Butterflies in a Changing Climate
BUTTERFLIES IN A CHANGING CLIMATE-Andrew Power
Global warming is a fact of life in 2016. It will be a fact of life for a great deal of time to come, but what does it mean for our natural heritage, and for our beautiful butterflies? Will be still have the species we enjoy now, or will we have new, more ‘exotic’ species? It is almost certain that if current predictions prove accurate, we will have a much drier climate during the warmer months of the year, with some extreme droughts. Such conditions are likely to have a great impact on our very best butterfly habitats, occurring as most of these do on skeletal and free-draining soils such as machair, sand dunes, cliffs, limestone grassland and limestone pavement, coastal heaths and grassland. Host-plants for the adults and immature stages will be under great pressure from drought; moisture-demanding plants will wither and the butterflies depending on them will quickly be lost. Repeated years of drought will prevent recovery of the host-plants and butterflies and extinction may follow, even of species that are currently very common. While this scenario seems far-fetched in Ireland at present, climate change modelling is foretelling a greatly different climatic future. A glimpse at what this future might look like is suggested in the following article which is based on “Conservation of the Sinai Hairstreak Butterfly Satyrium jebelia”, the doctoral thesis of Butterfly Conservation member Andrew Power. It describes the plight of a butterfly whose global survival is threatened by climate change…
I’ve always had a passion for wildlife and conservation and this lead me to study Zoology in Trinity College Dublin. I graduated in 2010 and it didn’t me take long to become disheartened with the amount of work available in Ireland for a wildlife conservationist. After quite a bit of shopping around I decided to undertake a Master of Research in the University of Nottingham. Much of their conservation work takes place in the Sinai Peninsula in Egypt and the University of Nottingham has a long established research history with the area and its people. Professor Francis Gilbert (my supervisor) has a deep love for the Sinai and has spent over 25 years researching there, mostly focusing on the protected area surrounding St Katherine. His obvious passion and enthusiasm for the region and its wildlife was one of the major reasons I eventually chose this Masters. We talked through a variety of ideas but it eventually boiled down to one exciting project. It was proposed that I could carry out the first ever study of an extremely rare endemic butterfly found only around the mountains of the St Katherine Protectorate – the Sinai Hairstreak Satyrium jebelia. While I have a broad interest in wildlife I have always been particularly interested in butterflies. I visited the Straffan Butterfly farm on a school tour when I was eleven years old and bought a fold out guide to the butterflies of Ireland made by the Dublin Naturalist Field Club (which I still have and use). My brother and I would spend every summer exploring Carlow and Wexford with that guide, a net and some empty jam jars. I dragged my parents to the Burren every year to go butterfly hunting. My love for butterflies never really left me but I became more involved with birds and mammals as I got older. There is no obvious full time conservation work with butterflies in Ireland; something I hope will change in the future. The Masters in Nottingham was the perfect chance for me to carry out some meaningful research on butterflies and gain some valuable conservation experience that I could take back with me to Ireland.
The Sinai Hairstreak was only discovered in 1974 and other than a basic description there was next to nothing known about it. Ultimately, this project was the perfect chance to carry out some old fashioned, pioneering Zoological research and was too good to pass up! I started work in Nottingham in January 2012. We had a vague idea of the flight season of the butterfly and to err on the side of caution (and to spend more time in Egypt) we booked my flights for a four month field season in Egypt. I was insistent that I was there before the butterfly emerged right up to the very end. My flight out was not until mid-April so I had considerable amount of time to do some preliminary research. This was a little frustrating because we had no idea what to expect and what I would be doing. I had to be prepared for any eventuality and the thought occurred to me that this species could be extinct! Up until that point there were only 14 confirmed records of the species with the latest being from 2001. My priority was to fully map its distribution and get the first ever population estimate for the species, absolutely essential information in wildlife conservation. It would also be impossible not to pick up some other useful information on the way. I researched everything from phylogeny to the best kinds of butterfly nets. The Sinai Hairstreak is intermediate in size between the Green Hairstreak Callophrys rubi and Purple Hairstreak Neozephyrus quercus that are found in Ireland. The underside is relatively similar to the Purple Hairstreak; both have short tails with orange scales at the base and have a characteristic white streak running across the forewing and hindwing. The Sinai Hairstreak is probably most closely related to the Blue Spot Hairstreak Satyrium spini found throughout western Europe as far east as Iran. The genus this butterfly belongs to is typically found in temperate regions of Europe and North America so why is it found in Egypt much further south than its cousins? The Sinai Peninsula and Egypt were once much cooler and had a much more European climate. Sinai Hairstreaks were probably much more widespread in the past but as the region became warmer the species started to die out. Butterflies are reliant on the distribution of their larval foodplant (what their caterpillars feed on) and it is likely that the Sinai Hairstreaks larval foodplant – Sinai Buckthorn Rhamnus dispermus – could not survive the extreme heat. The only way they could survive was to either move north to cooler climates or to move to higher altitude where the environment is much cooler. The St Katherine Protectorate boasts the highest mountains in Egypt and has the coolest temperatures, making it a biodiversity hotspot and the last remaining home of the Sinai Hairstreak. I spent a lot of time reading a PhD thesis by Mike James. He carried out the first ever study of the Sinai Baton Blue Pseudophilotes sinaicus. His thesis was the bible as far as I was concerned and a real inspiration. In one field season he carried out a 97 consecutive day Mark-Release Recapture experiment. Interestingly the Sinai Baton Blue was recently discovered in Saudi Arabia which makes the Sinai Hairstreak the only endemic butterfly to Egypt.
The St Katherine Protectorate is one of Egypt’s largest National Parks and is situated in the South Sinai, spanning an area of 4,350 km². Known as the ‘Roof of Egypt’ the area is predominantly mountainous with deep extensive dry valleys ‘wadis’ cut throughout the landscape. At the heart of the Protectorate lies the city of St Katherine, situated at the foot of Mount Sinai, where according to Abrahamic religions Moses received the Ten Commandments, and Jebel Katherine, Egypt’s highest mountain at 2,641 m above sea level. It is also home to the Monastery of St Katherine, the oldest continuously working Christian monastery in the world. The Sinai Peninsula is wedged between Africa and Asia and is very close to Europe; the area has an unusual blend of flora and fauna from these continents. The high mountains are sometimes covered in snow during the winter, and snow melt provides the area with water throughout the rest of the year. The relatively high amount of water available compared to the rest of Egypt has resulted in a high diversity of plants and animals. There are almost 500 species of plant in the area, many of which are endemic. The IUCN have declared the area as one of the most important centres for plant diversity in the Middle East. The area is also important for insects; there are 61 species of butterfly in Egypt (almost twice that of Ireland) and two-thirds of them have been recorded in the St Katherine Protectorate. I would be looking for the Sinai Hairstreak around the high mountain peaks in the heart of the massif.
I flew to Sharm El-Sheikh airport at the southern tip of Sinai (a popular resort town for sun seekers) and was picked up by a Bedouin from St Katherine. The word Bedouin is generally used to describe Arabic tribes of a nomadic lifestyle that live throughout North Africa and the Middle East. However, the Bedouin in St Katherine live a more settled lifestyle as they take advantage of the tourism to Mount Sinai and the Monastery of St Katherine. They belong to the Jebelia tribe and the Sinai Hairstreak is named after them – Satyrium jebelia. They are the guardians of the Sinai Hairstreak. I based myself at Fox Camp, lying at the foot of Mount Sinai. I was greeted by some familiar faces because there was a team of different Nottingham researchers there looking at everything from Hyenas and Wolves to the birds and bees. I was invited to join my fellow researchers and some locals by the fire in the Bedouin tent. This would become a daily routine, talking to my Nottingham friends, the locals and strange tourists over Bedouin tea.
The first thing I wanted to do was to map all the host-plants, Sinai Buckthorn Rhamnus dispermus (a rare and endemic species in its own right) before the butterfly was due to emerge. If I could find the host-plants I could find the butterflies. This proved a little more difficult than I originally thought. I had to rely on local knowledge to find these plants and the Sinai Buckthorn has no real value to the Bedouin so many people don’t recognise it. They often confused it with the similar looking (and more common) Sinai Hawthorn Crataegus sinaica. This lead to being sent on more than one wild goose chase. It is illegal to walk the mountains in the Sinai without taking a local guide with you. This also proved a bit of a nightmare at the start as the first guide I was given was 14 years old and didn’t speak English. I didn’t care too much that he didn’t speak English but he just didn’t understand what he was supposed to be doing, through no real fault of his own. He would take me to the top of a mountain and treated me like a tourist, not a scientist…..so I paid him and sacked him! Eventually I settled on my guide – Suileman Abusada- who spoke English. Unfortunately he didn’t really know anything about the plant but pretended he did. He was so eager to secure my services that he gave me rugs and gifts after our first walk. While he didn’t know much about the host-plant he did know the area very well, was a good cook and was willing to spend days on end in the mountains with me while I looked for the plants. I used a GPS to mark the location of any buckthorns I found and started the mapping process. Luckily there was one Bedouin who knew exactly what I was looking for – Nasr Mansour. He was incredibly knowledgeable and knew the local flora and fauna inside out. He was already a guide for someone else but I did manage to get him to bring me to some locations and educate Suleiman about what I was looking for.
The next few weeks followed the same pattern, long day trips to Wadis (valleys) around the protectorate looking for this shrub and enjoying the spectacular scenery of the region. The Sinai Buckthorn has a nasty habit of being found in remote areas and along steep rocky slopes. They were even found near the top of Egypt’s highest mountain! On the 10th of May the project really took off, I was climbing up the side of a particularly tedious hill to check out what I expected were two ragged Sinai Buckthorn. The Buckthorn was usually found in relatively high numbers so one or two trees were hardly anything to write home about. I was wrong; I saw the butterfly for the first time (several weeks before they were due to emerge). It was such a relief to the see the species I had been studying for the past four months for the first time. First off I photographed the butterfly (probably the 3rd ever photograph for this species). I then proceeded to watch them, trying to get familiar with their behaviour. I knew I had an awkward species on my hands as they were quick and would often disappear out of sight chasing after other species of butterfly or just vanishing altogether. Many arid species (such as the Sinai Baton Blue) rarely move more than a few metres but it was immediately clear that the Sinai Hairstreak was a strong flier. I started to practice catching them which was made all the more awkward because the Sinai Buckthorn is covered in thorns, fixing my net was a weekly occurrence. By that time I was fairly satisfied that I had mapped all the host-plants in the region and I knew that it was time to start to try and estimate the population. I had found six large sites containing Sinai Buckthorn and a couple of sites with one or two hostplants. I was confident the butterfly would be present in the larger sites despite it having only been recorded in two of the locations. My assumptions were correct and each of the six sites was teeming with butterflies! Hunting season was open! Finding Sinai Hairstreaks reminded me of looking for Green Hairstreaks in the hills around my home in Carlow. You wouldn’t see any Green Hairstreaks until you got to a gorse bush which could be crawling with them.
I wanted to have a reasonably good population estimate so I decided to visit each site for five consecutive days to carry out a Mark-Recapture-Release experiment. I would spend six and a half hours each day (8:00 – 16:30) for five days catching butterflies. This sounds easy but this was the hottest part of the day and the trees could be scattered along various different steep slopes. More often than not I was also competing against a dodgy stomach. Even the local Bedouin don’t like being out in the heat of the day, Suleiman rarely helped and spent most days sleeping in the shade. The sites were quite remote so I would camp for the five days with Suleiman. We would bring a camel, Abdul, with us to carry our food and water. Each butterfly captured was given an individual mark with a felt-tip pen through the net and released as quickly as possible. The location, behaviour and time were recorded for each capture or subsequent recapture. By looking at the proportion of marked and unmarked individuals, I estimated the population size using Eberhardt’s geometric model. Maps were created using Google Earth showing the distribution and movements of captured Sinai Hairstreaks and the distribution of Sinai Buckthorn. I used this method on all the sites except for one (the Wadi Ahmar region) because of the apparent high population of Sinai Hairstreaks there. For this site, I visited once marking as many butterflies as I could and then returned five days later to count the proportion of marked and unmarked individuals. The population size was estimated using the Lincoln index. Carrying out population estimates at each site took a good chunk of time and I was afraid the flight season would end while I was still doing it. As a result I worked non-stop during this time which was pretty intense but very exciting. I took notes on everything I could from predators to food-plants while I was catching the butterflies. I also decided to assess the habitat and larval foodplant requirements by recording 11 different features from the height and width to the slope and aspect of every single Sinai Buckthorn, 553 in total. This was much less enjoyable and much more labour intensive than catching butterflies!
One of my resounding memories of working in the high mountains of the south Sinai was the smell, the wildflowers and shrubs produce an astonishing fragrance. Horsemint, Oregano and desert Lavender were all plentiful and occasionally added to our tea! I spent four months taking in all the sights, sounds and scents of St Katherine. Mallow Skippers Carcharodus alceae, Mediterranean Skippers Gegenes nostrodamus and Mediterranean Tiger Blues Tarucus rosaceus were a common sight flying low around my ankles as I walked through the scented valleys. The large Desert Graylings Hipparchia pisidice also kept low to the ground and would frequently land on myself or Suileman as we took a break, perhaps attracted to our sweat. Long-tailed Blues Lampides boeticus, Pomegranate Playboys Deudorix livia were also common, flying higher up around the taller shrubs frequently fighting with the territorial Sinai Hairstreaks around the Buckthorn trees. Saharan Swallowtail Papilio saharae, Clouded Yellow Colias croceus and Painted Lady Vanessa cardui were the bigger, brighter butterflies that I would regularly see gliding past me. The Saharan Swallowtails in particular were always a joy to see flying powerfully overhead.
It wasn’t long before August came around and the Hairstreaks were completely gone by the time I left. The heat in August is blistering and I was ready to leave after four long months. I returned to Nottingham with a mountain of data and writing to get to work on. I estimated the total world population of Sinai Hairstreaks to be 1,010 individuals (less than Snow Leopard and Giant Panda). This is very low but unlike many endangered species the Sinai Hairstreak has a naturally small population size. As I mentioned before, the Sinai Hairstreak is a relict species that has become isolated on a mountain-top island to avoid the higher temperatures of lowland Egypt. The good news is the Sinai Hairstreak is not under direct threat from people; the foodplant is not used by the locals (they harvest the foodplant of the Sinai Baton Blue) or grazed heavily and the habitat is not being destroyed by human development. I was also keen to establish what population structure the Sinai Hairstreak has. Basing a conservation strategy on the wrong population structure has proved costly in the past. We can do this by looking at the proximity of sites and the dispersal ability of the butterfly. This definitely needs more research but we now know the Sinai Hairstreak is a good flier (I had one butterfly travel a kilometre in a day). The Sinai Hairstreak may exist as a metapopulation (a group of populations separated from one another in a landscape but which are connected by occasional dispersal or movement by individuals) or a panmictic population (a population that has no restriction on mating, an important feature in a population that exists in low numbers and distributed over a large area, especially in the case of some butterfly species that also have a prolonged emergence period). It certainly appears to be in a better position than the Sinai Baton Blue. If the Sinai Baton Blue becomes locally extinct in one patch of suitable habitat it is likely that patch will never be recolonized again due to its extremely poor dispersal ability. I also found an individual Sinai Hairstreak that was 25 days old (very good for a butterfly) which is another indication of how robust it can be. The bad news; the only serious threat that the Sinai Hairstreak is under is global warming; if current climate-change predictions are correct the habitat may become unsuitable and there may be no way for the Sinai Hairstreak to survive. They have already reached the top of Egypt’s highest mountain and have literally nowhere left to go to escape the heat. Global Warming is having a big impact on butterflies across the world. An analysis of butterfly surveys dating from 1992 to 2010 in North America showed a sharp increase in sub-tropical species that have expanded northward from warmer climates, indicating how butterfly ranges can change in response to global warming but also how quickly climate change is affecting species distribution. Similarly a study of European butterflies showed that the ranges of many southern species have retracted northward.
It was a pity that I did not get to spend more time looking for different butterfly species.
When I was looking for host-plants or the Sinai Hairstreak I had tunnel vision, everything else was ignored! I never saw the famous Sinai Baton Blue, possibly the world’s smallest butterfly. I had only one field season and I was determined not to be distracted, easier said than done. Of course I did have time off but looking for butterflies was not a priority! I spent that time exploring other aspects of Egypt such as the Pyramids of Giza, the Red Sea and the vast deserts. My work in Sinai was definitely worth it and was recently published in the journal of Insect Conservation and can be found here – http://link.springer.com/article/10.1007%2Fs10841-014-9707-8. After I finished my Masters I was invited to attend an IUCN Red List Assessment Workshop on Mediterranean Butterflies in Malaga as an expert in Egyptian butterflies and I was involved directly in the creation of a new regional Red List for Mediterranean butterflies. The information I collected was used to have the Sinai Hairstreak red listed for the first time as Vulnerable. Getting a species on the Red List is a necessary first step in highlighting the conservation concern of a species and I was delighted to get the ball rolling for the Sinai Hairstreak.
More photos of the wildlife and scenery of the Sinai can be found here.