Ask Peter

posted: 05/15/12
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Nile Crocodile

If you missed our Rumble in the River live chat with Peter Gros, former host of Mutual of Omaha's Wild Kingdom, we've got the transcript with your hippo and crocodile questions answered, right here.

Peter Gros: Good evening! This is Peter Gros, and I look forward to chatting with you and 'rumbling' with you about hippos and crocodiles!

Darlene: How did you first become involved with the Wild Animal Kingdom?

Peter Gros: I was a designer of endangered species reproduction facilities for animal parks and zoos in the United States, and I was successful enough that I started talking on national talk shows about out successes. I ended up meeting Jim Fowler one evening on the "Johnny Carson" show with the largest litter of tiger cubs ever born that we had to bottle-raise at that facility. After that show, Mr. Fowler asked me if I could participate in the "Wild Kingdom" show. I continued to work with zoos for the next five years, as well as becoming spokesperson for Mutual of Omaha with Jim Fowler, and co-hosting their famous wildlife show. To this day I still feel very fortunate to be able to affect public opinion and concern about our natural world through the relationship with Mutual of Omaha and Animal Planet.

Coolman: How often do you see alligators?

Peter Gros: Well, dude, I see alligators frequently while visiting in Florida, and years ago while filming them in China. The fact that they are direct descendents of dinosaurs, like the crocodiles in tonight's show still amazes me--how well and how long they have survived.

Mystic: What is the best thing to do if you find yourself face to face with a croc?

Peter Gros: Crocodiles are very fast, both in the water and on land. Hopefully, you would see one on land, and slowly turn and walk away. Crocodiles spend about 70 percent of their time eating small animals like fish. Considering the numbers of crocodiles remaining in the world, the estimated number of human fatalities is only 200. So there are many locations where man and crocodile do co-exist as long as the crocodile territory is respected and adequate space is given so they can retreat. The time I have spent working with researchers in the past, when we were trying to catch and tag the crocodiles, they were always trying to get away from humans and distance themselves from them. The best thing to do is to avoid waters that crocodiles are using for their habitat. Enjoy them at a distance.

Ellen: What's the largest alligator and croc on record? Where and when were they found?

Peter Gros: Boy! Ellen, I'd have to do a little research! It's not uncommon to hear of alligators being over 15 feet, and Nile crocodiles over 22 feet. We'll both have to look that up. Try a Google search!

Tracey: What is the best climate for a hippo to live in? And a Croc?

Peter Gros: Hippos and crocs flourish in a climate around 80 degrees F, although hippos don't have to be as careful as they are warm-blooded and can venture out of the warmth of the rivers at night when it's as cold as 40 degrees. Since crocodiles are cold-blooded, they can't really regulate their own body temperature. They have to be more careful of the length of time they can spend in low temperatures. Unlike mammals, crocodiles spend their mornings basking on a shore to warm themselves, and then slide into the water to protect themselves from the mid-day sun. They open their mouths in a wide yawn to allow the heat to escape, or dig burrows to avoid extreme temperatures. The preferred temperature for a crocodile is normally between 86-89 degrees F. As they heat up during the day, they move into cooler areas such as the shade or cooler water to prevent overheating. Geographically, they prefer to be closer to the equator, where the temperatures are best for their survival.

Drewster: What is it like to hold a tiger cub, Peter?

Peter Gros: (laughing) It's still a terrific feeling, although I have done this hundreds of times throughout my life. I've held tigers that were having trouble when they were first born, and been fortunate enough to raise one from two pounds until it was 500 pounds. Although it's not ideal for a tiger cub to be hand-raised (we prefer it if the cubs are raised by their parents). But in the wild, a percentage of the cubs don't survive, and are threatened or endangered animals like tigers in a captive situation where it looks as though the mother will not take care of the cubs, we have to hand-raise them. Unfortunately, hand-raised cubs can never be released back to the wild, since they build a bond with people and would have no fear of them. However, it's fortunate to have cubs that are bottle-raised and have no fear of people to be able to act as ambassadors for their species. I have noticed there's a very strong connection that happens the first time a child looks a tiger cub in the eye up close that makes that child want to do something to help preserve them in the wild.

Van Flint: Peter, I enjoyed the show. Do you consider the Nile or salt water crocodile more dangerous? Or is it a draw? Thanks.

Peter Gros: I would say it's a draw. They're both a very large, powerful carnivore that is happy to eat anything smaller than them, and, occasionally, animals that are larger than them! I have the utmost respect for both Nile and salt water crocs, or animals that have 68 large teeth and almost two tons of biting pressure! However, I don't want to paint the picture that crocodiles are huge, eating machines out there looking for people to devour. Considering the numbers of people who come into contact with crocodiles every year, the fatality rate is quite low, and a large percentage of the problems occur when people try to handle them or get too close to crocodiles. That should be left in the hands of professionals.

Caramel: How do crocs survive if they only eat once a week? Does their body just take a long time to digest?

Peter Gros: That's a very good question. Crocodilians have a very efficient digestion system, which is capable of digesting horns and bones. Most of the nutritional value of the food in terms of energy is stored in the body as fat in the tail and the back. So they are well adapted to survive for many months without feeding, relying on their stores of body fat to sustain them. A mature crocodile may be able to live for as long as 18 months in absence of suitable prey. The crocodile has had to adapt to severe climatic changes for many years. This may be an important way to survive long droughts.

Tracey: When is it reasonably safe to be in or near the water with hippos and/or crocs, and how would one know?

Peter Gros: When I go to locations to learn about hippos and crocs, and other potentially dangerous animals, I always travel with a local scientist, biologist, or expert. So if you're anticipating visiting some of these magnificent locations, I would suggest you contact a local travel company who uses experienced guides who will know exactly how close you can get, and where the safety zone is. This is important, because the guides are not only concerned about your safety as well as how close you can get to the animals without stressing them.

Hippo Lover: Can hippos grow back there tusks, and can crocs grow back there tails if they lose it?

Peter Gros: Crocodile tails are sometimes severely injured or bitten off in territorial encounters, and they do not grow back. However, many crocodiles will live a long life with a slightly shortened tail. I don't know if hippo teeth will grow back; it's something we're going to have to look up!

Susan: How often do hippos have babies?

Peter Gros: Hippos usually have one baby, after about an eight-month gestation period. Birth can take place on land, but usually occurs in water. The nursing or suckling takes place in the water as well, and that continues for about a year until the calf is fully weaned. The process of weaning begins at about eight months. At the same time they're weaning, they're starting to eat grasses as they graze at night, closely alongside their mothers. Fortunately, hippos reproduce very well in zoos and national parks, such as Murchison Falls National Park and Queen Elizabeth National Park.

Rdsatkc: Does incubation temperature only affect the females? Did I hear correctly that below 89 and above 94 makes females?

Peter Gros: Talking about crocodiles, yes, the incubation temperature does affect the sex of all crocodilians. I was amazed while working with researchers in the swamps of Louisiana to see these amazing animals that had been around since the time of the dinosaurs knowing which plant to break down and lay down on top of their nests of 70-100 eggs. As the material decays, the heat affects the temperature of the nest, and the hottest top portion of the nest would be female and the lower portion would be males. The warmest layer of eggs will be females, and the coolest will be males. The eggs look like a small chicken egg, and are leathery at first, and the females in some cases are very protective of the nests. Fortunately, captive breeding of both alligators and crocodiles is ensuring their survival. The eggs are simply removed from the nest and placed in an incubator, and the offspring are released back to the wild when they are about six inches to one foot long. This process has proven to be very successful in sustaining wild populations.

Ellie: Are hippos an endangered species? What can we do to protect the less than 200,000 that exist?

Peter Gros: Hippos are not an endangered species at this time. However, their numbers have been dropping. Fortunately, there's a tremendous effort to stop poaching for meat and ivory. Parks have been established which are saving large populations of hippos, affecting eco-tourism which brings an economic cash base to Africa, giving people an incentive to save these animals. More and more people are becoming interested—both locally and abroad—in preserving hippos and crocodiles, as well. There are roughly 86,400 in South Africa, 79,500 in East Africa, with most hippos still being in Zambia.

Paula: What happens to crocs and hippos during a drought?

Peter Gros: Crocs are quite well suited to handling drought because they are ectoderms, like reptiles. They don't need to eat regularly to warm their bodies, so they save enormous amounts of energy that can be put to other use or stored for a later date. If there's a year-long drought, the crocs have to congregate more densely in small remaining bodies of water, or bury themselves in the bans banks in the soft clay. But since a croc can go 18 months without eating or drinking, it can usually survive the time between droughts. So they key to their survival during these droughts is to dig burrows and hide from the heat. Hippos need water to survive, but if their wallows dry up they will move back to the rivers. As the rivers get lower and lower and fewer and fewer, you see more fighting among hippos because a smaller portion of water has to be shared by very territorial animals. They also need to wallow in warm waters to keep from burning calories. It's a highly efficient way of life. Because they don't feed on aquatic vegetation, as long as they can find grass at night and get back to the shallow wallows and rivers during the drought, they will survive. When they're out of the water, they are fortunate as they secrete oil that was thought to be blood sweat for years, and scientists now realize it is oil that acts like a sunscreen, and keeps sun from cracking the skin. So hippos are quite adept at handling extreme weather as well.

Patricia: What's the primary diet for a croc and a hippo?

Peter Gros: The primary diet for a croc is fish! About 70 percent of a croc's diet is fish and any other large mammal that comes to the water's edge to drink, whereas the large, powerful hippo is happy to leave the water at night and go foraging on grasses. Considering they're a huge animal, hippos are relatively frugal in their eating habits. They consume only about 1.5 percent of their body weight daily, about half that of a comparable mammal like the white rhino. During extreme scarcities of food, they will eat carrion.

Ellis: How many teeth do hippos have? When I see them in the zoo, it seems that they only have four large ones.

Peter Gros: Those are the four teeth that really do get your attention when it appears as though they're yawning at you in the zoo! But they actually have 36 teeth. The incisors that you noticed, and the canines, get to be 18 inches long. Those are used primarily for defending their young and establishing a territory. The reason we can see them so well is that a hippo can open his mouth 180 degrees, in comparison to a human that can only open 45 degrees. That gaping jaw displayed toward other hippos and other animals is a threat or a challenge, simply saying "I have large, sharp teeth. I'm very powerful. Stay away." I have paddled canoes along the lower Zambezi River to film elephants, and the hippos will often rise from the shallows to give us that wide-mouth yawn and show us their teeth, at which time we usually turn and paddle in the other direction.

Gerry: Do you have a favorite animal in the "Wild Kingdom," and if so, why?

Peter Gros: In terms of animals that live in the ocean, I was fortunate enough to dive with film dolphins in the Bahamas in the open ocean, and for four days they brought their young back to swim with us and entertain us. It was one of the most amazing experiences in a lifetime. I spent a fair amount of my life raising tigers--Bengal and Siberian--so it was certainly thrilling to see tigers for the first time in the wild, in the jungles near Katmandu. I was fortunate enough to be filming cheetahs in southwest Africa in November and was able to see a wild cheetah run full speed for the first time of my life, which was also an experience I will never forget! While there, I also experienced a giraffe come loping by me at about 20 miles an hour, as if striding in slow motion. So each time I go to a new continent, I'm always amazed to see animals in their wild state, and how magnificent they are. I hope to see Siberian tigers in the wild next year.

Ellis: How much does an adult hippo weigh?

Peter Gros: An adult hippo can weight over 6000 pounds, and can be 14 feet long. It still runs gracefully, on the tip of its toes. Fortunately, hippos spend a large portion of their lives in the water, where that massive body is supported. While it is still incredibly agile and fleet of foot on land, it can easily out-run a human.

Hippo Lover: Is it true that hippo's wastes products create habitat for many sea creatures?

Peter Gros: I knew that was coming! Yes, that is true. The hippo also practices 'muck spreading', which occurs when the tail is vigorously wagged to scatter feces far and wide. This has an orientation function, since bushes along the game trails to go to the grazing grounds are regularly sprayed. So it's a form of marking. This also takes place in the water, which is how it helps the fish. Some feed on it, and it also helps to create algae growth, which becomes a food source for other fish.

Van Flint: Peter, I've read that different species of crocodiles will breed with each other (American crocodile-Cuban croc, for example). But my question is has an American alligator ever been bred with a crocodile?

Peter Gros: Not to my knowledge. All captive animals in zoos in the U.S. are tracked by computer programs to prevent this happening, but not much is known about what happens in the wild.

Victoria: What does the future hold for you and the wild animals?

Peter Gros: I'm very optimistic about the future. In my lifetime, I grew up hearing stories of gloom and doom about so many animals that were becoming endangered, and about so much rainforest being destroyed, as well as forest, around the world. I heard about rivers being polluted, and some so polluted they would catch on fire. I also heard about oceans polluted, and beaches terribly polluted, and about air that we might some day not be able to breathe. I'm happy that in my lifetime I can now name species like the bald eagle, the grey whale, the peregrine falcon, the black-footed ferret, and the North American alligator that have been removed from the endangered species list. I have been in South America and seen sections of rainforest being replanted. I've seen rivers that used to catch fire being cleaned up to the extent you can now eat fish from their waters. The whales that I used to visit off the coast of Mexico, whose numbers were below 200 are now in the thousands. There are many, many success stories and I feel it's important to talk to young people about as much as we do the problems that we have in the natural world. Because I don't want the next generation to think it's too late. It certainly is not if we all do our part and contribute in a small way. For instance, recycling, planting plants in the back yard that will be a habitat for wildlife, helping community beach and park clean-ups, reading the label on products to be sure they're not from the rainforest. And probably most important, every time that you read or learn something on Animal Planet or Discovery about a species or part of the world that's doing well, share that with as many young people as you can. The more we share that, the more cooperation we're going to get from young people to save our natural world.

Animal Planet: Thank you so much for a great chat! Unfortunately, we are almost out of time. Do you have any parting words for us?

Peter Gros: Thank you so much for your phenomenal questions! You really keep me on my toes with all your research! I look forward to chatting with you after our next program.

Animal Planet: Thanks for joining our chat. We hope you enjoyed discussing the power and beauty of the hippopotamus and the crocodile with each other and with Peter Gros.

A Production of LiveWorld. Copyright 2004. All Rights Reserved.

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