Robin Hoskyns Nature Photography – Blog

Images and stories of nature, science and conservation.


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Poison Frogs and Convergent Evolution

Mantella baroni, common names include: Baron's Mantella, Painted Mantella, Harlequin Mantella, Variegated Mantella

Mantella baroni, common names include: Baron’s Mantella, Painted Mantella, Harlequin Mantella, Variegated Mantella

Although it is late in the season for finding Mantella frogs in Ranomafana, after a couple of hours of searching we found one. I say we but the hard work was all down to my guide Lova who knew exactly where to look. Mantella, even though brightly coloured, are hard to find as they tend to sit in refuges by streams and under leaf litter. The most reliable way to find them is by their call, a  short click noise, however they only tend to do this in the wet season when temperatures are higher so we just had to rely on Lova’s knowledge, a bit of luck and a couple of hours spent poking around in holes with a stick.

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At only 2.5cm these are small frogs!

The most interesting thing about these small brightly coloured frogs is that they share such striking similarities with neotropical Dendrobatids or Poison Dart Frogs.  Although genetically unrelated, Mantella and some Dendrobatid frogs share many of the same features: toxic skin chemicals, terrestrial eggs, small body size, toothless jaws, a specialist diet composed largely of ants, active diurnal foraging, and aposematic (warning) coloration. All of which are considered to have evolved completely separately, a process called convergent evolution.

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They also do not sit still making them very difficult to photograph!

Convergent evolution is defined as the process by which similar features evolve separately in species with separate lineages. In other words evolution creates animals with attributes that have a similar form or function that were not present in the last common ancestor of each species. These traits usually enable animals to fill very similar ecological niches.

In both Mantella and Dendrobatids, defensive chemicals appear to be closely associated with the evolution of aposematism (warning colouration) as a visual warning of their toxicity to potential predators, and active diurnal foraging, a behaviour that is generally rare in frogs.

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M. baroni is very similar to M. madagascarensis however it lacks the red flash marks on the legs and horseshoe shape under the chin.

Although wild poison frogs retain toxic skin alkaloids for several years in captivity, they do not seem to be able to produce their own toxic alkaloids in fact they accumulate these toxins from their diet. Toxic alkaloids have been shown to be absent in Dendrobatid and Mantella frogs when raised in captivity on a diet of fruit flies however these individuals will readily accumulate alkaloids when added to their diet.

The foraging behaviour and diet of Mantella is not yet well documented relative to Dendrobatids however ants are known to dominate the diet of Mantella. A study conducted in Ranomafana National Park collected Mantellid frogs and arthropods with the potential to be sources of alkaloid chemicals. The study found that 13 of the 16 alkaloid compounds found in the arthropods of Ranomafana are also known in other ants, beetles, and frogs endemic to the neotropics and that 9 of the 12 alkaloids found in Mantella are also found in Dendrobatids.

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Because ants are a common or even dominant part of poison frog diets the presence of suitable toxic alkaloids in ants may have been the essential requirement for the evolution of chemical defence in both Malagasy and Neotropical poison frogs. The finding that endemic Malagasy ants contain these toxic alkaloids is evidence to support convergent evolution. Furthermore the convergence seen between the two groups of frogs might itself have been driven by convergent evolution in the unrelated ant groups found in Madagascar and the Neotropics.

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Reference:

Clark, V. C., Raxworthy, C. J., Rakotomalala, V., Sierwald, P., & Fisher, B. L. (2005). Convergent evolution of chemical defense in poison frogs and arthropod prey between Madagascar and the Neotropics. Proceedings of the National Academy of Sciences of the United States of America, 102(33), 11617-11622.

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Frog Diversity in Ranomafana

Boophis madagascariensis

Boophis madagascariensis

In the past couple of weeks I have been going out photographing one of my favorite subjects, frogs! Ranomafana has one of the highest amphibian diversities of any national park in the country with only Andasibe offering any competition. Of the 300+ described species of frog in Madagascar all except two are endemic and at least 120 of those have been found in Ranomafana including 8 potential species endemic to the park.

Spinomantis aglavei

Spinomantis aglavei

Spinomantis aglavei

Spinomantis aglavei

According to the Global Amphibian Assessment (GAA) in 2004, Madagascar ranks as the country with the 12th highest amphibian species richness however it probably should be higher than this as over 200 candidate species have been identified since. This would make the estimated total number of frog species over 500 and would mean Madagascar is home to roughly 4.3% of the world’s amphibians whilst occupying less than 0.5% of the worlds land area.

Gephyromantis tschenki

Gephyromantis tschenki

Boophis reticulatus

Boophis reticulatus

The largest family of frogs in Madagascar is the Mantellidae which is very diverse and is estimated to have colonised Madagascar around 58 million years ago. Some species of the Mantella genus share convergent features with neotropical dendrobatids (poison dart frogs) with their sharply contrasting aposematic (warning) colouration being associated with toxic skin.

Mantella baroni, common names include: Baron's Mantella, Painted Mantella, Harlequin Mantella, Variegated Mantella

Mantella baroni, often called Painted Mantella or Harlequin Mantella

Boophis is another endemic genus of frogs belonging to the family Mantellidae. This genus is known for its brightly coloured eyes which it has been hypothesised act as an anti-predator startle response. The brightly coloured sections usually remain hidden during the day when the frog is resting but suddenly become visible when the frog opens its eyes.

Boophis tasymena

Boophis tasymena – Polka-Dot Bright-Eyed Frog

Boophis tasymena

Boophis tasymena – Polka-Dot Bright-Eyed Frog

Almost all Malagasy rainforest frogs are either terrestrial and diurnal or arboreal and nocturnal. This is probably because of alternating predation pressure from birds in trees during the day and snakes, tenrecs and other predators on the ground at night.

Mantidactylus femoralis

Mantidactylus femoralis?

Plethodontohyla notosticta

Plethodontohyla notosticta

As with amphibians elsewhere in the world Malagasy frogs face numerous threats. Ongoing habitat destruction has already led to destruction of 90% of the original vegetation and threatens most species to some extent.

There are recent reports of the arrival of Asian common toads (Duttaphrynus melanostictus) in Madagascar, most likely arriving inside shipping containers from Asia. This species’ relative, the cane toad (Rhinella marina), has caused widespread ecological destruction in Australia, and there is now concern that an invasion in Madagascar will have disastrous impacts. One positive aspect is that so far this species has never been recorded as a carrier of the Chytrid fungus, Batrachochytrium dendrobatidis (Bd).

Unlike the majority of the world’s amphibian populations Madagascar has so far escaped the catastrophic declines associated with Bd. However Between 2010 and 2014, Bd was recorded in five different areas of the country, including Ranomafana, although the virulence of the strain is as yet unknown and no die-offs have been reported.

Boophis elenae

Boophis elenae

Boophis elenae

Boophis elenae

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Black and White Dragons

 

A recently emerged Dragonfly opens it's wings for the first time. It' will never close them again.

A recently emerged Dragonfly opens it’s wings for the first time. It will never close them again.

In the last few months I have mainly been photographing Dragonflies and at some point I started thinking about getting good B&W images as something a bit different to the standard colour images. I love making B&W images because you can really push the editing and manipulate the image in a way that just looks very unnatural in colour. This is due to the fact we don’t naturally see in B&W therefore we are not expecting to see a natural scene.

There have been loads of dragonflies emerging from the pond in my garden. I have probably photographed about 15 individuals in various stages of emergence and there are many many more exuviae (the larval cases left after the dragonfly emerges) of the ones I have missed. I wouldn’t have thought that my smallish garden pond could hold anywhere near that many larvae at one time. Interestingly there was no frogspawn in the pond this year (lots of frogs though) however there are tons of smooth newt tadpoles for the dragonfly larvae to prey on.

Preparing for the maiden voyage.

Preparing for the maiden voyage.

The wings are open and have hardened but the veins are still slightly translucent.

The wings are open and have hardened but the veins are still slightly translucent.

In previous years I have seen a few common darters in the garden but the ones emerging from the pond are southern hawkers, a much bigger species. They seem to sit at the bottom of a stem for a few days before climbing out, apparently to start getting used to breathing air however I’m not sure how true that is as insects breathe through holes in their thorax and abdomen called spiracles. After crawling up an appropriate stem the dragonfly bursts out of the larval case and pumps haemolymph (insect blood) into its wings and abdomen to expand them. The newly emerged dragonfly then hangs off the stem for a while whilst its exoskeleton and wings harden, during this time they are pale and translucent. When it has hardened enough the wings open and the dragonfly vibrates the flight muscles to prepare for its maiden voyage. the whole process can take up to a couple of hours. Unfortunately I haven’t yet caught one in time to get the very start of the process but I have plenty of shots before the wings open.

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When the weather is bad Dragonflies seem to disappear.  In fact they are resting in trees, hidden away from predators so are difficult to find.

When the weather is bad Dragonflies seem to disappear. In fact they are resting in trees, hidden away from predators so are difficult to find.

Here’s a couple in colour as well to show them emerging:

Recently emerged from the pond.

Recently emerged from the pond.

Back-lit to show the translucency of the body and wings before they open.

Back-lit to show the translucency of the body and wings before they open.

If you enjoyed these images please check out my website or like my facebook page.


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From the Garden…

A few fairly recent macros from the garden!

If you enjoy these like my Facebook page and visit my website: www.robinhoskyns.co.uk

Thanks!

Green Leaf Weevil (Polydrusus sericeus)

Green Leaf Weevil (Polydrusus sericeus)

Green Leaf Weevil (Polydrusus sericeus)

Green Leaf Weevil (Polydrusus sericeus)

Rosemary Beetle (Chrysolina americana)

Rosemary Beetle (Chrysolina americana)

Rosemary Beetle (Chrysolina americana)

Rosemary Beetle (Chrysolina americana)

Red Mason Bee (Osmia bicornis/rufa)

Red Mason Bee (Osmia bicornis/rufa)

Red Mason Bee (Osmia bicornis/rufa)

Red Mason Bee (Osmia bicornis/rufa)

Red Mason Bee (Osmia bicornis/rufa)

Red Mason Bee (Osmia bicornis/rufa)

Blue Mason Bee (Osmia caerulescens)

Blue Mason Bee (Osmia caerulescens)

Wasp Beetle (Clytus arietis)

Wasp Beetle (Clytus arietis)

Wasp Beetle (Clytus arietis)

Wasp Beetle (Clytus arietis)

Bumble Bee (Bombus hortorum)

Bumble Bee (Bombus hortorum)


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Bees!

Hairy-Footed Flower Bee

Hairy-Footed Flower Bee

There have been steadily more and more bees frequenting the flowers in my garden and as these are some of my favorite macro subjects I have been spending a lot of time chasing them about.

Bees are very temperature sensitive (especially the solitary bees) with cooler temperatures slowing them down and even semi paralysing them therefore the best time to photograph them is on a cool intermittently sunny and cloudy day. It needs to be warm enough for  them to be active but when there are fast moving clouds bees can get caught out and won’t be able to fly off or move much until the sun comes out again. Often they will all just disappear but you just have to look very hard for the one or two that didn’t make it back home.

When these bees are cold they are very easy to manipulate onto a nice flower or stem and set up with a good background. They will often sense your body heat and try to climb on your finger where they will sit for a while until they have warmed up enough to fly. This makes photographing them much easier than trying to chase after them when they are active!

At the moment I have several species of bee including a few of the bumble bees, hairy-legged flower bee, red masonry bees, a couple of mining bees including only one tawny mining bee so far and a couple of nomada cuckoo be species.

I also spent a day building a “bee hotel” which should provide places for masonry bees and leafcutter bees to lay their eggs. It’s very easy to build your own bee hotel and I just used some old scrap wood and old bricks that I found in the garden with a few bamboo canes cut to the right size. If you are going to build a bee hotel there are plenty of good guides on the internet but the important things are to make sure that it faces south, receives full sun as early as possible, is sheltered from the elements as much as possible and is off the ground.

Whilst moving the bricks for the bee hotel I found about 7 Smooth Newts which I will post images of soon!

My Bee Hotel! Needs a bit more bamboo to fill the gaps.

My Bee Hotel! Needs a bit more bamboo to fill the gaps.

 

I hope you enjoy these images as much as I enjoyed making them and please like my facebook page or visit my website for more pictures! 

www.robinhoskyns.co.uk

Robin Hoskyns Photography Facebook Page

 

More Bee pictures:

A Mining Bee, probably an Andrena species.

A Mining Bee, probably an Andrena species.

A cold wet Mining Bee on my finger for warmth.

A cold wet Mining Bee on my finger for warmth.

Hairy-Footed Flower Bee closeup

Hairy-Footed Flower Bee closeup

Red Masonry Bee

Red Masonry Bee

Red Masonry Bee

Red Masonry Bee

Bumble bee

Bumble bee

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DIY “plamp” for under £5!

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I had a few people ask me about the DIY plamp that I used in my last post (First Macro of the Year!) so I thought I’d explain how I made it.

Firstly I’m not the first person to try this and if you search “DIY plamp for macro” then you will get many results with different ideas.

The idea is based on the Wimberly plamp and is used for attaching various things to a tripod. This is mainly useful in natural light macro to hold a branch with an insect in place on a windy day or to hold a reflector to get a bit of under lighting on the subject. The wimberley plamp is a great bit of kit and is well built however they cost nearly £40! I thought I’d try making one as it seems a lot to ask for a small bit of kit and managed to find all the bits I needed for under £5.

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Firstly search for “foam covered wire” and you get a fair few results also try “twist ties” or something like that. I got a pack of two for £3! You can also find them at garden and DIY centres for holding delicate plants to stakes and generally attaching things to other things. Then I bought a pack of clamps, I got the cheapest at £1.50 for eight! They probably aren’t the best clamps and are a little small to clip to my tripod but actually they are fine for what I need them for. I then attached the clamps to the twist ties with a couple of cable ties that I had lying around and that was it!

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I find that a single tie on its own is a little bit wobbly in the wind but by twisting two together it is strong enough. I also like that this gives the flexibility to use two if necessary. I attach them to the tripod just by twisting them around and it seems to work quite well however I may invest in some larger clamps at some point just for speed in setting up. I also taped some foam to one of the clamps to try to stop it squashing delicate flower stems but I think this needs a little more work.

So there you go, DIY plamps for under £5! Please feel free to leave any comments below.

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A few quick pictures taken with the plamp today:

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First Macro of the Year!

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I found a 7-spot Ladybird inside the house yesterday so I thought it would be a great opportunity to dust off my macro gear!

I’m hoping try out some slightly more “environmental” macros this year rather that full frame close ups so I thought I’d use the wireless flash control on the 7d to experiment with more of a field studio sort of set up. Since I got the 7d (well over a year ago now!) I have been meaning to try it out with wireless flash for macro work but up until now I haven’t had the time. I was wondering if this could be a way to get softer light on larger subjects as these need to be further away from the camera and I can experiment with much larger softboxes and diffusers which would be impractical to attach to the camera and it also might help to illuminate the background more with closer shots as light fall-off and black backgrounds are a constant problem with macro work.

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My Set-up with my coat to lie on as it was a bit damp still!

I used my new tripod which has a “tiltable” centre column to position my flash where I wanted it and my homemade “plamp” (some foam covered wire ties and some small clamps!) to hold the diffuser. This didn’t quite work as well as I’d hoped. The light didn’t seem as soft as I would like as there were still some blown highlights and it was difficult to find an angle where the reflections on the ladybirds shell were minimised. Anyway I got some shots that I was happy with and the benefit of this sort of set-up appears to be much better background lighting which Is what I was going for. I think it needs a bit more experimentation and I’m going to try and see if it also works for the MPE for much closer shots!

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A more detailed shot of the lighting setup where you can see my homemade plamp.

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