A pair of New Zealand falcons has remained resident and successfully nested within the proposed Hurunui Wind Farm envelope for the past two breeding seasons (2009/2010 and 2010/2011). During this period they successfully fledged one female nestling in each year. Monitoring of the falcons occurred over both years to assess their breeding success and falcons were radio tracked over the 2010 winter and subsequent breeding season to assess use of habitats and home range within context of the wind farm envelope. Data collected during monitoring the falcons’ movement patterns was used in a collision risk model (CRM) to estimate the rate at which collisions with turbines might occur once the wind farm is built.
Potential adverse effects to falcon breeding success associated with construction disturbance will be avoided with the implementation of a Falcon Construction Management Plan providing for the transfer of any eggs or chicks to a captive rearing institution and their subsequent release at a site approved by the Hurunui District Council and the Department of Conservation.
No adverse effects due to disturbance during operation of the Hurunui Wind Farm are expected.
Potential effects to falcons associated with habitat loss are considered negligible because most of the vegetative habitats where the falcons nest and which they favour are located deep in gullies, well away from construction zones. Rock outcrops are potential habitat for nesting falcons, although the resident birds also nest on the ground. An analysis of the removal of rock outcrops due to construction of the wind farm identified the removal of a single rock outcrop on a ridge on ‘E Road’. As the falcons are expected to continue to nest in more sheltered gullies and are not restricted to using rock outcrops as nest sites, it is considered that the loss of a single rock outcrop would have negligible effect on falcon habitat at the proposed wind farm.
The home-ranges of both adult and juvenile falcons were centred within and overlapped the area where the turbines are proposed to be built and all of the birds monitored were observed spending some time flying at a height that would place them at risk of collision with the turbines. As a result, detailed data on the movements and behaviour of the falcons at Hurunui was collected to provide estimates of collision mortality using CRM. CRM estimates that on average the time between potential collisions for the resident adult falcons could be approximately 4 to 5 years and every 50 years for juveniles during a three month predispersal period, after which they are expected to disperse from the wind farm. The collision modelling results reflect the location of the nest within the wind farm and the consequential high levels of activity within the wind farm. If the outcomes of the collision risk modelling are reflected in realised mortality, Golder considers that a local adverse effect is possible.
Based on the results of the monitoring and modelling we suggest that some or all of the following options could be used to ensure that any negative impacts to falcons as a result of the Hurunui Wind Farm are avoided, remedied or mitigated so that no net loss is achieved