New debate over zoos... wait no it is the same debate
Your dog is not happy being a house pet. He wants to jump on other dogs and sniff crotches. The fact you do not do this to him, worries him. You should start. Oh and not letting him poo anywhere he wants is un-natural and leads to urinary tract infections.
Your child wants to play with his friends all the time. He wants to hit other kids with sticks and though rocks. Not letting him do this causes him to display depression and reduces his exercise level. Feeding him in this state only leads over weight and type 2 diabetes.
We think of animal in a very stupid ways. Your cat is still a predator with claws and teeth that wants to kill and eat things. Zoo animals are still the same animals they were in the wild, with the same needs. A tiger sitting in a cage in a zoo needs to hunt as much as a tiger in Nepal need to. It is not the cage that causes zoo animals to get bored, it is that fact that we are not letting them eat the antelope across the way.
The truth is that what causes this type of behavior is that we are not entertaining the animals in zoos. Tigers, Polar Bears, and Elephants all require enormous amounts of space. Animals kept in even reasonably spacious exhibits can develop repetitive behavior. The key to solving this problem is keep the animals mind occupied. They should give the animal new things to deal with and new things to over come. If you saw a keeper feeding straw to an elephant, you would think the keeper was being mean. Straw has little food value. In the wild, 4 months a year that is what they eat. They have to travel 40 miles a day to find enough food to survive. That is the truth about the wild. If you really care about occupying their minds, you have to be willing to miss-treat them.
With the advent of television every child knows what an elephant looks like. They are pink or blue and live in the same land as Winnie the Poo. Banning Zoos in favor of Animal Planet would raise children that thought wild life was like the crocodile hunter. Trust me we do not want that.
Stop and think about it. It is about quality of life. If I dropped you on a desert island with predators that wanted to eat you, would you feel abused? This is what the wild is like. As humans, we like to think of it is the Jungle Book with all the singing and dancing animals. At the same time we tend to think a zoo cage is horrid. Do you live in an apartment?
What animals want is the same as you. To live a fun life where they get to face challenges and succeed. Giving zoo animals things to do will take letting go of our idealistic image of animals. We have to be ok with watching a monkey struggle to get enough food out of a feeder. Because in the wild that is what like is like. Anything else will lead to bored animals.
People like PETA and other have contempt prior to investigation of this issue. They view any interaction between people and animals as people abusing animals. At one time most zoo elephants were working elephants. Meaning that handlers would us them to do work. The practice is dangerous for both the keeper and the elephant. Due to the outcry of abuse, few elephants in zoos are handled anymore. This has lead to bored elephants.
We can not be both kind and good stewards all the time. Just like as parents you can not always be kind to your children.