Zullich's Blue, Agriades zullichi

There is much talk about climate change these days (about time!) and there is no better example of how this will impact on biodiversity than the Zullich’s Blue, Agriades zullichi.

This lovely little butterfly is endemic to the Sierra Nevada mountains in southern Spain. It only occurs in 39 small colonies in a zone between 2,500 and 3,000 metres in altitude.

The food plant of the caterpillars is Androsace vitaliana, a small clump-forming plant, only about 2cm high, which grows on exposed slopes in the Alps, Pyrenees and the Sierra Nevada. It grows in the same altitude range as the Zullich’s Blue.

It tends to grow in very fragile habitats of rocky scree with very little vegetation cover. These areas are vulnerable to landslides, trampling by cattle and most worryingly climate change.

When I first went in search of Zullich’s Blue in 2016, I was amazed to see butterflies surviving in such windswept and exposed locations

The butterfly is only about 20 to 25 mm across its wings and is well camouflaged. I love the subtle brown, grey and blue markings, but this does make them very difficult to spot! They only fly in late June and July.

Average temperature in the Sierra Nevada has increased by 2° in the last 30 years and it is projected to increase by a further 5 degrees in the next century. Snow is now melting earlier in the season, leaving the sloped more exposed to wind and resulting in the ground drying out.

This is a problem for the vegetation, which really needs to move up the mountains to a cooler environment in order to survive. Unfortunately, the dispersal of the seeds doesn't allow the plant to spread far each season.

Similarly the timing of the emergence of the butterfly is critical. If the temperature is warmer than normal, the butterflies may emerge too early in the season to find flowers to feed on, or they could be laying eggs on desiccated plants.

In order to adapt to the changing climate populations of butterflies will be displaced upwards. Even if the food plant could spread uphill in time to keep up, mountains get smaller the higher up you go. Therefore there will be less suitable habitats available for this already rare butterfly.

Thankfully, there is a lot of research going on in the Sierra Nevada about climate change and its impacts on biodiversity. It is hoped that this will increase our understanding of how climate change will effect species elsewhere and what can be done to help species adapt.

I really hope that something can be done to help protect this special little butterfly.

Back to Sierra Nevada

When I visited the Sierra Nevada on 4th July I had been disappointed to see so few butterflies in the mountains because of the high winds. I was delighted to see so many species in a lower meadow, but it seemed a shame to be in Spain and miss the opportunity to see some very special butterflies that live high in the Sierra Nevada.

So, on 10th July I drove back to take another look. I was very relieved when I arrived that it was a lovely sunny, still day, so I set of up the mountain from the Hoya de la Mora car park.

Initially, I didn’t see many butterflies, but suddenly I found myself in the middle of a colony of Nevada Blues, Polyommatus golgus. There were at least 20 of these beautiful butterflies catching the morning sun in a sheltered area.

A little further up the mountain I noticed a subtle change in the shade of blue and realised that I was now walking amongst Escher’s Blues, Polyommatus escheri. I was interested to notice that they were in discrete colonies, whereas on previous occasions I have seen these two species sharing the same space.

I continued up the mountain to an area where I had seen Zullich’s Blues, Agriades zullichi, in the past. I spent some time searching the area, with little luck. The ground seemed quite churned up, as if cattle had been grazing there on the very sparse vegetation. Certainly when I look back at pictures taken in the same area two years ago, it was a lot greener then.

I found some Spanish Argus, Aricia morronensis, which look quite similar.

And two or three Painted Ladies, Vanessa cardui.

There were also a few Spanish Brassy Ringlets, Erebia hispania, but as usual they were really difficult to approach without disturbing them.

Finally, I saw a Zullich’s Blue. They are very difficult to follow, as they fly low and blend into the background. Those that I saw looked very worn, but just as I was about to leave I saw a fresher-looking female. I was delighted to see this lovely butterfly again, but it is a little concerning that I only saw five individuals. Two years ago I estimate seeing more than 15 in this same location.

I then headed back down the mountain towards a stream that I have visited a few times in the past. It was interesting to see the difference in the butterflies I saw this time. The numbers were certainly lower than I had previously seen. There were the occasional Nevada Blue and Escher’s Blue, but the Common Blue, Polyommatus icarus, was more numerous.

There were very few Silver-studded Blues, Plebejus argus, in amongst the low-growing junipers. On previous visits there were a lot more numerous.

Occasionally I would see a Small Tortoiseshell, Aglais urticae, or Wall Brown on the more rocky slopes.

Down at the stream and along the wet grassy areas, where last year I had seen several Meadow Fritillaries, there were surprisingly few butterflies this year. I crossed the stream and searched a scrubby area, which had looked good from a distance, but amazingly there were no butterflies there, other than a couple of Small Coppers, Lycaena phlaeas.

The highlight for me was a beautiful Cardinal Fritillary, Argynnis pandora, that was sun bathing on a rock in the stream.

On my way back to the car I saw a couple of Small Whites and a long chase eventually allowed me to identify a Bath White. These white butterflies reminded me that I hadn’t seen any Apollos this trip. Just as I thought that, one flew past me and glided down the hill side. What a difference from two years ago when I saw so many.

Towards the end of my walk, I was surprised to find a snow bank blocking my route. I diverted around it and rejoined the path on the other side, which was wet with snowmelt. I was delighted to see some butterflies puddling on the path.

There were two Cardinals, two Small Tortoise shells and three blues.

The blues turned out to be a Common Blue, a Nevada Blue and an Escher’s Blue, demonstrating nicely the subtle differences between the species.

Had this been my first visit to the Sierra Nevada I would have thought that there were a lot of butterflies, but having visited previously I noticed that numbers were a lot lower than on previous visits. It is interesting to speculate why this would be.

Certainly, there was a lot more snow around, so possibly it had been cooler than in previous years. I also noticed that there were more cattle and goats than I had seen in previous years. Possibly they had grazed more of the wild flowers.

It is good to know that there are a lot of researchers working in the Sierra Nevada monitoring grazing and climate change and their impacts on invertebrates. It would be very interesting to talk to them and find out more about the long-term trends.

Sierra Nevada Butterflies - July 2016 (2)

I drove up to the car park at the ski resort at Hoya De la Mora. This is as far as you can drive, although it is possible to take a mini-bus further up the mountain. As I got out of the car I saw a Bath White, Pontia daplidice. I had seen a number of similar butterflies on the drive up the hill, so it was good to confirm its identity.

I started to walk up the mountain to another area recommended by Mike Prentice. Almost immediately I saw a Purple-shot Copper, Lycaena alciphron gordius.

Then a larger butterfly caught my eye. It turned out to be a Painted Lady, Vanessa cardui. We had just experienced an influx of Painted Ladies in Scotland and evidently they were doing well here, too. I saw another one just a little further up the path.

I was delighted to see so many Apollos, Parnassius apollo nevadensis. The sub-species in the Sierra Nevada has orange, rather than red, ocelli. They seemed a lot more approachable this year and a little later when a cloud came over they all landed and on a couple of occasions I very nearly stood on one! I guess with such large butterflies they need the energy of the sun to keep them airborne.

There were a number of Small Whites, Pieris rapae, flying in the same area as the Apollos along with one or two Small Tortoiseshells, Aglais urticae.

There were also blue butterflies there, which I could only identify by photographing them and enlarging their picture on the camera. They all turned out to be Escher's Blues, Agrodiaetus esheri.

A little higher up the Small Tortoiseshells were replaced by Queen of Spain Fritillaries, Issoria lathonia. The last time I was in Sierra Nevada I very briefly saw one of these a little lower down the mountain, but this time I saw seven or eight.

My reason for climbing further up this barren-looking mountain side was because Mike Prentice had suggested some sites I could check for Zullich’s Blue, Agriades zullichi. I was amazed that there continued to be plenty of butterflies despite the apparent lack of vegetation. I didn’t spot any Zullich’s Blues at the first area he had suggested, but I was over the moon to spot one at the second location, which was at about 2,650 metres above sea level.

I think there were about 15 Zullich’s Blues there and I saw some very similar-looking Spanish Argus, Aricia morronensis, flying with them. These were both new species for me.

It was lovely to watch them with an occasional fly past of an Apollo, which looked enormous compared to the small Lycaenidae. Some Nevada Blues, Plebicula golgus, also joined the party. I spent some time at that location and sat down on a rock with a snack while watching these rare butterflies.

It seemed like such a hostile environment for these small creatures to live in. This was the height of summer, but there was still quite a wind blowing and very little shelter.

Eventually I had to drag myself away as there were so many more places I wanted to explore. However, I was quickly distracted by a Spanish Brassy Ringlet, Erebia hispania. Unlike two years earlier these ones allowed me to take a picture. I saw quite a few as I started to descend the path.

Next I wanted to head down to a green area near the stream lower down the valley ...