Northern Saw-whet Owl
(Aegolius acadicus) fall Monitoring
Project at the BCCER
The Northern Saw-whet Owl (NSWO) Project completed its 4th
year of fall monitoring, contributing to local owl ecology and to the broader
monitoring program, Project OwlNet: http://www.projectowlnet.org/index.htm
We, the owl team were very well-prepared for consistent coverage this year. First, we were awarded two grants to purchase equipment and train volunteers. Second, I was able to subpermit Mike Fisher so we could monitor the site five nights a week. Third we had six competent and dependable volunteers that signed up for one to several nights to band with us.
Incredibly, we put in more nights of monitoring and net hours, 29 and 539 respectively, and captured the lowest number of owls (n=27) per effort in all four years (Table 1). The table provides the number, age and sex of NSWO and the banding effort for each monitoring year. Figure 1 shows the number of owls we captured in October and November as well as the banding effort (number of days for each month) over all survey years.
Figure 2 shows the number of owls captured and separated into two age classes; HY (birds hatched in 2008) and AHY (birds hatched in 2007 or before) in each survey year. We captured fewer hatch year birds than we had in all previous years. One of the big known environmental changes that occurred during the summer of 2008 was the many large fires that occurred in our region. Although there are many unknown variables, it is likely the fires impacted nesting or fledgling success, prey base, and potentially adult survivorship, resulting in lower owl numbers this year.
My appreciation and hearty thanks go to Mike Fisher, great crew of volunteers, BCCER staff, and grant committee for keeping this project going. I hope to see you in the dark- with headlamps- next fall, 2009!
Photo by Mike Fisher
Table of NSWO demographics and capture effort in four
years of fall monitoring at the BCCER, 2005-2008.
|
NSWO |
2005 |
2006 |
2007 |
2008 |
TOTALS |
|
HY-F |
7 (30%) |
27 (44%) |
8 (16%) |
8 (30%) |
50 |
|
HY-M |
2 (9%) |
5 (8%) |
4 (8%) |
0 |
11 |
|
HY-U |
1 (4%) |
5 (8%) |
4 (8%) |
1(3%) |
11 |
|
HY Total |
10(43%) |
37 (60%) |
16 (31%) |
9 (33%) |
72 |
|
AHY-F |
13 (57%) |
21 (35%) |
29 (57%) |
12 (44%) |
75 |
|
AHY-M |
0 |
2 (3%) |
4 (8%) |
1(3%) |
7 |
|
AHY-U |
0 |
1 (2%) |
2 (3%) |
5 (19%) |
8 |
|
AHY Total |
13 (57%) |
24 (40%) |
35 (69%) |
18 (66%) |
90 |
|
RECAPS |
2 |
6 |
5 |
1 |
|
|
Owl Totals |
23 |
61 |
51 |
27 |
162 |
|
# NIGHTS of effort |
19 |
20 |
27 |
29 |
|
|
NET HOURS (NH) |
340 |
322 |
327 |
539 |
|
|
OWLS/NH |
0.068 |
0.190 |
0.156 |
0.050 |
|
Photo by D. Garcia
Figure 1. Number of NSWO captured in October and November and number of days of effort in each month over four survey years
Figure 2. Number and age of NSWO captured over all monitoring years.
