The next goal is to wire the zoo and have the orangutans video chat with others elsewhere.
“Orangutans love looking at each other,” said [conservationist Richard] Zimmerman, adding that one of the apes, 31-year-old MJ, is a fan of David Attenborough programmes.
“The orangutans loved seeing videos of themselves - so there is a little vanity going on - and they like seeing videos of the orangutans who are in the other end of the enclosure.
“So if we incorporate cameras, they can watch each other.”
Other centres, zoos and sanctuaries are said to want to get involved “immediately” and are just waiting for more devices to become available.
“We’ve been limited to Milwaukee because we haven’t been able to get enough iPads,” Mr Zimmerman said.
“We’ve been waiting for the iPad 3 to come out to make the iPad 1 really obsolete, so we can pick up a few.