Egrets have another tough year at Audubon Canyon Ranch

07/21/2016

Egrets on Bolinas Lagoon had a tough nesting season, with nesting down compared to last year and only half of nests successfully fledging checks, said Scott Jennings, an avian ecologist for Audubon Canyon Ranch, a nonprofit that monitors great blue heron and egret nesting in the area. Since 2014, egret nests have fallen from 34 nests to just 17 this year, although there was a greater percentage of successful egret nests this year compared to 2015. Great blue heron nesting was stable. Mr. Jennings could not say for sure what the reason was—across the region, egrets are doing well—though he had a few theories. It’s likely that common ravens, which were seen nabbing egret great chicks this year, are one culprit. But he also mentioned that the colony could still be “experiencing the oscillating effects of the abandonment of Picher Canyon,” the preserve in Bolinas that the nonprofit owns. In 2013 the canyon had 100 percent egret nest failure. The nonprofit closed the canyon to the public starting in 2014, but that didn’t persuade the egrets to return, and it has been completely abandoned by the birds. The nonprofit reopened the canyon to the public this summer and is now focusing on monitoring egret and great blue heron nests on the Bolinas side of the lagoon.