www.ukbutterflies.co.uk

Hello,

How good are you at identifying the female blues?



Adur Butterfly & Large Moth List
http://www.glaucus.org.uk/Butterfly-list2010.html

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,

I'll have a stab.....

Top left - Chalkhill
Top right - Adonis
Bottom left - Adonis
Bottom right - Chalkhill

Cheers

Lee

Hello,

Underwings are identical. I cannot see how it is possible to tell the difference? All photographs taken in the last few days.

I know the answers because of mating behaviour.

Adur Butterfly & Large Moth List
http://www.glaucus.org.uk/Butterfly-list2010.html

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

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

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,

Wrong.

If you look carefully you will notice differences that are clues but not definitive.

More information on the local blues:

viewtopic.php?p=8760

viewtopic.php?p=8761

Adur Butterfly & Large Moth List
http://www.glaucus.org.uk/Butterfly-list2010.html

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

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

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

Hello,

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

Perseus wrote:

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

Hello,

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

Hello

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!

Cheers

Andy Horton

At least I got the ups right....

Lee

Perseus wrote: On the main part of Mill Hill, Chalkhills have shown disastrous numbers for seven consecutive years.

Hi Andy,

In your opinion why do you think that this is? Sites which are in optimum condition for the species have had two very good seasons, so why do you think that are they struggling at Mill Hill?

I've never been fortunate enough to visit Mill Hill but this topic does interest me very much.

Felix.

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!

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.

Undersides are harder, and very variable, but the jizz usually gives the species away.

Guy

Andy
I find it very interesting that you report no comparable decline of Chalkhill Blues on a north-facing site. There has been a spectacular decline of the Chalkhill Blue on the south-facing Purbeck chalk downs, and the species has shown no sign of a recovery for many years. About three years ago I walked a considerable length of these downs from Lulworth (Bindon Hill) eastwards. I found Chalkhill Blues in fair numbers in just two places, both of them north-facing, namely the north-west portion of Bindon Hill and the extreme eastern end of Bindon Hill, where the path descends towards Arish Mell, quite a steep north-facing slope. Elsewhere I saw none at all.

Misha

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.

Hi Andy,

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.

My transect are covers an area of 1.2 acres and takes about 20 minutes or 30 minutes if I stop for photographs. More later when I have time.

Andy Horton

Mill Hill and its Butterflies
http://www.glaucus.org.uk/MillHill2009Article.htm

Felix wrote:

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.

Hi Andy,

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.

PS: The north facing site is less disturbed and better draining.

Reference for local information on Chalkhill Blues:

viewtopic.php?p=8761