APPENDIX C

SUGGESTIONS TO IMPROVE THE SURVEY PROTOCOL
FOR THE GREAT GRAY OWL

The suggestions in this appendix represent the experiences of both field biologists and expert panel members. Their experiences may seem contradictory at times, but the great gray owl is an elusive bird that is difficult to detect. Suggested survey techniques are presented below including survey time, calling, survey visits, elevation and other factors.

1. Time of day

The best time to survey was not agreed on by biologists or panelists. In general, tapes are ineffective during daylight hours (one scientist in California found, however, that the owl will call actively after 1:00 p.m.). The following details the different opinions concerning the best time of the day to survey:

A. Survey Time

1. At dawn
2. Several hours before sunrise and several hours after sunrise
3. Two hours before dusk and two hours before nightfall
4. Four hours after nightfall
5. Just before dawn
6. From 1:00 a.m. to 5:00 a.m.

Suggestions:

1. Surveyors should use visual observations of likely foraging areas (forest/meadow edges) for predusk surveys
2. Surveyors should focus less on using the tape until visibility becomes poor (dark)

In general, daylight surveys should be combined with nighttime visits to effectively detect the owl. Daylight surveys only are not advisable.

B. Follow-up surveys

1. Don’t limit the follow-up survey time, that is, do surveys until surveyor is satisfied with results
2. Conduct daytime follow-up visits 1/2 hour before sunrise to about 10:00 a.m. and pre- night visits from 3:00 p.m. to 1/2 hour before sunset
3. Follow-up visits using tapes, unless young are out of the nest, are pretty useless
4. Follow-up visits should be conducted at dawn or at dusk

2. Call and response

In the field, surveyors use tapes and their own voice to get the owl to respond. The success of their efforts to obtain owl responses can be influenced by many factors, such as the quality of tapes and survey techniques. The following section will explore the different techniques used by surveyors. Again, the techniques used by biologists, surveyors, and experts to elicit responses differ according to their own experiences and geographic location.

A. Loudness and frequency of calls

Suggestions:

1. Tapes should be played back at conversational tone or level
2. Three hundred and twenty-five feet (100 meters) is too close while 650 feet is too far for a caller to call an owl and maintain a conversation tone/level
3. The tape/speaker system should be clear and audible at 300 meters
4. Owls can be heard calling up to 1/4 mile, with 650 feet (200 meters) from the surveyor
5. Testing the distance playback tapes should be amplified and used for various habitats and topographic conditions in each area where surveys are done
6. Use a wide speaker to broadcast calls, and play the calls at a low frequency (Hz)
7. Detection of owls increased by 40 percent when male territorial calls were broadcast for 20 seconds (panelist observation)

One panelist noted that the distance from which the owl responds is highly variable. This distance can be affected by whether or not the owl is mated or unmated. Responses also are influenced by timing or nesting.

B. Duration of listening periods

There was agreement among several panelists and biologists that the listening time at each station be increased. Many believed that it should be changed from a minimum of 3 to 5 minutes, as the current protocol suggests, to 5 minutes (One scientist noted it took 6.15 minutes according to his calculations). Longer calling-station time seems to be warranted.

C. Use of coyote-sized dogs

Owls respond to the presence of the dog, as it stimulates the predator/prey response. Young owls routinely jump from the nest before they can fly, and thus are vulnerable to ground predators such as a coyote or fox, the shape of which the dog imitates. Great horned owl calls also elicitsimilar responses. The use of coyote-sized dogs in daytime nest searches might help in detecting the owl, although this would be used only as a supplementary survey technique.

D. Tapes

Field biologists commented that they often were given either the wrong tapes or the tapes provided were of poor quality. They also stated that they were not issued any juvenile tapes. Some biologists from southern Oregon commented that they did not have much success with the tapes overall.

One panelist noted that surveyors (during visits five and six) typically used the juvenile begging call in to solicit adult or juvenile fly-ins or responses. He stated that at this stage, the adult male call would be more successful in obtaining responses from adult females and, if present, young. In areas where 3 to 5 young are raised (usually outside of the Northwest Forest Plan area), the juvenile begging call can be effective when the whereabouts of the young are uncertain, but using this call does not seem to be as effective as the adult call to elicit responses from the adults or young in an area when only one or two young are raised.

Suggestions:

1. Calling tapes should have a variety of calls

2. Tapes should include contact call of male and female owl and female food begging call (This call is effective in detecting young. One panelist states that this call is heard most often in the early evening--the "whoop" or "eee-ut" call.)

3. Day surveyors should quietly approach known detection sites within 200 feet to confirm nesting activity

Another panelist suggested that tapes with calls of young begging for food after delivery of prey to a nest by the female was highly effective in California for determining breeding in a particular site even if a nest was not found in the area. The panelist stated that a surveyor can determine if breeding has taken place, as well as fledging success, within 10 minutes by using this particular method (especially if the tape is used after June 10th in CA). He suggested using the tape from 5:00 p.m. to sunset (late in the day) for best results. The panelist states that if when using the method and a female is heard begging, then there is a good chance that there is a nest in the area if the owls are breeding that year. He comments, however, that the area around where a female is heard begging should not be considered a core area if the nest is not found.

3. Visits

Suggestions concerning field visits are presented below. These suggestions include such elements as the number of times, types, and duration of visits that can help surveyors detect the owl more readily. Again, these suggestions are based largely on individual experiences in the field.

One panelist noted that different survey methods need to be used because the number of owls nesting at any given site may fluctuate. The panelist believed that other techniques should be developed in addition to station visits. Another panelist emphasized the importance of habitat walking and recommended less roadside station calling. He said that surveys must consist of walking transects through habitat both during the day and night. Several biologists also commented that there should be less emphasis on roadside station calling.

Another panelist suggested that an additional visit to the survey site should be made later in the season (probably around August) for each of the two survey years. This visit would be directed at sights that did not have occupancy and in areas with meadows and clearcuts. The panelist suggested doing the follow-up survey during the day and indicated that surveyors should search the edge of meadows for feathers, pellets, and fecal spots. The site would then be verified as unoccupied if no signs of the owl were found during the follow-up visit, consequently, if something was found, then the site would then be re-surveyed (especially in the California portion of the Northwest Forest Plan).

4. Other comments on methods to determine occupancy

Two expert panelists noted that in the current survey protocol (p. 16, item 6), the statement, "If the owl is located but is observed roosting/sleeping and there are no other signs indicating a nest site, the follow-up visit is over," should be changed because males often roost and sleep near nest sites.

In the absence of owl responses and other signs, the presence of feathers and pellets can also indicate great gray owls in the survey area. One panelist suggested erecting one to six temporary nest structures in the survey area. These structures would be designed to retain some owl feathers and would be occasionally checked for the presence of great gray owls. Artificial nests could be used to detect the presence of owls because they will often sit in nest platforms, even when they are not nesting. Molted feathers found within these structures, thus, could be used to determine if owls are in the area.

5. Elevation guidelines

Several suggestions were made in regards to changing the elevation guidelines within this document. The great gray owl occupies a broad range of elevations throughout Oregon, Washington, and northern California. One scientists from the Blue Mountains region noted that the owl was found occurring from 3,600 feet to 4,900 feet in eastern Oregon (not 4,500-4,900 feet). Biologists from the North Umpqua Ranger District observed that a single hoot was detected at 2,000 feet on BLM land in 1995. Biologists at the Medford BLM noted that because owls have been found nesting down to 2,000 feet and because of the assumed-meadow role of a clearcut, the survey period will require more work months in southwest Oregon. They also notedseveral instances in which the owl was nesting at 2,200 feet and as low as 1,700 feet. Again, elevation guidelines need to be lowered in light of this information (from 3,000 feet to 1,700-2,000 feet).

6. Weather

One panelist suggested that the current survey protocol add that surveys should be suspended if wind gusts are greater than 12 miles per hour.

7. Supplemental field information

One panelist noted that great horned owl young always have brown facial disks whereas great gray owls always have gray facial disks. Information such as this could be included in the supplementary material suggested by the panelists in question 3. In addition, he states that in his experience, he has never seen the owl attack people and believes this is a very rare occurrence (protocol p. 2).