I don't know much about Owls, but I know what I like

[Goddlefrood]

No: HPFGUIDX 167598

> JW:
 
> To my recollection, JKR has never offered a clue.  Nevertheless, 
it happens.  HP has successfully sent owls to Sirius without 
knowing what CONTINENT Sirius is in (exactly where are the 
"tropics?"), much less the street address.  Somehow, the owls 
figure it out.

Goddlefrood:

The tropics are the area between the Tropic of Capricorn and the 
Tropic of Cancer. It straddles the globe. I live in them :). Both
of these are latitudinal lines.

JKR may simply not know a great deal about owls as she herself 
admits, here's a little snippet from her site's Extra Stuff:

"However, any owl expert would tell you that Hedwig is strangely 
atypical of her breed. Only after Philosopher's Stone had been 
accepted for publication did I realise that Snowy Owls are 
diurnal. I think it was during the writing of `Chamber of 
Secrets' that I discovered that Snowy Owls are also virtually 
silent, the females being even quieter than the males. So all 
of Hedwig's night-time jaunts and her many reproving hoots may 
be taken as signs of her great magical ability or my pitiful 
lack of research, whichever you prefer."

Found in full here:

http://www.jkrowling.com/textonly/en/extrastuff_view.cfm?id=20

So she does not know much about owls, but she knows what she likes
and uses them to whatever purpose is necessary. I'll leave it to
you to decide which of JKR's explanations is best ;)

Goddlefrood