Exhibit signage is the basic unit of zoo-based education - everyone exhibit has one, at the very least explaining what animal is in the enclosure. As technology has continued to develop, more zoos are moving towards more sophisticated, modern educational tools. Among those are touch-screens.
I first encountered touch-screens in a zoo setting at the Dallas World Aquarium. I found myself in massive, free-flight aviaries full of many species that I had never seen before and wanting to know more about. After stalking back and forth looking for more conventional signage, I finally noticed the computer screens scattered around the enclosure. A few random taps later, I was hooked.
There are many advantages to using computer touch-screens as opposed to regular signage. They can hold an enormous amount of information on a small device. You can put as much data on as you like, and have it expand out to meet the visitor's informational needs. If they just want to know what a duck in an aviary is called, they can see it easily. If that duck appeals to you for some reason, you can keep tapping away, seeing all the information that there is to display about it in great detail.
You want to add video or sound clips? Go ahead, it's a great way to highlight behaviors that are fascinating but might not be seen by many visitors, such as a rattlesnake striking, or a chimpanzee using a twig to fish for termites. You have a lot of visitors who speak languages other than English? No problem - you can have settings to change the language. Changes to the collection? These devices are much easier to update than traditional signage.
With so many advantages, why aren't these touch-screens in use everywhere?
For one thing, they are expensive. This is especially problematic if you have them in an outdoor setting, where they are exposed to the elements (or an indoor area, even, if it happens to be an aviary where birds are raining down poop and uneaten food on them). They may be installed in the fanfare and funding of a new exhibit, but once they are broken, they might not be replaced. Also, because they are expensive, there tend to be few of them, and they are quickly monopolized by folks who may be more interested in pushing buttons of the screen to see what happens then actually reading about the animals. I was at the Shedd Aquarium a few years ago, and almost had a seizure from the rapidly flickering touch-screens being manipulated by excited kids.
I think I'm also a slight hold-out just because of the technological aspect. Visitors - especially kids - spend much of their day looking at screens. Do we want them to come to the zoo and aquarium to look at more screens - or to look at animals?