AVIAN MORTALITY QUESTIONS AT WIND PLANTS
Initial List of Avian Mortality Questions
Before the meeting, a lengthy list of questions concerning the issue of bird mortality at wind plants was compiled by the meeting organizers and circulated to all attendees. It was hoped that this list would help the attendees identify the range of issues to be discussed. It was recognized that no one question from this list fully defines "the bird problem at wind plants". Collectively, however, these questions go some way toward defining the problem.
The organizers hoped that the list might serve as a starting point from which to begin formulating a prioritized list of major research questions relevant to the issue of bird mortality at wind plants. It was recognized that the list probably does not include all relevant questions. Meeting participants were asked to suggest other important questions that should be added to the list.
Many of the avian mortality questions on the initial list were suggested by the organizers and their respective organizations. Others were questions that came up at meetings of the Kenetech Windpower Avian Task Force, either during Task Force deliberations or from the public in response to Task Force presentations. Still other questions were suggested to the organizers by prospective meeting attendees during informal discussions in the weeks preceding this meeting.
While compiling the list, the organizers gave some attention to the wording of the questions in order to clarify the issues. However, no serious attempt was made to refine the wording to any "optimal" form. Some related questions were combined, but other overlapping questions remain separate. The organizers listed the questions under six more-or-less self-explanatory categories:
Structural Design of Wind Plants
Bird Populations
Wind Plant Siting in Relation to Habitat
Experimental Design
Management Approaches
General Questions
Some questions could have been listed under more than one category, but for simplicity are listed only once. The organizers made no attempt to set priorities, and the sequence of categories and questions is largely arbitrary.
The following is the list of avian mortality questions as circulated before the meeting, with a few italicized explanatory notes concerning the origin of the questions or the discussion of those questions during the meeting. After initial discussion, meeting participants decided not to attempt a detailed revision of these questions, but rather to formulate a new and shorter list.
Structural Design of Wind Plants
[This category deals with questions concerning the design, spacing and spatial layout of turbines, turbine support structures, and ancillary equipment.]
What aspects of a wind plant and turbine design result in vulnerability?
Is it possible that some parts or a part of the turbine (tower, support structure wires, blades, or the nacelle) are more responsible for mortality than other parts?
If yes, can the structural parts be (1) designed to reduce mortality? (2) redesigned or retrofitted?
Is this a species-specific issue?
Are wind turbines being used for birds to perch upon?
Is this a problem? If yes, can turbines be designed to prevent perching?
Is there a relationship between spacing and/or height of the towers in relation to kills?
Are the electrical pole lines and/or substations contributing to mortality if designed to the latest avian design specifications?
[The relevance of this question was recognized. However, meeting participants agreed that this question is largely separate from the question of mortality attributable to wind turbines per se. Therefore, most participants preferred not to deal with this question at the present meeting.]
Is there any difference between [the effects of] upwind and downwind machines on birds?
This category of questions is centered on population effects; critical points include the following:
how is population being defined?
what exactly is a population effect?
what segment(s) of the population are being killed, and how does this impact the population near- and long-term?
should population analysis be an integral part of all studies?
does direct mortality resulting from collision result in net increase in mortality in the region? (i.e., is compensatory mortality operating?)
what is the impact [of turbine-related mortality on dispersal of birds] to other populations?
Could mortality caused by wind turbines ever be reduced to zero by mitigation?
Wind Plant Siting in Relation to Habitat[Attendees agreed that this is impractical, because sooner or later birds collide with any tall object.]
What habitat features are being modified by wind farm development that might be attracting birds (e.g. ground disturbance that enhances squirrel habitat; creation of man-made perches)?
Are there opportunities for win-win situations, e.g. by using wind farms as a means to prevent alternate land uses that are more damaging for birds, e.g. housing developments?
Are there locations or situations where passerines would be impacted? [or other types of birds such as waterfowl, shorebirds, etc.; raptors may not be the birds most seriously affected in some parts of the country.]
Experimental Design[This category is recognized as a "catch-all" that overlaps other categories. It includes questions relating to fundamental research principles, the generality of results from specific studies, temporal and seasonal effects, and the need to aim for rigorous science so as to obtain results that will be widely accepted by all stakeholders.]
What data are needed and how can we gather these data?
How long is it going to take to get answers about the biology of the avian/wind-facility interactions? At what levels of funding?
What is the priority of species we should be studying?
How can we use site-specific research to validate or refine available tools-procedures-databases?
How can success be measured?
How can we ensure that any studies we define and describe will be accepted for their scientific content?
How and under what circumstances are birds being killed (perching, stooping); when are birds being killed (diurnal/nocturnal migration or otherwise); what birds are being killed (resident vs. migrant); are there geographic differences?
What use do studies in one area have for siting of facilities in other areas?
Is information (e.g. inventories, counts, databases) available that can be correlated to site-specific assessments of avian impacts? How can site experimental design relate to collection of this kind of information?
What existing tools or procedures can be used to improve inventories at sites where there is interest in development of a wind plant?
Should radar or other quick surveys be done at study sites?
How relevant are data on collisions of birds with other structures, such as transmission lines, radio towers, etc.?
What are the most appropriate procedures for assessing the potential impacts of proposed wind developments on bird populations, and for comparing the potential impacts of different alternatives?
What role does experimentation and/or adaptive resource management have in the development/design of future plants? That is, rather than deciding "all or nothing" for a facility, what about developing an experiment that allows production while refining understanding of the problem and/or mitigative measures?
What is the applicability of using surrogate species to the species in question (e.g. pigeons for raptors, hawks for eagles)?
What is the applicability of using passerines as surrogate species?
Do migration paths shift over time? How long do you have to take measurements to determine width of path? What species/region/topographic variations exist in path width and consistency?
Are there any man-made devices available that would deter birds from coming near wind turbines?
Management Approaches[This category applies mainly to the management of existing wind power facilities, although there are implications for new facilities as well.]
If no population impacts are seen, is mitigation necessary for the kills that do take place?
What can be done with existing plants if they are causing high levels of mortality?
Are kills of birds at wind farms "worse" than mortality from other man made-structures of the same size?
Are kills of birds at wind farms "worse" than mortality that would occur in the same area if there were no development?
Is direct mitigation a useful or legally legitimate approach, i.e. enhance habitat, increase populations in other areas to compensate for mortality by collisions?
General Questions[These questions, although considered no less important, did not fit easily into any of the previous categories.]
Can projects continue under development without probable irreparable damage to critical avian populations?
Can "safe" wind production zones be identified a priori, i.e. must topographically enhanced sites such as ridges and bluffs be avoided?
Would it be helpful to identify high wind resource areas and areas where birds are "funnelled" or locate in high concentrations?
If a national need for electricity is a given, should wind facilities be examined in the context of likely or probable alternatives, such as avian mortality associated with coal or natural gas plants (upstream plant and downstream effects)?
Toward a Prioritized List of Research Questions
Meeting participants held a lengthy and wide-ranging discussion of the procedures by which they might identify a smaller number of key questions that could, in turn, provide guidance for the design of high-priority research.
Recurring Themes in DiscussionHow can we define high and low priority? It was suggested that this question is itself a potential research question. This question will have to be addressed at some point even if it cannot be answered now. It is important to identify such issues even if they cannot be resolved at this time.
It is often difficult or impossible to separate technical from policy questions. Many of the questions raised above have direct or indirect policy implications. In many situations such as this, stakeholders identify problems, and technical specialists then decide how to address the problems through research or other technical measures. In the present situation, although there has been much discussion of the bird mortality issue prior to this meeting, no broadly-constituted group of stakeholders has yet identified a consensus position on the key components of the problem. The National Wind Coordinating Committee, and particularly its Avian Workgroup (see p. *), may ultimately fill this role. However, that group is still in its early stages, as described in Appendix 2A. In the meantime, wind power developments are being planned and constructed, and avian-wind power research is being planned and conducted in various parts of the country. Many attendees felt that, in this situation, it was appropriate for a technically-oriented group to do its best to address research needs at this stage, and to submit its recommendations to the NWCC and other interested parties as the basis for a continuing round of discussion and refinement.
There is a need for good scientific work that is not unduly constrained by the policy agendas of various stakeholders. Some attendees indicated approval of an approach whereby policymakers would identify a few key questions, and then would allow research to proceed without micro-management by stakeholders.
Many participants believed that, in the above context, it is desirable for a technical group to attempt to set policy matters aside, insofar as possible, and to focus on research priorities, research design, and other technical issues. Others believed strongly that technical and policy issues are so intertwined that research priorities cannot be defined adequately in isolation from further consideration of the policy context. In practice, the attendees focused most discussion on technical issues, and attempted to rephrase some policy-related matters in more technical terms. However, policy-related matters including questions about wind power economics, legal issues, risk-analysis and other issues going beyond purely technical issues arose periodically throughout the meeting.
The best sequence for discussion of research questions and existing information on birds at wind plants was discussed. Some attendees considered it better to defer discussion of research priorities until after research conducted to date had been summarized. Others felt it best to raise some of the questions early in the meeting to serve as a basis for discussion of the research-to-date presentations. In the end, the attendees made some progress toward narrowing the list of key research questions prior to the detailed discussion of research-to-date, and further discussed the key research questions later in the meeting.
Many meeting attendees believed that the main research focus should be on the existence, severity and mitigation of wind plant effects on avian populations. Notwithstanding this, there appeared to be broad agreement that efforts should also be made to reduce individual fatalities of birds even if these deaths have few or no effects on the bird populations. However, different attendees placed varying degrees of emphasis on the importance of research to find ways of reducing individual fatalities. The meeting recognized that, from a legal perspective, any mortality of protected birds is sometimes deemed to be unacceptable, whether or not it has population consequences.
Some attendees felt that an initial focus for research should be "whether there is a bird problem" at wind plants. Others felt strongly that the existence of a bird problem is self-evident given the scientific, legal, political and ethical concerns that have been raised. One industry and utility perspective is that, as a result of presently threatened regulatory and legal actions, some existing wind plant operations may be curtailed and some new wind plants may be delayed or prohibited. From that perspective, the regulatory and legal threat constitutes "the bird problem". In that regard, the bird problem is real and self evident regardless of the consequences to birds.
Attendees' views on the importance of addressing whether or not there is "a bird problem" were related in part to their views on the relative importance of population effects vs. individual fatalities. Attendees who emphasized population approaches also tended to emphasize the need to conduct research to investigate whether there is "a bird problem", i.e. an effect on bird populations. Some attendees who expressed strong concerns about individual fatalities independent of population effects felt that the existence of a bird problem was self evident.
A related view is that there exists a "bird problem" until we can be reasonably sure that there will be no significant population impacts from a mature wind industry. In evaluating potential impacts on bird populations, it is important to consider the likely effects of the number of wind turbines that wind industry proponents foresee being operational in coming decades. For example, 100,000 turbines might cause significant problems for bird populations even if 10,000 turbines do not.
These approaches, which are not mutually exclusive, suggest two research goals: (1) Determine effects of wind turbine mortality on bird populations. (2) Identify methods to lower and/or mitigate wind turbine mortality.
Pre- and especially post-construction assessments of birds at U.S. wind plants have been restricted to a rather small number of situations. Almost all U.S. data on impacts of operating wind turbines on birds concern effects on birds in California, where raptors have been the main recognized casualties. Other types of birds, including waterfowl and night-migrating passerines, could be a larger concern in other parts of the U.S. where wind plants are now being planned. The extent and nature of the bird problem are not yet well defined for the U.S. as a whole.
Some attendees noted that, in assessing the magnitude of the bird mortality problem, it would be useful to have comparative figures on avian mortality attributable to other methods of electrical generation—traditional and renewable. Some data on avian mortality and habitat-mediated effects are obtained for certain other types of generating facilities. However, there is presently no coordinated program to obtain these data, and research and monitoring methods are not standardized. Attendees accepted the view that this information would be valuable, but that it is beyond the scope of this meeting to develop a research program concerning the impacts of other methods of power generation. It was also noted that the occurrence of some bird mortality at other types of generation facilities does not necessarily mean that mortality at wind power facilities is acceptable.
The 14-Point List.—After discussion of the above themes, meeting attendees compiled a list of 14 research areas that were considered important. These items were presented in no specific order, and are numbered below strictly for reference purposes. These item numbers do not imply any priority sequence:
What are the population effects of avian mortality, including long-range cumulative effects?
Assess avian mortality attributable to wind turbines: population effect? if not, how many individuals?
Identify ways to reduce or mitigate mortality.
Develop capability to predict avian mortality at new sites.
Develop methods to reduce mortality, whether or not that mortality leads to population consequences.
Assess the overall ecological significance of avian mortality: what are the ecosystem effects?
Determine whether wind plant mortality is additive or compensatory. (Additive mortality refers to deaths that would not occur in the same time frame in the absence of the phenomenon of interest, here a wind plant. Compensatory mortality refers to deaths that would have occurred for another reason if the wind plant had not been present.)
Estimate the decrease, if any, in the average annual survival rates of species of interest.
Of the available turbine designs and layouts, what configurations result in minimum mortality?
What are the most appropriate research design protocols?
What factors cause avian mortality at wind turbines (what aspects of siting? turbine design? environmental conditions?)
What win-win situations exist under which wind park developments may lead to net improvement in conditions for birds and other biota.
What are the "indirect" effects of wind plant development on avian populations, including disturbance and habitat-modification issues?
What role can the lay person fill in monitoring and assessment of wind plant effects.
Seven-Point "Distilled" List.—A subgroup of the attendees reviewed the above list of 14 points and concluded that they could be reduced to seven main research topics by combining related items. These seven points, again not in any logical or priority sequence, were as follows:
What are the population effects of avian mortality at wind plants, including cumulative effects?
Ø Determine whether wind plant mortality is additive or compensatory
Ø Estimate the decrease, if any, in the average annual survival rates of species of interestDetermine avian mortality, including consideration of appropriate and comparable tools, methods, and techniques.
Identify ways to prevent or mitigate mortality or enhance avian viability:
Ø Develop ability to predict impacts
Ø Develop methods to reduce unnecessary mortalityWhat causes avian mortality from wind turbines or wind plants?
Ø bird behavior
Ø turbine design
Ø wind plant design
Ø location of wind plant
Assess overall direct effects and indirect ecological effects of avian mortality at wind plants.
What are the indirect effects of wind development on avian populations, i.e. disturbance and habitat modification effects?
Agreement on research design protocols, including how to involve lay people in monitoring and assessment of wind plant effects.
There was considerable discussion as to whether items 1 and 2 should be combined into a single point: "Determine avian mortality". It was noted that items 1 and 2 overlap, and that there are difficulties in any population-level assessment. However, many attendees believed that items 1 and 2 refer to different concepts—population vs. individual effects—and should be kept separate.
Five-Point "Sequenced" List.—Some attendees recommended that the seven point list be further condensed and reorganized. In this case, the numerical sequence was deliberately chosen to represent a progression that, to some attendees, seemed logical. Again, however, the sequence does not represent any consensus on priority:
Assess mortality attributable to wind turbines at existing sites (including control data from "no turbine" sites).
Predict mortality at planned wind power sites, based in part on (1).
Predict population consequences.
Identify ways to reduce bird kills at wind plants.
Set values for off-site mitigation.
Some attendees preferred this five-point formulation and others preferred the preceding seven-point list. Some felt that the sequence of approaches identified in the five-point list is logical. Others were uncomfortable with this sequence on the grounds that, in their view, it might imply that construction of additional wind plants is a foregone conclusion.
There was general agreement that the above lists of potential research areas, whichever version one prefers, provide a good indication of the research topics that the meeting attendees collectively considered important. The majority of attendees believed that it would be premature, at this stage of the meeting, to attempt to set priorities among these potential research areas. It was agreed that the best approach would be to move on to a review of previous and ongoing research on bird-wind power interactions, and then to a discussion of research design principles applicable to this area. It was agreed to give further consideration to research priorities later in the meeting.
