Tuesday, May 13, 2014

Bird Deaths at Wind Farms (Part 2)

Finding Dead Birds at the Base of Wind Turbines: The Protocol

In my last post, I listed the studies estimating bird deaths at wind farms. I plan to discuss each of them over the next week. 

Research Protocol:

But first, I want to describe the methodology for most of these studies. You can see these procedures in action in the video about bird deaths at the Altamont Pass wind farm here.  The discussion runs from 9:56 to 11:00 minutes into the clip. 

The developer/operator should place wildlife biologists into the wind farm on a regular basis to do a carcass count. Ideally, assuming the developer devotes the needed resources, the biologist should conduct the fatality searches within a radius of 50 meters of the turbine base. The searcher should mark out 100 meter square plots to record carcass findings for study longitudinally. 

    Scientists studying bird fatalities recommend the use of a search protocol involving 120 meter long transects spaced at 20 meter intervals or circular transects extending out to 45 meters from the turbine tower or base. 

      Each study area should consist of 10-15 turbines. For large wind farms, the searcher should focus searches on turbines close to landscape features that birds likely use. The searcher can also randomly select additional turbines to survey. The turbines surveyed should vary to assess whether one part of the farm creates more fatalities than other parts of the farm.

        The searcher designers must attempt to account for variations in landscape (cliff edge) and vegetation conditions (very dense scrub), which might affect visibility or accessibility to carcasses. They should make the search area smaller or section off those more difficult areas from the search area so the searcher can cover the same area easily from search to search.

          The searcher should check each turbine daily for small wind farms or every 5 days at larger farms. The carcass surveys should begin at dawn or one hour after dawn to limit loss to day time scavengers. The study should attempt to account for carcass loss based on overnight scavenger activity. One study showed that scavengers cart off a very large number of dead birds overnight.

          The searcher should use a slow and regular pace spending 30 to 90 minutes at each tower designated for search.

            The searcher should record:
            • GPS coordinates for the carcass,
            • Direction to the wind turbine the bird was found,
            • Distance to the tower the bird was found
            • State of the carcass,
            • Type of wounds or injuries observed,
            • Vegetation height were the bird was found,
            • Species,
            • Sex (if known),
            • Age (if known),
            • Date and time of finding, and
            • Condition of carcass ( intact, scavenged, dismembered).

            In addition, the searcher should:
            • Photograph the carcass, and
            • Map its location on a detailed map.

            Depending on the scope of the survey, the searcher may:
            • Do a field necropsy,
            • Collect carcasses for a lab necropsy, or
            • Take samples of carcasses for a lab necropsy.

            Taken together, this data, collected on a regular basis, can help wind farm operators decided when to shut down farms to protect migrating birds -- either by hour, day, or season.  The data can also reveal whether a certain turbine is especially dangerous to birds.  If so, the operator can dismantle the turbine. This video discusses that option at 6:00 to 7:30 minutes into the clip.

            Based on my reading of the literature, we still know very little about bird deaths associated with wind farms.  These types of fatality surveys are key to gaining that knowledge.  Obviously, they are expensive to conduct, even if the operator/developer uses graduate students to do the survey work. 

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