Difference in number of successful nests in control vs. treatment blocks at James Campbell National Wildlife Refuge (JC), Ka Iwi (KC) and Turtle Bay (TB). Numbers above zero indicate points where there were more successful nests in the treatment block (Paired t-test: t-ratio = 4.05, DF = 19, P > t = 0.0003). The two Turtle Bay points did not have successful nests due to flooding.