1 APRIL 2011 VOL 332 SCIENCE www.sciencemag.org 42 POLICYFORUM from about $12 to $173/acre (with a most likely scenario of $74/acre) in a cotton-dom- inated agricultural landscape in south-central Texas ( 12). Here, we extrapolate these esti- mates to the entire United States as a fi rst assessment of how much the disappearance of bats could cost the agricultural industry [see supporting online material (SOM)]. Assuming values obtained from the cot- ton-dominated agroecosystem in Texas, and the number of acres of harvested cropland across the continental United States in 2007 ( 13), we estimate the value of bats to the agri- cultural industry is roughly $22.9 billion/ year. If we assume values at the extremes of the probable range ( 12), the value of bats may be as low as $3.7 billion/year and as high as $53 billion/year. These estimates include the reduced costs of pesticide applications that are not needed to suppress the insects consumed by bats ( 12). However, they do not include the “downstream” impacts of pesticides on ecosystems, which can be substantial ( 14), or other secondary effects of predation, such as reducing the potential for evolved resistance of insects to pesticides and genetically modi- fi ed crops ( 15). Moreover, bats can exert top- down suppression of forest insects ( 1, 2), but our estimated values do not include the ben- efi t of bats that suppress insects in forest eco- systems because economic data on pest-con- trol services provided by bats in forests are lacking. Even if our estimates are halved or quartered, they clearly show how bats have enormous potential to infl uence the econom- ics of agriculture and forestry. Although adverse impacts of WNS on bat populations have occurred relatively rapidly, impacts of wind energy development appear to pose a more chronic, long-term concern. WNS has caused rapid and massive declines of hibernating bats in the northeastern United States, where this disease has persisted for at least 4 years ( 5). Thus, the coming growing season may be the fi rst in which the adverse effects of this disease will become notice- able. Because of regional differences in crop production, the agricultural value of bats in the U.S. Northeast may be comparatively small relative to much of the United States (see the fi gure) (SOM). However, evidence of the fungus associated with WNS was recently detected in the Midwest and Great Plains, where the estimates of the value of bats to agriculture are substantial (see the fi gure). Additionally, because this region has the highest onshore wind capacity in North America, increased development of wind energy facilities and associated bat fatalities in this region can be expected ( 16). Thus, if mortality of bats associated with WNS and wind turbines continues unabated, we can expect noticeable economic losses to North American agriculture in the next 4 to 5 years. Policy A recently stated goal of the United Nations Environment Programme is to demonstrate the value of biodiversity to policy-makers and the public ( 17). In keeping with this goal, we hope that the scale of our estimates and the importance of addressing this issue will resonate both with the general public and policy-makers. Bats provide substantial eco- system services worldwide, and their benefi ts to human economies are not limited to North America. For example, pioneering research in tropical ecosystems shows the impor- tance of plant-visiting bats in the pollination of valuable fruit crops ( 18, 19). Although the economic impacts of mass mortality of bats associated with WNS appear to be confi ned, at present, to North America, wind turbines are also causing bat fatalities in Europe ( 20), and the potential for WNS to spread to other parts of the world is unknown. We suggest that a wait-and-see approach to the issue of widespread declines of bat pop- ulations is not an option because the life his- tories of these fl ying, nocturnal mammals— characterized by long generation times and low reproductive rates—mean that population recovery is unlikely for decades or even centu- ries, if at all. Currently, there are no adequately validated or generally applicable methods for substantially reducing the impacts of WNS or wind turbines on bat populations. To date, management actions to restrict the spread of WNS have been directed primarily toward limiting anthropogenic spread (e.g., cave and mine closures and fungal decontamination protocols) ( 21). Other proactive solutions for understanding and ameliorating the effects of WNS include developing improved diagnos- tics to detect early-stage infections and fun- gal distribution in the environment defi ning disease mechanisms investigating the poten- tial for biological or chemical control of the fungus and increasing disease resistance through habitat modifi cation, such as creation of artifi cial or modifi ed hibernacula that are less conducive to disease development and transmission ( 11, 22). Other approaches, such as culling of infected bats have been widely discussed and dismissed as viable options for control ( 23). New research also shows that altering wind turbine operations dur- ing high-risk periods for bats significantly reduces fatalities ( 24, 25). Specific action on these issues will benefit from scientific research carefully aimed at providing practi- cal conservation solutions for bats in the face of new threats and at assessing their economic and ecological importance. We as scientists should also make concerted efforts to develop and use more effective methods for educating the public and policy-makers about the eco- system services provided by bats. Bats are among the most overlooked, yet economically important, nondomesticated animals in North America, and their conser- vation is important for the integrity of ecosys- tems and in the best interest of both national and international economies. In our opin- ion, solutions that will reduce the popula- tion impacts of WNS and reduce the mortal- ity from wind-energy facilities are possible in the next few years, but identifying, substan- tiating, and applying solutions will only be fueled in a substantive manner by increased and widespread awareness of the benefi ts of insectivorous bats among the public, policy- makers, and scientists. References 1. M. B. Kalka, A. R. Smith, E. K. V. Kalko, Science 320, 71 (2008). 2. K. Williams-Guillén, I. Perfecto, J. Vandermeer, Science 320, 70 (2008). 3. D. S. Blehert et al., Science 323, 227 (2009). 4. P. M. Cryan, C. U. Meteyer, J. G. Boyles, D. S. Blehert, BMC Biol. 8, 135 (2010). 5. W. F. Frick et al., Science 329, 679 (2010). 6. P. M. Cryan, R. M. R. Barclay, J. Mammal. 90, 1330 (2009). 7. T. H. Kunz et al., Front. Ecol. Environ 5, 315 (2007). 8. J. O. Whitaker, Jr., Am. Midl. Nat. 134, 346 (1995). 9. E. L. P. Anthony, T. H. Kunz, Ecology 58, 775 (1977). 10. A. Kurta, G. P. Bell, K. 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