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Hello,Lee Hurrell wrote:In my experience, which is no doubt more limited than some users on UKB, the Adonis underside is cleaner in ground colour than the Chalkhill, which in most females I've seen is normally chocolate brown or grey ish.
By cleaner, I mean it lacks the grey blue dusting you see in Common Blues around the basal area of the underside hindwing, which can be present in Chalkhills.
The top right to my eye seems cleaner and lacks this dusting, hence my thought of Adonis, while the bottom right seems more grey in ground colour and also has hints of the dusting hence Chalkhill.
This is only based on my observations of the two species though and I won't claim to be 100% correct!
Was I wrong?
Cheers
Lee
Hello,millerd wrote:My first guess (with little to back it really!) was that they were actually all Adonis. Definitely the bottom left one, and almost certainly the top right. I looked at definite Chalkhill pictures I had from sites where Adonis is not present, and the others did not look very like Chalkhills either.
Hmmm.... Still not a bit certain
Dave
Perseus wrote:Hello,millerd wrote:My first guess (with little to back it really!) was that they were actually all Adonis. Definitely the bottom left one, and almost certainly the top right. I looked at definite Chalkhill pictures I had from sites where Adonis is not present, and the others did not look very like Chalkhills either.
Hmmm.... Still not a bit certain
Dave
The top two are Chalkhills and the bottom two are Adonis.
On the top left there is a bit of "dusty" blue on the underwings you can see near the abdomen. This is a clue. The spots seem identical. When fresh Adonis females have a more chocolately brown upper wing colour. Except they fade and then it is nigh impossible to tell the difference.
On the main part of Mill Hill, Chalkhills have shown disastrous numbers for seven consecutive years.
Mill Hill Reports 2010
http://www.glaucus.org.uk/MillHill2010.html
Mill Hill and its Butterflies
http://www.glaucus.org.uk/MillHill2009Article.htm
Cheers
Andy Horton
glaucus@hotmail.com
Adur Valley Nature Notes
http://www.glaucus.org.uk/Adur2010.html
Adur Valley Nature Notes: September 2010
http://www.glaucus.org.uk/Sept2010.html
Sussex Downs Facebook Group
http://www.facebook.com/group.php?gid=111843132181316
Hi Andy,Perseus wrote: On the main part of Mill Hill, Chalkhills have shown disastrous numbers for seven consecutive years.
I find the scaling outside the hindwing submarginal lunules on the upperside to be reliable. I haven't taken the trouble to find if there are any exceptions, but in general the presence of blue scales there indicates Adonis, while white scaling is characteristic of chalkhill. Even quite worn Adonis blues usually show some blue on close examination, and with the exceptionally high quality of photography these days it is often possible to see on a digital image what you miss with the naked eye. Your pictures show this difference quite clearly.Perseus wrote: Alas, further observations have changed my mind. except for mating with the males there does not seem to be a reliable method of distinguishing female Adonis Blues and female Chalkhill Blues to the human eye. And sometimes even the butterflies get confused!
Hi Andy,Perseus wrote: Virtually all the possible answers have been ruled out. It is optimum condition for the species. What is the maximum per acre hour count on the other sites please in the last two years.
Felix wrote:Hi Andy,Perseus wrote: Virtually all the possible answers have been ruled out. It is optimum condition for the species. What is the maximum per acre hour count on the other sites please in the last two years.
That's not the sort of data that I have to hand. Besides, it could be inconsistent/misleading, i.e. max counts per acre of site (eg. reserve, down, hillside etc.) or max counts per acre of suitable breeding areas within the site, or max counts per acre of suitable breeding habitat+roosting areas+nectaring areas?.
My observations around this come from transect data as well as personal observations. The factors that unite the sites on which the CHB numbers are increasing are (amongst others) a profusion (and I mean real profusion) of nectar sources as well as a considerable area of vegetation that is suitable for roosting imagines (which of course has to be topographically correctly situated as well). A super abundance of larval food plant alone does not seem to equate to a super abundance of butterflies; although clearly there is a relationship between the quantity of larval food plant in the correct topographical situation+relative sward height to gradient etc. and the size of the population that the site is able to support.
It is interesting that you state that the habitat at Mill Hill is optimal and yet also suggest that the population is in decline. Hence my line of enquiry on your thoughts as to possible causes of decline at Mill Hill when upon sites where the conditions (by definition) are excellent to optimal the butterfly is recovering from a decade or there abouts of decline. There is as much to be learnt from sites where the population is in decline as well as from sites where the butterfly is increasing.
Some fairly small sites (a few acres) are able to support a population of massive relative density (several thousand at peak) when conditions allow.
Felix.
