I have a general question about community challenges: when there is a star requirement for the animals, such as the latest "release three star birds to the wild" one, must the animals be three stars and no more, or do four and five star animals work too? For whatever reason, I had almost no birds that were eligible for release that had three stars, but I had a few that were four stars I released as well. I only saw credit for one bird release, though, which suggests to me the birds must be exactly three stars.
I found the bird challenge really hard. In spite of having zoos with numerous peafowl, penguins, and ostriches coming out my ears, very, very few ended up having more than one or two stars, and the ones that did had been on display for a very long time and had excellent genetics. Even among those, though, almost none ended up qualifying. The various bird species just don't seem to be that popular with guests, even when I made a walkthrough peafowl exhibit that always had a ton of people in it.
It didn't look like that challenge was on a trajectory for success last time I saw it, though (only about 20% complete as of this AM), and it's closed now, so maybe everyone else had as much trouble getting three star birds to release as I did?