Bird Death Risk - Wind Farm. Impact Assessment

From Executive Summary: A total of 52 species were recorded on or near the site. Native species comprised the bulk of the observations, particularly on the beach, lakes and wetlands, but introduced species predominated among birds resident on the inland dunes and plantations forests within the project footprint. The point-count surveys showed that many resident native species were only recorded outside the site or within coastal or wetland corridors within the site and confi rmed the need for turbine-free buffer zones along these waterways. These surveys also provided baseline data for comparison with post-construction estimates of bird numbers and activity. The migration study confirmed that the site lies on a major north-south migration route for shorebirds. 1,558 flocks of migrants were recorded in summer 2008 and 1,171 flocks in winter 2008. These flocks were detected using a combination of observers and radar. About 98% of all migrants in flight that were identified to species were South Island pied oystercatchers (SIPO). Radar was estimated to have detected 39% of SIPO fl ocks fl ying over or past Taharoa. It provided very detailed information on fl ight paths of those fl ocks that were detected and was the main means of detecting fl ocks during southward migration at night. At the sensitivity settings used, the radar was unable to detect smaller species of birds. During northward migration, 97% of detected SIPO flocks passed over or near the site during the day; on southward migration, about 82% of detected flocks passed the site at night. During northward migration in January 2008, when most data were collected, 49% of detected flocks passed the site over the sea and 51% over the land; 25% passed over the wind farm site, and of these, 52% were estimated to be flying at rotor height. Collision risk modelling (using the Band model and Monte Carlo simulations) was undertaken for migrant shorebirds. For the two main species of concern, this modelling predicted mean annual mortality of 28 (95%CI 4 - 60) SIPO and a mean of 2 (95%CI 1 - 5) wrybills. These values allow for uncertainties in the data and a lack of information on inter-annual variation in flight heights and traffic rates through the site. Appropriate mitigation for this mortality is required. Population modelling suggests that these predicted levels of additional mortality will result in relatively minor longterm population effects on SIPO and wrybills when projected over a 50-year period. Insufficient data were collected to calculate collision risk for the small resident population of New Zealand dotterels for for lake birds at night. The Taharoa study is the most detailed assessment of potential risk to birds yet undertaken at a proposed wind farm site in New Zealand, and is the first use of radar for ornithological study in the country. A great deal of information has been gathered, but there are still large gaps in our knowledge of bird interactions with the site. Overall, the impacts on avi-fauna are predicted to be minor, but still need to be assessed during wind farm operation. Actual mortality rates need to be compared with predicted values. Based on our experience at Taharoa, a number of suggestions are made which should improve risk assessment at other potential wind farm sites in New Zealand. Purpose: This study was undertaken between 2007 and 2008 at Taharoa Beach, 6 km south of Kawhia Harbour, to investigate the potential effects of a proposed 27-turbine wind farm on resident and migrating birds. The methodology for the study included (1) fixed-point counts, (2) monitoring of shorebird migrations, (3) monitoring of resident New Zealand dotterels, and (4) counts of waterbirds on the adjacent Taharoa Lakes.

This report evaluates the risk of collision of resident and migratory birds at the proposed Taharoa Wind farm site. The report was produced by an advisory group who collated, analysed, and interpreted data collected at the Taharoa Site during 2007 and 2008. Contents page from report: 1. EXECUTIVE SUMMARY...............................................................................................i 2. TABLE OF CONTENTS ...............................................................................................iii 3. INTRODUCTION .......................................................................................................1 3.1 Background .....................................................................................................................1 3.2 Project timeline ................................................................................................................1 3.3 Site description ................................................................................................................4 3.4 Project description ...........................................................................................................5 3.5 Research objectives ..........................................................................................................8 3.6 Best practice guidelines ....................................................................................................9 3.7 Key native species ............................................................................................................9 3.8 Defi nitions .....................................................................................................................11 4. METHODOLOGY - Resident Populations .................................................................12 4.1 Objectives .....................................................................................................................12 4.2 Field methods ................................................................................................................12 4.3 Analysis .....................................................................................................................18 5. RESULTS - Resident Populations ............................................................................22 5.1 Point counts - corridor surveys ........................................................................................22 5.2 Beach surveys ................................................................................................................28 5.3 New Zealand Dotterel .....................................................................................................29 5.4 Lake surveys ..................................................................................................................31 5.5 Other species of potential signifi cance .............................................................................34 5.6 Collision modelling ........................................................................................................35 6. CONCLUSIONS - Resident Populations ..................................................................36 6.1 Corridor / non corridor ....................................................................................................36 6.2 New Zealand dotterel .....................................................................................................36 6.3 Wetland species ............................................................................................................36 6.4 Other species .................................................................................................................37 7. METHODOLOGY - Migrations ..................................................................................38 7.1 Objective .....................................................................................................................38 7.2 International best practice ..............................................................................................38 7.3 The Band model .............................................................................................................38 7.4 Migration periods ...........................................................................................................40 7.5 Field methods ................................................................................................................41 7.6 Data analysis .................................................................................................................53 8. RESULTS – Migrants ...............................................................................................58 8.1 Seasonal Summary .........................................................................................................58 8.2 STAGE 1: Population size and species metrics ...................................................................66 8.3 STAGE 2: Taharoa migrations - South Island Pied Oystercatcher SIPO ................................67 8.4 STAGE 3: Proportion of population at risk.........................................................................71 8.5 STAGE 4: Modelling scenarios .........................................................................................73 8.6 STAGE 5: Collision modelling ...........................................................................................75 8.7 Estimating variance by Monte Carlo simulation .................................................................78 8.8 Population modelling ......................................................................................................79 9. CONCLUSION – Migrations .....................................................................................87 10. CONCLUDING COMMENTS ......................................................................................89

2007-2008

A number of methods were used, and are detailed fully in the report: Baseline “fixed point - fixed period” bird utilisation survey. Study of lake and wetland habitat value Study of NZ Dotterel Beach Surveys Beach wreck - survey of dead birds following storms. Incidental/opportunistic counts.

However, there are still substantial gaps in our knowledge of the ways in which birds interact with the Taharoa site, and consequently in our ability to assess the risks to some species. Good information now exists on many of the resident bird species on the site, and for pied oystercatchers, which migrate through the area twice a year in large numbers. There is much less information on smaller migratory shorebirds (which were not detected by radar), on resident New Zealand dotterels, and on waterbirds using the Taharoa Lakes. Many of the gaps in our knowledge result from the limitations of both human observers and radar, and in particular from our inability to monitor the movements of most species at night, the time when collision risk is assumed to be highest. Data quality: Varied and discussed in report. Completeness: Complete

Environmental impact assessment related to windfarm application.

Report available through the Department of Conservation

Complete