Tagged: fieldwork

What’s your tongueworm?

Most of you will probably know what a earworm is: a tune or song that gets stuck in your head, that you cant get rid off. But do you know what a tongueworm is? No, not this. Here is what i call a tongueworm: a food or drink which you can’t stop thinking of, especially when you know that there is no way you can have it in the near future. Let me explain.

A little while ago, Sneha and I did fieldwork together in Anshi national park. We would go on long treks looking for birds and mixed-species flocks. Often, this turned out to be quite boring because we saw nothing. And worse still, it would be hot and humid. In these situations, for lack of anything better to do, I would turn to Sneha and yell “green apple granita“. And Sneha would be stuck with a tongueworm:)

(For the animal behaviourist , this might just be a nice example of spite; even I would have really liked a green apple granita at that point!)

So, what’s your tongueworm? Sneha’s is green apple granita. Mine is cold coffee from a place called Shakes N Creams in Madras. What is that one food or drink you crave for in field and have no way of getting it? Instead, what is the first thing you crave to eat/drink when you get back to the city?

Do tell. The person who provides the most surprising answer will be rewarded with the tongueworm of his/her choosing…by ESS!

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A sea of galaxies

life of piI watched Life of Pi with my family about two weeks back. And when the image on the left appeared on screen, I could hardly contain my excitement. I remembered that I’d written about the Lakshadweep incident somewhere, and at the time it had felt almost surreal, but words couldn’t describe what I saw. And thus I hadn’t mentioned it to many people. But here it was.

We didn’t have our cameras with us that evening – Anne and I, we were not supposed to be on the boat. We were sulking at home a little earlier – when Rohan, Teresa, Rucha, Amod and Vardhan were putting their dive equipment together. Anne and I had got our diver certificates just a month back, and couldn’t dive deeper than 18 meters with our basic certification. All the others were advance-level divers, some having decades of dive experience. The preparations were on for a night dive, but Anne and I weren’t qualified enough to join the rest, and were pretty peeved. But we did end up on the boat with others that evening, having decided that we would sulk some more in the dark while the rest were on their precious night dive.

Underwater torches were tested, chaperones were assigned and divers plopped into water from the boat over the reef. There still was feeble light in the horizon and we saw beams of torch light crisscrossing downwards as people descended. The beams soon got polarized several feet below and disappeared in one direction. I think it was Anne who suggested that we take a dip, and by the time we put on our snorkels and fins, it was pitch dark. We could only hear Shaafi’s voice as he asked us not to drift too far from the boat, and we jumped in.

biolum summary

I remember having seen plankton luminescence before – in the open sea between Agatti and Kadmat islands, when I saw sparks in the wake of the boat by which we were travelling. I was initially scared that there was some neural short-circuit happening in my eyes, before Anne explained what it actually was. But it was quite different now as we finned in the water, and the sight was unbelievable.  Each of our movements in the dark water was followed by a trail of luminescence, which would disappear soon after. The more we moved in the water, the brighter was the illumination. As we paddled with our fins, our legs created the brightest sparks. When we swam we left behind glistening Tinker bell trails. Anne and I were soon giggling and yelping, wriggling all over to create neon outlines of ourselves. We were slapping the water surface with our hands, kicking with our feet, duck diving and creating symmetric arcs in the water column as we moved towards each other and surfaced with a gasp.

It is one of the happiest memories I have of Lakshadweep. While the rest of the divers were gushing on about how amazing their night dive was on our boat ride back, I couldn’t care less. We had our own glowing little secret.

 biolumbiolum uses

Click on the images to visit source page. For more on bioluminescence, go source article, or visit this page.

When animals don’t behave

Last December, I sailed to the Lakshadweeep with a headful of island dreams. I was to study the foraging behavior of green turtles in the shallow lagoons of the Lakshadweep islands, where this lone herbivore among marine turtles feeds on seagrass beds. I wanted to understand drivers of green turtle movements within island lagoons, and believed it was mainly the distribution of foraging resources. Kartik and I hoped that this preliminary study would give us clues to understanding larger inter-island movements that were reported by Rohan and Nachiket in their previous work in the Lakshadweep. I knew from studies in other locations that green turtles were permissive to behavioural observations in places such as the Hawaii islands. Given this, a part of my planned work was to identify green turtles individually and follow them to collect behavioural data. Meanwhile, I also spun a million dreams of swimming with greens in turquoise blue lagoon waters, quite apart from scientific objectivity. What I expected to record was something like this.

Green turtles are no dolphins. Because when I eventually did snorkel in the Kadmat lagoon, the turtles did a Sonic the Hedgehog on me. All I saw were sand plumes left behind by fleeing turtles, even before I could spot them in the lagoon. Interestingly, unlike several other places around the world where green turtles are found, they seem to be especially skittish to approach by snorkelers in the Lakshadweep. And the pattern differs between islands and island zones, seemingly based on boat traffic. Green turtles show more spunk near jetties, and in islands where human activity is relatively high – closer to the shore and in islands like Agatti which boasts of several tuna boats. Also, on our dives near the reef, green turtles were quite unwary of divers in the water column. They would swim past us slowly – droopy-eyed, with a stoned look on their faces (which makes me wonder, do turtles get narced?)

Since sand plumes don’t make good data, I decided to shift strategies. With a lot of help from Teresa, a seagrass biologist from Barcelona, I designed cafeteria experiments to study feeding choices in green turtles. I pitched my seagrass plots in the Kadmat lagoon, duck diving till I got breathless, and waited to see signs of turtle herbivory. But nothing happened for several days. Once in a while a stray fish nibbled on the leaves, but the turtles didn’t bother. One evening after setting up yet another pair of plots, I sat by the resort steps waiting to see if I had got the location wrong, if there were any turtles there at all. Even before a minute was up, I saw them pop up one after another right around the spot where the seagrass plots were. But strangely, they just wouldn’t feed. And to my annoyance they sounded like they were blowing raspberries at me when they surfaced, mocking at my predicament. After many attempts I  eventually gave up plans of behavioural observations, and dejected, set to finish the rest of the work I had planned.

However, I did not leave the islands without realizing my dream. It was a fateful February afternoon when Kartik and I met Patrick. Pat (also known as ‘Hol(e)y’), is a big male green turtle which hangs about in the only strip of seagrass left in Kavaratti, adjoining the Sandy Beach coffee shop. It was wonderful following Pat around the lagoon, as it glided slowly through filtered beams of sunlight cutting across the water column, surfacing once in a while. His long tail kept curling and uncurling as he swam, as if asking me to follow. Kartik and I swam with him for a long while and then moved to where Anne was following her mixed species shoals of fish, which were putting up quite a show. After the day’s work, we sat drinking cups of coffee at Sandy Beach looking at the pictures we’d just taken. I asked Kartik about the curling of Pat’s tail which I had noticed in some of the pictures, wondering if it had any behavioural significance. Kartik jokingly said that male green turtles were known to quite indiscriminately mount any moving object that they saw. Maybe it was beckoning me to join him – Anne said, and we all had a good laugh.

I’d forgotten about the incident until much later once I got back to Bangalore, when I came across this.

Kartik was not joking after all. :^/

Yenu sahebre!

 It is a cold, dripping December morning and we are looking for racket-tailed drongos in the moist deciduous forest around Dhoomanagadde Raaste.  As we walk down the trail, we see signs of elephant, gaur, wild pig and civet.  A startled sambar stag runs away with thudding hooves.  Very few birds are calling, and no drongos are in sight. A couple of hours pass and we slowly thaw in the growing warmth of the sun.  And then, a racket-tail flies across the trail with a flock of jungle babblers! For the next ten minutes or so, it stays low in the undergrowth, feeding on insects disturbed by the babblers foraging on the ground.  It crosses the trail again, and disappears into the foliage. We wait for a bit – it might come back. But it flies further in, and we follow.  After crawling through lantana thickets, we reach a clearing and there it is again, in the shrubs at the edge. Other species have joined the flock – grey-headed and black bulbuls, flameback woodpeckers, hill mynas, a paradise flycatcher, a bar-winged flycatcher shrike, bronzed drongos and brown-cheeked fulvettas.  The air is filled with the calls of these birds, but the drongo is silent at present. It flies off again, and after a while, we realise that we can’t go after it – the lantana is too thick here. So we trace our way back towards the trail. It is 0821 am.

As we step onto the path, a chital calls from the gully a few hundred metres to our right.  A minute later, a bonnet macaque gives the special alarm call that it reserves for big cats, and we are instantly on the alert. The macaque is close, just around the bend, and we can’t see what it is calling at. But we hear it the next moment, as the tiger growls! We are very close, and I’m not sure if it isn’t headed our way. I instinctively take a few steps back, but Jadeya, my field assistant, gestures for me to hold his machete while he takes the video camera out. I hold on to the machete with trembling hands, and slowly follow him around the bend.  We see the tiger walking slowly down the path, and follow as silently as we can. It pauses to sniff at a tree trunk, and scrapes the ground.  I am almost sure it can hear my heart pounding in my head.  It walks on, and I notice that it has two bright, white spots on the back of its ears.

MM

It stops again, and sprays a tree trunk. We walk with it for about a hundred metres before it leaves the path and disappears into the forest. Jadeya finally turns and grins at me – and I beam back at him. The ‘kere’ is just ahead, and we are sure it is going in that direction. We jog down the path towards the kere, and there it is, sitting at the bank on the opposite side. It looks at us for a few moments, then yawns and sits down behind some bushes. It starts licking itself, and then rolls over with its paws in the air. We chuckle silently – it is a very contented tiger. We watch for a while, and then Jadeya says that all he needs to do is say ‘Yenu sahebre!’ (“What’s up sir!”), and it will look up and he can take a picture, but I beg him not to.  The tiger is still sunnning itself. I whisper that we should leave – if we don’t disturb it, it might show itself to us another day.

M

It is 0908 am when I say “Ta ta” to the basking tiger. On the way back, I can hardly contain myself, and hug trees when Jadeya is not watching.  We are on top of the world.

Can I believe my own data?

I want to discuss something I have often wondered about when collecting field data. How can I be sure that my data collection is not biased by my own expectations?

Let me explain this with an example. Imagine I’m interested in comparing the abundance of a bird species at different altitudes. Based on a particular ecological theory, I expect this species to be more abundant at lower altitudes. To test my hypothesis, I walk transects at low and high altitudes and count all the individuals that I see of that species. However, it is likely that detectability is not perfect; the further away an individual is from a transect, the more likely am I to miss it. Therefore, I also visually estimate the distance of each individual from the transect. Using the distance measurements, I can examine how the number of individuals seen, drops off away from the transect line. I can then use this information to calculate how many individuals I missed seeing and adjust my estimates of abundance accordingly (I’ve described it in very simplistic terms; the actual process is a bit more complicated (pdf )).

You will notice that the accuracy of the abundance estimates depend on two factors: my ability to accurately identify the species-of-interest (i.e. to be able to tell it apart from other similar-looking species) and to accurately estimate distances of individuals to the transects (underestimates of distance will inflate abundances and vice-versa). Given that both (species identification and distance estimation) are done visually, there will be some measurement error associated with my estimates. What we generally assume is that this error is equally likely in our different treatments (low and high altitudes in our example) and therefore will not bias our results in any direction. But is that assumption really valid? I went into the study expecting to find more birds at lower altitudes. Is it possible that my desire to find this result biases my data collection without me being aware of it? For example, am I more likely to classify an individual of uncertain identity as belonging to the species-of-interest in lower altitudes? Am I more likely to underestimate distances of individuals in lower altitudes? I think what i describe will be an issue whenever there is strong motivation to obtain results in a particular direction. Given this, it is likely to be particularly problematic in research areas such as conservation science where researchers are even more strongly wedded to their hypotheses (e.g. forests better than plantations; protected seas better than trawled seas).

In lab-based experimental research, this bias is avoided by doing ‘blind’ experiments, i.e. where the person recording observations is unaware of which the control and which the experimental group is (in experiments involving human subjects there is an additional complication. The subjects also need to be kept unaware of the treatment groups and therefore ‘double-blind’ experiments are carried out. Fortunately we don’t have that problem with animal or plant subjects….or do we?).

Unfortunately, in field research there is no way to hide the identities of ‘control’ and ‘experimental’ groups. One can’t blindfold and airdrop researchers in a site and hope that they don’t figure out where they are! More generally, in any situation where there are cues that give away the identities of the different treatments, this problem is likely to arise; so this is not a problem unique to field observational research. What is the way out then? One possibility is to get someone who is unaware of the hypothesis being tested, to collect the data. But is this feasible? Is it even ethical to hide details of a project from the people working on it? Another way out is to try to reduce subjectivity in data collection as far as possible. In other words, to collect data like a robot would! But is this easier said than done? Finally, might it help to have multiple alternative hypotheses, instead of just one? What do you think?

This problem is not restricted to the data-gathering stage of research. It can creep in to our choice of study sites; during data entry and analysis; in our interpretation of our results and in what we choose to write-up as papers (more on this in a future post maybe).