Published: 10 August 2015

Becoming an expert: Potential impacts of Marine Renewable Energy Installations on Alderney’s seabirds

Victoria Warwick-Evans

Victoria Warwick-Evans is a 3rd year PhD candidate in the University’s School of Environmental Sciences, under the supervision of Dr Jonathan Green.

“My research is looking at the effects that Marine Renewable Energy Installations may have on the population of Northern gannets who nest on Alderney in the Channel Islands.

Marine Renewable Energy Installations (MREIs) such as offshore wind farms and tidal turbines are becoming increasingly prevalent as we strive to meet targets to obtain energy from renewable sources.

However, many of these devices are still in the early stages of development and, therefore, the effects of these installations on the behaviour and productivity of seabirds has yet to be ascertained in detail.

These impacts may include; collision mortality, displacement, habitat exclusion and increased energy expenditure as a result of disturbance during installation and if the device creates a barrier between foraging and breeding grounds.

Although Seabirds are primarily suited to life at sea, during the breeding season they are constrained to land, acting as central place foragers and returning to the nest between foraging trips in order to provision chicks. This imposes a limit on the area of suitable foraging habitat available to them. As a result, any suitable foraging areas which become excluded as a result of the installation of an MREI may alter the birds energy budget, and thus may impact breeding success.

The Northern gannet is a generalist predator with a diet consisting primarily of shoaling fish and fisheries discards. Their main foraging strategy is high speed plunge diving, generally to depths of 10m to 15m although they can dive up to 34m. They have a large foraging range, up to 640km in the breeding season, and are often away from the nest for periods of 20- 30hrs. The island of Alderney, in the English Channel, supports a colony of nearly 8,000 breeding pairs, which accounts for over 2% of the words population. These gannets forage throughout the English Channel, specifically off the south coast of the UK, and the north coast of France, and their foraging grounds overlap with nine sites proposed for the development of MREIs.

A first step to predict possible impacts from these devices is to determine quantitatively how dependent seabirds are upon proposed areas for development, thus we need to collect information on where these birds are going. The use of GPS technologies to track the movement of seabirds has grown considerably in recent years as they have become increasing smaller and more affordable. This has enabled us to track the movement of chick-rearing  gannets from Alderney over four breeding seasons using GPS devices. Up until this year the devices which we have used store the data in the device itself. This results in the need to re-catch the same bird in order to recover the data. As some birds are challenging to re-catch, approximately one third of devices are lost at sea, resulting in the collection of GPS data from between 13 and 18 individuals per year. This year we trialled novel devices which send real-time information about the location of the individual. These innovative devices relay information every three hours when in range of a gsm signal. We deployed twenty of these tags on Alderney’s gannets and have been tracking them since early June. One of the gannets has travelled nearly 800km, to the North Sea and back on a 32 hour foraging trip from Alderney.

We can use these 4 years of GPS data to assess the frequency of visitation to offshore wind farm development areas off the south coast of England and the north coast of France by the population of Northern gannets from the Alderney colony.

We have found considerable inter-annual variation in the use of these sites. We are using this information in order to parameterise spatially explicit individual based models, and we will use these models to make predictions about the effect that the proposed wind farms will have on this population of Northern Gannets.”

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