Effects of Seismic Operations on Louisiana's Nesting Bald Eagles

Schlumburger Geco-Prakla (SGP) conducted seismic operations in St. Mary and Terrebonne parishes of Louisiana, between October 1997 and March 1998. This area is located on the marsh-swamp interface and contains approximately 40% of the state's nesting bald eagles (Haliaeetus leucocephalus). The Louisiana Department of Wildlife and Fisheries and the U.S. Fish and Wildlife Service used spatial buffer zones with a 460-m radius to protect all eagle nests located on properties of the SGP seismic operations. Bald eagle production during seismic operations (1998) was compared to the previous season (1997) and the following season (1999). Production did not differ (P=0.85) for the interaction between year and area (seismic affected nests/non-seismic affected nests). Experimental airboat disturbances were used in the 1998 and 1999 nesting seasons to evaluate flush response at distances closer than 460 m. Flush response increased as the distance from an airboat to a nest tree decreased. About half of the bald eagles (0.49) flushed when an airboat approached within 230 m of their nest tree. Considerably fewer eagles (0.17) flushed when approached to within 310 m of their nest tree. The authors feel that a reduction in the primary protection zone radius from 460 m to 310 m is an appropriate recommendation for the southern portion of Louisiana. There was no detectable impact of SGP seismic operations on nesting bald eagles.

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