Vol 6 Test 1 Part 4

Section 4
17:09
Section Four. You will hear part of a presentation on recent crocodile research in Australia.
First, you have some time to look at questions 31 to 40.
18:11
Now listen carefully and answer questions 31 to 40.
18:18
Hello, everybody. I've just arrived back from my field trip, and Professor Martin has asked me to tell you about it today in our research forum. As many of you know already, my dissertation relates to crocodile behaviour. My specialty is the saltwater crocodile, which is much larger than the freshwater crocodile.
I've just come back from the Northern Territory where I've been part of a groundbreaking study observing crocodile movements. It’s not the only time crocodile movements have been followed, but this study is unique because we tracked crocodiles using a satellite. Up until now, studies like this one have only been able to track crocodile movements using radio.
Not only was this method more stressful for the animal, which had to be caught several times, but it was also not very reliable, as the signal was often lost.
So you might be wondering why we chose to track crocodiles.
Well, crocodile attacks on people and livestock are rare, but when they do happen, the government believes that the problem crocodile should be relocated rather than killed. But can we be sure that the crocodile won't simply return to the place where it came from?
So we designed a study to try to answer these questions.
We wanted to establish, firstly, how far crocodiles can travel over a period of time.
The second thing that we wanted to know was how easy it is for crocodiles to navigate — could they find their own way home again if they were moved to another location?
Of course, the biggest challenge when observing crocodiles is that they are very secretive animals. They stay well away from people if they can, which makes them really difficult to follow.
20:10
I'll give you some information about the design of the study now.
There were three crocodiles in our study, all from the Northern Territory and measuring between three and four-and-a-half metres in length. The crocodiles were captured, measured and tagged, and then taken by helicopter to new locations up to 400 kilometres away from where they were found.
We were then able to use the tracking data to monitor their movements.
We used a specially designed transmitter, which we attached to each animal's head. The transmitter collected the data and relayed it back to us.
The results of our study were quite astounding. After they were released, each crocodile remained in the release site for some weeks, making random movements around the site each day — but then they each swam home, travelling by the most direct route.
These crocodiles showed remarkable navigational skills and stamina to swim such long voyages.
So what conclusions did we draw from this?
Well, we proved that crocodiles are clearly capable of making marathon swims to find their way home. This meant that the current policy should be reconsidered.
You might be wondering how the crocodiles managed to get home.
We concluded that they used factors such as sight, smell, and their position relative to the sun to point their way.
It's a little-known fact that crocodiles are more closely related to birds than they are to any other reptile, so we believe it’s possible that they use the same system to negotiate long journeys.
21:53
That is the end of Section Four. You now have half a minute to check your answers.