Millus, S. A.
Kelly, J. P.
Condeso, T. E.

Publication Date: 

Jan 2013

Type of Document: 

Technical Report

This is the final, comprehensive report regarding the 2013 nesting season at the Picher Canyon heronry at Martin Griffin Preserve, Stinson Beach, CA. As background information, the report contains relevant information about Great Egret nesting biology and a summary of the history of Great Egret nesting activity in Picher Canyon. This report also includes the complete evaluation of factors that may have contributed to the 2013 nesting failure, which is identical to a previous report (Millus et al. 2013, An assessment of the 2013 decline in Great Egret nesting in Picher Canyon, ACR Technical Report 67-1-2). Based on this information, we present a general management framework that incorporates the “precautionary principlea” to maximize the potential for colony recovery in the 2014 nesting season. The management framework includes the following key actions:
Institute regular discussions involving science staff and Martin Griffin Preserve staff regarding changes in management at Picher Canyon Intensify monitoring of the heronry, including the installation of an infrared video camera Delay the public season until a minimum level of nesting success is observed Close the Henderson Overlook until a minimum level nesting success is observed Modify preserve maintenance activities in the canyon, January-August Eliminate or reduce traffic in the canyon January-August Close the canyon to major events January-August
These actions will minimize disturbance and promote conditions that returning herons or egrets may require to initiate new nests next season. In addition, the framework provides a structure for stewardship needed to appropriately manage ACR programs and activities in Picher Canyon.

a The precautionary principle or states if an action or policy has a suspected risk of causing harm in the absence of scientific evidence that it is harmful, the burden of proof that it is not harmful falls on those taking an act.

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Millus, S. A., Kelly, J. P. and T. E. Condeso. 2013.  Management framework for protection of the heronry at Martin Griffin Preserve: An assessment and response to the 2013 decline in Great Egret nesting in Picher Canyon.  ACR Technical Report 1967-1-3 © September 2013, Audubon Canyon Ranch Cypress Grove Research Center P.O. Box 808, Marshall, CA 94940