Directing nest site selection of least terns and piping plovers.

摘要

Endangered Interior Least Terns (Sterna antillarum athalassos) and threatened Piping Plovers (Charadrius melodus) nest in Nebraska at gravel mines where they are vulnerable to disturbance and nest loss. Conflicts occur when their nesting and protected status delay mining activities. The possibility of shifting nesting from active to inactive mining areas by using a deterrent (mylar flagging), an attractant (gravel and driftwood spread on bare sand), and a control (untreated sand) was evaluated. Experimental plots (mean 0.36 ha) were established at 18 different gravel mines, twelve in 2000 and seven (one repeat) in 2001 along the Platte and Elkhorn rivers prior to nesting season. Of 117 tern nests, 73% were in attractant, 2% in deterrent, and 26% in control plots. Of 23 plover nests, 61% were in attractant, 9% in deterrent, and 30% in control. Colonies used plots containing less vegetation and more driftwood than unused plots. Within control plots, both tern and plover nests were Surrounded by more large (>15 min) gravel and less coarse sand than was available at random points. Within attractant plots, substrate at the nest did not differ from random points. In all plots, Least Tern nests were more likely to have driftwood by the nest than was available at random points. Hatching rates did not differ between attractant and control plots. To attract Least Terns and Piping Plovers, sand covered with 15% small gravel, 5-10% large gravel, 3% vegetation, and about ten pieces driftwood/1,000 m2 was found to be effective. As deterrents, mylar streamers 7 in long, 30 min wide, and 0.025 min thick, attached to I in poles arranged in a 7 in grid were used. The combination of attractant and deterrent treatments provided a mechanism to protect nesting birds and avoid conflicts.