I’ve discussed this with Jerry Olsen who has commented –
Hi Geoffrey
I'm not on this birding site so pass this along if you like. In short, I agree with Chris, and he's probably seen more PO attacks than we have. Owls attack with their feet thrown forward and hit prey and then kill through contraction and piercing by talons. However, falcons and owls differ from hawks and eagles in that owls and falcons bite the neck of prey and can dispatch it (so falcons called 'noble' by ancient falconers). Hawks and eagles kill mainly by construction so a slow death for large prey and were called 'ignoble'. I suspect that POs must deal with Brushtails this way, biting the neck. Brushtails are very tough customers, and dangerous. and as Chris says, you can have a zillion rabbits underneath a PO roost or nest and these rabbits will be ignored i.e. Nat'l Bot Gardens no rabbits recorded as prey. They don't like coming to the ground, though they occasionally do. By contrast, Boobooks and Tyto owls commonly take ground prey.
j
From: Birding-Aus <> On Behalf Of Chris Lloyd
Sent: Sunday, 16 December 2018 12:32 PM
To:
Subject: [Birding-Aus] Powerful Owls
I am happy to stand corrected here and there are some real specialists in the field (Bilney, Mott, Olsen et al) but on the 20+pairs of POWLs in the Georges River studied for around five years and a couple in the southern tablelands and Illawarra, prey capture was by the feet. The talons are long enough to penetrate the dermis and muscle layers of smaller marsupials and all birds, so death is usually through lung/air sac or heart puncture. The exception was Brushtail Possums where some prey were still alive when brought to the butchery tree but did not survive long afterwards. The characteristic severing of the head is a butchery process for consumption and I have never seen an animal dispatched this way. While the bill is more than capable of puncture and tearing it is not strong enough to deal with dismemberment without significant assistance from the feet. The POWLs I have been bitten by in the hand can do some damage minor damage with the bill but nothing on the flying bolt-cutter (Sulphur Crested variety) and I would suggest something in the 120-180 PSI range. The feet are in a league all of their own and may be the reason for the “powerful/strenua” moniker. These could b about half of the Wedgetail which I think lies in the 1 tonne range.
It is unclear from the study what happens in the case of larger prey items such as the anecdotally reported attacks on dogs and foxes. The POWL tends to take largely arboreal prey and I personally have not witnessed attacks on ground dwellers nor seen data to this effect. However I did watch one pair in suburban Sydney attack my fox terrier cross on a track at dusk and credible reports of similar attacks on fox cubs and dogs in two other territories. These all appeared to be intimidation or hit and run but in all case the talons and legs were extended and facing forward with the bill being used for some threatening clapping. Larger Brushtails, that could not be lifted, were dropped and occasionally partially dismembered at ground level before the torso was brought to a butchery branch.
The low aspect ratio of the species and its breast muscle mass make speculation on its lifting capacity an interesting calculation and I for one would be interested to hear any data on this area. Ciao
