Barn Owls get around. A lot.
Just as a general comment, Owls (both barn owls and standard owls) are
great distributors. Meaning, they're good at getting lost and finding a
nice new places to live ;-) Some families seem to be really good at this
and, consequently, you find them in remote and far-flung locations. Some
common example families s from living species that come to mind are
ducks/geese, doves/pigeons, parrots, gallinules, and rails. Many of these
families also have wide global distributions. In Hawaii, as an example, the
"Pueo" is a subspecies of the mainland's "Short-eared owl" (Asio flammeus.)
The last I was paying attention, the idea was that after human settlement
and massive landclearing, the Pueo found a nice new home in the grasslands
of Hawaii with tasty rodents. (Prior to human settlement, much of the
islands were covered in thick bush down to the sea and there were no native
mammals other than seals and a microbat.) Every winter on the islands you
get a few confused mainland ducks (Pintails and Shovelers, for example), a
few seagulls, and sometimes something more exotic (Aleutian Goose, eagles
from Asia.) Hawaii is about as remote as you can get on this planet, so if
birds can make it there every year, then they can get a whole lot of places
more regularly.
The picture of what species distribute well (as in "get lost regularly")
would be even clearer, but such vast numbers of species were wiped out from
oceanic islands before study. Still, sub-fossil remains and early reports
show that there were lots more ibis, ducks, owls, and other far-ranging
creatures in the Pacific and Indian Oceans than there are today.
And, for what it's worth, Barn Owls in particular are champion distributors
- check out their global range map. Although I believe they've been split
into multiple regional species, that only goes to show how good their
ancestors were at colonizing new lands.
It would be interesting to hear whatever the current thinking is on Aussie
owl colonizations and radiation because the picture here seems a bit
unusual. Namely, we've got one genus in each family but then a whole bunch
of of species in each genus. So, a whole range of Ninox owls at different
sizes and then this amazing variety of Tyto owls. Is there anyone on the
list that knows the background on Aussie owl systematics at some level
higher than species?
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