The Queens subjects.

The Queens subjects.


The fig tree has for long been considered the Queen of trees. Botanists and biologists confirm that, worldwide, something like 1,200 vertebrate species depend primarily on figs to survive. It is this diversity of life dependant on the fig tree that gives it the distinction of being the Queen of trees.  A study in late 1990’s showed that ten per cent of all birds and six per cent of all mammals depend on figs as part of their diet– (see Who eats figs? Everybody)

Why are fig trees so important to the survival of wildlife? The answer is simple; fig trees have multiple cycles of fruiting with some fig species producing flowers and figs year-round. This means a year-round supply of food for birds and mammals is available. In lean times, a fruiting fig tree can be a godsend for starving animals. (see A job for conservation’s keystone cops).

There are over 750+ species of fig trees in the tropics with most being pollinated by a single species of Fig wasp. The fig trees depend heavily on these wasps to survive. The wasps pollinate the flowers ensuring that the fruits form and the next generation of fig trees can spread their shade over a new patch of the forest. The wasps use the figs as hosts to lay their eggs in. The female wasps enter the fig through a ‘gate’, feed on the figs and make their way down a tubular structure to the flower where they unload their payload of pollen from pollen sacs in the abdomen onto the flower to pollinate it. The wasps use pollen as a bribe to the Queen in exchange for her services as an incubator for her eggs. Fossil evidence showed that wasps used the same method of pollination 65 million years ago with microscopic analysis revealing striking similarities in the pollen sacs of the fossils and their descendants.

Female Fig wasp showing her ovipositor.

The female fig wasps live for about a day and each wasp species can only lay its eggs inside the flowers of its specific fig partner. The winged females have to squeeze through the narrow gate to gain access to the flower and in doing so she rips out her wings and at times even bursts her abdomen. This epitomizes the theory of the ‘struggle for existence’ with the females making the ultimate sacrifice while making their way to their fleshy graves to ensure the survival of the species. Once the female lays her eggs, she dies within the fruit itself. As soon as the eggs hatch, the males break out of their casings and eat into the casing of the females, not to release them, but to mate with them. The males live a short life and after they have mated they begin to die. The drive to perpetuate the species fires up their instinctive response and the males begin to eat at the fruit to help the females break out.

Female fig wasps try to make their way past the ‘gate’.

I had been observing a particular fig tree outside my classroom window in college for quite some time during boring lectures on Hepatitis B. I noticed that the same set of fruits had been on the tree well over a month and a half ago. When I checked the next day, almost all the fruits were unripe, with barely a handful reaching more than 8mm in breadth. Oddly, none of them showed any signs of being pollinated or having fig wasps in them. I had seen this fig tree fruit sometime in February, (roughly 7 months ago), and here it was, with unripe fruits still hanging in clusters on the tree, the characteristic mat of fruits below the tree being nowhere in sight. Surely housekeeping wasn’t so diligent that they wouldn’t let a single fig touch the ground?
(watch: https://youtu.be/8fpKDtLjvaI)

I took a fig early next morning off the tree and with great curiosity split it open. I was surprised to see a number of females fly out from this unripe fig. The fig wasn’t even ripe, it was still hard. Yet the wasps had somehow gotten to it. But if the figs had wasps in them, why weren’t there any ripe fruits on the tree. The White Cheeked Barbets had stopped visiting now, and the squirrels only visited the tree on a bright sunny morning. The cacophony on the fig tree had stopped with the Rosy Starlings, our European migrants being nowhere in sight this time. Last year there were hundreds on the fig tree. 

Fig wasps inside a raw fig.

Why did this happen this time around? I would assume it was due to the fig wasps dying out this season owing to the blistering heat the city faced in March and April with the mercury hitting the roof. When the wasps were exposed to temperatures between 25°C and 38°C and to a various levels of humidity, the lifespan of all four species fell steadily as the temperature rose. By 36°C, the lifespan of three of the species had fallen to just two hours. In the wild this severely reduces the time a wasp has to find a fig of the right species, pollinate it and lay its eggs. In the 1990s, fig-wasps in northern Borneo went locally extinct after a severe drought, and in Florida they disappeared when a hurricane wiped them out. Both species survived thanks to their ability to disperse tens of thousands of kilometers in such short life spans.

While all of this sounds like the species can recover easily… with sustained rises in global temperature; the life span of these wasps is expected to take a hit with a marked change in fruiting patterns that may also affect other creatures over time. The failure of the figs ripening this year seems to be a clear indication of this. And the number of figs that show the presence of the wasps also suggests a decrease in populations of the figs. Only time can tell if the figs will ripen or if they will fall to the ground unripe like they have been doing so for the past few weeks and if the Queens subjects live to pollinate another set of flowers.

Do check out this amazing video to get a better understanding of what exactly happens during the course of a wasp’s life. (PS: 52:00 mins long, so watch it if you are really keen on knowing what a wasp does--- 

References:

·         Jevanandam, N., Goh, A.G.R. & Corlett, R. 2013. Climate warming and the potential extinction of fig wasps, the obligate pollinators of figs. Biology Letters 9: X-X.  Published online March 20, 2013 doi: 10.1098/rsbl.2013.0041

·         http://www.sanctuaryasia.com/magazines/features/10208-no-climate-for-fig-wasps.html

·         The Influence of Temperature on the Reproductive Success of a Fig Wasp and Its Host Plant Areej Alkhalaf, Rupert J. Quinnell, and Stephen G. Compton

Walking the Ghats.

Walking the Ghats:

It has always been a dream to visit a sky island and climb all the way to the top of the Ghats to look down and marvel at the sheer beauty of such an untouched pristine eco-system. I have had multiple opportunities to observe birds at lower altitudes in the Ghats at multiple locations among which Ooty, Mudumalai, and Agumbe were my most memorable experiences.
But all of these sites were to the north of the Shencottah Gap. The second largest geographical barrier in the Western Ghats eco-system.  Recent research by a team of scientists has shown that such deep and wide valleys can cause nested phylogeographic variations in bird populations. Which, simply put  is the effect of such large geographical gaps serving as barriers for dispersal of populations leading to populations on either side evolving into a separate species over time. 

The Shola forests gradually make way for Montane grasslands at altitudes of 1100mtrs.  It is this fragmentation of habitats across the peaks and on the hills themselves that causes populations to be isolated from others.

I had never observed birds across a gap, so when the opportunity presented itself I hurriedly packed my bags, picked up my gear and set off by train to my destination- Tirunelvelli. Making my way up the mountain terrain, I noticed that while the birds looked similar to their relatives on the other side, their song pattern was different when compared to the ones I had previously heard. Research has shown that birdsong is genetically determined and variations in the song do exist across populations that have been isolated and exist completely independent of each other. Most seasoned birdwatchers will not be able to tell the difference between some of these birds if both specimens are placed together. However, molecular evidence provides strong proof for the existence of genetic variations amongst populations sampled from both sides of the Ghats.


A yellow browed bulbul whose song differed markedly from its relative to the north of the Shencottah Gap.

When I had my first sighting of the birds that were restricted to the south of the Shencottah gap, I found that I was unfamiliar calls. But the birds making them were all too familiar. It is mind boggling to see how the existence of these gaps can influence speciation in such a massive manner. Once you make your way to the top of the peak, only then will you understand the scale at which these gaps may influence dispersals and distributions. At that moment, you are suddenly reminded of the great scientist, Charles Darwin aboard the H.M.S Beagle and you start to wonder if there are really multiple species hiding in plain sight, and you’ve just brushed them off because they didn’t look all too different to you.

It may be hard to understand the scale of isolation being spoken about here, but if you stood on one of the larger peaks to the south of the Shencottah, you wouldn’t be able to find another mountain peak for the next 40kms. Which mind you, is a very long distance for specialist birds to fly across. The main constraint being that these birds require specific microclimates and microhabitats to survive without the existence of which, dispersal is impossible for these feathered beauties.


Even among the mountain peaks of the same range, the gap is quite noticeable.

These are two neighboring peaks and while the bird populations on both sides was to a great deal similar, there was not much variation between them. But imagine this on a larger scale.
As part of my Masters thesis I will be studying populations at multiple locations and mapping the exact location of endemics In the Western Ghats. Only time can tell what surprises these hills hold. 

A Russel's Kukri from the Hills of the Western Ghats


A Nyctibatrachus (Night Frog) photographed in a waterfall from the hills.


A Malabar Torrent Dart Damselfly from a freshwater stream in the Ghats


A Kalakad Dancing frog- Another Endemic of the Western Ghats.


A typical stream in the hills

With such a diverse landscape holding hundreds of enigmatic creatures, this habitat is filled with surprises. The Bio-diversity of this region is evident in the bird population that calls these hills home. Some of these birds are found nowhere else in the Sub-continent, let alone in the world.

I will be leaving in November to the Ghats for 3 months to map and document the endemic birds of the Ghats. More surprises then.

Watch this video to get a glimpse of "The jewel of South India".

Why is endemism important ?

Endemism as Wikipedia puts it can be defined as an ecological state of a species being unique to a defined geographic location, i.e. an island, nation, country, range, zone or a particular habitat type. The Western Ghats of India is a hotspot for endemic birds with close to twelve species being found only here and nowhere else in the world. The Ghats un along the western edge of the Deccan plateau in Peninsular India starting just north of Bombay and ending in the south at the tip of the peninsula. Most of the endemics can be found distributed in highly restricted localities in the states of Maharashtra, Goa, Karnataka, Kerala and Tamil Nadu, although a few of these restricted-range species have also recorded from disjunct localities in the hills to the east, in northern Tamil Nadu and southern Andhra Pradesh. The levels of endemism among these restricted range species varies to a great deal with seven out of the sixteen endemics being found from sea level to c. 1500 mtrs across the Ghat ranges. While some species like the White-Bellied Shortwing can be found mainly above elevations of 1500 mtrs and in select patches in these hills. Another bird that is hard to come across and can be found only in select locations is the Black and Orange Flycatcher.

                                 

The Nilgiri Flowerpecker, endemic to the Western Ghats, but found distributed across a wide area.  (©Joiston Pereira)

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The question then arises as to why endemics are so important to an ecosystem. Endemic birds are extremely selective in their habitat preferences and minor changes in their habitats will have cascading effects on the distribution and population of these birds. For example birds that are restricted to selected patches and colonize the moist understory, prefering a particular micro-climate will be most susceptible to the effects of climate change when compared to other endemics that are widespread across the Ghats. In the case of restricted endemics such as the Shortwing or the Black and Orange Flycatcher, the slightest alteration in habitats as a result of anthropogenic activities or global climate change will lead to severe declines in populations. Therefore these birds can help serve as indicators for the health of an ecosystem.

Black and Orange Flycatcher

Ultramarine Flycatcher- another endemic from the Ghats.


Certain birds such as the Shortwing and the Broad tailed Grassbird can be found only in certain locations in the Ghats such as Grasshils in Ooty, the Avalanche hills, Peppara hills, and a handfull of other sites. With such varying levels of endemism, it is possible to determine the effect of habitat fragmentation, climate change as well as indirect effects of human presence in these previously untouched areas of the Ghats. The level of endemism exhibited by a species also helps to understand the specialist nature of its habitat preference as well as to create a map of the endemic birds and their exact distributional ranges in the Ghats. Current efforts are on to create a map of the various populations of endemics which would provide an exact picture of the level of endemism being exhibited by various species as well the size and distribution of specific populations.

Among the endemic birds, some such as the Malabar Grey Hornbill, Malabar Parakeet, Heart Spotted Woodpecker, etc can be found distributed across a wide area in the Ghats with populations from Tirunelvelli in the south to Bhigwan in the north, successfully being able to colonize the landscapes across the three major geographical gaps (see Mind The Gap). While some species have been unsuccessful in dispersing across these gaps owing to the specialist nature of their habitat preferences. 

Heart SPotted Woodpecker (L) and Malabar Grey Hornbill(R)
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Endemism therefore it would seem is important to determine the effects of habitat modifications, adaptations, distributional patterns, etc that may be influenced due to anthropogenic pressures or due to climate change events. It is after all a criteria for evolution, and if 'survival of the fittest' doesn't go in favor of these birds, we can very well say goodbye to some spectacular winged jewels of the hills.