Small tortoiseshell butterfly in UK

It's coastal so very probably.

Bob

I have recently seen on the television that the Small Tortoiseshell population in the UK is officially down by 77%. That is a massive drop in the population of a common butterfly.

Habitat loss isn’t ridiculous . You have to remember that a nettle does not immediately mean that it is a nettle. This sentence is a bit cryptic but will become clear with the following explanation.

Each butterfly has requirements to his habitat in different phases of his life, egg, caterpillar, pupae and imago. Some university, I think it was Leiden, has once studied why Callophrys rubi is so scarce in the Netherlands despite the fact that its host plant is thriving anywhere. The result of the study was that this butterfly has specific requirements on the heat found within the micro climate around the host plant and that the adults needed individual trees for sleeping and resting. Given these requirements only a tiny fraction of host plants where a suitable habitat for all phases of the butterfly and the scarceness could be explained. No habitat no butterfly.

With Aglais urticae it probably is the same thing. They do like nettles but the small patches of nettles that modern agriculture lets untouched are not worth to be considered by the butterfly. They are either too hot, too cold, or simply just too exposed in the sunshine and would need more vegetation around it.

I have a set of about 7000 sightings of Aglais urticae that I am currently analyzing through for another project. I quickly gave a look into it in regards of absolute numbers and you can see a severe decline since 1985.

Have just observed a female small tort lay her egg batch under a nettle leaf in my garden in Dartford Kent.
Managed to get some caterpillars from a friend earlier from near Durham.These were reared and about 50 released near Gravesend Kent last month.
I will do the same with this egg batch.Every little helps.

The Small Tortoiseshell - Aglais urticae seems to have made a remarkable come back from its serious decline a few years ago in the U.K. Lepidopterists were right to fear for one of our most beautiful butterflies. The Large Tortoiseshell - Nymphalis polychloros saw a great fluctuation in numbers before it became extinct here, which may have also have been also caused by larvae parasites. So it has been a great relief in my area to have seen large numbers of A. urticae this spring , with the warm winter helping the hibernating butterflies. Those first emerging seem to take nectar from the humble Dandelion, Taraxacum species. This common flower is a very important nectar source for many early insects. I took a walk this weekend in a lowland Thames valley, where good numbers of Aglais urticae were visiting Sallow and Willow catkins with a few Polygonia c-album and Inachis io . The latter were mostly seen basking on bare earth and when they came into contact with any A. urticae they would dogfight and spiral high into the air. Both species, but especially A. urticae were also visiting drifts of Lesser Celandine - Ranunculus ficaria, I do not remember seeing this before. They were joined here by a few of the delightful Bee Flies of the Bombyliidae family. At this lowland River Cole site, the Blackthorn was just coming into flower and the snow white blossoms also were attracting a few of the over-wintering Nymphalids.
Here are a few of my photographs of A. urticae that I took recently.Hopefully we will see further good number of this wonderful species this coming summer.


My first A. urticae of the year. Visiting Dandelion in early March.

A. urticae this weekend.


Visiting willow catkins.

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Feeding at Sallow catkins.


Visiting the buttercup, Lesser Celandine.

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In my garden, visiting Flowering Currant.

Ooop the photos did not turn up, I have added them again.