Increasing bird flight height accuracy and precision in digital aerial surveys

When it comes to collecting digital aerial survey data, they are broadly two methods – grid design and transect design. There are subtle but significant differences between the methods, but the most important factor is reducing the uncertainty in the data captured.

Designing world leading surveys

APEM Group’s use of grid-based survey design eliminates the risk of missing significant portions of the survey area that transect-based surveys can introduce. Grid surveys systematically sample the survey area collecting a greater sample number and a much more even spread of data points leading to a wider coverage of underlying environmental variables, which is why they represent the best method for site-specific surveys.

This is especially relevant where a seabird species has significant flocking tendencies as it reduces variations between images, resulting in a greater confidence in abundance estimates and a higher degree of precision than transect designed surveys. In turn this gives added confidence to the regulator that any baseline and impact assessment conclusions based on this data are sound, having been utilised in Australia, the UK & Ireland, the US and across Europe.

Innovative technology design, increased species identification

APEM Group’s design of camera systems allows data collection at 1.5cm ground sample distance (GSD) improving species identification. Added to our in-camera measurement systems – GNSS¹, IMU² and an externally mounted GPS³ antenna, our cameras can record the in-flight altitude as well as aircraft movement resulting in a more accurate geospatial data. With an accuracy of plus/minus 3 to 5m, our effort data is based on actual survey information is captured rather than planned altitude. This is crucial to inform species abundance and density estimates as well as ‘size-based’ flight heights.

¹ Geographical Navigation Satellite System)

² Inertial Measurement Unit

³ Global Positioning System

APEM Group’s level of species identification reaches the high standards required by regulators throughout the world for the collection and analysis of data used in impact assessments for offshore wind permitting projects. All individual birds recorded are provided with details of their age, sex, and moult status wherever possible. Additional behavioural information observed for each bird is recorded to provide data on whether a bird is sitting, flying, diving, or perched and orientation of flights.

The global standard for bird flight height precision and accuracy

Using a set of rules developed in-house we can estimate the flight height of birds with a range of error and confidence intervals unseen in the industry. Following various trials to better understand the accuracy and precision of bird flight heights generated from high resolution DAS imagery, APEM Group developed a robust approach to generating confidence intervals for bird flight heights. These estimates allow for variation in the size of individual birds, aircraft flight height measured by GPS, aircraft pitch, roll, and yaw, and analyst measurements.

APEM Group has also pioneered the use of LiDAR (light detecting and ranging) technology in an innovative new technique to measure bird flight heights combined with ultra-high resolution digital still imagery.

Using pulses of light from lasers to measure the distance to the seabird from the sensor, the height of birds above the sea surface can be determined to within 5 cm accuracy. APEM Group brought this approach to Australia for the first proposed offshore wind farm development, Star of the South.

The guarantee of quality

APEM Group’s species identification process allows for both internal and external quality assurance (QA) and delivers industry leading levels of species identification. Unlike some DAS providers whose rates include “possible” identifications, our identification rates are based on definite identifications.

Based on training from the world’s most experienced DAS analysts, our identifications are based on sound knowledge of species phenology, behaviour and ecology and are only made to definite identifications.

All survey data goes through an internal QA process, where bird identifications are reviewed and checked by APEM Group’s dedicated QA Manager to confirm that all species are correctly identified. In addition, our survey data can be subjected to external QA upon request by our client.

Reducing risk and increasing confidence

The precision provided for each element of our DAS data provides consultants, developers, conservation bodies and regulators with the confidence required to undertake robust impact assessments. Impacts can be more accurately understood as input parameters for abundance estimates, collision risk modelling and displacement analysis have tighter confidence intervals, reducing uncertainty.

When considering potential impacts from multiple different offshore wind projects on seabirds, higher degrees of confidence ensure that the correct level of precaution is included in the assessment process. This in turn allows for a more efficient permitting process to be achieved with more robust and accurate risk analysis being afforded from the beginning when using APEM Group’s DAS services for offshore ornithology.

We give global renewable developers the confidence that financial, environmental and delivery risk can be successfully mitigated first time, every time and on budget.

For more information on our DAS methods or how the APEM Group can help you visit our APEM Group Australia website and complete the contact us form at the bottom of the page.

About the author, Sean Sweeney

Sean Sweeney is Country Manager for APEM Group in Australia and leads the company’s efforts in supporting renewable developers and regulators find the innovative solutions to ensure Australia can meet its ambitious targets for offshore wind capacity.

A global expert on offshore ornithology, Sean has designed and led innovative seabird surveys, behavioural studies and impact assessments at APEM Group for over 12 years. His contribution to advances in seabird science and how they interact with offshore wind developments is backed by multiple scientific papers and presentations at international conferences.

Sean brings significant experience in the process of gaining consent for offshore wind development projects, including the first project in the world to rely on Digital Aeriel Survey data to characterise its baseline for offshore ornithology assessments.

Acknowledgement of Country

We acknowledge the Traditional Owners of Country throughout Australia and recognise their continuing connection to land, waters and culture. We pay our respects to their Elders past and present.

About APEM Group

With locations across the globe, APEM Group provide independent environmental consultancy and expert scientific advice to a wide range of industries including water, renewables, infrastructure, power and utilities, ports and harbours as well as to regulators and governments around the world.

We provide a range of services to clients including our world leading digital aerial wildlife surveys, environmental impact assessments, marine, water & terrestrial ecology, geospatial insights, shipping and navigational risk assessments and landscape visualisation.

Find out more: www.apemgroup.com

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