Chapter 18 - Zambia's Lake Kariba & Crocodile Farm

From Victoria Falls, Toto drove through the country of Zambia to Lake Kariba. The lake is formed by a dam on the Zambezi River, downstream from Victoria Falls. The border between Zambia and Zimbabwe runs through the middle of the lake, as the river still forms the border here. Actually, the middle of the lake is also the safest place to swim, since the lake is home to many wild crocodiles and hippos, which stay closer to shore. I'm sure you remember from Chapter 16 that hippos are quite dangerous. I probably don't have to tell you that crocodiles can be dangerous, too. This is especially true when they're big, and I saw some big ones at the crocodile farm on the Lake Kariba.

There are several species of crocodiles, found around the world in Africa, Australia, Papua New Guinea, and Asia. The species in Africa and Zambia's Lake Kariba are Nile crocodiles. (The Nile river is a river in northeastern Africa, most notably Egypt.) You've probably seen belts, shoes, wallets or purses made from crocodile skin before. Well, just like leather, which comes from cows, the skin for these items comes from crocodiles, which must be grown on crocodile farms. The largest crocodile farm in the world is on Lake Kariba, so I went to see it.

The farm has two parts. In one fenced area, they have many ponds filled with really large crocodiles whose job it is to lay eggs. We went around in the back of a truck while they fed these mama and papa crocodiles. Let's just say I wasn't at all interested in getting out of the truck, as these animals were really big! Most of them had been captured on the lake, to prevent local people from killing them to protect their livestock.

It takes at least twelve years for crocodiles to get this big and start breeding. Some crocodiles live up to one hundred years old in the wild! At this farm they had 1,500 breeding crocodiles, mostly females, because they are the ones who lay eggs, which happens around October. In the wild, each female lays an average of thirty-four eggs. When I was there, the farm was advertising for temporary seasonal workers to collect the eggs in a couple of months. The advertisement said that job applicants must be able to "swim, run fast and be brave!" The farm also buys wild eggs collected from locals, because the Zambian wildlife department wants its very poor citizens to think of crocodiles as valuable. Otherwise, they might just kill the wild crocodiles as a nuisance.

The interesting thing about crocodiles is that the sex of the crocodile is determined by the egg's temperature while it's in the nest. A temperature of 32 degrees Celsius (90 degrees Fahrenheit) results in females, while 38 degrees Celsius (100 degrees Fahrenheit) results in males. Since the farm wants to save energy and have more females, they keep the incubator at 32 degrees Celsius.

45,000 eggs go into the incubator each year, which is the second area of the farm. When moving eggs to the incubator rooms, the collectors have to keep each egg in the same position it was in the nest, so that the egg hatches properly. This is because the baby crocodile is attached by a tiny tube to the egg yolk, which feeds it. If the egg is turned to a different position, the feeding tube from the yolk might get clogged, killing the baby crocodile inside the egg.

After about ninety days, the eggs begin to hatch. The first crocodile to hatch emits a noise as a sign to the other baby crocodiles, who then all start hatching together. In the wild, the mother hears this cry and opens the nest to help the tiny babies  (20-30 centimeters long) into the water. At the farm, workers help the eggs to hatch in a special hatching room. To prevent all 45,000 eggs from hatching too early or all at once, the workers take all the eggs that are close to ninety days old and move them from the incubator into a separate hatching room.

The farm raises the baby crocodiles in a controlled environment, to ensure that as many as possible survive. By the time they're two years old, they live in pens like this. In the wild, only one percent of eggs survive, but the processes at the farm ensure that seventy-five percent of the eggs hatched there survive. This gives them more crocodiles skins to sell.

Of course, to get their skins, the farm has to kill the crocodiles when they reach four years old. The farm ships the skins to Japan and Singapore in Asia, where factories turn the skin into shoes, belts, bags, and other expensive accessories. This is like killing a cow for its leather hide, except that cows are typically killed for their meat, not for the skin (the leather is considered a kind of bonus). The farm, on the other hand, sells some crocodile meat (it tastes like chicken, honest), but people don't buy crocodile meat the way Americans buy beef, so they don't sell all of it. Instead of throwing it out, they feed the meat to the 1,500 big crocodiles--who don't seem to care that they might be eating their relatives!

Unlike warm-blooded mammals, crocodiles are cold-blooded reptiles. This means they have to rely on the sun's heat to warm their bodies. Humans and other mammals have a constant body temperature, while reptiles can allow their body temperature to change. This means they can slow down their heart rate to only three or four beats a minute. The farm told me that a crocodile can also hold its breath for up to three hours underwater. (Don't try this at home!) In the Serengeti National Park in Tanzania, there are seventy- to one-hundred-year-old crocodiles that surprise the wildebeest crossing the river by holding their breath for so long that the wildebeest forget the crocs are there. These old crocs can live for a whole year just from that one big meal!

Watching the Zambian farm feed the big crocs, I saw that they don't really chew their food--one crocodile ate an entire chicken in one gulp. If you've ever seen a snake (another reptile) eat, you know that they eat the same way, taking a long time to digest their food. Crocodiles eat quickly and digest slowly, which is why they can live so long off one big meal. Since you're not a reptile and digest your food relatively quickly, I suggest you continue to chew your food at home.

Another interesting thing the farm told me was that crocs open their mouths while in the sun, like this one. Do you know why? They do it to cool their brains! Their brains must operate at a cooler temperature than the rest of their body, so the crocodiles do this so their brain works better. Next time a grown up tells you to close your mouth, you can tell them that you're just cooling your brain like a crocodile so you can think better!

Travel Questions about Zambia & the Nile Crocodile:

1. What was the name of the lake that Toto visited in Zambia?
2. What kind of crocodile do they have in Zambia?
3. How old can crocodiles live?
4. How many eggs does a female lay in her nest on average?
5. What determines the sex of the eggs when they hatch?
6. If you wanted to work at the farm collecting eggs, what three skills does their advertisment say you'd need to have?
7. Where does the farm send the crocodile skins to be made into handbags, shoes and other fashion items?
8. What is the difference between warm-blooded and cold-blooded animals?
9. Why do crocodiles sometimes keep their mouths open in the sun?

Global Nomad Questions on Zambia:

1. Draw a picture of a worker collecting eggs from a crocodile nest.
2. If one centimeter (cm) equals 0.39 inches, how many inches is a 30-cm baby crocodile when it is born?
3. Being cold-blooded is just one thing that distinguishes reptiles. What are other characteristics that make reptiles unique?
4. Zambia and Zimbabwe used to be part of Rhodesia. Research when Zambia got its independence and why it was once called Northern Rhodesia.
5. Crocodiles are different from alligators, even though they look similar. Do a cybersearch to find out the difference and write a paragraph about what you learned.
6. Some people do not approve of raising animals just to be killed for their skins. In Zambia, the farm provides jobs and promotes wildlife conservation for this poor country, which the government believes is a good thing. Do you agree with this or not? Write an essay explaining your opinion on the issue and why you feel that way. Does your behavior support your opinion?
   

Comments

[Bill Mulders]

The ideal incubation temperature of eggs varies between 28 to 33 degrees centigrade. Minimum of 28 will ultimately result in a majority of females and 32 - 33 will result in a majority of males. Exceeding 33 will cook the eggs. The sex is determined within the first few days of incubation depending on temperature.
Crocodiles bask in the sun with their jaws open in order to regulate body temperature and not cool their brains.