Great Blue Heron Foraging Study

Skagit County is home to the greatest concentration of nesting Great Blue Heron in the Salish Sea.  This concentration is centered around Padilla Bay in Skagit County, where the largest eelgrass meadow in the region is located.

Due to this concentration of breeding herons, an effort was launched in 2014 to document heron foraging near the two largest colonies located on Samish Island and March Point.   The Skagit Heron Foraging Study is a Citizen-Science project, led by heron biologist Ann Eissinger, utilizing trained volunteers to record heron numbers from specified shoreline observation points at Samish Bay, Padilla Bay, Fidalgo Bay and Ship Harbor.

The heron foraging study has continued over five seasons with data collected over 4-5 months each year to coincide with the heron nesting season.  The data collected is expressed in a spatial format using a “heat map” of the study area.  Concentrations of herons are visible on the map in a color gradient from green to red – with red as the highest concentration.  The results are both visually useful for tracking heron feeding movement over the study area, and for identifying feeding concentrations.  In addition, the underlying numerical data provide the actual number of heron at each location indicated on the map.  For example, for one site near March Pt., 631 heron were recorded in one observation.  High numbers like these reflect both significant heron aggregations, and also high concentrations of marine fish and other organisms which support the heron’s reproduction.  As an ecological indicator, the Great Blue Heron serves a vital role.

heron study mapSkagit Heron Foraging Study Observation Map 2016
Red balloons = observation points

The Skagit Heron Foraging Study is supported by the Wildlife Conservation Trust in cooperation with Oregon State University Department of Biological and Ecological Engineering.

For more information please contact:

Ann Eissinger
PO Box 2891
Corvallis OR 97339

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