being necessary for there being any chance of finding the less-common species, has some validity IF USED WITH CAUTION.

Jack

[Piers]

Adonis Blue sites always have Chalkhill Blue...

That ain't necessarily so...

Felix.

[Jack Harrison]

Adonis Blue sites always have Chalkhill Blue...

That ain't necessarily so...

Oh? Where for example. Curious.

Jack

[Piers]

Hi Jack,

It just struck me reading the posts that there are several sites on the Purbeck Hills (my neck of the woods) where Adonis occur in the absence of CHB's.

On a lot of the downland in Dorset and Wilts the Adonis is also the commoner species following the CHB crash across the two counties.

I liked the theory though!

Graylings of course have another habitat where SS Blues certainly do NOT occur, that being coastal dunes.

Excellent SS Blue colonies occur on the Cornish dune systems...

Felix.

[Jack Harrison]

Good discussion this. We are all (self included) living and learning.

What is the SS Blue larval foodplant on Cornish Dunes?

Jack

[Rogerdodge]

What is the SS Blue larval foodplant on Cornish Dunes?

Jack
My understanding is bird's-foot trefoil.
I stand to be corrected.
Roger