Re: Swamp Harrier on an 'ecological release' - Film

[David Rees <>]

Agree that there is more dead creature about now in a more open environment.  Vultures find food by sight as you say, however their American analogues the turkey vultures have a very good sense of smell in addition to sight.  The ability of these birds to find dead prey under dense canopies of trees is well known.  There is a nice demonstration of this on Attenbough's 'Life of Birds' series.  That is not to say predatory birds in NZ had a sense of smell since they are obviously related to Eurasian stock.  NZ was covered with temperate rainforest (still plenty of it about) but for alpine and some rain shadow areas. That eagle hunted Moa in that forest, which was probably grazed by them at floor level to a more open state than it is now.  

On Thu, Nov 30, 2017 at 10:52 AM, Philip Veerman <> wrote:

Thanks for all that. I have not been to NZ but I am in general aware of all those things, apart from the extinct harrier. That is a new one on me. Also I did not know about that possum numbers have declined. Even with the Moa and that Eagle, in prehistoric times, although I can’t have proof, I still would be surprised if there was as much available carrion then, as there surely would be now, with cars, wallabies, rabbits and big birds such as feral turkey and plenty of sheep......... Prior to people’s impacts there would not have been many large prey and predators. For carrion feeding to be effective to birds, the food needs to be big enough to be found easily from flying above, as perfected by vultures.

 

Philip

 

From: David Rees [
Sent: Wednesday, 29 November, 2017 6:39 PM
To: Philip Veerman
Cc: <m("canberrabirds.org.au","canberrabirds");" target="_blank">org.au>
Subject: Re: [canberrabirds] Swamp Harrier on an 'ecological release' - Film

 

Philip

 

For extinct harrier see http://nzbirdsonline.org.nz/species/eyles-harrier  and the eagle http://nzbirdsonline.org.nz/species/haasts-eagle

 

Re NZ Falcon - It occurs in the area where I filmed this bird, and I have seen it there.  Totally different, something between an Australian Hobby and a Peregrine in size and habit.  I have held a tame male and female NZ falcon trained for falconry on my arm, female is much bigger,  Normal food are small/medium birds. Has apparently adapted to living in the vast commercial pine plantations in this area. 

 

Re carrion - don't forget the Moa and that Eagle.  Possums can be super abundant, authorities use 1080 in industrial quantities to keep them down, often applied by helicopter over large areas, not popular with some.  In forests in the central north island that I have known over the last 10 years there there seems to be less of them about now, e.g. given the level of road kill currently to be seen on the busy roads compared to previously - car numbers have not dropped!  Seen the odd wallaby to and there are rabbits and big birds such as feral turkey and plenty of sheep.  Possums, stoats and rats are the main mammalian threats to birds there - esp. given they can climb trees to get eggs and nestlings, which are vastly more vulnerable than the adults.   Degree to which individual species can cope with these predators varies between native species, some cannot cope at all, others can cope a bit and some seem to do OK in areas where little or no pest control is undertaken.  

 

David

 

 

 

 

 

On Wed, Nov 29, 2017 at 3:41 PM, Philip Veerman <> wrote:

The book Birds of Prey of Australia. By Stephen Debus records carrion as food of the Swamp Harrier. HANZAB says “In NZ often take carrion; less so in Aust.”.

 

I wonder what are the several other now extinct harriers.

 

I like the way this film shows the big difference in pattern of the central tail feathers compared to the others, thus giving a very different impression of top and underside of the tail.

 

There is of course the other native raptor, the NZ Falcon. HANZAB says “rarely carrion” for it.

 

There probably was not a lot of carrion in NZ before possums, wallabies & cars.

 

Philip

 

From: David Rees [
Sent: Tuesday, 28 November, 2017 5:52 PM
To: <m("canberrabirds.org.au","canberrabirds");" target="_blank">org.au>
Subject: [canberrabirds] Swamp Harrier on an 'ecological release' - Film

 

Those familiar with New Zealand birds would know that the Swamp Harrier is the only member of the hawk family currently extant in New Zealand. There were once others, including a huge eagle that hunted Moa (plus children according to Maori tradition) plus several other now extinct harriers. 

 

There being no Crows (except for a few European Rooks in a few places) and no kites etc in NZ, it basically has the scavenging/hunting thing to itself and has become ubiquitous.  Here we see one doing something I cannot say I've seen one do in Australia - feeding on roadkill, a not uncommon sight in NZ.  Interesting to note that the remains it is feeding on is another animal on an 'ecological release' over there - a Brush-tailed possum!

 

No real audio on this footage as it was filmed from inside a car - optics not great, but these are very nervy birds when like this.

 

Filmed recently on visit taken at short notice to NZ.

 

https://vimeo.com/244778352

 

More to come...

 

 

Regards

 

 

David