Reason for Osprey absence in NZ?

[Brendan T]

Having made the hop from Australia to NZ myself, a topic of enormous interest to me is vagrants from Australia, and with a few recent threads on similar or adjacent topics, I wanted to specifically discuss the Osprey (and to a lesser extent, the Peregrine Falcon).

Given the cosmopolitan nature of both these species, I was rather surprised back when I started doing my research prior to moving here, to discover that NZ has such a dearth of birds of prey, and in particular the lack of these two species. Of course, there's the possiblity of vagrants, and I do note an unaccepted UBR of an Osprey in the Chathams in 2004, but I'm less curious about the Osprey's lack of vagrancy and more interested in why they never became a breeding resident way back when.

I imagine it is in part due to climate, as although other subspecies occur in rather cold climates, the Australasian subspecies has only very rarely shown up in Tasmania, which I suppose is a fairly good litmus test to look at the possibility of them making it here. When looking into this, I was surprised to learn that elsewhere, ospreys are actually migratory, since our Aussie birds are not (in fact, neither p. h. ridgwayi or p. h. cristatus migrate, both notably occuring in rather warm areas, namely Oceania and the Carribean), and so I wonder if perhaps ssp. cristatus' lack of migration may also contribute, both in terms of dispersion, and in terms of having less tolerance for living in a country like NZ).

In fact, given all this, if I weren't living in NZ, I'd probably show more curiosity as to why the Osprey hasn't colonised Madagascar, as their absence there is more puzzling, yet since I am living here, their absence in NZ is of far more immediate curiosity. With such a wealth of knowledge on these forums, perhaps someone can offer some science-backed insight as opposed to my mere educated guessing? Cheers

[sav]

Hey Brendan,

No science from me, but I'm sure that your educated guess is spot-on.

cheers

[Jan]

I first saw Osprey in Scotland as a teenager when the farmer who owned the campsite our family was staying at, offered to take me to see the only site where they nested. I think at Loch Garten. I was 15 or so. I can't say that I really became familiar with the species in decades after that, except for seeing them in Aust. a few times.
BUT, I was on that Chatham Is. voyage in 2004 when british birders were convinced that an 'osprey' had flown over the ship from stern to bow and they raved about it. It just seemed like an old Swamp Harrier to me, very pale, but nothing out of the ordinary. Brian Bell was the bird guide on that voyage and he also said Harrier, thank goodness he was there!

[Brendan T]

Thank you both. That's very interesting, Jan. I couldn't find any info on what the UBR contained or why it was rejected, but that makes sense. I suppose the Osprey remains just a potential vagrant, then. It'd have to be near to the top of non-wader possible vagrants, though.

[Jan]

Hi Brendan, It's a long time ago, but I think Biz Bell may have been the UBR secretary back then. She might be able to find the file for that unaccepted Osprey sighting, if it still exists. She runs www.wmil.org.nz if I've remembered that correctly.

[Jan]

sorry, try info@wmil.co.nz

[corbettja]

Another reason might be that having evolved to live in coastal areas (this is true for peregrines and ospreys together) these birds are quite resilient to being blown offshore during storms. Peregrines in particular are very adept flyers so can probably navigate strong winds better than the other raptors that we see arriving here, e.g. barn owls, kestrels.

[paradoxdinokipi]

Believe also the fact that the Australian subspecies of Osprey & Pergerine are quite sedentary, or at least compared to the Northern Hemisphere where subspecies are far more migratory and thus more vagrants (such as Eastern migratory Pergerine vagrating to Aus, aswell as Peregrine records in Hawaii, the Midway Islands, etc).

[Brendan T]

Thanks corbettja, that's a really good point. I hadn't thought of that, but it makes good logical sense.

Thanks paradox, I do mention neither p. h. ridgwayi or p. h. cristatus being migratory for the osprey, but don't know enough about peregrine falcons to know if the same holds true for them (though I do know there are some records of the SIberian subspecies in Aus).