Forestry and Wildlife Service lets down the Hawaiian Hoary Bats

Comments to the Final PEIS for new Habitat Conservation Plans for four Hawaii wind farms

The background to the proposed changes to the Habitat Conservation Plans (HCP) for three Hawaii wind farms and the requirement for an initial HCP for one that never had one is that the take (harassment, damage, kill) of Hawaiian Hoary Bats has been much higher than anticipated since the projects launched. For some of the wind farms, there is also a concern of unexpectedly high take of Hawaiian Nēnē and Petrels. Sierra Club appreciates the significant contribution of the wind farms to replacing fossil fuel energy production but feels every effort must be made to save what remains of our endangered Hawaiian animal species, including our only native land mammal.

The Final Programmatic Environmental Impact Statement (PEIS) covers HCP modifications to three wind farms, whereof two on Maui, and the addition of an HCP to a fourth wind farm. We focused on the proposals for the two Maui wind farms – Kaheawa II above Maʻalaea and Auwahi – and on the consequences for the Hawaiian Hoary Bat there.

We still lack information on the total number of bats on Maui, their distribution and their population trend. This is partially due to insufficient research, partly to ineffective detection technology. It is important to invest in increasing our knowledge of the bat population on Maui and what the effects of mitigation efforts on that population have been. For this reason, we support research funding as a partial mitigation. Without knowing what the bat population and trend is, it is difficult to say if the taking of an additional 119 bats at Auwahi (beyond the current HCP limit of 21) through the current 25-year period ending in 2037 is an existential threat to the endangered species on Maui.

Besides research, the proposed external mitigation is to increase the amount of restored forest habitat thought to be preferred by the Hawaiian Hoary Bat.

Our comments to the Draft PEIS are included in Appendix K of the Final PEIS. All of our requests for additional bat protection were rejected, as were almost all the requests from all other commenters.

1. Sierra Club feels that the risk of a catastrophic decline in bat population due to a major wildfire in a restored habit should be mitigated by providing at least three non-contiguous managed roosting areas and three non-contiguous foraging areas. The FWS responds that it is up to the HCP applications (the wind farms) to decide whether or not to provide multiple independent habitats and to ensure that “identified success criteria” are met even if there is a fire. If the bat population is mostly exterminated in a major wildfire, the bat take at the wind farms will almost certainly fall and be under the limits of the PEIS. Is that a success?

2. If some bat fatalities are not detected, we may be underestimating the actual take at any given wind farm. Sierra Club supports the recommendation of the wildlife agencies to expand the buffer zone searched for carcasses by 20%. The FWS responds that the requirement should only apply to future wind farms.

3. Similarly, we proposed increasing the frequency of searches for carcasses to once every two days (instead of once/week) for at least a year to see if the detection rate changes. Dead bats may be removed by predators before being counted. The FWS responds that “reducing the uncertainty is based on a specific sites characteristics”.

4. Hawaiian Hoary Bats roost during the day and forage at night. The only operational mitigation known to reduce fatalities is to not run the wind turbines below a cutoff wind speed threshold from sunset to sunrise, or not run them at all during that time. The bats are able to detect and avoid the turbine blades if they are spinning rapidly. Data from mainland studies indicates that raising the cutoff threshold from 5.0 meters/second wind speed (as proposed by Auwahi; Kaheawa II is already at 5.5 meters/second) to 6.9 meters/second is effective in this regard, while raising it additionally has little or no effect. Sierra Club proposed a 6.9 meters/second cutoff for all wind farms from 30 minutes before sunset to 30 minutes after sunset year round. The FWS responds that “It has not been possible to confidently calculate the reductions in Hawaiian hoary bat fatalities in Hawaiʻi that have resulted from the local implementation of low wind speed curtailment… The perceived reductions in bat fatalities from the implementation of low wind speed curtailment have shown promise at some projects in Hawaiʻi, though evidence is largely anecdotal because of the lack of a simultaneous control.” So why then does the FWS reject our proposal, when this is the only known way to reduce fatalities?

5. The rate of fatalities has been much higher than anticipated. Minor changes in wind speed cutoff are proposed by the wind farms to reduce them. Sierra Club feels that the results of the changes in wind speed cutoff should be monitored closely. If they do not reduce the observed rate by 50% from the average of the last three years (the basis for the proposed new rates), additional steps should be taken to reduce the take (increase the cutoff rate, not run the turbines at night at all). While we strongly support the restoration of forest habitat for the bats, there is no knowledge whatsoever of the quantitative impact it has had or will have on bat survival, while the take at the wind farms is certain to occur and can be estimated with 80% probability. The FWS says no action can be recommended if past take rates are surpassed, only if the new ones are, and refers to the individual HCPs of the wind farms for what is to happen then. If the new, higher take rate is surpassed, Auwahi proposes to

1) raise the cutoff threshold to 6.9 meters/second the first six hours of the night from August through October
2) redistribute curtailment nights between their two banks of turbines
3) “implement an acoustic deterrent system or an alternative minimization technology (provided they are commercially available, demonstrated to be effective in Hawai’i, and determined not to negatively impact other wildlife)”.

Kaheawa II says

“Once the permittee and/or wildlife agencies have determined the observed take is exceeding the permit year trigger, the appropriate minimization technique determined in consultation with the wildlife agencies would be implemented immediately if minimization includes just a change in wind turbines operation.
Minimization will include any or any combination of the following:
1. a higher level of Low Wind Speed Curtailment if additional research demonstrates a higher
likelihood of success than does current research,
2. periods of complete cessation of operations during the night (such as during the first 2 hours
of the night or during annual periods of highest activity, for example),
3. implementing deterrents that have been proven to reduce fatality rates on at least 50% of the
wind turbines (with the highest bat detection and/or fatality rates),
4. implementing “early-warning” systems on at least 50% of the wind turbines (with the highest
bat detection and/or fatality rates) that detect the presence of bats and shutting down at least
50% of the wind turbines (with the highest bat detection and/or fatality rates) for at least 15
minutes (assuming no additional bat activity is detected),
5. or a not yet identified option.”

That is unsatisfactory – requiring that additional research show higher success rates for low wind speed curtailment than current research; they should go with the current research if there is no better research at that time. The rest is speculative and non-committal.

There are no proven bat deterrent technologies yet, although a wind farm on Oʻahu will use a new technology for evaluation as a pilot project.

Sierra Club feels that applying fines to the wind farm companies if they exceed their take is not an acceptable outcome. The companies must commit to curtailing operation to the extent required to reduce the observed take rate so as to not risk jeopardizing the survival of this unique Hawaiian animal.

In summary, the FWS has not defined a course to definitively reducing the take of Hawaiian Hoary Bats at the wind farms or even to improving the accuracy of the estimation of the take. While reforestation for bat habitats is a good thing to do, we don’t know yet what the effects of that work will be on the bat population, while we do know that bats are being killed by the wind turbines. Wind energy production is renewable and a valuable contributor to Maui’s electricity needs but optimal output has to be weighed against the consequences to endangered native species. Rather than codifying the observed increase in take compared to the current HCPs, steps should be taken to reduce the actual take.


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