Deciphering elephant corridor reports

If you are interested in conservation, you have heard the term “corridor”. There are several ways to define corridors. The simplest is to consider that a corridor is an elongated habitat linking two wildlife reserves.

Corridors are important because, in our world dominated by humans, protected areas are becoming increasingly isolated from each other. Wildlife movement is blocked, which results in genetic isolation and increased risk of local extinction. This is particularly the case for elephants who are large and vagile species. Without space, the species cannot survive. Consequently, elephant need to move from protected areas to other protected areas and places that connect these populations must be protected.

India is making major strides in ensuring that elephant populations are connected by enacting legislations. Several reports are dedicated to identifying and positioning elephant corridors to initiate protective measures. The Right of Passage (Menon et al., 2005; 2017) and Project Elephant, MoEF&CC, Government of India, 2023) are such reports based on the expertise of numerous field personnel.

These reference documents are important to all stakeholders, including citizens, lawyers or decision makers because the management of elephant corridors involves protection of land. The number and location of corridors also matter to wildlife biologists who carry out research on this topic. Unfortunately, digitizing the corridors, creating a geographic information system (GIS) document, is challenging for plenty of reasons.

  • A huge impediment to the research community lies in the fact that none of the above-cited reports provide a vector map of their corridors. Probably dozens of students would like to represent some of these corridors on a map, but unfortunately, they will have to digitize them from the PDFs, which is error prone. There are not many reasons why the public should not have access to corridor vector layers. One reason may be that the authors are concerned that people would consider the corridor lines to be as tangible as the border between two states, a “thing” existing in the field and fixed once and for all. Obviously, this cannot be the meaning. Elephants do not follow a single path, the corridor line should be interpreted as an approximation, not unlike linear models that go through a cloud of points.
  • Often map legends are not legible. Not only are details difficult to interpret, but the map coordinates can be impossible to decipher. A map produced by a GIS is first exported to an image, second inserted into a text editor and third exported to a PDF. There are many reasons why the quality of the map should vary at each step. In spite of the numerous steps, the reader should be able to comprehend every detail of the maps. The quality control is neglected at the expense of comprehension.
  • Some maps lack context. Some corridors are large and the surrounding landscape will contain a village limit or a river. In this case, the corridor line will appear together with other symbols representing various landscape elements. This helps with the digitalization. Other corridors are small. Sometimes, the only landscape elements represented are portions of reserved forests. As no context is provided in these cases the reader cannot visualize the corridor’s location relative to other landscape elements, and it makes the digitalization challenging or impossible.
  • Often, no coordinate system is provided with the maps. The Right of Passage (Menon et al. 2017) produced maps without geographic references. This makes it very difficult to the reader to even figure where the region in question is located. Additionally, most maps are turned at 45 degrees, and the reader must keep on reorienting the document to examine the maps, which is extremely inconvenient on a computer.
  • Differing geocoordinates formats: authors sometimes use different format in the same document. In places geographic coordinates are decimal (ex: 11.899945˚ N) in other places they are in degrees, minutes and seconds (ex: 76˚ 2’ 0”). The lack of homogeneity is difficult to work out because it requires constant recalculations. Moreover, if you take the georeference and calculate its precision, you will be surprised to see that its precise to the millimetre, which does not correspond to reality.
  • Lack of valid spatial references: some maps have only one latitude and one longitude displayed without a scale. It is like having a single point on a cartesian reference system without the means to calculate distance to other points. Whether the map represents a small or a big area is for the reader to guess.
  • Incomplete legends: authors focused on representing forest divisions (often with serious alignment errors) and add other landscape elements symbols for convenience such a road or a railway line. Often, these elements do not appear in the legends, and their colour scheme is not much different from forest divisions limits. On the whole, this adds confusion to the map and unless the reader validates with a third document, the symbols can be confusing.

In conclusion, maps from these reports should be checked by a geographer. But if you want to digitize some elephant corridors, you will have to be patient and very careful to use each and every available detail on the maps. There will be misses as some corridors in the Western Ghats will be impossible to locate. Otherwise, you can request the authors for their vector files or ask them to put their results online.

Jean-Philippe Puyravaud, 21 June 2026

References

Menon, V., Tiwari, S., Ramkumar, K., Kyarong, S., Ganguly, U., & Sukumar, R. (2017). The right of passage—Elephant corridors of India (Second edition). Wildlife Trust of India.

Menon, V., Tiwari, V., Easa, S., & Sukumar, R. (2005). Right of Passage: Elephant Corridors of India. Wildlife Trust of India.

Project Elephant, MoEF&CC, Government of India. (2023). Elephant corridors of India 2023.

Acknowledgements

Priya Davidar reviewed this article.

About this post

This post was written without the use of AI.

Global plant diversity

Our latest paper (here) in the prestigious journal Nature Communications is about global patterns of plant diversity. Species richness is usually described with alpha diversity (number of species in a plot), beta diversity (change of species among plots) and gamma diversity (regional to continental number of species). This paper is about alpha diversity.

The number of species found in a plot is related to the plot size. As any chosen plot size is arbitrary, the question was to check how alpha diversity would change with different plot sizes (also called grain) and how the alpha diversity measured at different grains would be distributed over the world. The number of species was also correlated to climate, soil and topography.

Global maps of alpha diversity were produced from more than 170,000 plots worldwide. The number of species in these plots was extracted at three different scales (say small, medium and large).

The maps of alpha diversity worldwide classically show an increase of local diversity from the temperate to the tropical regions. However, the three grains do not exactly produce the same maps, which shows that alpha diversity is not accumulated at the same rate from region to region. The African forests have high coarse grain richness whereas Eurasian temperate forests have high fine grain richness. The cause of these differences are still unknown and among the potential candidates are: history, species assembly rules, selection.

India’s plant alpha diversity in general is intermediate with a regular accumulation of species from fine to coarse grain. The North-East and a small part of the Himalayas have a very high alpha diversity at small grain but not at coarse grain. Alpha diversity hotspots are small or non-existent even though the gamma diversity is intermediate in the Western Ghats and the assemblage unique due to endemics.

It should be noted that non-forest plots appear as data deficient in north India: is it because data could not be found online or because there are too few studies on vegetation?

Jean-Philippe Puyravaud

A tribute to Bellan, Forest Watcher

Bellan, Forest Watcher, on the right.

 

Nassim Taleb, one of my favorite authors, wrote about heroes in his book “The Black Swan”. He said something a bit startling: if an administrator had taken the proper safety steps, the destruction of the Twin Towers in New York may not have happened. This administrator would have been a hero but no one would have known because nothing would have happened in the first place. Heroes are characterized first by their sense of duty.

The term “wildlife hero” we hear too often has become overused. We see so much craving for fame in the little world of conservation that any designated wildlife hero will suddenly believe in a stratospheric status and never come back to earth.

Mr. Bellan, a simple forest watcher, who died at sixty a few weeks ago, was not into self-promotion. Of humble origin, he never expected rewards and he would have been astonished to see that people took an interest in him. He was from a family of shikaris and had a deep, intuitive understanding of wildlife.

The first time I met Bellan was when I had been charged by an angry elephant. People had burst fire crackers near our house and I wanted to tell them to stop disturbing the elephant which was around. Unfortunately, I did not know the elephant’s exact location and he charged on seeing me. It was a miraculous escape. Bellan came when we complained about the fire crackers and we told him the story. He also had escaped an attack. The elephant stepped on him, breaking a few ribs. It took him six months before he recovered from the shock, even though he looked tough. This was sort of healing for me to realize that to be unsettled under these circumstances was natural.

Recently, Bellan had to take charge of Rivaldo, the local elephant star. Rivaldo is radio-collared and constantly under supervision to make sure he does not get fed by people. Every time Rivaldo decided to come to drink at our tank, we could meet with Bellan. It was fascinating because he knew the jungle just like the old folks. We were so happy to see a person with whom we could share our ideas and be understood. For example, we hide when we see Rivaldo. So many of the forest staff who were noisy and fully visible to the elephants, mistook our behavior for something else. They thought we were frightened when in fact we just prefer elephants not to get used to human presence. Bellan understood why we were going away and he himself was quiet and inconspicuous.

Bellan told us that the anti poaching watchers were insufficiently trained to be in the jungle. We could not agree more with him. The watchers are a walking disturbance now armed with their mobile phones with which they keep on taking selfies and probably post the pictures on social media. We have seen watchers being charged when the provocation was completely avoidable. So, he trained them and did what he could given that he was in the lower rank of the hierarchy.

Earlier, Bellan was requested to follow Ronaldo who was the most powerful and aggressive tusker in the region. Ronaldo had been injured on his back the first time, and on the second time a flaming object was thrown on him. The elephant suffered and died in agony. Bellan was the man who was saying a tearful goodbye if you read “Tamil Nadu forester bids emotional goodbye to dead elephant link required. Watch a heart-wrenching video.”* His name never appeared in the paper. If I can speak for Bellan who is no more, his tears may not have been only because he was a sensitive guy who liked elephants, but also because many such incidents could be avoided. The newspaper said Bellan was a Ranger. He was only a Watcher. People of his capability don’t get promoted. And, yes, he was a hero.

Jean-Philippe Puyravaud.

*We never watched the video. We knew too well what it was to lose Ronaldo.

Incidents with elephants and deforestation

Located amidst imposing mountains in Karnataka with a perpetually misty landscape, Coorg is the place to be for all nature lovers. https://www.holidify.com/places/coorg/

 

Contrary to what is advertised, nature lovers might be a bit lost in Coorg.

We just published this paper “Deforestation Increases Frequency of Incidents With Elephants (Elephas maximus)” available here, in Tropical Conservation Science. It may be the first paper that shows a correlation between the intensity of deforestation and increased incidents with elephants.

The region this paper focused on was Coorg or Kodagu, in between the Nilgiris Biosphere Reserve and the Badra Tiger Reserve. In approximately 50 years, most private forests were transformed into coffee plantations. The Indian Forest Act did little to halt the degradation of forests. Today, the corridor between the Nilgiris Biosphere Reserve and the Badra Tiger Reserve is gone. Elephants remaining in this landscape are terrified, hungry and lost. They kill people and provoke destruction. To add to people’s difficulties, the price of coffee sometimes goes down, which is a reminder that monoculture may not be the best way to wealth. With global warming, the monsoon will probably become weaker, bringing less water and the “cleaning” of the forest may not bring the expected economic returns.

We avoided to use the word “conflict” to prefer the word “incidents”. Elephants are not in conflict with humans. They just attempt to survive in their former habitat that happens to be in between protected areas. The term “conflict” is convenient whenever we want to prove that elephants are responsible for a situation. But as we show in this paper, the only conflict is what we want to do with our world.

Jean-Philippe Puyravaud

Global warming will destroy elephants

Following the 2017 drought, when many elephants died in Tamil Nadu and Karnataka, there was attempts to reassure the public regarding this particular situation (https://www.downtoearth.org.in/news/wildlife-and-biodiversity/elephants-in-drought-hit-karnataka-tamil-nadu-die-to-hunger-thirst-57661).

We posted a blog in this website to warn that if elephant populations were regulated by natural conditions centuries ago, today “unnatural” conditions imposed by humanity, prevail.

Indeed, we have just published an article based on thousands of observations in India and Nepal. With the lead author Dr. Rajapandian Kanagaraj an alumni of the Wildlife Institute of India, and currently at the National Museum of Natural Sciences at Madrid, Spain, this paper shows that global warming will destroy half of the elephant habitat in India. A first modelling technique detected the relationship between environment and elephant range. Then a second set of models proposed range changes under different climate change scenarios.

The results show that by the end of the century, 42% of the present elephant range will be lost because of global warming and land use changes. The temperature increase will affect the vegetation to provoke irreversible ecological damages and make ecosystems unusable by elephants. With impacts of this magnitude, we would also be wise to accelerate adaptation of farming practices because crop and animal production will certainly be badly affected as well.

The view of “business-as-usual” with wildlife – and our world – is an attitude of the past. We enter a period where all efforts possible to protect and mitigate global warming must be made.

Jean-Philippe Puyravaud

Trees comparative ecology

Plant conservation is driven by local protection and science. We have published a paper in the New Phytologist (soon to be available), on the organization of plant conduits (called xylem). Understanding the anatomy and physiology of plants has plenty of uses, including predicting reaction to global warming and species success in ecological restoration.

Astonishingly, the maximum xylem size (Dmax) of each organ showed similar scaling with plant size and consistent widening from leaf mid-vein via stem to main root across species, independently of growth form, relative growth rate and leaf habit. We also found strong coordination of Dmax with average leaf area and of stem xylem area with whole-plant leaf area. It appears that seedlings of ecologically wide-ranging woody species converge in their allometric scaling of conduit diameters within and across plant organs. These relationships will contribute to modeling of water transport in woody vegetation that accounts for the whole life history from the trees’ regeneration phase to adulthood.

In other words, something as simple as vessel size in plants (measured in standardized conditions), tells a lot about the tree species ecology and allows comparisons among species, that can be used in a variety of applications including conservation action and restoration.

Jean-Philippe Puyravaud

Rarity of forest trees

We have recently published a scientific paper (here) on rare tree species in the Western Ghats of India with colleagues belonging to different institutions.

In general, rarity is of interest to conservation biologists because rare species tend to be at greater risk of extinction than common species. The Western Ghats rain forests have a high proportion of endemic trees (around 64% of evergreen trees ≥10 cm girth at breast height), found only in this biogeographic region. Therefore rare species that are endemic are doubly vulnerable. We estimated that around 48% of 514 species were rare, of which 28 endemics were found in only one site. Rare species had narrower ecological amplitudes, being restricted to particular regions such as the southern Western Ghats and montane forests. Rare species with broader geographical distributions tended to be both wide ranging and locally sparse and narrow ranging and locally dense, and some from single species families could be relictual. Rare species were more likely to be threatened, although 39% have not been evaluated by IUCN. Rarity and endemism increased with increasing family size, indicating that the Western Ghats wet forests are both a cradle of new species (which are rare) and a museum of disappearing species (which are also rare). These forests have been the source of major crops (mango, jackfruit, pepper, cardamon) and should be properly protected because of their unique evolutionary history and biodiversity.

Priya Davidar

If you think India has a population of 2000 tigers, you are mistaken

Photo: Rémi Daudin

I follow Conservation Bytes (https://conservationbytes.com), a blog maintained by Dr. Corey Bradshaw, an Australian scientist. He specializes in mathematical modeling of ecological processes, in particular, that of population genetics. In a recent post (https://conservationbytes.com/2018/04/03/why-populations-cant-be-saved-by-a-single-breeding-pair/ and https://theconversation.com/au), he warns that animal (or plant) populations should not become too low, otherwise the species will be lost, even though some individuals remain alive.

The basis of calculation is as follows: a population of 250 to 500 is needed to obtain fifty effective individuals, i.e., those who can breed. However, to retain evolutionary potential – to remain genetically flexible and diverse – the IUCN criteria suggest that at least 500 effective individuals are needed, which requires a population of 2,500 to 5,000.

Variation exist from species to species. But, is seems a “huge” number of individuals are needed for species to survive forever (say thousands of years). As you may know, most tiger and Asian elephant populations are lower than 2,500. If the Asian elephant population in and around the Nilgiris Biosphere Reserve (the largest in the world) seems to be of an adequate size, the tiger population of this region (also the largest in the word for this species) is only about 600 individuals.

The sad reality is that most tiger and Asian elephant populations are too low and the tiger is on the verge of extinction. The 2,000 tigers or so remaining in India is just a number of little importance. The number we should remember is that the largest population approximates 600 tigers, which means that the species is hanging by a thread. Other large populations in India and abroad are badly needed if we want to keep these species.

Jean-Philippe Puyravaud

Forests of the world

Classification of the tropical forests of the world

We recently participated in a scientific article published in the prestigious journal “Proceedings of the National Academy of Science of the USA” (www.pnas.org/cgi/doi/10.1073/pnas.1714977115). The paper entitled ‘a phylogenetic classification of the world’s tropical forests’ was about the classification or relatedness of trees in the tropical forests of the world. For most of us, a forest is a sum of trees, like say, a plantation. In reality, forests are very complex and have different species composition in different parts of the world. Forests of Asia are different in tree species composition than the forests of South-America. Trees may belong to different genera and different families. For example, the mango tree, Mangifera indica, a native of the Indian subcontinent, belongs to the Anacardiaceae family and the eucalyptus (from Australia), belong to the Myrtaceae family. Looking at many forest plots and the species they harbor, it is possible to detect differences in forest species composition. Our paper shows that the world’s tropical forests can be divided into five major floristic regions (Indo-Pacific, Subtropical, African, American, and Dry forests) and not the traditional neo- versus paleotropical forest division (America vs Africa-Asia). Why should it be so?

Because of the movement of continents at the surface of the earth, a huge continent, Gondwana, split into south-America, Africa in the west and Australia, Antartica, India in the east. The timing of the split of continents tends to explain how closely related trees are globally. In general, the closer trees are in space, the closer they tend to be genetically. The split of Gondwana and not just the formation of the Atlantic Ocean explains vegetation patterns. This is an amazing finding that shows again how important the unique geology of the earth is, for vegetation.

To obtain these results, the main author, Dr. Ferry Slik of the University of Brunei, put together a large database contributed by approximately 150 scientists. The dataset originally included 439 locations containing 925,009 individual trees! Such large networks are more and more frequent in ecological research and help analyze information no individual or laboratory could gather otherwise. It is unfortunate that in spite of all the efforts to know better the biosphere, we continue its destruction at an ever accelerating rate. This may not be wise because the biosphere is our only habitable world.

Jean-Philippe Puyravaud