Halensee: Good morning

Copyright © Natasha Mhatre If you're reading this without attribution to me anywhere other than at my blog Talking Pictures, its probably being plagiarized.

Coot

Copyright © Natasha Mhatre If you're reading this without attribution to me anywhere other than at my blog Talking Pictures, its probably being plagiarized.

Trompe d'oeil

Go ahead, download it and turn it upside down, it still doesn't make any sense. Until...a-ha.

Copyright © Natasha Mhatre If you're reading this without attribution to me anywhere other than at my blog Talking Pictures, its probably being plagiarized.

Polar bears: work in progress

You can probably guess what research this wordle covers...

Opposite world

It does not look like this outside right now.

Copyright © Natasha Mhatre If you're reading this without attribution to me anywhere other than at my blog Talking Pictures, its probably being plagiarized.

Glorious spring at Hurst castle

Click to see it big

Wiki


Copyright © Natasha Mhatre If you're reading this without attribution to me anywhere other than at my blog Talking Pictures, its probably being plagiarized.

Electric fields are everywhere: Dominic Clarke

We have a guest blogger today. My labmate Dominic Clarke: physicist, biologist, musician, general genius at building stuff and resident bee-man! This is a wordle from a paper Dom was lead author on which showed that bees can perceive electric fields generated by their pollinators. More from Dom himself.

Electric field perception in bumblebees:

We know that electric fields are used extensively by sharks and rays and other marine animals as methods of detecting and even incapacitating their prey¹. The reason this is prevalent in the ocean is that water has a high relative permittivity (a measure of how easily an electric field can be set up in a material). Water has about 80 times higher permittivity than air so the tiny electric potentials created within animals are able to perturb the background electric field over much greater distances in water than the same potentials can in air.

So it may seem that terrestrial animals would not be well served by the electric sensitivity of a shark or a ray. The much longer-range efficacy of other sensory modes available would seem to overwhelm any benefit conferred by an electrostatic sense. But what if those much shorter distances are important to your survival? Bumblebees around a flower-bed are constantly making decisions about which flowers to choose and which flowers to avoid. They, like us, use memory, instinct and knowledge gained from others in making their decisions. A flower of a particular type may have been very rewarding in the past and so warrants future visits. The reward might have simply been a bumper crop of nectar, but it can also be more subtle. The temperature of a flower can be considered a floral reward since less energy is lost when the bee lands and feeds, so less is required to start flying again².Even the ease of handling and manipulating a flower is a factor in the decisions a bee makes. Easier flowers to handle can be visited more quickly so more flowers can be visited in a shorter period. In short, the worker bee seeks to maximise the efficiency of her foraging trips, returning home with as much food as possible for the least energy expenditure possible. The stakes are higher than simple energetics too. Each time a bee visits a flower, she risks being eaten by crab spiders and other predators³. All these decisions are made in very close proximity to the flowers, of which there could be thousands of individuals, across hundreds of different species in any given area.

Once all this information is processed and a preference for a particular flower is established, it then has to be remembered. This is where the myriad sensory signals produced by flowers come into play. The colour, shape, texture and smell of a flower all act together to produce a distinctive ‘brand’, so that bees can single out flowers of that species easily. The plants’ motives are very similar to those of product advertisers; they want customers to prefer their product, and just as importantly, to keep coming back to their product, if possible, to the exclusion of their competition. Brand recognition and brand loyalty is vital to the reproductive success of the plant, because a flower’s pollen must land on a conspecific or else, from the plant’s point of view, it is wasted.

Previous research has shown that flowers produce electric fields and that the forces involved may even assist the transfer of pollen between flowers and pollinators⁴. As sensory biologists, we wanted to know if bees could actually perceive the small electric fields around flowers, and if so, could use them to make foraging decisions. To this end, we gave the bees a choice between artificial flowers that were rewarded with sugar, and identical flowers that weren’t.  The only differences between the two kinds of flowers were the electric fields that they produced. We show that bees are able to reliably distinguish between flowers marked with a small electric field (of similar magnitude to natural flowers) and unmarked flowers. Another group of bees were trained to distinguish not just between the presence and absence of electric fields, but between two fields of similar magnitudes but different geometries, such as might be present on two flowers of different species, showing that the bees could learn some of the distinct features of a given electric field and as well as simply sense its presence or absence.

But what use is this information to bees? What information can a bee get from the electric field that it couldn’t already get from sight or smell? To answer this, we go back to the idea of flowers as advertisers. A television advert typically shows the company’s logo (an easily recognisable combination of colour, text and shape), repeats the name of the product in the voice-over and accompanies all this with a short, catchy piece of music. It’s often the same information given multiple times (the name of the product in the logo, jingle and in the VO) so why wouldn’t one of these methods alone be good enough? Because giving the same information across multiple sensory modes is more effective at getting the viewers’ attention, but more importantly, it is more easily remembered and more readily recalled when it is time for the customer to make a choice about which product to buy (to find out why this is the case, and for a nice primer on Signal Detection Theory, see http://www.cns.nyu.edu/~david/handouts/sdt/sdt.html). The bottom line is that extra information is not redundant, it helps to maximise the efficacy of the advertisement, which is of course in the interest of the advertiser.

Detail from main image

To show that electric fields, when presented as floral cues, actually confer this benefit to the bees, we performed one further experiment. We asked one group of bees to distinguish between flowers of one hue from those of a similar but slightly different hue. This is a purely visual task which the bees can perform fairly easily. We recorded the amount of visits each bee required to be able to find the rewarded flowers with 80% accuracy (if they were choosing at random, they would average 50% accuracy because half of the flowers are rewarded and half aren’t). A second group of bees were trained with exactly the same stimuli but this time, the group of flowers that had the first hue were presented with an electric field of one particular geometry, and the flowers of the second hue, with another. The bees that had both electric field and colour information to work with reached 80% accuracy significantly faster than the bees that were given hue alone. This shows that the electric field, when paired with another stimulus, actually improves the bees’ ability to learn and to remember which flower provided the best reward. This is beneficial to the bees of course, because being better able to identify a rewarding flower and distinguish it from the others means fewer wasted trips to unrewarding flowers. But it also benefits the plants because it helps their product ‘stand out from the crowd’, improving reproductive success.

This may not be the only benefit of having the ability to sense electric fields. Since bees are also electrically charged, when they alight on flowers, they create measurable changes in the floral electric field. If other bees can perceive these changes, they may be able to use the information to avoid recently visited flowers that are empty of nectar, again saving them precious energy reducing the number of risky floral visits they have to make. It is also in the interest of flowers to be honest in their advertising. Just like us, if bees are suckered in by a misleading advertisement, and not given the promised reward, they are less likely to try that product again in the future. It might therefore be in the interest of the flower to show the bees a kind of ‘no vacancies’ sign for the short time it takes them to produce a little more nectar. It is time-consuming and costly for a flower to radically alter its appearance every time a bee lands only to change it back again when it’s ready to accept pollinators. The bees’ electrical footprints may offer a fast and energy-efficient way for flowers to communicate their nectar status with their pollinators and avoid false-advertising.

The weather also plays an enormous role in the day to day activities of bees. The number of workers sent out of a hive to forage is strongly influenced by factors such as temperature, sunlight, humidity and rainfall.  The background electric field in the atmosphere, which on a fine day is typically around +100-150 V/m (yes, that means 150 volts between your head your feet when you stand outside), is highly variable⁵. Fluctuations are caused by charged clouds moving overhead can change the electric field at ground level by as much as 200%, with the field easily reaching +/- 1000-1500 V/m in storm conditions. This is well within the magnitudes of the fields we used in our experiments. Since clouds tend to precede precipitation and precipitation is something that bees wish to avoid, being able to tell what kind of clouds are overhead might give bees the advanced warning they would require to get inside before the storms break. A five minute warning may not be of much use to a meteorologist, but it may be all the time a bee needs to find shelter.

The discovery of the electric sense in bumblebees highlights the electric field as a potentially fruitful area of study in sensory biology, especially in small invertebrates. Electric fields may turn out to be more important or at least more interesting to sensory biologists than we had thought.

Dominic Clarke.

Original article: Science 5 April 2013: Vol. 340 no. 6128 pp. 66-69 doi: 10.1126/science.1230883

References:

1.       A.J. Kalmijn - J Exp Biol 1971 

2.       S. Rands & H. Whitney - PLoS ONE 2007

3.       T. Reader et al. - Behavioral Ecology 2006

4.       Y. Vaknin et al. – Plant Sys Evol 2000

5.       A.J. Bennett - Journal of Physics: Conference Series 2008 

Text copyright © Dominic Clarke.

The rhino story, part 3: Okaukuejo waterhole in Etosha National park, Namibia

Rhinos come in second only after elephants in the size catergory of land mammals. The average southern white rhinocerous male weighs in anywhere between 1.4 and 3.6 tonnes. On all fours they stand as tall as the tallest guy I ever met, 6ft 8 inches. All very good reasons for why what this animal did should have been impossible. Yet it wasn't. And to be honest elephants do it too, the sneaky b***s.

We didn't see it coming until it had walked halfway into our direct line of sight. A huge male rhinocerous had walked straight to the water, silent as a mouse and he was on our side of the water. He shouldn't have been able to do that.

As silent as a ghost.

And he was huge! Two massive magnificent point horns on his forehead, he was quite the specimen. I was thrilled. Since he was so much closer to the massive spots, he reflected back an amazing amount of light and would make amazing images compared to puny beasties across the water. The fourth rhinocerous that night! Was this going to get any better?

He walked up to the edge of the water, non-challantly dipped his head and drank. Drank his fill, unhurried and still, as befit a big regal male. You've met him on the blog before. He's this male.

If you haven't had the chance to before, click on that image now, its an image that E P Gee would approve of, every wrinkle sharp as a tack. With this lens, with all its fungus and its haze, at an exposure time of 1 second! I should also add at ISO 1600. There are many miracles that come together to make this single image possible, amazing sensor technology, a very cooperative animal, dumb luck...and perhaps a little preparedness. Technologically at least, this was an impossible image not so long ago.

But back to the animals. As the big male regally drank his fill, on the far shore the female and her calf who had left came back to the waters edge. There were now four at the waterhole. The male got curious and took a direct approach to matters. Instead of walking around to the other side, he decided that the shortest distance was a straight line, even if it got him a bit wet. It was a warm night anyway, a swims always good for you right?

The rhino on the other side, the one we thought was a male, placed himself between the big guy in the water and mommy and her baby. He stood his ground, the hulking form in the water stood his as well. This stand off lasted a while, mommy and baby decided it was a good time to bail and off they went.

They disappeared off into the darkness and then there were two. The male in the water and the other rather animal on the other shore. They just stood there. We could only wonder, was that animal somehow related to the mother and the calf? Is that why he defended them? And why they were so comfortable with them? Do rhinos carry knowledge of their kin with them like elephants do? Or it occured to me much later, was he mate guarding her as male rhinos do, trying to prevent her from leaving his territory?

I'll relate what happened next and you'll realise that exactly what happened here will remain an unsolved mystery, but you can weigh in with your theories.

The two rhinos stood there. Just for a little while. And then there were three! A rhino appeared again on the far shore. Who this new one was we had no idea! Was it the female that had just left? Did she want to have a chat with the fellow in the water? Could she come back without her calf trailing her? Or was it a completely new fifth rhino we hadn't seen before. The animal looked bigger and more angular at the shoulder blade and so perhaps not the female. Clearly both animals at the water were interested in him. The big guy edged closer to the action but stayed in the water and on the shore the newest one squared up against the first animal.

After a brief snuffle, the two stepped back as if for a a run up.

And then they took the run up, grunting loudly breaking the hush around the waterhole and rushed towards each other. They engaged horns, but pulled out just before any real damage happened. Or rather one of them pulled back, the newcomer.

They did this a few times; every single time, the newcomer pulled back. He never did have the bottle. In the meanwhile the male in the water just remained there, constantly readjusting his position to get the best possible view of the proceedings.

Yet, what would happen now was already eminently clear. The two would square up, charge, grunt, the crowd hold their collective breath and then exhale when the weaker one gave ground. And so it did again and again and again. Until the weakest, latest addition to the waterhole community decided he had had enough.

Exit stage left. As is on cue, it started raining, pretty hard. The big bull in the water decided he had enough excitement for the night. He wheeled out of the water and made his very quick move away. Second exit stage left, as silently as he had come.

I looked up to see the hub-bub in the crowd and the look on everyones face, as if they could not believe what they had witnessed. The rain was pouring hard now. The man a few benches down started packing his cameras away one by one, a DSLR, another DSLR and a handheld video camera. I couldn't help but think he'd had the right idea for tonight!

The crowd that had waited so long decided it was time for bed. They started streaming away, leaving the lone male at the water's edge without any witness. I wanted to wait it out and tried for a while. The newcomer male did try to come back. The strange seemingly purposeless battle between the two continued for some time, at the very edge of where the floodlight met the darkness beyond. But the park wardens had tired, the magic moment was over; everyone had packed their many cameras away. Away from the wicked wetness that destroyed electronics. The wardens switched off the flood lights and I made my way back to my tent through the packs and packs of Jackals picking at the largesse we'd left behind in the dustbins.

It was a night that had made everything worthwhile. Go to Namibia, go to Etosha, I recommend it highly.

Copyright © Natasha Mhatre If you're reading this without attribution to me anywhere other than at my blog Talking Pictures, its probably being plagiarized.

Genesis: Sebastiao Salgado

He's one of my heros.

Copyright © Natasha Mhatre If you're reading this without attribution to me anywhere other than at my blog Talking Pictures, its probably being plagiarized.

The rhino story, part 2: Okaukuejo waterhole in Etosha National park, Namibia

I began wildlife watching as a kid, and I learnt very early is that its a good idea to be inconspicuous. This is relatively easy to achieve in terms of sound and sight, sense we humans understand and use the most. Everyone around that water-hole was cloaked by the bright lights and it was quiet as a concert hall. But it is easy to be too human and forget that all animals do not perceive the world as we do. There are other senses that are much more important to other animals; smell for instance.

Our noses aren't great. Many other animals absolutely rely on them however, and rhinos, with their poor eyesight, do. An apt name then. While the old man's cigarette didn't bother any human even a yard away, the rhino at the water probably did smell it. Then it probably also smelled the sweaty mass of humanity congregated around that waterhole.

As it turned out, the rhino did not react to the cigarette. I cannot recall if it even so much as lifted its head. And then, the couple got bored and left. Not for them this slow unfolding of events where not much happens; an animals bends its head to the water and drinks and then looks up and waits. Most often it hopes nothing will happen. But rhinos, big as they are, are afraid of nothing. In their mind perhaps there is muteness, or the hope tha another rhino, the right sort, the other sex, will come along.

As it happened, that imputed wish came true. The slow monotony was punctuated by a new arrival. Two tentative shadows appeared at the edge of the darkness. A big weighty ponderous one around which flitted another smaller, impatient form. A mother and her calf had arrived. They made their way down to the water's edge and calmly started drinking.

I cannot, for the life of me, remember what the male was doing when the two arrived. My attention shifted completely and I forgot about the male. All I've managed to piece together comes from my images and a few key moments are missing. I know that he did not stay at the water's edge the whole time but I think he remained within view. In the end, the male and female drank from the water a few meters from each other while the calf comfortably milled around. Both unperturbed by the presence of the other animal.

Incidentally. since I've not mentioned it yet, these are all Black rhinoceroses.

Eventually, perhaps after her belly was full, she looked up and made eye contact with the male. She left the water's edge and silently ambled towards the male. The male did the same thing. They stood snout to snout, and snuffled, not loudly. All this while the baby flitted about, unafraid and completely at ease. In the photograph below, you can see that he has left his mother's side and has gone over behind the male, a sign that he feels entirely secure in this situation. They stood like that, snout to snout, nearly motionless, at least a few minutes.

This was a scene straight out of the first episode of the latest BBC series, Africa. They had filmed rhinos socialising extensively at a waterhole at night, for the first time ever. I had not expected to encounter anything quite like it, yet, here it was. I had imagined it was an extremely rare and unusual occurence which the Africa crew had worked very hard to capture. I had merely turned up at a waterhole in Etosha along with a sea of humanity, no particular effort required. And yet there it was, a mother and calf rhino quietly and unthreateningly interacting with a male.

All the reports I'd read of African safaris said that seeing a rhino was a rare occurence. We got lucky; so far we'd seen not one but three and had even been lucky enough to observe some interesting behaviour. That said right at that moment, we weren't on 'safari'. We were stationary, at a waterhole, waiting and watching. The thing about being on an African safari is that you're on the move too much. You're driven for hours and hours, between place A and place B.Once you're in place B, you're on a schedule. Not on your own schedule, but that of the fastest or slowest person along and of the trip itenarary itself. This is not great for the way I like to photograph, familiarising myself with an area, its animals, returning and working it for the best possible shots.

But the best thing about being on safari is also that you move about a lot. We covered much of Namibia in 10 days. Its a large country, with an extremely varied and beautiful landscape. We drove through Etosha's scrub forest and salt pans, we drove through flat featureless salt-flats as we approached the Skeleton coast, the coast itself, we dipped and rose through the sculptural Damarralands and the Nauklufts and not least of all, through the Sossusvlei in the desert. That sort of broad sweep requires time or if you don't have that, a safari, where someone else does the heavy lifting and you're along for the ride.

The next time I go to Africa, would I do this again? Perhaps, if someone would gaurantee that the night of the rhino's would happen again and I know no one can. So its an odd answer, that says roughly I had an evening that outweighed any misgivings I may have had about a certain mode of exploring a place. You may or may not have that evening but then you may or may not have my misgivings.

Back at the waterhole, the two rhino's were done interacting. The male broke off first and went back to the water's edge. The calf richochetted between mum and her friend merrily. They don't gambol, rhinos, bit this certainly was a bucolic scence.

This scene changed suddenly, as suddenly as rhino's can change. With the inertia of something like an air-craft carrier the until now comfortable mother left the waters edge. The calf followed, this once sticking to her side. Whatever had scared her, would startle the bejesus out of us as well.

More soon.

Copyright © Natasha Mhatre If you're reading this without attribution to me anywhere other than at my blog Talking Pictures, its probably being plagiarized.

PS: I had very specific reasons for doing this safari and I enjoyed it and do not mean to slag them off. They are perfect for some needs, but I do think they bear thinking about, especially since so many of them are so expensive and in the end so insular. More on that too...

The rhino story, part 1: Okaukuejo waterhole in Etosha National park, Namibia

The Okaukuejo waterhole is a huge floodlit water-hole surrounded by a camp and luxury houses in Etosha. When we arrived at the waterhole, most of the seats around the periphery were already occupied. There were people lined up with their binoculars, cameras on tripods, video cameras , some with more than one camera, most with more than one lens, all kitted out to the nines. But then there were the others, in nothing but their shorts and a can of beer or coke depending on their taste and age. This was not wildlife watching as I had ever known it. A crowd perhaps 300 strong. At this point I wondered if I'd see anything at all, but I'd also learnt that Africa was a bit different. I had learnt not to sneer.

The rains were late this year in Namibia as I'd heard from every Namibian I'd spoken to. Admittedly not many, but they were all praying for it to arrive and watching the skies. Today those skies were a bit cloudy, and only a little light was still left in them. The birds nontheless were still active. The drongos and communal weaver birds were still flying sorties in the four powerful floodlight beams mounted high in the trees. They were hunting, successfully, for the many insects flying about it in the light. Apart from their calls, there was an eerie hush around the wall. This, at least, was familiar. As much as they might enjoy their wildlife watching easy style, everyone here seemed to have signed up on a common pact of doing the best they could to ensure we saw something.

We found an unoccupied bench at the far left corner of the perimeter. I set up my tripod and lenses and started fiddling with settings. The light had nearly gone out of the sky and you could see the near shore, the water-hole and then about another 100 meters after which it was now pitch dark. An eagle-owl landed on the near shore and started hunting for food in the rocks. It was a lucky break, I managed to find and optimise the settings I was going to use over the rest of the night. Of course, at this point I didn't know what that night was going to be like.

 

Not too long after, a hulking shadow appeared at the far corner of my vision. My eyes were inadequate for the job, I swung my lens around and clicked. There in the centre of my preview screen, there was the first rhino I'd ever set eyes on. His skin, for he was a he in my mind already, was wet below a neatly etched line that ran through all four legs and pendulous belly. The whispers running around the waterhole were true then, there had been a rhino there before now.

He stepped out of the shadowy edges of the water-hole. Unperturbed by the powerful head-lamps that shone in his miniscule eyes he ambled down to the waters edge, and started drinking. I imagine all he could see was a wall of light from beyond which came a few murmurs, soft as the wind in the bush. His ribs stood out in high relief against his enormous...what? Where did his chest end and belly begin? Were his lungs that massive? By the end of the evening we would know something of how much power they could produce.

Abiude, one of our tour guides had joined us at some point in the evening. He laughed at my excitement and perhaps was a little relieved we had finally seen a rhino. Its all about the sightings in their trade. Ensuring the client 'sees' the big four or five if they're lucky. I'd come on this safari knowing that this was not ideal to my temperament. I don't want to see things, or rather that is never going to be enough for me. I want to spend time with things. This evening was probably going to be the closest I came to my ideal wildlife watching.

But again I didn't know that yet, all I could see right then, was that there was a great big hulking beast at the water, drinking unperturbed. Looking up occasionally when someone broke the silence with a cough or gasp, sometimes for no reason at all. I kept shooting, hoping to get a few good images from it. Rhinos are incredibly slow animals, steady on their feet. Only really moving their heads, if that, while their feet stay planted. It made for great photographs. I was taking a risk, but I shot at low ISO to reduce the noise in the image and counted on the tripod to be good for long exposures. I silently blessed myself for hauling my beast of a tripod all the way there. I had had my doubts, but it was the waterhole on the itenarary that had finally swung me.

As my shutter clicked away, I heard another familiar but unwelcome click over at the next bench. An American couple sat there (I say this but I don't really know). The were old, what the British would called pensioners. He was in shorts and boat shoes, she had sunglasses propped on her head and wore too much make-up. He also had a whisky highball in his hands and the click was the sound of his Zippo lighting a cigarrette.

More to follow.

Copyright © Natasha Mhatre If you're reading this without attribution to me anywhere other than at my blog Talking Pictures, its probably being plagiarized.

The business end: Walvis bay, Namibia

I don't know if I like this image, do you?

Copyright © Natasha Mhatre If you're reading this without attribution to me anywhere other than at my blog Talking Pictures, its probably being plagiarized.

Quiver tree: Namibia,

The quiver tree is an aloe, a succulent growing in a desert. Indigenous to southern Africa, their branches are hollowed out and ostensibly used to make quivers for arrows. Hence the name. This one along with two companions stood in the middle of a very desolate landscape as we drove towards the coast.

 
Copyright © Natasha Mhatre If you're reading this without attribution to me anywhere other than at my blog Talking Pictures, its probably being plagiarized.

Twyfelfontein, Namibia

Dussy rat

Copyright © Natasha Mhatre If you're reading this without attribution to me anywhere other than at my blog Talking Pictures, its probably being plagiarized.

Look Ma, no hands: Walvis bay, Namibia

Copyright © Natasha Mhatre If you're reading this without attribution to me anywhere other than at my blog Talking Pictures, its probably being plagiarized.