Getting Scientific….. Or at Least Trying!

11-14 

In the words of the late great Steve Irwin... What a Beauty! Just look at his eyes!

 Hey Everyone!

I’m fresh back from a long but exciting day! Michael (from A Rocha) and I woke up at around 630am today to catch the bus to the upper western village of Kulmasa.  Kulmasa’s name roughly translates to cold pond in the native tongue, and it is the site of a large dam. This dam is where the crocodile survey will be performed.  

 Legend has it a very long time ago,  Kulmasa’s founding chief was on the run from a neighboring country. As he ran from his enemies he came to a lake and used several floating logs to cross it. When he got to the other side he looked back and noticed all the men chasing him we’re being devoured by these “logs” in the water. He realized that these were not logs, but crocodiles that had spared him and allowed him to cross and also protected him from his enemies. From that day on he declared that no one in the newly founded Kulmasa will take crocodile meat, and they shall live in harmony with the animals till the end of time.  Now onto the “sciencey” stuff!

Daryl, Michael, James, the Mole park staff, and I have all been discussing back and forth about the most efficient way(s) and cost effective ways to establish a survey of the crocodile population. Establishing it not only for the short time that I’m here, but for long term so that monitoring can continue long after I have left.

Originally my idea was to work with staff from Mole to trap and mark individuals though well documented means.  However there are two flaws that won’t enable a conventional  “mark-recapture” project to occur. 1) The Mole staff do not have the funds to travel to Kulmasa all the time so I would be with little or no help when attempting to capture adult crocodiles (IE Not a good idea, and not going to happen!), 2) The Adult crocodiles are the Eco-Tourism “Sell” of Kulmasa and potential capture and tagging/marking could hinder their ability to market the “friendliness” and harmonious relationship the crocodiles and people share if said crocodiles were to become people shy after the procedure.

So from here we discussed alternate options and came to an idea I got from watching my best bro Matt Nicholson doing work on Great White Shark fin IDs. He is using special software that works by analyzing the contour and shapes of dorsal fins to distinguish between individuals and thus create a “capture” or sighting history of the individual without even needing to mark or capture it.  As some of you know the crocodiles have large modified scales on their tails known as scutes, a feature that got the wheels in my head turning! I contacted Matt shortly after thinking of  using a similar idea for photo Id work in the crocodiles potentially using color patterns and shape as ID factors. Matt responded with links to the analyzing software as well as a link to a paper the employed a photographic identification key using the natural varied markings of Nile Crocodiles to generate capture histories from afar (Swanepoel, 1996) . 

From here I did a little more digging and was able to contact a Professor from Dartmouth University who had developed a photo analyzing program for African ungulate identification based upon the patterns displayed on their sides. I asked him his thoughts about using the program for my own survey with the crocodiles, and he thought that the program would work reasonably well assuming I was able to good solid pictures.  So ever since I’ve gotten ahold of the software I’ve been fooling around with it, and have found it to be very accurate thus far when using test subjects. 

So for the Adult crocodile population we will be attempting to use photographic Mark-Recapture, something that hasn’t really been done much in regards to crocodilians. However the major flaw involved in this method is the availability of the animal, if they aren’t basking or visible, pictures aren’t going to work out to well, but I am excited to test it out regardless!

We also decided that due to the reported abundance of hatchling and small juvenile crocodiles in the dam, we would attempt to trap and mark these individuals using a scute notching method that has been used by many specialists for several years (I also have experience with this from helping with an Alligator survey back home!).  This will be much more feasible considering the manpower and equipment available.  This however does lead to some biases in terms of recapture potential and what not, considering the potential of the juveniles to be spooked after being captured and marked and the general detectability of smaller crocodillians.  However we have decided to exhaust all options in order to get at least an initial base-line population structure developed, and the go-ahead has been given!

As mentioned before Michael and I traveled there today and did a scouting trip of the dam area, the dam itself is not very big and has a circular path all the way around it allowing for almost unlimited visibility of basking crocodiles. This bodes extremely well for survey potential, along with the fact that the dry season has limited the other water sources to the main dam and a few small pools adjacent to it, likely forcing the crocodiles to congregate in one or two areas along the survey route. 

During our survey one of the gentlemen who will be working with me exclusively (Numu the resident crocodile expert), showed me the interesting relationship the town has with the animals first hand!

He walked near the water and began clapping, and before we knew it a large 7 foot crocodile was on the banks and crawling towards us. I immediately got my camera out and got as close as possible (within 4 feet!).  The crocodile appeared to be content sitting on the bank, with us, however he got a little cranky at one point and took a big lunge at the four of us standing there! I hopped a few steps backwards, while Numu stood unbothered, Michael and his friend Morrison however nearly toppled over each other in surprise! The crocodile was then quick to settle back down, however I will keep in mind for future reference, that despite this “rapport” they share with the people they are still wild animals, and still the definition of an apex predator!

Very excited to get this study underway! Gonna be a lot of trial and error I think, but should be fun to do regardless and most importantly will help the local population of both people and the crocodiles!

Much Love, and Godbless!

“Can you draw out Leviathan with a fishhook or press down his tongue with a cord? Can you put a rope in his nose or pierce his jaw with a hook? Will he make many pleas to you? Will he speak to you soft words? Will he make a covenant with you to take him for your servant forever? Will you play with him as with a bird, or will you put him on a leash for your girls?- Job 41:1-5