I don't know. But if it wasn't removed for some moderation issue (not saying it was, just one reason why a skin can be removed) perhaps the author is updating it. Sometimes a skin will disappear (the author can remove a skin) and then an updated version appears but that may take some time as it has to go through moderaion again.
I didn't get around to downloading that particular skin while it was up, but it looked interesting (and of course I liked the animals too).
Thanks, sig101. I had downloaded it yesterday and was going back today to make positive comments on it. I, too, like the animals. I wasn't sure if the colors would be kind on my eyes - having bright, bold colors, but I was pleasantly surprised to find I can work with it w/o problems - and it is a quality skin overall. I hope it shows up again. I'd like to tell Gail she did a fine job.