Category Archives: Tenerife

Fire and rain (Darwin’s Unrequited Isle part 4)

I’ve seen fire and I’ve seen rain,

I’ve seen sunny days that I thought would never end…

On Sunday I arrived back in Tenerife with my students for our annual field course. This is now my 14th trip to the island and James Taylor’s song Fire and Rain provides an apt soundtrack to some of what we’ve seen during our current stay on Darwin’s Unrequited Isle.

When we were here in 2013 the pine forest on the slopes south of Las Cañadas looked black and bare, having burned a few months previously:

Trunks of the endemic Canary Island Pine Tree (Pinus canariensis) were blackened and showed very little foliage:

That was April 2013. Twelve months later, following one of the wettest winters that Tenerife has experienced, we were greeted with a sight of rejuvenation. The pine trees are re-sprouting and the landscape is full of colour as plants such as Erysimum scoparium, Echium wildpretii and Argyranthemum tenerifae flower in abundance. There are also more butterflies that I can previously recall seeing in these habitats:

James Taylor’s song is about loss and grief; but from fire and rain also comes new life and new beginnings, a positive environmental stimulus for the endemic biodiversity of Tenerife. The fire has opened up the vegetation, allowing seeds to germinate, and the winter rain has stimulated growth and flowering in these summer-drought habitats.

….I’ve seen lonely times when I could not find a friend,

But I always thought that I’d see you again.

Garlicky archipelago

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“Garlicky” is a great word, redolent of hot, pungent flavour and nose-filling odour: a Pavlovian word that ignites the senses as it’s uttered. Perhaps I love the word because garlic is one of my favourite vegetables, a pleasure to both eat and grow. A Garlic Festival is therefore not to be missed, and my family and I had the opportunity to attend one on the Isle of Wight during a short holiday a couple of weeks ago. We were joined by university friends I’ve referred to previously, as the first one of us to reach a half century celebrated his 50th birthday. There was more to the festival than just garlic, but for me its highlight was seeing the sheer variety of different garlic types that can be grown, testament to how this vegetable has been modified from its ancient wild origins in central Asia. Karin and I bought seed bulbs of four different varieties as additions to the horticultural biodiversity of our vegetable plot, to be planted later in September. These included the notable Elephant Garlic with its massive individual cloves, which, I’ve just learned while researching that link, is not a true garlic at all but rather a variety of leek. We live and learn!

Archipelago is another great word and the time we spent on the Isle of Wight, travelling over by ferry from Southampton, served to remind me that the British Isles, with over six thousand islands of various sizes, is by any standards a significant archipelago. Since at least the explorations of Alexander von Humbloldt, island groups have been known to host unique species, isolated taxonomically and physically from their closest continental relatives. Darwin’s later researches showed that archipelagos such as the Galapagos Islands are important as natural evolutionary laboratories, and in previous posts I’ve briefly discussed his unrequited desire to visit to the Canary Islands. The Isle of Wight is too close to the continent of Europe to have evolved any unique biodiversity but I did pick up the hint of a subtle Island Biogeographic Effect whilst compiling a list of all the bird species I saw over the course of the week. The list topped out at about 30 species, which I thought was rather low. Some of the omissions surprised me (not a single blackbird, for instance) and I saw very few individuals of some other common British species. Now, it could be due to my lousy birding skills I suppose, but it could also be due to the fact that we were on an island, even though it’s less than 1500m across The Solent to the mainland at its closest point. This is close enough for bumblebees to fly to the island: I’ve seen them shadowing the ferry. But nonetheless it might be far enough to affect both the diversity and population sizes of the bird life. Enough wild speculation; I’d be interested to know what serious ornithologists who actually know something about the subject make of this.

As I finish writing this post I’m on the other great island of my home archipelago, sitting in a bar in Terminal 2 of Dublin Airport. I’ve been working at University College Dublin as external examiner for their MSc Applied Environmental Science course. It’s been a fun couple of days reading theses and interviewing chatty, engaged students, which began with a dawn alarm yesterday in order to get to the train station and then Birmingham International in time for a 0850 flight. Whilst waiting for my taxi I popped into the garden and paused to enjoy the early morning stillness before opening up the chicken coop. A large flock of black-headed gulls passed low above me, backlit by a thin sliver of moon and silent except for the shuffle of feathers. From the direction they were travelling I think they were heading from a roost on Pitsford Water and on to destinations unknown. The garden was also busy with early risen blackbirds and a couple of flitting bats, whilst a little later my taxi passed a rangy fox idly trotting through low mist on the Racecourse park. It was urban biodiversity at its most sublime.

All this talk of Northampton is making me feel homesick to be back with the family (Karin, kids, cats and chickens) and start planting garlic. But there’s just time for another Guinness before my gate opens. Sláinte!

A coiled Spring

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April, according to T.S. Elliot, “is the cruellest month”. Not sure about that, though April 2013 proved to be both frustrating (as we in northern Europe waited for Spring to arrive) and busy, as I tried to pack in a whole set of activities. That’s my only excuse for not updating my blog, so the aim of this post is to catch up with biodiversity-related activities and observations over the past few weeks.

Just as iconic decades begin part-way through a given ten year period (the 60s didn’t really kick off until about 1963, for instance) so April for me actually began at the end of March. In the last week of that month I completed my formal teaching for the term and celebrated the first anniversary of the Nene Valley Nature Improvement Project. I also picked up my daughter Ellen from Heathrow Airport, on a two week visit back from working in China. On the way I counted over 20 red kites flying near the M40 motorway – what an incredible success story their re-introduction has been!

One of the reasons Ellen had come back was that I was due to give my inaugural professorial lecture, entitled “How many bees does it take to wake up in the morning? The importance of biotic pollination in a changing world”. Another reason was to to celebrate my eldest son Patrick’s 18th birthday the following day. Both once in a lifetime events and both had family at their heart. It was a great week.

Some leave time followed, much needed after what seemed like an endless 12 week university term, during which I hoped to plant potatoes and do some other work in the garden. But Spring refused to uncoil. The northerly winds brought cold weather that froze all vernal activity in the act. Flower and leaf buds were there waiting to unfurl; insects would occasionally appear then just as quickly disappear; and birds clearly wanted to get on with the important activities of raising young. But all was delayed. One could sense the tension, the build up of seasonal energy, biology waiting to happen.

A talk at Earlsdon Gardening Club near Coventry on Monday 8th April was well received and took my mind off the organisation of the biennial Bumblebee Working Group meeting on the 11th. This semi-formal get together of scientists, NGOs, and other Bombus-minded individuals, shifts between venues every two years. At the last meeting in 2011 I volunteered to host the next event and then put it out of my mind for 18 months. Organising a scientific meeting is always a bit of a mad panic as the day draws closer and one wonders if anyone will actually turn up. But as it turned out the event was well attended, with over 80 people listening to talks on diverse topics including the effects of neonicotinoid pesticides on bumblebee colonies; I’ve uploaded a copy of the programme.

Friday 12th April was a frantic dash around office and lab to get books, equipment and sundries organised for our annual undergraduate Tenerife Field Course, which was flying out on the following Sunday. A great time was had by all as we explored the biodiversity of Darwin’s Unrequited Isle and we came back with a wealth of great data plus not a little sunburn. No matter how often I tell students that they really need to wear a hat and use sun block, some will never listen.

Arriving from Tenerife early on Monday 22nd, I slept for a few hours then was back at the university for the oral PhD examination of Hilary Erenler, whose work I have mentioned previously. These exams are always stressfull for both student and supervisors but in the event Hils performed wonderfully and passed with only minor amendments. A great result! Now looking forward to publishing some papers from that work.

April ended, and May began, with a change in the weather. Much warmer winds blew in from the south west and life suddenly erupted: pressure had been removed from the coiled Spring. Lots of pollinators appeared in our garden including: Anthophora plumipes, one of my favourites for its glossy, black females and aggressively flower patrolling males; the relatively newly arrived Bombus hypnorum; the bee fly Bombylius major; and several different butterflies.

Clearly it’s time to plant those potatoes!

The Roof Tiles of Chirche (Darwin’s Unrequited Isle part 3)

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Architectural analogies in evolution are not new. The most famous (and, in its time, controversial) is perhaps Gould and Lewontin’s “Spandrels of San Marcos and the Panglossian Paradigm” in which these prominent evolutionary biologists suggested that some features of the biology of species were secondary “emergent” structures which formed from the conjunction of other, evolved characteristics. That is to say these features are not evolved in their own right, they are simply by-products of the evolution of other factors. In this respect they are like “spandrels” – the ornamented space between two structurally significant elements, for example the arches and the domed roof they uphold in the Basilica di San Marco in Rome. Gould and Lewontin were following a metaphorical path that had been traversed by many major figures in evolutionary biology. Most notably, Darwin used the notion of the architect, contrasting natural with artificial selection, in a number of his books, including “The variation of animals and plants under domestication”.

Another architectural analogy occurred to me over the past couple of weeks, time Karin and I have spent back in Tenerife pursuing field work funded by a small grant from the British Ecological Society. We are staying in a cottage in the pretty village of Chirche in the west of the island. The older properties, our rented castita included, are roofed with traditional, hand made rough clay tiles that are slim, curved and tapering towards one end. Tiles are carefully laid curve up and curve downwards in alternating rows so as to both shield the building from the weather and to shed the rain from the roof in the channels formed by the up-curved rows. These same tiles are used along the ridges of the roof, in contrast to roofing back in the UK where differently shaped tiles would serve for roof and ridge. Not only that but the same basic curved and tapering form serves as a structural element for the tops of walls, as half pipes to direct the flow of water, and as building blocks for chimney stacks, etc.

It’s a wonderful example of economy of manufacture and purpose, using the same basic element to serve multiple functions. What has this to do with biodiversity you ask? It’s a fitting observation for this trip, in as much as we are studying flowers and their visitors. Flowers are another great example of the economy of evolution: all of their basic elements (male stamens, female stigma style and ovary, petals and sepals) have evolved from the same basic botanical element – leaves. If that seems unlikely take a look (a really close look) at some of the fancy, highly bred flowers for sale at your local garden centre or plant nursery. Some will have leaf-like structures deep within the flower where genetic mutations have resulted in the expression of organs rather more like their ancestral form than like stamens or petals.

The purpose of returning to Tenerife is to collect more data as part of an on-going project I’ve been running within our undergraduate field course. The Canary Wallflower (Erysimum scoparium) has flowers that change colour; they are pure white when they first open and from the second day onwards they darken to violet then ultimately purple, staying on the plant for up to 10 days. At the same time the flowers stop producing nectar. The pollinators learn to associate white flowers with more reward and focus their attention on the newly opened blossoms. This is clearly an evolved strategy as it benefits the plant to have its most recent flowers preferentially visited, rather than the older flowers that have already received pollen.

In an earlier paper we demonstrated, by removing purple flowers from experimental plants, that these older flowers act as a long-to-medium range advertisement to pollinators (the plants look purple from a distance). It’s a very intriguing system. We now have about 10 years of data showing that the main pollinator is an endemic solitary bee (Anthophora alluadi). But there seems to be some variation between years, with a wider range of different bee species present in years following very dry winters (such as this one) when there are fewer other plants in flower. So the idea that we are testing is that the relative specialisation of the plant (i.e. how many pollinator species it has) is context dependent: in some years/sites it is a specialist, in others a generalist.

Biodiversity is not fixed in time or space. It varies at all scales and, for this plant and its pollinators, the biodiversity of interactions between them is stable only over modest time periods. Over the millions of years these plants and bees have existed in the Canarian archipelago, their exact roles within the system have probably varied enormously, like actors improvising their parts dependent on the whims of external forces, in this case weather conditions. The roof tiles of Chirche saw little rainfall during the last winter; bad for the local farmers and the other people who depend on this rain. But good for ecologists wishing to study how variation in climate can affect biodiversity.

Darwin’s Unrequited Isle (part 2)

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During our field trip to Tenerife the two vehicles covered over 900km each, which is not bad on an island only about 80 km in length along its main axis. We experienced temperatures that ranged in one day from a few degrees above freezing to the mid 20s centigrade. Up in the laurel forest I mentioned last week the weather was cold and foggy, whilst in the Malpais de Güímar it was hot and dry and we sunburned. We put in long, tiring days of walking transects, identifying, measuring and recording plants, and observing bee and bird behaviour. And there were ticks that had to be picked off skin in one of the barrancos we visited. The Romantic Adventurer within me would therefore like to believe that the aching limbs and upset stomach I suffered when we got back to the UK were due to some exotic virus passed on by these blood sucking arachnids. However the Cynical Traveller thinks it was more likely to be due to a hamburger of dubious age and temperature that I ate at Tenerife Sur airport on the way home.

The Tenerife Field course was hard work but great fun and I think (I hope!) the students learned a lot. At the very least they have now experienced just how diverse habitats can be on a small oceanic island. In that diversity rests both the beauty of Tenerife and part of its scientific interest. This variability in habitats is a result of its altitude (Tenerife is the second highest oceanic island in the world after Hawaii), subtropical latitude, climate, proximity to Africa, and geological history. In a single day one can travel from high alpine habitats, through sub-alpine desert scrub and pine forest, into succulent dominated low altitude desert scrub, back up to laurel forest (a form of subtropical rainforest), as well as distinct deep valley and strandline vegetation.

Add to this the occasional hurricanes and forest fires that tear across parts of the island, not to mention volcanic eruptions, plus the human impact, and it makes for a rather dynamic environment at a range of time scales. These processes probably add to the overall biodiversity, as predicted by the intermediate disturbance hypothesis, plus formation of new land area can select for novel proto-species. It begs the question of whether volcanic oceanic islands are more diverse than their coralline counterparts, which we might expect to be less dynamic environments. Has anyone investigated this? That’s one of the things that keeps my interest in biodiversity going: there are too many questions for a single lifetime.

I’m hoping that “Darwin’s Unrequited Isle” will take off as a new name to refer to Tenerife, replacing the Island of Eternal Spring cliché it currently holds (and shares with Madeira). Especially as many of the days we were there were spring-like only in the sense that they were wholly unpredictable. On the roof of Tenerife, in Las Canadas, our car thermometer registered 3 degrees centigrade at 1100am. And it snowed. I’ve never experienced that at this time of the year. We’ve had torrential rains storms but never snow. In late April. In the “Island of Eternal Spring”. I’m not complaining though, it all adds to the fascination of this most interesting of islands and is why we come back year after year. It’s also better conditions than my colleagues Duncan McCollin and Janet Jackson endured with those students who elected to do field work in Northamptonshire rather than Tenerife. For most of the time we were away it poured with rain back home, turning the drought-imposed hosepipe bans into flood warnings in some places.

Needless to say, the day of the snow was the day we were due to make some observations of bee behaviour. By and large bees don’t like snow and low temperatures ground most of them. So that planned activity was delayed until later in the day when it finally warmed up sufficiently for them to start flying.

This theme of variability in the weather, on a day-to-day basis and compared to previous years, was a recurring one all week. Tuesday was hot, as I recounted in my previous blog. But Wednesday was a huge contrast as we headed up into the cold, wet laurel forests of the Anagas Mountains. It’s always a little chilly on this part of the island due to the prevailing moisture-laden trade winds, but this year was colder and foggier than I can remember. The students collected data on the distribution of plants up a vertical cliff face that we can compare to similar data from another site collected last year. I’m intrigued by the way succulent plant groups such as Aeonium and Monanthes are able to survive on these water limited, nutrient poor environments, vertical versions of the desert scrub lower down the mountains. These succulents add to local plant species richness within the forest and provide nectar and pollen resources when they flower, increasing the overall levels of biodiversity of an already diverse habitat.

As well as studying plant diversity we also did some work with the animals of Tenerife. The bees I’ve already mentioned, but for the first time we also made some observations of how bird behaviour changes in tourist areas compared to more isolated spots. Even within a very short distance, no more than a few hundred metres, it’s clear that bird diversity, abundance and range of observed behaviours were greater in the areas where tourists congregate to barbecue and relax. We did some similar work with lizards for a few years and found that they were bolder close to tourist car stops than further away. Humans can impact the life of this island in very subtle ways.

We also spent a morning with volunteers from the Atlantic Whale Foundation (AWF) on one of their trips out to record individual whale and dolphin activity off the south west coast. The AWF piggy backs on one of the commercial whale watching boats and the students are encouraged to think about the synergies and tensions between the conservation-motivated scientific observation of the AWF and the commercial motivations of the tourist boats. It gets to the heart of what “eco-tourism” is all about and the point at which it does more harm than good. The only strong opinion that I have about it is that the value of eco-tourism is context dependent; some activities are better than others in some circumstances but not others. Regardless, the trip is always popular with the students (except one year when a student spent the whole time aboard with her eyes closed, suffering chronic sea sickness) and this year was exceptional, with great views of bottle nosed dolphins and pilot whales, as well as long distance spottings of common dolphins and a 20m fin whale.

The final day of the trip, prior to getting to the airport, is traditionally spent at the Pyramids of Güímar ethnographic park where the students discover some of Thor Heyerdahl’s left field views about possible pre-Columbian links between Canarian, Mediterranean and New World peoples. Whatever the truth behind the origin and function of these enigmatic structures, the visit is a pleasant way to end the field course. Nestled within the protective bowl of the Güímar Valley, I often wonder if it’s a coincidence that the Güímar structures look out towards the three cinder cones adjacent to the Güímar Badlands. Approaching from the south along the TF1 road, these hills take the form of a heavily pregnant woman lying on her back. Was it of symbolic significance to the ancient Tenerifeans in the days prior to the Spanish conquest? I like to think so though we probably will never know.

A small grant from the British Ecological Society means that I’ll be back in Tenerife at the end of May for ten days to do some follow up field work. Hamburgers will be avoided.

Darwin’s Unrequited Isle (part 1)

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A busy week of biodiversity-related activities terminated last Friday in a frantic rush to make sure everything was organised for this week’s field course in Tenerife. The field course has been running for 10 years and has proven to be both popular with students and productive, generating data for a couple of research papers, with more in the pipeline.

Tenerife is an extraordinary island as Charles Darwin recognised; it’s the place that Darwin really wanted to go to when he embarked on H.M.S. Beagle, though he never made it due to the Beagle having to be quarantined before anyone was allowed onto the island. The captain decided to sail away and Darwin was devastated. Hopefully the rest of his trip made up for it, but it’s interesting to speculate whether Darwin’s ideas about evolution may have taken a different path had he been able to visit the Canary Islands, in many ways an Atlantic analogue of the Galapagos……but I’m getting ahead of myself…..this week I hope (time willing) to post some updates about out Tenerifean activities. But back to last week.

The comments sections below the articles on the Times Higher Education Supplement are frequently mires of vile, obnoxious trolling that would embarrass even Shrek. However an interesting article by Alice Bell has raised a debate about what exactly it is that scientists (and other academics) should be writing. Widening science communication should also include giving talks about one’s work to a non-specialist audience. Which is exactly what I did on Wednesday evening when I spoke to an audience of 65 beekeepers, gardeners and farmers in South Warwickshire. They were very attentive and asked some insightful questions for about 40 minutes after I’d finished speaking, stopping only when someone mentioned that the tea and biscuits were ready. All told it was a 90 mile round trip through heavy rain but worth it for such an engaging audience.

Earlier that morning I had been interviewed by BBC Radio Northampton about a report that has just been released indicating that the “native” [sic] Black Honey Bee variety is more common in the British Isles than previously thought. Lovely. Good news for the beekeepers I told them. Now let’s pay a bit more attention to our 250 REALLY native bees, many of which have declined numbers, and 23 of which have gone extinct since 1800. Not to mention the butterflies (though there’s recently been some good news as far as they are concerned too) and the hoverflies and other pollinators.

Thursday was Think Tank day for the SEED project and I took part in the biodiversity session, which was ably chaired and coordinated by Gareth. It went as well as we could have wished and hopefully some concrete partnerships are going to come out of it. But ultimately it was a talking shop and biodiversity should be about doing and experiencing more than talking. Which brings us back to Tenerife.

On Monday we took the students up to the Guimar Badlands (Malpais de Guimar) a 40 minute drive north east from where we are staying in San Eugenio. I like to take students to Guimar on their first day in the field: the pine and laurel forests that we visit later in the week are physiognomically similar to such forests in Britain. But the succulent dominated xerophytic scrub of Guimar is utterly unlike anything that most of them have experienced previously. The field work we do at this site is always related to plant community structure, trying to understand how the biodiversity of the primary producers is “organised”. There’s lots of different ways to measure community “organisation” in an ecological sense, of course, and this year we are looking at how the plant community changes along a gradient from the strand line limit of the vegetation, inland and away from the salty influence of the sea. It’s an exercise I’ve wanted to do for a while because it’s always been clear that the plants DO change; we’re just never put numbers on it. So we ran out four 120 metre transects and identified all of the plants that they intercepted at 5m intervals. Lots of student frustration as they used a combination of identification keys, hints from me and guesswork to put a name to these unfamiliar species. But by the peak of the day’s heat in the mid afternoon we had a data set and several sunburned students [no matter how often you mention the word “sun block” there will always be some who think they don’t need it].

Back at our apartment complex there was time for a rest/shower/power nap, depending on your preference, before we reconvened to enter the data into spreadsheets and start generating some graphs. And these preliminary data look really good, showing how the salt tolerant halophytes are replaced by the various euphorbias and other species that dominate the rest of the Badlands within about 40m of the lower limit of the vegetation, with other species even less salt tolerant and only making a show after about 90m. This is biodiversity doing interesting things………

Tuesday was a trip up through the pine forest zone to Las Canadas at the foot of Mt Teide. A long day through some spectacular scenery, interspersed with collecting data on bird behaviour at a picnic site and checking some populations of an endemic plant the Canary Wallflower (Erysimum scoparium). Interestingly the populations to the south of Las Canadas have more or less failed to flower this year, probably because of the very dry winter on Tenerife. Many other species have also not flowered and there are some implications for the pollination biology of this plant which I’m hoping we can quantify later in the week. Will report back when I get a chance………..over and out for now.