Effects of predator exclosures on nest survival of Red-necked Phalaropes

We placed wire mesh predator exclosures around the nests of Red-necked Phalaropes Phalaropus lobatus at a tundra site outside of Nome, Alaska, in 2011 and 2012. Exclosures were made of 2.5 cm x 5.1 cm wire mesh and were approximately 0.8 m high, 0.8 m in diameter, with a flat top, and were secured to the ground with three metal stakes. We compared rates of nest success for these exclosed nests to those of unexclosed phalarope nests in 1994, 2010 and 2013. Both daily nest survival and apparent nest success of phalarope nests was higher in years with exclosures (daily nest survival of 0.990 ± 0.003 vs. 0.940 ± 0.007). We also compared the hatching success of exclosed phalarope nests to that of sympatrically nesting (unexclosed) Western Sandpipers Calidris mauri and Semipalmated Sandpipers C. pusilla in 2011 and 2012. Daily nest survival of exclosed phalarope nests was higher than for unexclosed sandpiper nests in the same years. The rate of nest abandonment was slightly higher for exclosed versus unexclosed phalarope nests (13 vs 2%), but we found no evidence that this was a result of adult mortality. At our site, predator exclosures were effective at substantially increasing hatching success. The effectiveness of similar exclosures elsewhere is likely to vary with the local predator community.