Opportunistic Vessel-Based Detections of Migratory Bats in the Gulf of Maine

M. Wing Goodale^1,*, Paul Knaga², Sarah Dodgin¹, Ethan Gilardi¹,Joshua M. Guilbert¹, Marian Howe¹, Brianna Frankina¹, and Cory Stearns³

¹Biodiversity Research Institute, Portland, ME 04103. ²Canadian Wildlife Service, Environment and Climate Change Canada, Dartmouth, NS B2Y 2N6, Canada. ³Maine Department of Inland Fisheries and Wildlife, Augusta, ME 04330. *Corresponding author.

Northeastern Naturalist, Volume 32, Issue 2 (2025): 168–178

First published early online: 10 May 2025

Abstract
Offshore wind energy is being pursued in the Gulf of Maine (Gulf) to reduce dependence on fossil fuels; yet wind turbines pose a collision risk for bats. Previous efforts to monitor bat activity in the Gulf have involved acoustic surveys from stationary platforms, such as buoys and islands. However, acoustic monitoring from vessels opportunistically transiting through the Gulf offers a promising method to capture bat activity further offshore and across both spatial and temporal gradients. To explore the utility of this approach and expand on the growing research on bat presence in the Gulf, acoustic bat detectors were deployed on marine vessels in the Gulf and collected data during periods from April through May and August through October 2024. A total of 69 offshore bat passes were recorded, including calls from Lasiurus cinereus (Hoary Bat), Lasionycteris noctivagans (Silver-haired Bat), and Lasiurus borealis (Eastern Red Bat). Eastern Red Bat and Silver-haired Bat detections were the furthest from shore (136 km and 169 km, respectively), indicating the presence of bats near offshore wind-lease areas during both spring and fall.

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