Leopard cat publication update 2015 to 2017

Some leopard cat publications were out in the last two years, and I try to keep track of as many as possible. Some quick thoughts and summary:

Nakanishi & Izawa took a look at the importance of frogs in the diet of the leopard cats from Iriomote Island, Japan. I must say that the Japanese are the gold standard in leopard cat species biology work with the population on Iriomote Island. They examined the stomach contents and compared the results to scat analysis, which is traditionally more frequently used as it is less invasive. Frogs appeared to be important, but under represented compared to scat studies.

Meanwhile. Srivathsa et al. were one of the first to use camera traps to estimate leopard cat population density in India. The density in in forests there appear to be similar to Sabah, but below what we have on Pulau Tekong, Singapore.

Going back about 5,000 years ago, it seems that leopard cats had some close interaction or relationship with Neolithic people in China. The authors (Vigne et al.) use the term “domestic”, but I’ll hesitate to do so in the strict sense of the word.

And finally, a molecular phylogeography of the leopard cat sampled across its global distribution. Rather important that this is done, and the coverage is quite admirable. I cannot say the results are unexpected though (see image below).

Distribution of leopard cat subspecies suggested by Patel et al. (2017). Image from paper.

Arjun Srivathsa, Ravishankar Parameshwaran, Sushma Sharma, K. Ullas Karanth. (2015) Estimating population sizes of leopard cats in the Western Ghats using camera surveys. Journal of Mammalogy 96(4): 742-750. doi: 10.1093/jmammal/gyv079

Nakanishi, N. & Izawa, M. (2016) Importance of frogs in the diet of the Iriomote cat based on stomach content analysis. Mammal Research 61: 35. doi:10.1007/s13364-015-0246-9

Riddhi P. Patel, Saskia Wutke, Dorina Lenz, Shomita Mukherjee, Uma Ramakrishnan, Géraldine Veron, Jörns Fickel, Andreas Wilting, Daniel W. Förster. (2017) Genetic Structure and Phylogeography of the Leopard Cat (Prionailurus bengalensis) Inferred from Mitochondrial Genomes. J Hered 2017 esx017. doi: 10.1093/jhered/esx017

Vigne J-D, Evin A, Cucchi T, Dai L, Yu C, Hu S, et al. (2016) Earliest “Domestic” Cats in China Identified as Leopard Cat (Prionailurus bengalensis). PLoS ONE 11(1): e0147295. https://doi.org/10.1371/journal.pone.0147295

Crowdsourcing: Make no bones about it

This leap frogs a few Doing the dirty job posts, but I think the following story is worth sharing and compelling enough to stand on its own.

Right now, I have extracted DNA from the collected scats, analysed the genetic information, and moved on to washing out the scats for prey remains to determine the diet of leopard cats in Singapore. Most of the remains are hair, bones, feathers, scales and exoskeleton.

A day in the office: typical crime scene.

However, here comes the problem: I belong to the generation of biologists with comparative anatomy and mophology swapped out from our curriculum in favour of cell biology and molecular genetics — therefore, not too good at identifying animal bits at all. To compensate though, I did a fair bit of reading up on hair and skeleton before starting.

Bones are a little more tricky than hair (which I have a reference collection of), but excellent diagrams help a lot. Every now and then, strange things pop up, but are usually relatively easy to resolve.

After more than 30 samples, something odd appeared that I have yet to encounter. It was a bone fragment that looked like a product of two fused bones. Unfortunately, it was not complete, otherwise it may have been easier to identify. So there it started: the case of the mystery bone.

I had my suspicions of what it may be, but I also needed to know where to look and had no comparative material for skeletons. The Raffles Museum of Biodiversity Research collection is closed to prepare for the move to its new premises, and I did not want to be a nuisance to the collections manager. So, knowing that Twitterverse is full of accomplished workers in the field of science, I decided to try crowdsourcing to get more experienced/expert opinion in bone identification:

In a nutshell, I must say I was humbled by the responses and the helpful scientists on twitter.  Full story and final reveal on the mysterious bone below.

N.B.: Some tweets may have been lost if tags have been changed or if they are of a different time series.

Read more

Doing the dirty job – part 1

Tracking rare and elusive wild carnivores can be challenging as there are not that many of them to begin with and they are mostly shy and tend to move about a lot. Fortunately, there is an easier way to study these animals as they tend to leave behind clues of their presence which tend to be more permanent. One important clue I seek out is scat, i.e. their droppings.

Other than a sign post that says “I was here”, scats are after all, the end products of digestion and can reveal what an animal has been eating. Although it is not as as clear as looking at stomach contents like what I did in my previous post, undigested remains such as bones, hair and feathers can still be used to identify the food items. Furthermore, the surface of each piece of scat may have rubbed off an animal’s digestive tract and picked up cells on the way out. These cells contain DNA which when extracted and analysed, can be used to identify species (with an algorithm called BLAST) and individuals.

Fuzzy bits of fur can be seen coming off the scat.

It is not difficult to identify leopard cat scats in the field as they tend to lay them along the trails, possibly for scent/territorial marking purposes. Like domestic cat droppings, they are typically about 1.5 to 2 cm in diameter and around 10 to 15 cm long, sometimes in fragmented pieces. One end is usually rounded, and the other ends in a pointy twirl, often with some hair.

There are usually no plant parts, but sometimes a bit of grass are present.

Fresh leopard cat scat usually appears to be in various shades of brown and have a distinctive musky smell. Old scats turn white due to the amount of calcium present.

Aged white scat.

Scat that is found is collected in a sealable plastic bag and then frozen at -80o C to preserve the DNA. I cannot wait to start analysis on the 33 pieces of scat that I have amassed since the start of the project.

Other researchers in Singapore who have been successful with finding out more about diet or genetics with scat are those done on the common palm civetsmooth-coated otter and banded leaf monkey.

A story the dead cat told

In the debut post, I wrote about how two road kills in 2001 and 2007 were the only verifiable evidence that leopard cats still exist on mainland Singapore. In fact, every carcass tells a story and are valuable to scientists and natural history museums (footnote 1). This post is about the story that a dead cat told.

The value of a carcass is that each one is record of the presence of a species at a location and it provides important clues about its biology. In studying a carcass, scientists can tell its sex, age, determine the cause of death and even its last meal! Even the tissue is valuable for the DNA that can be extracted.

Mandai 2001 road kill. Photo by Charith Pelpola.

The story so far: The road kill on 11 Jun 2001 was reported by Charith Pelpola, a kind member of the public who recognised it as a leopard cat and passed it to my current supervisor, Mr N. Sivasothi, who was then working at the Raffles Museum of Biodiversity Research (RMBR). The body of the animal was examined, measured and preserved by Siva, while the internal organs were stored separately with the foresight that someone may study them one day. And that was where I came into the picture.

Kelvin (left) and Siva (right) preparing the specimen in 2001. Photo from Habitat News.

Preserved specimen of Mandai road kill at RMBR.

Last year (2011 – exactly 10 years later), deep  in the bowels of RMBR prep room known affectionally as “The Dungeon”, I finally got the chance to examine the gut of the 2001 leopard cat road kill.

On first inspection, the twisted tubes of cat gut sitting in a jar of formalin looked harmless enough from the outside and that did not prepare me fully for the decade of funk that it emitted when it was poured out. Sorting out the party-digested mix of chyme, fur and feathers was like assembling an exciting but morbid jig-saw puzzle. Kelvin Lim, the museum’s collection manager, was as excited as I was in identifying the contents of the leopard cat’s last meal.

Me trying to solve the jig-saw. Photo by Kelvin Lim.

After about an hour and a half, it was done. We now know the prey items of one leopard cat in Singapore. The contents included 1) a mammal – rat (Rattus sp.), 2) a bird – red legged crake (Rallina fasciata) and 3) a lizard – many-lined sun skink (Eutropis multifasciatus).

Remains of a rat. Feet and fur can be clearly seen.

Remains of a red legged-crake. Black and white barred, and chestnut-coloured feathers, and the red feet are obvious.

Remains of a many-lined sun skink.

In short, the leopard cat carcass told us that on 11 Jun 2001, an adult male leopard cat that just ate a rat, bird and lizard met its demise as it was hit by a vehicle as it was crossing a road in Mandai. The preserved carcass and separated gut contents are now stored in RMBR, where it would be one of over 500,000 specimens of value for research and education.

Footnote 1: To report a road kill, call the Raffles Museum of Biodiversity Research at 6516 5082 or email rmbr@nus.edu.sg. A photo or description of the animal, its general condition and detailed location would be most useful.