I don't read the first page to say that you must be 3. You must be 8 to do the Sunset Safari but I don't see an age requirement on the Sunrise.
I've done it twice and thought there were kids under 3 but was always paying more attention to the animals then the kids on the safari with me.
I would ask AKL IPO if there is an age requirement.
Here's what I was told last December by club-level IPO ... For the sunrise safari, open only to Animal Kingdom Lodge club-level guests, you must be at least three, or maybe four, years old to go.
I believe they discontinued the special extended safari that any club-level guest could book (Wildlife Discovery Excursion:
http://allears.net/tp/ak/wildexcursion.htm) last year when the new animal adventure was introduced.
The new adventure was reviewed on The Dis podcast:
http://www.disunplugged.com/2011/03/14/wild-africa-trek-at-animal-kingdom-at-walt-disney-world/) and they said you had to be at least nine to do it.
For the special, Animal Kingdom Lodge-only guests Wanyama sunset safari and dinner, you must be at least eight years old, according to the Disney website (
http://disneyworld.disney.go.com/dining/wanyama-safari-resort-tour/).
I was told that my son, who was three (almost four) at the time, was not eligible for either of the special Animal Kingdom Lodge-only safaris, and it was one of the reasons we decided against staying at Animal Kingdom Lodge after originally having it booked due, in large part, to me thinking that the private, guest-only safari sounded like something he would love and reading very good reviews here. He WAS old enough to go on the special safari any club level guest could book, but, like I said, my impression (which could be wrong as I haven't looked into it since) is that it was ending in December 2010. (We had booked it but it was cancelled due to weather.)