Research
Interim
Report
Feb 1998
(752k)
Interim
Report
(232k)
More
information
about
Marbled Murrelets
PNW
Funded Projects
2001
2000
1999
1998
1997
1996
1995
PNW Project Overview 1996
Evaluation of the Marbled Murrelet Inland Forest Survey Protocol (IFSP) with Radar
Principal
Investigator:
Brian
Cooper,
ABR, Inc
Awarded: $47,096
Project
Description:
The
goal of the study is to use radar techniques to evaluate the Inland Forest
Survey protocol (IFSP, Ralph et al. 1994) for marbled murrelets. The null
hypothesis for this project is: There is no difference in number of radar
targets observed using a stand and number of audiovisual detections of
murrelets in that stand. Results from the study would be used to analyze
the problems and effectiveness of the survey protocol so that managers and
biologists would have a better understanding of what the numbers derived
from the standard survey protocol actually mean in terms of numbers of
murrelets using a particular timber stand.
Objectives: The goal of this research is to evaluate the terrestrial survey protocol by comparing the results of concurrent radar surveys. The specific objectives of the study are to:
- Evaluate the relationship between detection rates and numbers of murrelets and develop an error rate or correction factor for the terrestrial survey counts;
- Measure the proportion of murrelets that fly into a stand before audiovisual detections begin to occur (these may be the breeding birds of primary interest);
- Assess the proportion of murrelets that are double-counted as they circle or fly over the stand;
- Measure the proportion of murrelets that are detected by the audiovisual observers that fly over a survey stand and then continue on to another stand;
- Begin to determine the effects that weather, time of year and time of day have on the aforementioned proportions and relationships.
Project Status:
ABR
Inc. submitted an interim report in December 1999. Project continued with
1997 funds.
Interim
Report Abstract:
Concurrent radar observations and audio-visual observations that followed
the current Pacific Seabird Group (PSG) protocol were made on 38 mornings
during late May through July, 1997 during the murrelets’ dawn activity
period (i.e. approximately 105 minutes before sunrise to 75 minutes after
sunrise). All of the radar
sites were located within 1 kilometer of a stand classified as occupied by
previous surveys. Most of the
sites consisted of an isolated old growth stand that was surrounded by a
clearcut or by young trees. In
total, ABR field personnel observed 1,437 radar targets and had 441
audio-visual detections of Marbled Murrelet at nine sites.
Preliminary results indicate a large amount of both within site and among site variation in total numbers of radar targets and audio-visual detections. Radar correctly distinguished murrelets from other fast flying species 100% of the time. Data from this first year of study suggest that the number of audio-visual detections recorded during official murrelet surveys generally is a highly conservative measure of the number of birds in the stand. Further, if 91-97% of all murrelets at a nesting stand are missed by these surveys, it is likely that observers may not detect any bird at sites with low numbers of nesting birds. Thus, audio-visual surveys also may be a highly conservative measure of both presence and occupancy at stands with low nesting densities. On the other hand, data suggest that there is a small probability that a stand could be considered to have birds “present” according to survey guidelines, when it actually did not have birds present.
