Research

Interim Report
Feb 1998
(752k)

Interim Report
(232k)

More information
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Marbled Murrelets

PNW Funded Projects
2001
2000
1999
1998
1997
1996
1995

PNW Project Overview 1998

Development of Ornithological Radar as a Tool to Increase the Accuracy and Efficiency of Inland Surveys for Marbled Murrelets 

Principal Investigator:  
Brian Cooper,  ABR, Inc.

Awarded: $41,998

Project Description:
The goal of the study is to develop and test radar techniques to improve the efficiency and accuracy of the terrestrial survey protocol for Marbled Murrelets, which currently is based solely on audio-visual methods. Specifically, the project will compare radar and audio-visual techniques and address the following null hypothesis: There is no difference between radar methods and standard audio-visual methods in number of days needed to detect presence of murrelets in a stand. Previous radar studies funded by ONRC in 1996 and 1997 (Cooper and Blaha 1998) found that many more murrelets were detected by radar than by audio-visual observers. These results suggested that radar could be used to improve the efficiency of the survey protocol by more quickly and more accurately determining the presence or absence of birds (especially at low-use sites). If these radar techniques were found to improve the current survey protocol, results from this study would provide land managers with a tool to more accurately, more quickly, and less expensively assess murrelet presence in a stand.

Project Status:
Project continued with 1999 funds.
Interim report received in December 1999.

Interim Report Abstract:
The report summarizes the first year of this two-year study to test and develop ornithological radar as a technique to improve the efficiency and accuracy of the inland audio-visual survey method for Marbled Murrelets (Brachyramphus marmoratus).   ABR, Inc. examined 50 of the Washington State Department of Natural Resources’ murrelet survey stands in the northwestern Olympic Peninsula to assess their suitability for radar-based observations.  Fourteen of these sites were used for radar sampling.  Most of the sites consisted of an isolated old-growth stand that was surrounded by a clearcut or by young trees.  Concurrent radar and audio-visual observations that followed the Pacific Seabird Group (PSG) protocol were made from early May through July on 44 mornings in 1998.

The previous study funded by ONRC in 1996 and 1997 focused on the numerical relationship between the number of Marbled Murrelets observed on radar and the number of them detected audio-visually, whereas this study compared the ability of the two techniques to determine the presence of murrelets.  It is important to make these comparisons because, when actual IFSP surveys are conducted, it takes only one survey on which at least one bird was seen or heard to classify the site as having murrelets “present.”  In 1999, ABR, Inc detected birds 100% of the days with radar; thus, the mean number of days required to determine “presence” with radar was 1.0.  The number of days required to determine “presence” with the audio-visual technique was significantly higher, ranging from 1 to 5+ days, with a mean greater than 2.3 days.  Thus, preliminary results indicate that a lift assisted radar is a powerful tool for more quickly determining the “presence” of murrelets at a stand than the standard audio-visual technique.

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