Wednesday, 7 March 2012

A New Future for Post-Construction Wind Farm Monitoring?

Post-construction surveys at operational wind farms are an essential part of the on-going monitoring that all wind farm developers should undertake. The monitoring protocols are recommended in guidelines for wind farm surveys published by Scottish Natural Heritage (SNH 2010)[1] and Natural England (NE TIN069, 2010)[2].

Reasons for Post-Construction Monitoring

Post-construction monitoring is an integral part of wind farm survey protocol and is primarily used to test the accuracy of pre-construction survey methods and assessment and to ascertain whether there are any unforeseen impacts of an operational wind farm on birds and bats. In addition, whilst the methods for wind farm assessment are robust they need to be constantly monitored to keep them up to date.

The methods used in the UK to assess the impacts of collision mortality on bird’s uses a theoretical Collision Risk Model (Band 2005). This model is not flawless and when devised assumed that birds would largely avoid operational wind turbines, in the same way that birds generally avoid other structures such as buildings. The avoidance rates were, at the time, a ‘best guess’ and this is one area in which post construction studies have increased the knowledge of the true effects of operational wind farms on birds. 

The original avoidance rates were estimated at approximately 95% for most species however as a result of post-construction studies most have been revised up to between 98% and 99%. There are a couple of exceptions, such as White-tailed Eagle and Common Kestrel, which appear to have worse avoidance rates than other similar species and remain at 95%. In essence for most species this means that the model assumes that between 98% and 99% of flights within a wind farm area will avoid the operational turbines.

Post-construction monitoring will usually involve a repeat of pre-construction surveys as well as completing carcass searches. These searches are very important to show the true number of birds and bats that have collided with the operational turbines. 

Carcass Searches
At present surveys involve walking linear transects within a search area around each operational turbine looking for bat and bird carcasses, with surveys normally completed every 7 – 14 days (Drewitt and Langston 2008, Lucas et al. 2000 and Osborn et al. 2000). These methods are very time-consuming, impractical and biased as they rely on visually searching an area that greatly depends on the skills of the observer, the size of the carcass, vegetation cover and topography (Drewitt and Langston 2008).

Bats are generally found within an area half the length of the turbine tower however bird carcasses are found over a larger area; usually up to the length to turbine tip. With the advent of new larger more powerful turbines this can mean search areas up to 9.0 ha, which can take a staggering 9 – 10 hours searching by a trained ecologist. That equates to a single days work just to search one turbine.

A study at operational wind farms in Portugal was completed in 2011 where specially trained dogs were used to search for carcasses. The findings supported previously completed trials and were quite eye-opening in terms of both searcher efficiency and detection rates (Paula et al. 2011). This should also be good news for wind farm operators as increasing efficiency of post construction surveys will have a knock-on effect of reducing costs. The dogs were shown to increase efficiency rates of between 4 and 12 times, therefore increasing the speed of the surveys per turbine and detection rates of almost 100% in all habitat types. Detection rates for human searchers were as low as 10% in tall, denser vegetation.

Dogs really are the way forward for completing carcass searches in terms of both providing a cost effective service to clients and increasing the validity and value of post-construction surveys. This latter point will increase the robustness of pre-construction assessment processes and serve to enhance the‘green’ credentials of renewable energy. 

The Future is Bright –It’s Liver and White

Back in August 2011 Turnstone Ecology bought a Clumber Spaniel puppy in order to train her as a specialist search dog for operational wind farms. Named Luna (which was not intended to be short for Lunatic but is quite apt!), she is now 7 months old and we’re waiting for her first season and then search training will begin in earnest. Currently she’s being trained to the whistle and various hand signals but she already covers the ground very well and seems to have a very good nose; mostly for chocolate, plastic or anything chewable! The blog will be kept updated with her progress.

In the mean-time we have contacts to other dogs with the ability to complete post-construction studies, which will assist in passing on the cost saving that the efficient searches provide. Alternatively we can continue to do them the old fashioned way.

Turnstone Ecology has experience of both pre- and post-construction wind farm studies, including activity and vantage point surveys. We are constantly looking for innovative ways of making the process of planning such developments simpler and more efficient and have recently developed a model (based on Band 2005) that assists us with the Collision Risk Assessment process. This allows for the changes within turbine layout and removal of turbines to be reflected within the output of the Collision Risk Assessment and saves both time and costs within what is always a highly iterative process.

If you are planning a new wind farm project or need some advice or assistance with an operational wind farm we would be delighted to hear from you.Please contact us at for further information.

Wednesday, 18 January 2012

Happy New Year

Looking Back at 2011 and Forward to 2012

Happy New Year.  A quick review of an exciting end to 2011 and a look forward to what will hopefully be another successful year in 2012.

Before the main 2011 survey season came to an end we were lucky enough to be involved with a couple of interesting projects in the UK.  The first was a leisure development in Shropshire where we'd already found and mitigated for Dormouse but needed to complete appropriate bat mitigation under a Natural England licence.  After bat boxes had been erected and a specially designed bat loft incorporated into the site's new machinery shed it was time to exclude bats potentially roosting in buildings set for demolition.

During the exclusion and demolition five Soprano Pipistrelles were found behind a door frame and successfully relocated to nearby bat boxes.

November 2011 also saw the conclusion of a successful Badger exclusion in Staffordshire. After evidence of Badger activity had been recorded around our previously constructed artificial sett (see blog post - 7th June 2011) the exclusion process was completed under Natural England licence and demolition of the majority of the natural sett soon followed.

Inside the sett
Prints in artificial tunnel entrance

Once the natural sett was demolished back to the boundary fence, chain link was fixed along the bank to prevent access to open holes and deter Badgers digging back in to the subsequently landscaped bank.  Gates and chain-link were removed from Badger holes on the other side of the fence and Badgers are now free to use these once again. 

In October 2011 Turnstone Ecology were commissioned to assist with the assessment of a proposed wind farm in Mainland, Orkney.  The fieldwork is being completed by local ornithologists  and we were able to complete a visit to the site at the end of November.  In addition to familiarising ourselves with the site and meeting the client we were able to do a little birding around this very beautiful island. 

The Ring of Brodgar
The journey to and from Orkney was fairly eventful.  On the way north we had a stop over Stirling where we very nearly got flooded in!  High winds and rain followed us up the road - but did abate enough for Tristan to have a 'life tick' (Crested Tit) at the RSPB Loch Garten reserve.  The boat across to Orkney was a little bumpy to say the least.  We had a two day break in the weather whilst on the island which was very well received by all - especially when completing field work!

Adult Iceland Gull
We managed to do a little birding on the final day on the island - the highlight was an adult Iceland Gull in Stromness Harbour (best loaf of bread I've ever purchased!).  We also had very good views of Black Guillemots, Eiders and Purple Sandpipers.  Mark even managed to break 200 birds seen in a single year!

Black Guillemot
Male Eider

The return journey was fairly uneventful other than a little snow and ice in the Highlands however it transpired that we were very lucky to get off the island as the boat we caught was the last boat to leave Orkney for a couple of days due to very high winds and rough seas! 

Looking forward to 2012 where we will hopefully return to Orkney to complete surveys on one of the most northerly bat populations in the UK. 

2011 ended with Turnstone Ecology increasing our International experience with survey work and site meetings in Galati, Romania and a review of the Polish Guidelines Concerning Impact Assessment of Wind Power Stations on Birds for the Polish Wind Energy Association (PWEA).

After a long but fairly straight forward trip out to Galati, eastern Romania, we completed a site assessment of four proposed wind farm projects and met with local ornithologists who have been undertaking intial survey work.

Syrian Woodpecker

White-tailed Eagle mobbed by corvids

Following our highly commended review of the Polish Wind Farm Guidelines we were invited to Warsaw to speak at the PWEA 13th Wind Energy Forum .  Not a birding trip, so no pics, but an excellent and valuable experience and a good way to finish 2011.

We are all looking forward to another busy year of ecology surveys.  Timing of these surveys is critical as many are very constrained by the season and/or guidelines and it is possible that the results of surveys may not be accepted if completed outside of the guidelines.  We have included an abridged version of the ecology survey calendar.
Type of Survey
Phase 1
Site Initial Ecological Assessments
Great Crested Newt

Presence/Absence Surveys


Presence/Absence Surveys


Nest Box/Tube Surveys
Nut Search
Sett Surveys
Sett Exclusions/Disturbance



Surveys conducted all year but limited by high water levels
Water Vole

Peak months- April, May and September

If you are planning a development (large or small) in 2012 please bear in mind the survey seasons.  If you require any more information or would like us to provide a fee proposal for any works please contact us -