May 2019

Great Spotted Kiwi (GSK) Project - Chris Richards

Hi All GSK supporters,

Jen our favourite GSK DOC Ranger/instructor has suggested 29th May as a training date, at DOC, for volunteers to learn, up date, and or remember, how to analyse recordings from recorders that have been out in the park, looking for GSK's.

We have helped with this before and it is a vital part of our involvement in the proposed GSK translocations. We currently have 4 volunteers and a few more would be most helpful.

If you can help and/or attend the training on the 29th May please let me know.

If it helps I am completely technophobic but did it last time and found the exercise very absorbing, interesting and helpful.

Looking forward to being inundated!

Regards, Chris.

Items of Interest- Peter Hale

A new design for a self setting trap. It will be interesting to see where this design goes, I imagine it will be quite expensive. http://www.nzautotraps.com/ The videos are worth watching.

Among all the environmental gloom and doom stories it is encouraging to read something positive: https://www.radionz.co.nz/news/national/387513/northern-dotterel-back-from-brink-after-protection-programme. Community involvement was crucial to the success and the story also highlights the importance of long-term data collection (bird counts).

Bird Population Dynamics and Predator Control - Peter Hale

We are all aware that predation by introduced mammalian pests is the primary cause of past extinctions as well as current declines and limitations of birds in the remaining areas of NZ forest. The response to predator control varies with different species and with different habitat. Species response is also influenced by a number of other limiting factors such as food supply and competition, habitat loss and modification and disease. If predator control removes predation as a limiting factor we need to understand the other factors that limit population.

You may have read this recent article on the changes in the Zealandia bird populations. The results show that what we perceive as normal or natural bird populations is dramatically different from what was in existence before the arrival of humans with their species introductions (both bird and mammal) combined with habitat destruction and modification. Our bird populations are in a state of constant change and we all can succumb to "shifting baseline syndrome". All the species that were present in the Zealandia area before it was predator- fenced have declined except tui. The translocated endemic species, stitchbird (hihi) and saddleback (tieke) along with tui have come to dominate the environment, pushing out the introduced species and natives such as silvereye and fantail plus the endemic grey warbler to the margins.

A similar picture has been described in many papers covering both mainland and island sites. Grey warbler declined during intensive multi-species pest control at 3 mainland sites, Te Urewera, Trounson and Mototau, possibly due to competition for food from whiteheads in the case of Te Urewera. Rat eradication on Kapiti Island saw a decline in tui and tomtit. Grey warbler are rare on Kapiti in spite of being one of the most widespread endemics on the mainland and again this is thought to be due to competition for food from whitehead, bellbird and robin. On Tiritiri Matangi Island grey warbler and silvereye declined and bellbird increased following kiore eradication.

Similar interactions have been reported for other species at different locations. Eradication of cats and goats and the exclusion of domestic cattle on Cuvier Island saw 4 introduced species plus fantail and silvereye disappear or decline. Following the arrival of ship rats on Big South Cape Island, tui and tomtits increased after robins and saddleback disappeared and bellbird greatly declined. Blackbird, chaffinch and dunnock all increased. Pest control in the Hunua ranges to protect kokako saw no change in grey warbler and fantail populations and a similar picture was seen at Boundary Stream.

For more detail on this subject see, Predation and other factors currently limiting NZ forest birds.

Julie Robilliard