The possibility that bats may regularly occur miles offshore is a source of revelation and surprise to many, including those already familiar with the behavior and seasonal traits of these same species on land. There exist, however, numerous long-standing records and accounts of individual bats and flocks of varying sizes occurring up to several hundred miles offshore that have been logged by fishermen and seafarers over time. Whether these bats or flocks were actively undertaking a regular seasonal migration or simply hapless victims of errant winds has to-date been only a matter of conjecture and speculation.
Additionally, concerns over potential mortality risks associated with bat/turbine collisions at terrestrial wind energy facilities has sparked parallel questions among offshore wind developers, resource agencies, and public/private entities concerned with avoiding adverse impacts to bat populations. These concerns have been further enhanced with the recent proliferation of White Nose Syndrome in eastern North America.
This document provides a comprehensive compilation and summary of known available literature and recorded observations related to bats in offshore environments. It examines potential threats related to offshore energy development, and identifies critical gaps in information requiring further research and study. Investigations into the proclivity of bat occurrence offshore and potential turbine collision risk include a compilation and statistical analysis of existing offshore and terrestrial acoustic data sets from which comparisons are drawn regarding bat activity and presence at inland, coastal, and offshore locations.
These efforts were funded by a federal contract administered by BOEM. This document provides a fundamental base of information regarding an otherwise little-known topic and offers a series of specific recommendations designed to advance that base over time. It further sets a stage for future analysis that will enable a more definitive understanding of offshore bat activities and seasonal presence, and in so doing, support balanced decision-making in the management and development of renewable energy in the offshore arena.