Try:
[[Media:Morepork.ra|Sound of a morepork]]
I don't think it's appropriate to put Realaudio on Wikipedia.
The only sound format that is readily usable by freely-available
software on multiple platforms and that is compressed for Web
transfer is Ogg Vorbis. Especially now that they've released
1.0, I see no reason to use anything else.
The software already semi-enforces this by accepting ".ogg"
files without complaint while it warns about other extensions.
That's also one reason I haven't chosen to document the "media:"
feature yet--I wanted to get some consensus about its appropriate
use, and maybe do it differently.