Another problem coloniser

The barn owl is a bird species that apparently colonised New Zealand some time around 2007, when a pair bred on private land in Northland and produced one chick; the chick survived and nearly fledged until it was found injured and subsequently taken into captivity, where it remains. The original pair of barn owls have allegedly produced other offspring since and formed a small population, but due to the fact that they are on private land and the land owner wants all but a few of the people who want to see them to keep their distance, this is difficult to determine.

Obviously, birds of prey are probably the most concerning birds when it comes to their ecological impact once they colonise a place where they did not previously exist.

This varies between species, however; for example, if the nankeen kestrel, a rare vagrant to NZ, became a coloniser, as has been long-anticipated, it is unlikely that it would have a significant impact on any of NZ's species that could serve as its prey. It shares habits with the harrier and NZ falcon; having a preference for open country like the harrier, and having a similar physiology to the NZ falcon. Therefore, it's nothing new to NZ's prey species.

The barn owl, however, is very different from the nankeen kestrel, and I have found enough to suggest that its presence here is something to be concerned about.

Denny's 'A Photographic Guide to the Birds of Hawaii', published in 2010, reads, 'The Barn Owl can be found throughout Hawaii. Sugar planters introduced it in the late 1950s in an effort to control rats in the fields. Rodents do make up a large part of its diet; but the Barn Owl also preys on birds and has been responsible for nesting failures of seabirds at Kilauea Point National Wildlife Refuge'.

So significant is this impact on Hawaii's native species that their eradication from the state is planned.

NZ's barn owls are likely to have a similar impact, should they spread, and there are going to be plenty of easy targets in store if they do. In my opinion, they need to be watched closely... Or would need to be, if they weren't on private land...

If NZ's barn owls had been introduced, I can guarantee that there would have been efforts to 'nip the bud' immediately, but that's just the omnipresent native-vs.-introduced double standard at work...

If NZ's barn owls do spread and become an ecological pest, it wouldn't be the first time a species of large owl became a problem after reaching a foreign land under its own steam. In the National Geographic Field Guide to the Birds of North America (2011), a part about Bermuda reads, 'Surprising northern species that have occurred include Northern Hawk Owl, Snowy Owl, Bohemian Waxwing, White-winged Crossbill, and Pine Grosbeak. The single Snowy Owl (1987) took to predating the endangered Bermuda Petrels and had to be collected. (Sometimes conservationists have to make hard choices!)'.