Deterring Harriers from predating nests

[Dave Houston]

Can anyone offer some useful suggestions to Thelma?

We have a problem with Harriers / Kahu predating Kokako chicks on Tiritiri Matangi Island.  To the best of our knowledge, a couple of Harriers cruise across the channel from the Whangaparaoa Peninsula reasonably regularly (about 3pm each day and head back again around 8pm).  Tiritiri has a low and developing forest canopy, making nests easy to find and the Kokako being targeted are descendants of the last Taranaki Kokako, so we are very keen to prevent the chicks becoming lunch.
 
The Harriers in question seem very wily & people averse, so we are trying a variety of methods to protect the nests - setting up a carrion table on the end of the adjacent Peninsula, to entice them to stay put, placing a scarecrow near to nest trees and attempting to string up some nylon fishing line above the treetops near the nests.
 
I'd appreciate hearing from anyone who has found either deterrents that do or don't work, so we are not re-inventing the wheel.  We will also look at live trapping, but a deterrent would be great.  There are only 5 nest sites and all are easy to find. The island has a large number of visitors daily, so methods also need to be people friendly. 

All suggestions appreciated.

Thelma Wilson
Mainland Biodiversity Programme Manager
Kaiwhakahaere Koiora Rereketanga Toiwhenua
Warkworth Area Office

[janice lodge]

We live on the Whangaparaoa and also have a hawk "Kahu" who has been making regular passes around our neighbourhood since the nesting season began.  He also crosses the Wade River and scans the Weiti Forest.

When he "arrives" kereru and tui take to the air, often this is what alerts me to his presence. You might think I am mad (my husband does!) but since this has been happening I have gone outside, waved, shouted and banged whatever I can get my hands on to "see him off". This seems to work...... and our kereru and tui numbers are increasing so it doesn't seem to have affected them 

I appreciate however that the situation on Tiritiri Matangi is somewhat different due to the lack of inhabitants.

Interested to see what suggestions are offered.