Wednesday, 24 February 2016

Felid field work (part 2)

So after 2015's minor successes, we got a new BSc student to pick up the force plate and video project with the cats. We first tried to work at the Cat Survival Trust (CST), but had a complete failure with any and all of the cats there (best summed up by Ed Yong here). Disheartened, but not broken, we went to the Wildlife Heritage Foundation where they have an incredible diversity and number of felids. We also took some additional fancy kit for dealing with small cats (2 mini force plates and a high speed camera) as we were trying to fill in some of the species in the small-medium size range.

Day 1 started with the fishing cat (Prionailurus viverrinus), a small/medium size felid from South and Eastern Asia. As you can guess from their name they have a penchant for feeding on fish, and will, in a very un-catlike fashion, go swimming for their food. Because of this they have evolved short ears and tails, and partially webbed feet. Aquarius (our lucky volunteer cat) turned out to be a great subject as he would happily run back and forth across the platform, with the keeper calling and feeding him on one side, before I called him back and fed him at the other. I must admit, my cat feeding skills with tongs through a fence were not great to start, and he showed me what he thought by trying to grab me through the enclosure fences. I learned my lesson, and he ran back and forth until the keeper said we should stop, for fear we would soon have a rolly polly fishing cat from all the food.
Aquarius looking a bit startled when I visited on Day 2 to get a better picture when we weren't doing science with him
After such great success with Aquarius, we went to visit the Jack the jungle cat (Felis chaus) who it turns out is the only one of his kind in the UK. Jungle cats are somewhat unfortunately misnamed as they are regularly found in most environments except jungles from China to Egypt. Jack, was a shy cat and refused to come out despite the keeper's best attempts to bribe him out of his hide.

Jack when he did appear, but only after we had packed all our kit away
After the failure, we decided to go try with the cheetahs. We already worked with a cheetah at Colchester (another cat called Jack), but his walk was so consistent in speed we wanted to see if we could get something a bit different from the trio of males in the big enclosure. As they are relatively tame and it would be incredibly difficult to get all 3 into their house at the same time, the keeper escorted me in with all the equipment and stood gaurd as I set up. Or at least, I tried to:


It turns out that our platform, probably due to a snow leopard at the CST marking it, was really interesting to the cheetahs leading to them spending ages sniffing, licking, chewing and rolling all over it. After a while, the keeper decided it was best to try and focus on just one, and with a bit of coaxing (bribed with food) managed to get him to walk back and forth (the cheetah, not the keeper) over the platform a few times. With that, time was up for the day with looming clouds rapidly making it too dark to keep working. Typically Jack the jungle cat was busy climbing all over the fences...

Day 2 started bright and early (and a little damp) with a new keeper, and Yazhi, a beautiful small adult puma. She, like the rest of the big cats, was initially a bit skittish around the platform, but quickly become comfortable running around her enclosure and across the platform with some food treats. She, and the other pumas won the hearts of my colleagues who have announced they are now their favourite species of felids.
One of the pumas looking out through the glass at the crazy scientists in the rain. Photo by Viv Allen

From the pumas, we went onto the snow leopards. They remain one of the most gorgeous cat species (in my mind), and we were luck enough to work with the female, named Laila. If you are wondering how we picked which inidividuals to work with, it was all down to the keeper suggestions on which cats would be the most amenable to the work we were trying to do/bribery to get them to do it.

Laila walking perfectly over the forceplates
Laila was somewhat skittish to start, even chewing on the protective rubber matting, but after a bit of bribery she walked over the platform as we hoped. That is, until the wind blew and the tarp we had down on the ground rustled, and Laila become another one of the scaredy cats and went back to bed.

We then went on to work with Manzi, a very large lion weighing in at 200+kg. Due to the damp conditions when we first started he was sliding about a bit on the platform, so we extended the route he was walking and put wood chips down across the platform to take some of the mud off his feet. Soon enough he had it figured out and was happily walking about for his meaty treats.

Manzi walking off the platform
After all the successes with the "big" cat species we decided to see if we could have any more luck with some of the small species later in the afternoon, a time we were ensured would be our best chance as that is when they get fed and are more likely to be active. We attempted to work with the little rusty spotted cat, arguably the smallest of modern felid species, (Nuwara, our subject, weighs in about 1kg) that looks a bit like a kitten in size, but is a feisty felid:
Spot the tiny head
As you can probably guess, we had no luck with the furry little fiend who hid himself in a cave in his enclosure so went on to see if we could try the Pallas cat. Tula was our shy little subject who took a long time to come out of hiding, and even when she did was just a giant ball of fluff up the top of a tree.
Tula showing of the typical Pallas cat pose of just two eyes on a ball of fluff, cautiously watching the world

Suffice to say we didn't get any data off of her, but the disappointing end did not overshadow the great amount of success we had across the rest of our time at the WHF. We have to thank all of the keepers and personnel who helped us and accomodated us with our science. I am looking forward to seeing all of the data combined, and the resulting publication that it will inevitably lead to.

Felid field work (part 1)

As part of the ongoing felid research grant I am involved in for my postdoc, we have been studying felid scaling. The literature shows that cats maintain the same standing posture at all body sizes (whether small or big), but we wanted to find out what the felids are doing whilst under steady state locomotion (walking, trotting or galloping/running at a constant speed). John and colleagues had collected some data previously from domestic cat, ocelot, caracal, serval, leopard, and tigers from Amazing Animals, and a couple of locations in the USA. However, with the 40ish species of felids, this covers only a tiny diversity of those. As such, we managed to put together a BSc project at the Royal Veterinary College (RVC) for a student in the bioveterinary sciences degree programme to go collect some more data and analyse the "historical" dataset.

We first went to Colchester Zoo last year (2015) to see if we could work with their felid collection. Having done a recon. of the site we figured we could work easily with their tigers and cheetah. But we needed a platform to put the forceplate within allowing the cats to walk steadily (not up or down hill or up/down steps).

Force plate platform
Platform setup showing how I put together the platform, with and undercut on one side allowing the cables to exit so the cats didn't chew on them. Red is the forceplate
So I designed what was a very simple system for the Colchester enclosures. Basically layers of marine plywood stacked on top of each other and secured together. Fortunately they were the same thickness of our forceplate, so I was able design it so that we could sneak the cables out one side so the cats wouldn't chew on them. The first platform was built, and shipped by courier to Colchester. Somehow during the trip (all of 2hrs up the road), the forceplate platform turned into a box of books... or at least that is what was delivered to Colchester. Due to this, we had to rebuild the platform and try again so we got delayed by almost a month, but finally it got there.
Platform (II) with plate installed. Cables were run out the left (my right in picture) and buried under wood 
Data collection
So we had two days with the tigers and cheetah collecting data, although in truth the data collection only lasts an hour or two as we don't want to stress the cats.
Setting up the forceplate whilst being watched by the test subjects
One thing that we would come to quickly learn, is that scaredy-cat works as a description for most species of felids. The tigers were initially less than happy to go onto the plates, even with food bribes.

The tigers would scrape the food back off the platform/plate and eat it. I have to say I was impressed by their dexterity and picking up food with a paw to get to their mouths, but it didn't help the data collection. We got them moving across the plate, but not how we wanted:


Eventually, after much coaxing, we did get them to walk over the plate. We (the incredibly helpful keepers) even managed to get them to manage a trot from time to time.

Tiger with right front foot on the plate (marked by the grey duct tape in the middle)

Luckily Jack the cheetah was much easier. He has an area that he regularly paces when he is off exhibit between being fed and being let back out. As such we stuck out platform right there. We had the funny realisation though that after the first go, we needed to stick a log on the side nearest the fence otherwise Jack would continually walk down the side and not on the plate.

Jack being a beautiful test subject with a nice right front foot on the plate

Whilst we do not have a full set of results to show you, I thought it would be useful to show what the output of forceplate is for those of you who don't know:
Force trace from one of the trials for a tiger
For walking felids what we get is a more or less m-shaped major peak in forces corresponding to the vertical force. The first peak of the m is caused by the foot impacting the ground and the second peak caused as the animal pushes off the ground. The front-back force trace tends to look like a sin-x graph (although the one above is messy). This is again as the foot impacts the ground it causes a deceleration force (negative), before transitioning to an acceleratory one (positive). The remaining line is the mediolateral forces (side to side). This force is generally minor but is linked to any number of joint rotational forces (e.g. pronation/supination). These forces and shapes of the traces all change depending on the speed of the animal (with the m becoming n shaped at running speeds). Combined with the video data we are able to calculate running speeds and posture (or at least joint angles) and see how they change across an animal at different speeds, as well as across different species/body sizes.

End of part 1
So two days of work, we had a lot of data and a very busy student. Unfortunately due to the delays, we were unable to do anymore in 2015. However, that is not the end, and part two has actually just finished now so will appear imminently on the blog. It includes a lot more pretty pictures of exotic cats, as well as more successes, and some terrible failures.