Tame me a Tegu!

Argentine black and white tegu (Salvator merianae)
Argentine black and white tegu (Salvator merianae)

I came across quite a few tegus – large lizards – when visiting Iguazu National Park in northern Argentina. As far as I can tell, they are all the Argentine black and white tegu (Salvator merianae), also called the Argentine giant tegu (1). They wander round quite happily, despite the presence of large numbers of people coming to see the waterfalls.

Argentine black and white tegu (Salvator merianae)
Argentine black and white tegu (Salvator merianae)

Tegus seem to eat just about everything! That is why are called omnivores: omni means ‘all’ or ‘every’. They will apparently consume invertebrates (millipedes, arachnids, insects and molluscs), vertebrates (birds, fishes, amphibians, lizards and small mammals), bird and turtle eggs, fruits, carrion and mushrooms (2). It’s not surprising given this diet that they grow so large! Over four feet long.

Argentine black and white tegu (Salvator merianae)
Argentine black and white tegu (Salvator merianae)

Tegus look a lot like monitor lizards (an Old World group) but they are not closely related, so must be assumed to have evolved to fill a similar niche (convergent evolution). There are 7 species of tegus, which were originally placed in a single genus, Tupinambis. But tegu taxonomy seems to have gone through some changes recently and the Argentine black and white, or giant tegu, was recently reclassified as Salvator merianae (3). For the record, the genus Salvator now consists of three species: S. duseni (The Yellow tegu), S. merianae and S. rufescens (The Red tegu), which mainly occur in open ecosystems (4). The genus Tupinambis now contains four species: T. longilineus (The Rondonia tegu), T. palustris (The Swamp tegu), T. quadrilineatus (The Striped or Four-lined tegu) and T. teguixin (The Golden tegu); and these tegus are mainly to be found in forest ecosystems (4).

Argentine black and white tegu (Salvator merianae) with a more golden pattern
Argentine black and white tegu (Salvator merianae) with a more golden pattern

Some of the tegus I photographed, like the individuals shown above and below, had a more yellow or golden colour and I wondered if these could have been Golden tegus (Tupinambis teguixin). Tegus are separated on the basis of a large number of characters, one of which is the number of loreal scales they have (3, 4). These are the large scales between the eyes and nostrils. All of the individuals shown here seem to have two large scales, so they cannot be T. teguixin, as that species only has one large loreal scale (4).

Argentine black and white tegu (Salvator merianae)
Argentine black and white tegu (Salvator merianae)

Surprisingly, tegus make good pets! Apparently, they are quite docile and can be house trained; they also get quite attached to their owners and get aggressive if they are not handled regularly! (1, 2). There are a number of Facebook sites (e.g. ‘The Tegu-phile’ and ‘Tegus from Around the World’) for people who love tegus! Unfortunately, not everyone appreciates their good nature and many are hunted for food and skins (5). Despite this fact, their numbers seem to be holding up.

There were also some very nice waterfalls as well as lizards!

Iguazu Falls in full spate from the Argentinian side
Iguazu Falls in full spate from the Argentinian side
  1. http://www.inaturalist.org/taxa/318758-Salvator-merianae
  2. http://carnivoraforum.com/topic/9508642/1/
  3. Harvey, M.B., G.N. Ugueto and R.L. Gutberlet Jr. 2012. Review of Teiid Morphology with a Revised Taxonomy and Phylogeny of the Teiidae (Lepidosauria: Squamata). Zootaxa 3459: 1-156.
  4. Passos, D. C., Lima-Araujo, F., Melo, A. C. B., & Borges-Nojosa, D. M. (2013). New state record and distribution extension of the golden tegu Tupinambis teguixin (Linnaeus, 1758)(Squamata: Teiidae) to the Caatinga biome, northeastern Brazil. Check List, 9(6), 1524-1526.
  5. Embert, D., Fitzgerald, L. & Waldez, F. 2010. Salvator merianae. The IUCN Red List of Threatened Species 2010:e.T178340A7526681. http://www.iucnredlist.org/details/178340/0

Bunches of butterflies

Aggregation of mainly Changeable Grass Yellows (Eurema simulatrix) and some Blues
Aggregation of mainly Changeable Grass Yellows (Eurema simulatrix) and some Blues

When visiting Doi Chiang Dao – a place I have written about before (1) – last November (2015), I came across some interesting aggregations of butterflies; composed mainly of Blues (lycaenids) and Yellows (pierids). I may have been a little bit late, as October is said to be the best month to see butterflies in this area, but there were still large numbers of them around.

Aggregation of mainly Changeable Grass Yellows (Eurema simulatrix)
Aggregation of mainly Changeable Grass Yellows (Eurema simulatrix)

The place with good aggregations of butterflies is at the army camp at the entrance to Chiang Dao Wildlife Sanctuary (2), where most of the photographs shown here were taken.

View of Doi Chiang Dao (not the summit) on the way to the entrance to the park
View of Doi Chiang Dao (not the summit) on the way to the entrance to the sanctuary

The soldiers place fruit and dead fish to attract the butterflies; fermented fish mixed with fermented pineapple extract was found by researchers to attract the most species (3).

Hill or Changeable Grass Yellows, Zebra and Ciliate Blues
Hill or Changeable Grass Yellows, Zebra and Ciliate Blues

I came across a Common nawab (Polyura athamas) feeding on the dead fish (below). It might be common, but it is, like all nawab butterflies – species in the genus Polyura – exquisitely marked and very attractive. Presumably, the patterns and colours have a more practical purpose than to satisfy our aesthetic yearnings!

Common nawab (Polyura athamas) on fish
Common nawab (Polyura athamas) on fish

The Yellows appeared to be mainly Changeable Grass Yellows (Eurema simulatrix), also called Hill Grass Yellows. There were also other yellow pierid species present in smaller numbers, including Yellow Orange Tips (Ixias pyrene), and probably others. Common and Three-spot Grass Yellows all look very similar, at least to my untrained – in pierid taxonomy that is – eyes!

Aggregation of mainly Changeable Grass Yellows (Eurema simulatrix) and some Blues
Aggregation of mainly Changeable Grass Yellows (Eurema simulatrix) and some Blues

There were also lots of small, black-and-white butterflies – called Pierrots – present, including: Straight, Elbowed and Banded Blue Pierrots (Caleta roxus, Caleta elna and Discolampa ethion, respectively).

Straight and Banded Blue Pierrots
Straight and Banded Blue Pierrots

There are various subspecies of these widely distributed butterflies which I do not feel competent to identify, other than by location.

Straight Pierrots (Caleta roxus)
Straight Pierrots (Caleta roxus)

There were also fairly large numbers of Zebra Blues (Leptotes plinius), Common Ciliate Blues (Anthene emolus) and Plain Hedge Blues (Celastrina lavendularis). There were probably other species, including The Bi-spot Royal (Ancema ctesia ctesia), present amongst the aggregations; remarkably at least 426 species of lycaenids have been recorded in Thailand.

Zebra and Plain Hedge Blues
Zebra and Plain Hedge Blues
The Plain Hedge Blue, Celastrina lavendularis
The Plain Hedge Blue, Celastrina lavendularis
Common Ciliate Blue (Anthene emolus)
Common Ciliate Blue (Anthene emolus)
The Bi-spot Royal (Ancema ctesia)
The Bi-spot Royal (Ancema ctesia)

Like the Yellows, all of these Blues and Pierrots like puddling, or mud puddling: sucking up salts on moist ground or for example, from dung, carrion or bird droppings.

Straight, Elbowed and Banded Blue Pierrots
Straight, Elbowed and Banded Blue Pierrots

These aggregations of puddling butterflies usually consist largely of males, which are thought to be replenishing their sodium-reserves, lost (or soon to be lost) in the process of delivering a spermatophore to females during mating. Or more prosaically, it may be to enable the males to produce a ‘nuptial gift’ in the form of sodium, for the females (4). Absorbing nitrogen-rich resources will also give the males added “oomph” or, in other words, increase their reproductive success (5).

Blues and Yellows puddling away!
Blues and Yellows puddling away!

If this blog has whetted your appetite and you want to see some better, truly amazing macro photographs of butterflies from this location, then I recommend this website (6), which shows the beautiful photographic work of Antonio Giudici (7). I can only aspire to the quality of his work, but I have ordered a better macro lens for my next visit! I think the last word should be with the mountain (below).

Doi (=mountain) Chiang Dao
Doi (=mountain) Chiang Dao

References

  1. https://rcannon992.com/2014/04/30/chiang-dao-mountain/
  2. http://peacockroyal.blogspot.co.uk/2013/11/butterflies-do-chiang-dao-thailand-part.html
  3. Lapkratok, Sukanya, and Pongthep Suwanwaree. “Bait Selection of Butterflies at Dong Phayayen-Khao Yai Forest Complex World Heritage, Thailand.” Advanced Materials Research. Vol. 1030. 2014.
  4. Molleman, Freerk, et al. “Is male puddling behaviour of tropical butterflies targeted at sodium for nuptial gifts or activity?.” Biological Journal of the Linnean Society 86.3 (2005): 345-361.
  5. Beck, Jan, Eva MuÈhlenberg, and Konrad Fiedler. “Mud-puddling behavior in tropical butterflies: in search of proteins or minerals?.” Oecologia 119.1 (1999): 140-148.
  6. http://www.butterflycircle.com/showthread.php?14873-Chiang-Dao-(Northern-Thailand)-March-2015/page2
  7. https://www.flickr.com/photos/angiud/

Grasshopper legs

Grasshopper Calliptamus barbarus f. marginella (Costa, O.G., 1836) Galicia, Spain
Grasshopper Calliptamus barbarus f. marginella (Costa, O.G., 1836) Galicia, Spain

I came across this grasshopper at a site I have blogged about before, called Punta Corveira. This beautiful headland is located on the north coast of Galicia – between Cedeira and Valdoviño – in Galicia, Spain. In spring and summer it is covered with wild flowers, and one can see many interesting birds, including red-billed chough, peregrine falcon, blue rock thrush, raven and many more.

Punta Corveira – between Cedeira and Valdoviño – Galicia, Spain
Punta Corveira – between Cedeira and Valdoviño – Galicia, Spain

In flight, these grasshoppers are quite distinctive on account of their red wings. But at rest, with wings folded, they are perfectly camouflaged against the dry vegetation. Another feature that is not apparent in this photograph is the colour on the inside of their legs! One might ask why is this important? Well there are apparently two different forms (or bio forms) which are differentiated by the colour of the inner side of the hind femora (1). In one form, the inner side of the hind leg is a ruby colour (and has three black spots); the other form, has pale orange inside legs (with only one large black spot). The two forms also make different mating sounds (songs?) by grinding their mandibles together (1). The orthopteran equivalent of grinding their teeth together?!

I found it difficult to identify this species at first. It did not appear to be like any European species I could find, e.g on the excellent site ‘Orthoptera and their ecology’ (2). This was because the species has a very wide distribution, from the Mediterranean to Siberia, and there are different forms or subspecies, as already mentioned. I eventually found some images online – what would we do with out Google images? – which indicated that it was Calliptamus barbarus f. marginella (3). A form which differs significantly, at least superficially, from other images of this species (2). There is clearly more to find out about this particular form and whether the individuals found at this site in northern Spain have red or orange inner legs. I will gently prise them apart the next time and go there, assuming I can find another one!

  1. Larrosa, Esther, et al. “Sound production in Calliptamus barbarus Costa 1836 (Orthoptera: Acrididae: Catantopinae).” Annales de la Société Entomologique de France. Vol. 44. No. 2. Taylor & Francis Group, 2008.
  2. http://www.pyrgus.de/Calliptamus_barbarus_en.html
  3. http://www.actaplantarum.org/acta/faunagallery1.php?id=127

Northern Gannets at Bempton cliffs

Northern Gannets at Bempton cliffsThe great news about gannets – the northern gannet (Sula bassana) – is that their numbers are increasing (2). With all the horror stories about wildlife suffering depredations – mainly at the hands of Man – around the world today, its uplifting to find a species that is actually thriving. They are highly adaptable, able to vary their diet according to what is available, and also, able to fly long distances in search of food.

Gannet colony at RSPB Bempton Cliffs, Yorkshire

Northern Gannets at Bempton cliffs

Northern gannet (Sula bassana) above Bempton Cliffs
Northern gannet (Sula bassana) above Bempton Cliffs

Gannets are amazing! Not only are they sublimely beautiful – well the adults are, perhaps not the chicks! – but they exhibit such marvellous aerial behaviour: soaring flight, hovering and plunge diving.

Gannets and chicks at Bempton
Gannets and chicks at Bempton on 15/07/15

Northern gannets only lay one egg and they take very good care of their offspring, brooding the chick to keep it warm and safe, cleaning it and most importantly of all, feeding it. The adults feed their offspring for 11-12 weeks, until they are ready to leave the nest and go down to the sea to fend for themselves (1).

Gannets and chicks at Bempton on 15/07/15
Gannets and chicks at Bempton on 15/07/15

The other great news about gannets – the northern gannet (Sula bassana) – is that their numbers are increasing (2). With all the horror stories about wildlife suffering depredations – mainly at the hands of Man – around the world today, its uplifting to find a species that is actually thriving. This is thought to be because the are highly adaptable, able to vary their diet according to what is available, and also, to be able to fly long distances in search of food.

Gannets and chicks at Bempton cliffs on 15/07/15
Gannets and chicks at Bempton cliffs on 15/07/15

There are over 220,000 breeding pairs of northern gannets around the UK, according to the RSPB (1), and some 12,000 pairs occur on Bempton Cliffs – between Bempton and Flamborough Head in Yorkshire – which is a great place to watch these birds.

Gannets and chicks at Bempton Cliffs on 15/07/15
Gannets and chicks at Bempton Cliffs on 15/07/15

Bempton Cliffs is a nature reserve, run by the RSPB, at Bempton in the East Riding of Yorkshire, England.

Gannets and chicks, Yorkshire
Gannets and chicks, Yorkshire

I feel privileged to live so close to these birds and to be able to enjoy them every year.

Gannet colony at Bempton
Gannet colony at Bempton
Bempton cliffs
Bempton cliffs
Northern gannet (Sula bassana)
Northern gannet (Sula bassana)

1. https://en.wikipedia.org/wiki/Northern_gannet

2. http://jncc.defra.gov.uk/page-2875

A carrot by the sea!

Central umber of Sea carrot (Daucus carota subsp. gummifer) Galicia
Central umber of Sea carrot (Daucus carota subsp. gummifer) Galicia

This attractive member of the Carrot family (Umbelliferae) grows near the sea on rocky cliffs and headlands. Perhaps it likes the views! It’s hard to imagine a more aesthetically pleasing shape than this globe of tiny white flowers!

Sea carrot (Daucus carota subsp. gummifer) is a subspecies of wild carrot; the central umbel is white and spherical, whilst the surrounding umbels are flatter and pink in colour. It almost looks like two different flowers growing side by side!

Sea carrot (Daucus carota subsp. gummifer)
Sea carrot (Daucus carota subsp. gummifer)

I took these photographs on an attractive headland called Punta Corveira – between Cedeira and Valdoviño – in Galicia, Spain. Not to be confused with Punta Corbeira, near Ribadeo!

Rocky coastline and sea cliffs at Punta Corveira, Galicia, Spain
Rocky coastline and sea cliffs at Punta Corveira, Galicia, Spain

Seaside flowers: the good, the bad and the invasive!

Arctotheca calendula flowers, Galicia, Spain.
Arctotheca calendula flowers, Galicia, Spain.

Arctotheca calendula is an attractive flowering aster known as cape weed, cape dandelion or cape marigold. It originates from South Africa where it widespread in coastal areas or on disturbed soil. It has however, spread right around the world, including around the Mediterranean. I came across it in northern Spain (Galicia), where all these pictures were taken.

In many of the countries where it has spread to, A. calendula is seen a Noxious Weed (USA) or an Invasive Alien Plant (1); primarily, because it can infest turf and pasture and also because it can compete with economically important crops. It seems to have taken a special liking to Australia, where it has become naturalised, and very large infestations covering acres of land can be seen in southern, central and eastern regions of Australia (3). It has to be said, that it is doing quite well in NW Spain as well (see below), although most people seem to like and admire this plant when they come across it on the coast in Galicia. Judging by the number of people who take pictures of it whilst it is blooming.

A field of Arctotheca calendula flowers growing near Cabo de Bares, Galicia, Spain.
A field of Arctotheca calendula flowers growing near Cabo de Bares, Galicia, Spain.

Despite being invasive, it is said not to compete well in natural – i.e. undisturbed ecosystems – or with native species, but when established, can have a moderate impact on native plant communities (2). I have however, seen it growing in grasslands, inland for the sea. Nevertheless, it is good at growing right at the margins of the beach, actually on the sand, where it does not seem to be competing with any other native plants, not even Marram grass. I came across this clump on Morouzos beach on the Ria Ortigueira.(https://rcannon992.com/2014/10/28/morouzos-beach-a-unique-and-fragile-dune-habitat/). It is present right along the north coast of Spain, from Galicia through Asturias and Cantabria and into the Basque Country (9).

Arctotheca calendula clump on the beach at Morouzos, Ria Ortigueira, Galicia.
Arctotheca calendula clump on the beach at Morouzos, Ria Ortigueira, Galicia.

Carpobrotus edulis is another South African invasive with a long list of bad habits; it forms impenetrable mats which shut out native species and cause a reduction in the number of plant species. It is commonly known as the Hottentot fig, Cape fig, ice plant or pigface, the latter sounding more like an insult rather than a plant name! Confusingly, it also hybridises with another succulent in the same genus, C. acinaciformis, forming patches of the hybrid (hybrid complex known as C. affine acinaciformis) containing flowers of mixed colours (8).

Carpobrotus edulis in Galicia (Cabo de Bares)_edited-1

This succulent perennial is now distributed all round the Mediterranean and up along the Atlantic coasts of Portugal, Spain, France and the British Isles. It is particularly well suited to the conditions found on sand dunes and on sea cliffs. In Spain, it is called uña de gato (cat’s claw) which is a bit confusing as there are other plants around the world with this name. I am calling the plants in these photographs Carpobrotus edulis but they might be the hybrid, C. affine acinaciformis (see 10). Such hybridisation, can of course increase the vigour, and hence the invasiveness of such species.

Carpobrotus edulis in Galicia (Punta de Estaca de Bares)
Carpobrotus edulis in Galicia (Punta de Estaca de Bares)

It is possible to remove this species by hand-pulling, but it would be an enormous under-taking which would have to be done on a regional basis to prevent re-invasion (10). Whilst it might be desirable, it is very hard to imagine that such a coordinated and costly undertaking would ever be carried out – particularly under present financial constraints – and given the fact that many people like these plants. It would involve a huge task of re-education of the public to the desirability of native flora over such mixed ecosystems. It would be nice to see more studies on the effects of this invasive on native species such as the sea pink, Armeria maritima (see photo below), or Bladder campion, Silene vulgaris (next photo down).

Carpobrotus edulis surrounding sea pinks in Galicia (Cabo de Bares)
Carpobrotus edulis surrounding sea pinks in Galicia (Cabo de Bares)

What’s going on here? Are the native species co-existing with the invasives, or are they being squeezed out before our eyes?

Carpobrotus edulis surrounding Silene vulgaris (Cabo de Bares)
Carpobrotus edulis surrounding Silene vulgaris (Cabo de Bares)

Despite being invasive, noxious and weedy (!) these plants are probably here to stay. There are simply too widespread and established to be eradicated. Additionally, they may have some benefits which have not been fully appreciated, despite their bad reputations! They are bright and colourful, and people certainly like them (unaware for the most part of their invasive natures). So, the questions we need to ask about these plants, is: are they all bad, or do they have some redeeming features?! The ‘costs’ of invasive organisms, plants and animals, are well documented, but the ‘benefits’ are less well understood. In areas where native species have been eliminated – i.e. are extinct – some invasive species have taken over the roles of the original natives. They have formed a ‘novel ecosystem’ (4). In many, if not most cases, it will not be possible to completely restore the original ecosystem – and we may not even wish to; we may prefer the new one! Or at least one that contains novel species but is under control (i.e. the native species remain). So, in cases such as this, where the stable door has been left wide open, so to speak, and the invasive species are highly established, we are probably going to have to work to manage and stabilise these novel ecosystems (6). Many people, growing up with ‘invasives’, will probably not even know what the original habitat looked like, and would arguably miss their invasive species if they all disappeared, be they cape marigolds, cape figs or grey squirrels! It’s a complex world. We have altered these ecosystems for better or worse, and we now need to make some difficult choices. Go all out to eradicate the invasive species – a massive and costly undertaking – or try to manage them and minimise their impact on the native species we love as well.

1. http://www.eppo.int/INVASIVE_PLANTS/iap_list/Arctotheca_calendula.htm

2. https://florabase.dpaw.wa.gov.au/browse/profile/7838

3. http://keyserver.lucidcentral.org/weeds/data/03030800-0b07-490a-8d04-0605030c0f01/media/Html/Arctotheca_calendula.htm

4. Hobbs, Richard J., Eric Higgs, and James A. Harris. “Novel ecosystems: implications for conservation and restoration.” Trends in ecology & evolution24.11 (2009): 599-605.

6. https://www.conservationgateway.org/News/Pages/you-can%E2%80%99t-evolve-if-you%E2%80%99r.aspx

7.  http://issg.org/database/species/impact_info.asp?si=1010&fr=1&sts=&lang=EN

8. http://www.europe-aliens.org/pdf/Carpobrotus_edulis.pdf

9. Campos, Juan Antonio, et al. “The role of alien plants in the natural coastal vegetation in central-northern Spain.” Biodiversity & Conservation 13.12 (2004): 2275-2293.

10. Andreu, Jara, et al. “Vegetation response after removal of the invasive Carpobrotus hybrid complex in Andalucía, Spain.” Ecological Restoration 28.4 (2010): 440-448.

 

Forest walk

Visitors to Chiang Mai usually head up the mountain to visit Wat Doi Sutep. Beautiful and impressive though this temple is, it can get quite crowded on weekends and holidays. But just beyond the temple, and hardly visited at all, is a lovely peaceful national park (Doi Sutep-Pui NP) where it is possible to walk through the forest, look up at towering canopies and visit tranquil waterfalls. It is also a good place to look for birds and butterflies.

Wat Doi Sutep from Doi Sutep-Pui National Park
Wat Doi Sutep from Doi Sutep-Pui National Park

The park headquarters are located just beyond the hustle and bustle of Wat Doi Sutep (there is even a path leading up from the temple to the HQ). I have never stayed in the park, but there are a variety of differently sized bungalows and a camp site; school and university parties sometimes stay here.

Bungalow at Doi Sutep-Pui NP
Bungalow at Doi Sutep-Pui NP

From the HQ it is possible to walk along an old track through the forest which eventually leads, after quite a few miles, to a Mong village.

Path through the forest in Doi Sutep-Pui National Park
Path through the forest in Doi Sutep-Pui National Park

There is also a footpath leading off the track which goes down to the small Sai Yoi waterfall, but it is steep, so care is needed.

Sai Yoi Waterfall in Doi Sutep-Pui NP
Sai Yoi Waterfall in Doi Sutep-Pui NP

I have walked this track for many years. A few years back however, I was quite surprised to see signs appear, which stated that it was not permitted to walk the paths without obtaining prior permission. Since one had to go all the way back to Chiang Mai city to get permission, this presented one with something of a dilemma! I was however, most relieved on my last trip (in December 2014) to see that the signs had been taken down and the policy seems to have reverted to that of advising visitors to take care. There must have been some incident which led to the strict policy and it is certainly a good idea to go with a friend, or let someone know where you are going. Having said that, I enjoy the experience of walking in the forest by myself! It is not exactly an unspoiled wilderness; mountain bikers also use this track, so it you take care it is quite safe.

Common Earl (Tanaecia julii odilinia)
Common Earl (Tanaecia julii odilinia)

It is a good place to see butterflies and other insects, especially around the streams which run across the track in some places. Birds also tend to congregate near water. I saw my first silver-breasted broadbill (Serilophus lunatus) on this walk. Some butterfly species are very common, including the Common Earl (Tanaecia julii odilinia) – see separate blog: The Common Earl, a butterfly with green eyes! – and The Tailed Judy (Abisara neophron chelina), both of which tend to alight on foliage along the track.

The Tailed Judy (Abisara neophron chelina)
The Tailed Judy (Abisara neophron chelina)

Another species, which is very common, is the Dark Judy (Abisara fylla), which typically alights on the dried, fallen leaves on the ground where it is perfectly camouflaged.

Dark Judy (Abisara fylla)
Dark Judy (Abisara fylla)

Another type of insect which I enjoy seeing on this walk are damselflies. These delicate little jewels are particularly common near the streams and waterfalls, where they hunt for insects. They perch on foliage, with their huge eyes looking out for suitable prey items to sieze!

Damselfly  (Vestalaria smaragdina)
Damselfly
(Vestalaria smaragdina)
 Anderson's Greenwing (Mnais andersoni)

Anderson’s Greenwing (Mnais andersoni)

To try to capture my experiences of walking this track, I painted a picture where I incorporated a few butterflies, based on photographs I had taken. I an not sure whether it does it justice, but at least it reminds me of the many enjoyable walks I have had through this piece of forest in northern Thailand.

A painting entitled 'Butterflies on the Path at Doi Sutep-Pui National Park' by Ray Cannon
A painting entitled ‘Butterflies on the Path at Doi Sutep-Pui National Park’ by Ray Cannon

As well as the species already mentioned, the other butterflies I included in this painting are the Red Lacewing (Cethosia bilbis bilbis) – see separate blog: Cethosia biblis Drury, 1770 – and the Glassy Tiger (Parantica aglea) which is flying upwards at the top of the painting.

Darwin’s finches: evolving into the future

Darwin's ground finches on the The Galápagos Islands
Darwin’s ground finches on the The Galápagos Islands

A recent paper published in the journal Nature, reports the results of sequencing the genomes of all fourteen of the so-called Darwin’s finches, found on the  Galápagos islands (1). These, now famous bird species evolved from a common ancestor as recently as 1.5 million years ago (possibly 2.3 mya) according to previous mitochondrial DNA dating, adapting to different habitats and forming separate species on the basis of beak size and shape, body size, plumage and feeding habits.

Darwin's ground finch
Darwin’s ground finch – but which one? Medium I think!

I must confess that I found them all very confusing when I visited the Galápagos islands, and in truth never succeeding in confidently identifying them.  I was never quite sure if I was looking at a small, a medium or a large ground finch!  So it comes as no surprise to me to find out from this latest work, that genes have been flowing back and forth between the species, which have been hybridizing to form new species of mixed ancestry throughout this period!  What is new, is the discovery that a gene (called ALX1) which is responsible – although they may be other factors involved – for determining beak shapes.  These birds have been changing and evolving beak sizes and shapes in response to environmental change, and this is still going on (2). Changes in the genomic DNA (i.e. mutations) associated with such a gene produce the phenotypic variation – in beak size and shape – that can be selected in response to environmental changes such as droughts, which regularly occur on these islands (2).

This present study builds on the phenomenal work carried out by Peter and Rosemary Grant (of Princeton University) who have been studying Darwin’s finches since 1973.  They had previously found that in some situations, on some islands, there is so much interbreeding that two separate “species” might fusing back into one species (3). In other words, although the species have diversified (a process called adaptive radiation) there are in effect, no great barriers between them, to prevent the exchange of genes. To my mind, it all points to a great plasticity within nature. What we see now, is in effect a snap-shot in time (our time, the Anthropocene) but changes which produced the extant species will carry on – assuming we allow these iconic species enough space and protection to continue evolving into the future.

Darwin's Ground finch feeding on rice in the airport at Baltra, on the Galapagos Islands

As a footnote, I should add that all of the ground finches shown here were photographed at the airport on Baltra Island.  They seemed to be adapting very successfully to Man’s presence, even flying into the restaurant and stealing food.  Not sure if anyone is studying these individuals!  I’ll call them Medium Ground finches, but I’m not sure!

1.  Sangeet Lamichhaney, Jonas Berglund, Markus Sällman Almén, Khurram Maqbool, Manfred Grabherr, Alvaro Martinez-Barrio, Marta Promerová, Carl-Johan Rubin, Chao Wang, Neda Zamani, B. Rosemary Grant, Peter R. Grant, Matthew T. Webster, Leif Andersson. Evolution of Darwin’s finches and their beaks revealed by genome sequencing. Nature, 2015; DOI: 10.1038/nature14181

2.    Grant, Peter R., and B. Rosemary Grant. How and why species multiply: the radiation of Darwin’s finches. Princeton University Press, 2011.

3. http://www.evolutionnews.org/2014/03/nature_galapago083531.html

 

A sea-going lizard

Marine iguanas (Amblyrhynchus cristatus sbsp. venustissimus)
Marine iguanas (Amblyrhynchus cristatus sbsp. venustissimus)

Marine iguanas (Amblyrhynchus cristatus) have probably been living happily on the Galápagos islands for over 10 million years (1).  The first human being they saw was the Bishop of Panama in 1535 (2).  I don’t suppose they took much notice!  They look to me like they are not easy to impress.  I guess 10 million years on a bunch of rocks makes you rather laid back!

When I first saw marine iguanas in The Galápagos, I was surprised how small they were.  My expectations were I suppose, formed by close-ups taken by BBC camera crews. The seven subspecies do however, vary considerably in size, as do individuals within a given population.

Marine iguana (Amblyrhynchus cristatus) on Fernandina
Marine iguana (Amblyrhynchus cristatus) on Fernandina

There is nothing more primeval that a pile of iguanas; and they really do lie about in heaps.  One of the guides commented that he fantasizes that someone collects them and piles them up on the beach at the end of each day!  The casual arm draped by one lizard over the back of another, suggests a certain capacity for affection (below).

Marine iguana (Amblyrhynchus cristatus) piled up on Fernandina
Marine iguana (Amblyrhynchus cristatus) piled up on Fernandina

This propensity to cuddle up together, may be a result of thermoregulation:  “A [more] likely explanation for the formation of beach piles is that iguanas gather at spots that offer a slightly better (i.e., warmer) microclimate during the late afternoon hours, when piles usually develop”.  But it may also have something to do with managing ticks, which remarkably enough – given that they take regular dips in the sea – seem to plague these animals (4).  It’s a fascinating subject!

Marine iguanas (Amblyrhynchus cristatus) in a pile on Fernandina
Marine iguanas (Amblyrhynchus cristatus) in a pile on Fernandina

Despite their long residence on these islands, and the existence of a number (7) of different races or subspecies, marine iguanas show relatively little evolutionary divergence (1).  This is probably because, being a sea-going lizard and good swimmers, they have moved or been dispersed between the different islands.  The large males can dive down to 9m for algae in the subtidal zone, but they cool down quickly in the cool waters of the Galápagos archipelago.  Many spend their time feeding on exposed algae in the intertidal zone around low tide, but in total only 5% (a little over an hour) of each day is actually spent close to or in the water (3).  The rest of the time, I guess, they just spend dozing, at least that’s what it looked like to me.  This particular individual – a pinkish variety – was clinging to a rock like  Sisyphus!  Or was he just thinking?  There I go, anthropomorphizing!

Marine iguana (Amblyrhynchus cristatus sbsp.  venustissimus)
Marine iguana (Amblyrhynchus cristatus sbsp. venustissimus)

Marine iguanas have an endearing habit of sneezing (without the use of a handkerchief!).  They blow salt from their noses through a specialised gland which removes it from the salty food they consume.  The salt does however, often remain stuck to their heads, which gives the tops of their heads a sort of white, encrusted look (next two slides, below). Amazingly, the nasal salt glands are capable of removing up to 95% of salt ingested as food or with sea water (5); they are veritable desalination units!

Marine iguana (Amblyrhynchus cristatus sbsp. venustissimus)
Marine iguana (Amblyrhynchus cristatus sbsp. venustissimus)
Marine iguana (Amblyrhynchus cristatus) on Fernandina
Marine iguana (Amblyrhynchus cristatus) on Fernandina

Marine iguanas have all sorts of tricks up their sleeves.  They can shrink down to a more manageable size when food is in short supply (6); they can change colour to reflect their state of randiness (!); and if all goes well, they can live to a ripe old age of sixty (7).  I’m happy to say that there are thought to be a good few hundred thousand Marine iguanas remaining on the Galápagos islands (go count!); but they are subject to predation by invasive cats and dogs, so I hope the next 10 million years will be good for them as the last 10 million.

1)  Rassmann, K., et al. “The microevolution of the Galápagos marine iguana Amblyrhynchus cristatus assessed by nuclear and mitochondrial genetic analyses.” Molecular Ecology 6.5 (1997): 437-452.

2) http://www.galapagosislands.com/galapagos-history/galapagos-modern-history.html

3)  Trillmich, Krisztina GK, and Fritz Trillmich. “Foraging strategies of the marine iguana, Amblyrhynchus cristatus.” Behavioral Ecology and Sociobiology 18.4 (1986): 259-266.

4) Wikelski, M.  (1999).  Influences of parasites and thermoregulation on grouping tendencies in marine iguanas. Behavioral Ecology 10 (1):22-29. http://beheco.oxfordjournals.org/content/10/1/22.full

5)  Shoemaker, Vaughan H., and Kenneth A. Nagy. “Osmoregulation in the Galápagos marine iguana, Amblyrhynchus cristatus.” Physiological zoology(1984): 291-300.

6)  Wikelski, Martin, and Corinna Thom. “Marine iguanas shrink to survive El Niño.”Nature 403.6765 (2000): 37-38.

7) http://www.galapagos.org/about_galapagos/reptiles/