snowy_plover_point_reyes_national_seashore
Devon O’Rourke, a volunteer ranger, mans a scope at North Beach, where a handful of snowy plover nests are under constant scrutiny by biologists hoping to bolster the success of new hatches.  David Briggs

In spite of ravens, wind and sprawling invasive grasses, Western snowy plovers’ nests have nearly tripled at Point Reyes National Seashore since last year. 

Still, the seashore’s snowy plover biologist, Carolyn Campbell, worries. Half of the federally threatened birds’ 20 nests have failed this breeding season, which began in March. Just two of seven failed last year.

Ms. Campbell surveys a roughly six-mile stretch from Kehoe Beach to North Beach five days a week, combing…