How much do animals eat?
Jennifer Watts: For larger animals, it ranges between 2 and 5 percent of body weight but can increase to upwards of 25 percent in smaller animals with fast metabolisms. For example, poison dart frogs need to have fruit flies and inch crickets available at most times, while larger frogs and toads get full-size crickets every other day. Our Andean condors get a rat or rabbit three times a week. Humboldt penguins, which weigh 7 to 8 pounds, get fed about ? to 1 pound of fish daily (supplemented with vitamin E and thiamin); dwarf mongooses get 6 grams of dry dog food, 6 grams of wet cat food and about 3 grams of mealworms and/or crickets daily. They also get a mouse, fish, or rib bone once a week.
The lions and tigers (which weigh anywhere from 350 to 550 pounds) get fed about 4 to 8 pounds of commercial supplemented meat product six days a week; marine mammals weighing 300 to 450 pounds are offered between 10 and 15 pounds of fish daily; and the grizzly bears (700 to 900 pounds) are offered between 7 and 40 pounds of food, depending on the time of year.
Hoofed animals eat the majority of their diet as hay, but again, size is a huge factor. Small duikers (African forest deer) weigh about 4 pounds compared with bison or giraffes that are both around 1,400 pounds.
Do animals eat for no reason? Out of boredom?
Jennifer Watts: In the wild, no, but boredom is rarely an issue in the wild. Besides all of the non-diet reasons animals move and forage, food items come into season at different times and can be difficult to procure and/or open. In captivity, the presentation of the diet makes it easy to eat, and foraging time is greatly reduced. To introduce variety, we try to offer diet items that are not peeled or husked so that the animals need to work for the food, and the animals seem to enjoy it. Watching gorillas and orangutans cracking coconuts is very entertaining because they do it with such fervor and determination!
Many animals will eat what is placed in front of them to the point of obesity because they have evolved to eat opportunistically whenever food presents itself. Some non-mammalian species, such as carnivorous birds and herbivorous reptiles, seem to have much more ability to self-regulate caloric intake, but it also depends on the species and the individual.
