Due to gloomy weather.
Every male and female Pacific golden plover that I observe in my neighborhood left Hawaii after 3 p.m. on Wednesday, April 18, 2018.
Last year, the males left on April 18, and the females left on April 22. I suspect they left together because it was wet for months, and they didn't want to risk leaving in less favorable conditions.
Soon after Couch Potato (one of the plovers that I watch) left, the huge juvenile that tried to share one-third of its land returned to search for food. I didn't see that bird since last September.
I nicknamed that bird "Yacker" because it's quite vocal. It's also somewhat friendly to humans. It'll walk towards humans if they stay still.