Sunday 15 September 2019

What Do Butterflies Do In A Drought in Portugal When Their Food-plants Are Dead?

How do Small Coppers and Meadow Browns survive a drought?
Small Copper (Lycaena phlaeas) Photo in Public Domain/Pixabay

As I walk the burning sandy path through local scrub and woodland here in Portugal I often wonder where do the remaining butterfly females lay their eggs? The once lush vegetation has been shrivelled in the heat of the ongoing drought and what is left is tinder-dry and brown. The Meadow Brown and Small Copper are two butterflies confronted with this problem. Earlier in the year the same location was covered in masses of wildflowers, clumps of Rockrose were in bloom, green grass was plentiful, as were other forms of greenery. There were lots of butterfly species to be seen, including, the Swallowtail, Clouded Yellow, Speckled Wood, Red Admiral, Green Hairstreak, Spanish Festoon, Small White, Bath White, and Small Copper.
Meadow Brown (Maniola jurtina) Photo: Public Domain/Pixabay
Meadow Browns become common in early summer here in the same location. It looks like a paradise for butterflies, and for other forms of wildlife, but as the long days of sun and heat take their toll, all short vegetation dies back to the ground, shrivels up or becomes dead and brown. The butterflies seen flying become less and less as the drought intensifies its hold with no rain at all, or if there are a few scattered showers, the water evaporates as soon as it falls. This year has been particularly bad. Even plants like Echium creticum (Cretan Viper’s Bugloss) failed to bloom successfully and shrivelled in the heat.
Echium creticum in the drought (Photo: Steve Andrews)
One of the only plants that has stood up to the drought conditions is the Rush Skeletonweed, which is an invasive species suited to very arid and semi-desert conditions. On top of this, the local Portuguese authorities have employed teams of workers to clear the land of dry scrub and vegetation in many places. This is a new legal move aimed to be a precaution against wildfires, which have become a new ‘norm’ here.
Land clearance (Photo: Steve Andrews)
In earlier summer I have seen groups of the last of the first emergence of Meadow Browns sheltering under the shade of some old trees here. A few Scabious plants provide nectar and some grass is still alive right under the trees and under bushes. Most other butterflies, such as the Swallowtail and Small White are sustained by the gardens of the town where people water their plants, and some caterpillars can feed on Rue and and plants in the cabbage tribe respectively. But my question remains for the next brood of Meadow Browns and the Small Coppers. As for the Speckled Woods they seem to have vanished. The Meadow Brown female must find grass to lay her eggs on but there is none still green. I wonder, is it possible for the larvae to feed on dried up grass?

The Small Copper I think has an even more difficult, if not impossible task. It has to find any species of Sorrel (Rumex species) or Dock. From what I can tell from my studies in books and online there are no other food-plants. Of course, I do not have as keen a sense of sight and smell as a butterfly, but I am still very able to observe signs of life in any location. As far as I can tell, all Sorrel species have shrivelled away to the ground. I cannot find any. Meanwhile, every time I walk the woodland path here I witness several male Small Coppers in battles and chasing each other. There is an established colony and they don’t seem to mind the heat or intense sunshine. But where can the females find anywhere to lay their eggs? Had I known how bad it was going to get, maybe I could have grown some Sorrel in pots in the garden? If I had taken a pot to the Small Copper territory I am sure the females would have gladly used it for their eggs. There is no Sorrel there as as as I can see. Even flowers of any sort to provide nectar are in very short supply with just a few dried up and struggling Carline Thistles.
A mile or so from this location I was walking down the main road and came upon a single Meadow Brown female fluttering along a dried up and strimmed roadside. She did find a single Scabious in bloom that had missed the strimmer in the land clearance effort but there was no green grass anywhere to be seen. But she had her job to do, she must keep going in search of a few blades of grass on which to lay here eggs. Looking around didn't give a very optimistic outlook for her, and if she was blown or strayed into the traffic she would become another victim of roadkill. Living here in Portugal has shown me graphically one reason that butterfly species are declining: they are unable to find food-plants in good condition because the natural growing seasons have been disrupted and destroyed by the terrible effects of the Climate Crisis. I wonder how many other people here are wondering how the butterflies manage?