[obol] 2006 Bald Eagle Nest Survey Results

[Frank Isaacs]

Highlights of the 2006 survey of bald eagle breeding areas in Oregon 
and the Washington portion of the Columbia River Recovery Zone. 
Compiled by Frank B. Isaacs and Robert G. Anthony, Oregon Cooperative 
Fish and Wildlife Research Unit, Oregon State University, Corvallis.


* 2006 was the 29th year of our census of bald eagle breeding areas 
(1978-2006) and the 36th year for which we have tabulated data 
(1971-2006) on nesting bald eagles in Oregon (OR) and the Washington 
portion of the Columbia River Recovery Zone (WA).

* 2,098 observations were used to summarize the 2006 survey. 341 
people, including volunteers and representatives of 40 organizations, 
contributed thousands of hours to the effort. We thank all of them! 
Without their help the results would have been much less complete.

* History of bald eagle use has been compiled for 1,549 nest trees and 
2 manmade structures (1,382 in OR, 169 in WA) at 613 breeding areas 
(544 in OR, 69 in WA). Bald eagle nests have been discovered in 33 of 
36 (92%) counties in OR, and 6 of 7 (86%) counties in the WA portion of 
the Columbia River Recovery Zone. Counties in OR with no reported nests 
are Sherman, Gilliam, and Morrow. There are no nests known in the 
Benton Co., WA portion of the study area.

* 77 previously unknown nests were documented in 2006 (67 in OR, 10 in 
WA); 29 were at 27 previously unknown breeding areas (26 at 24 in OR, 3 
at 3 in WA), and 48 (41 in OR, 7 in WA) were at previously known 
breeding areas.

* 528 of 552 (470 of 492 in OR, 58 of 60 in WA) breeding areas surveyed 
(96%) were occupied (OC) by bald eagles. 495 nestlings (433 in OR, 62 
in WA) were observed at 490 OC breeding areas (437 in OR, 53 in WA) 
where nesting outcome was determined. 7,000 eaglets have been reported 
at nests on the study area since 1971 (6,494 in OR and 506 in WA).

* Nesting success was 64% in OR and 74% in WA, resulting in 5-year 
nesting success of 65% in OR and 64% in WA. Young/successful breeding 
pair was 1.55 in OR and 1.59 in WA. Three nestlings were observed at 3 
breeding areas in OR and 1 in WA during 2006.

* Productivity was 0.99 young per occupied (YG/OC) breeding area in OR 
and 1.17 in WA, resulting in 5-year productivity of 1.03 YG/OC breeding 
area for OR and 1.04 for WA. This was the 5th consecutive year that the 
5-year productivity for OR was greater than the Recovery Goal of 1.00 
and the first year that the 5-year productivity for WA surpassed that 
goal.

* Nesting success for Recovery Zones (RZ) with at least 5 OC breeding 
areas was highest in RZ 09 (Blue Mountains) with 1.38 YG/OC breeding 
area, and lowest in RZs 13 and 22 (Oregon Coast and Klamath Basin) with 
0.90. Productivity was ³1.00 YG/OC breeding area for all but RZs 13 
(Oregon Coast; 0.90) and 22 (Klamath Basin; 0.90).

* Net increase in the OR population was 3.1% for 2006. Annual net 
increase averaged 6.9% from 1995-2004. The annual increase for 2005 and 
2006 was 3.2% and 3.1%, respectively. We suspect that the recent 
decline in the annual increase was the result of changes in survey 
technique instituted in 2004 rather than a real decline in population 
growth.

* The number of occupied bald eagle breeding areas reported in the 
Columbia River RZ (133) was greater than for the Klamath Basin RZ (126) 
for the 2nd year in a row. For the first time since this study began in 
1978, the number of occupied breeding areas in the Klamath Basin RZ was 
fewer than the previous year, 126 in 2006 vs. 129 in 2005. Reasons for 
that decrease include a 5% decline in breeding areas surveyed and 
little effort searching for new breeding areas. We doubt that the real 
population has declined and suspect that it continues to increase.

* Our survey has always been an attempt to monitor all known bald eagle 
breeding areas on the study area, including searching for new breeding 
areas as time permitted. In 2005 and 2006, it became apparent that the 
population was larger than we could monitor with available resources. 
Since 2002, breeding areas surveyed decreased by 6% and breeding areas 
with unknown outcome increased from 4% to 7%. In addition, little time 
was spent searching suitable habitat for new breeding areas.

* 2007 will be the 30th year of our study. We intend to make a special 
effort to conduct as thorough a census as possible. Contact Frank 
Isaacs (isaacsf at onid.orst.edu) if you would like to participate. Happy 
New Year!

- Frank
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Frank B. Isaacs
24178 Cardwell Hill Dr.
Philomath, OR 97370

Home & Office Phone: 541-929-7154
FAX (call for instructions)
Email: isaacsf at onid.orst.edu

Senior Faculty Research Assistant
Oregon Cooperative Fish & Wildlife Research Unit
Oregon State University
Corvallis, OR
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