Type of Document:
As top wetland predators that operate over large areas of the San Francisco Estuary, herons and egrets depend on extensive tidal marshes, seasonal wetlands, and associated freshwater systems. The State of the Estuary Report uses two indicators based on the status of nesting herons and egrets to assess ecological conditions across broad wetland landscapes. The Heron and Egret Nest Density Indicator provides an index of regional heron and egret population sizes. The Heron and Egret Nest Success Indicator is based on nest survival through the breeding cycle (not on the productivity of successful nests) and is used to assess the dynamics of nest-predator populations, human disturbance, and changes in human land use that can affect the size and distribution heron and egrets nesting colonies. The chapter on “Processes-Feeding Chicks,” in the 2015 State of the Estuary Report, summarizes the Heron and Egret Brood Size Indicator, which uses the number of young produced in successful nests to index conditions that affect the availability of food, the productivity of estuarine food webs, and the quality of wetland feeding areas. For details, see State of the Estuary 2015: Processes – Heron and Egret Brood Size Indicator document.
Web Page Link:
Kelly, J. P., and N. Nur. 2015. Wildlife–heron and egret nest density and nest survival indicators:. Technical summary and appendix, in State of the San Francisco Estuary 2015:Status and Trends Update on 33 Indicators of Ecosystem Health, San Francisco Estuary Partnership. [www.sfestuary.org/about-the-estuary/soter/]