Actually, horses, birds and the small woman (which is called a trow wife) don't work in the Uru version. So if you're playing on DI, you can wait as long as you want to, you won't see them. They are only available in the Crowthistle demo.
Such topic tends to get lost in the amount of threads on this forum, but I published a
fix for a few things for the Uru version (edit: don't forget to scroll down to D'Lanor's post, he also found a way to increase performances). It fixes the horses, the birds and maybe another thing or two. The trow wife, though, still doesn't work, nor the reflective water, etc. It wasn't added to DI because it requires the user to manually edit the Drizzled version of the files, which would be really tedious to get to the Ages.
More or less related, there is a way to play Crowthistle in
hi-rez.