Responses of pinnipeds to Navy missile launches at San Nicolas Island, California

Citation

Holst, M., C. R. Greene, W. J. Richardson, T. L. McDonald, K. Bay, S. J. Schwartz, and G. Smith (2011). “Responses of pinnipeds to Navy missile launches at San Nicolas Island, California”. In: Aquatic Mammals 37.2, pp. 139-150. DOI: 10.1578/AM.37.2.2011.139.

Number of Citations: 11

Abstract

To document the responses of pinnipeds to launches of missiles and similar aerial vehicles, three species of pinnipeds were observed during 77 launches from Navy-owned San Nicolas Island off California from August 2001 to October 2008. Pinniped behavior and flight sounds during each launch were recorded by unattended video cameras and acoustic recorders set up around the island’s periphery, usually in pairs, as vehicles flew over or near haul-out sites. Multiple logistic regression was used to assess dependence of pinniped responses on received sound, distance from flight path, type of vehicle, and natural factors. The majority of observed California sea lions (Zalophus californianus) startled and showed increased vigilance up to 2 min after each launch; responses often included movement on the beach or into the water and were significantly related to received sound level. During the majority of launches, most (average 68%; range 7 to 100%) observed harbor seals within $$4 km of the launch trajectory left their haul-out site by entering the water; harbor seals hauled out again at the same site several hours after a launch. Despite these short-term behavioral reactions, the effects of launch operations are likely to have been minor and localized, with no consequences for local pinniped populations as pinniped population sizes on San Nicolas Island are stable or increasing.