Flammulated Owl (Otus flammeolus) Inventory, Okanagan Region, 2007

Prepared by:

Nigel Jackett, Megan Traicheff, Kersti Vaino and Vicky Young BC Conservation Corps

Penticton, BC

Prepared for the

BC Ministry of Environment

September 2007

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Executive Summary This report examines Flammulated Owl (Otus flammeolus) inventory work conducted in 2007 by the BC Conservation Corps South Okanagan Species at Risk crew for the BC Ministry of Environment. The survey effort was focused in the Okanagan, Kettle, Thompson, Shuswap and Similkameen drainages. Thirty-six acoustic-lure (call playback) surveys were conducted over the period of May 18 to June 12, 2007 with a total listening time of 9007 minutes or 150 hours. A total of 205 owl detections were made, including six owl species, with the highest number of detections being the Flammulated Owl at 157. The 2007 Flammulated Owl detections will be added to the existing database and could possibly fill in data gaps regarding population size and distribution. This new data could help refine the provincial habitat suitability model for Flammulated Owl as well as potentially designate suitable areas for Wildlife Habitat Areas (WHAs).

Acknowledgments We would like to thank: Ministry of Environment biologists Jared Hobbs and Orville Dyer for providing historical data, maps and guidance; Tolko Industries, Pope & Talbot and the BC Conservation Corps for providing funding for this project; and the BC Conservation Foundation for providing administrative support. We would also like to thank Tolko Industries for providing habitat suitability maps, Pope & Talbot for providing biogeoclimatic zone maps and the BC Conservation Corps for providing all field equipment and supplies.

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Table of Contents

Executive Summary .......................................................................................................... 2 Acknowledgments ............................................................................................................. 2 Introduction....................................................................................................................... 4 Study Area ......................................................................................................................... 4 Methods.............................................................................................................................. 5 Results ................................................................................................................................ 8 Discussion......................................................................................................................... 12 Conclusion and Recommendations ............................................................................... 12 References ........................................................................................................................ 13 Appendix 1. Owl Survey Data Forms ........................................................................... 14 

List of Figures Figure 1. Survey stations completed in the 2007 Flammulated Owl inventory.................. 5 Figure 2. Examples of the typical open Ponderosa Pine – Douglas fir mixed forests that were targeted in the 2007 Flammulated Owl inventory...................................................... 6 Figure 3. (a) M. Traicheff broadcasting Flammulated Owl territorial calls and (b) K. Vaino recording data........................................................................................................... 7 Figure 4. Number of each owl species (by species code) detected during the 2007 inventory. .......................................................................................................................... 10 Figure 5. Flammulated Owl (O. flammeolus) detections (red) in the Okanagan, Thompson, and Shuswap drainages for the 2007 inventory. ............................................ 10 Figure 6. Flammulated Owl (O. flammeolus) detections (red) in the Kettle drainage for the 2007 inventory. ........................................................................................................... 11 Figure 7. Flammulated Owl (O. flammeolus) detections (red) in the Okanagan and Similkameen drainages for the 2007 inventory. ............................................................... 11 

List of Tables

Table 1. The number of transects, stations, owl detections and total listening time for the 2007 Flammulated Owl inventory. ..................................................................................... 8 Table 2. Number and relative percentage of each owl species detected during the 2007 inventory. ............................................................................................................................ 9 

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Introduction The Flammulated Owl (Otus flammeolus) was designated as a species of Special Concern by COSEWIC (the Committee on the Status of Endangered Wildlife in Canada) in 2001 and was listed on Schedule 1 of the federal Species at Risk Act. Provincially, the owl is Blue-listed by the Conservation Data Centre (BC Conservation Data Centre 2007). Important nesting habitat for the Flammulated Owl includes multi-age class stands of Douglas fir (Pseudotsuga menziesii) and Ponderosa Pine (Pinus ponderosa) with multiple canopy layers, including a veteran tree component for nesting and roosting (Cannings and van Wouderenberg 2004). In British Columbia, the owl occurs within the Southern Interior Forest region in the elevational band characterized by dry Douglas-fir forests (Cannings and van Wouderenberg 2004). The Flammulated Owl is managed under the Forest and Range Practices Act and is listed under the Identified Wildlife Management Strategy (IWMS). To help guide management decisions regarding this species, the BC Conservation Corps (BCCC) South Okanagan Species at Risk crew was tasked with conducting Flammulated Owl surveys within the Okanagan, Kettle, Thompson, Shuswap and Similkameen drainages over the 2007 field season. Surveys were conducted from May 18 to June 12 using the acoustic-lure (call-playback) method. The two main purposes of this inventory were to: (i) clarify the distribution and area of occupancy of the Flammulated Owl within BC’s southern interior in order to locate areas potentially suitable for establishing WHAs and (ii) help refine the habitat suitability model designed by the Ministry of Environment (MOE). Surveys were concentrated in areas where Pope & Talbot and Tolko Industries operate so that these companies could make use of the location data and habitat suitability model in their forestry practices. Additionally, some of the areas surveyed included suitable habitat within Pope & Talbot’s proposed Old Growth Management Areas (OGMAs).

Study Area The main areas of interest for this survey were the Okanagan, Kettle, Thompson, Shuswap and Similkameen drainages in the southern interior of British Columbia (Figure 1). Call playback surveys targeted open Douglas-fir - Ponderosa Pine mixed forests (Figure 2).

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Figure 1. Survey stations completed in the 2007 Flammulated Owl inventory.

Methods Otus flammeolus populations were inventoried using the provincial MOE owl survey protocols (Hausleitner 2006). However, the methodology used in this study strayed from provincial standards in two ways: (i) the call playback surveys started at sunset instead of thirty minutes after and (ii) crews continued to survey in wind up to a four on the Beaufort scale when these winds were not constant but were intermittent gusts. The surveys started at sunset as owls were often heard calling at this time. Acoustic-lure stations were set along pre-determined roadside transects selected with the aid of habitat suitability maps provided by MOE and Tolko Industries as well as biogeoclimatic zone maps provided by Pope & Talbot. Efforts were concentrated in areas deemed as having high habitat suitability and some areas of medium habitat suitability based on the provided habitat suitability maps. Visual searches of suitable habitat during daylight hours were used to finalize transect locations and to mark station waypoints using Global Positioning System (GPS) units (Garmin; GPSmap 60Cx, Legend Cx, or Vista C) in UTM, NAD83. Stations were placed approximately 500 metres apart as permitted by the habitat until all suitable habitat that was easily accessible by road in the area was covered. The average transect consisted of 15 stations and covered an approximate linear road distance of 7.5 kilometers.

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Photo by M. Traicheff Photo by M. Traicheff

Photo by M. Traicheff Photo by K. Vaino

Figure 2. Examples of the typical open Ponderosa Pine – Douglas fir mixed forests that were targeted in the 2007 Flammulated Owl inventory. Call playback surveys began at sunset (determined using the GPS sun/moon function) and continued until all stations were covered, for an average survey time of five hours per night. Surveys were terminated if it began to rain or if the wind reached four or greater on the Beaufort scale for longer than thirty minutes. Stations lasted 17 minutes, which consisted of an initial two minute period spent listening for spontaneous calling followed by a 15-minute call playback survey period. During the 15-minute period, a territorial call lasting one minute was broadcast (using a CD-player connected to a megaphone) every 4 minutes with surveyors listening for an owl response in between broadcast bouts. Broadcasting was stopped immediately if a Flammulated Owl was detected. All relevant data was collected (Figure 3) and surveyors completed that station by listening for additional owls without broadcasting again. If Flammulated Owls were calling spontaneously at a station, surveyors listened for 15 minutes (without broadcasting)

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before moving on to limit disturbance to the owls. Additional time was added to stations where there was loud traffic or other noise to compensate for the poor acoustics and the diminished ability to hear owls. Extraneous noise such as highway traffic, rivers and creeks, wind and other background noise such as dogs barking was also noted if it affected our ability to hear owls calling. Therefore, it is important to note that our results indicate a presence or a presence not detected and not an absence of owls.

Photo by K. Vaino Photo by M. Traicheff (a) (b) Figure 3. (a) M. Traicheff broadcasting Flammulated Owl territorial calls and (b) K. Vaino recording data. Data from the owl surveys was recorded on data sheets provided by the MOE (Appendix 1) according to provincial, Wildlife Species Inventory (WSI) standards. For each transect, the names of the surveyors, the time of sunset, the date as well as a transect description including start and end UTMs (Universal Transverse Mercator zone, easting and northing in NAD 83), a map of the transect area and a brief description of the targeted habitat was recorded. At the start and end of each transect, the wind speed class (using the Beaufort scale), air temperature, precipitation (none, light rain, moderate rain and heavy rain) and cloud cover (clear, <50%, >50% and 100%) was recorded. At each station, the survey name, station name, start and end time of the station, UTM from a GPS unit (Garmin, GPSmap 60Cx, Legend Cx, or Vista C) and any owl species detected were recorded. Additional observations recorded were extraneous noise, and other wildlife observations. When an owl was detected, the station number, species code (ie. FLOW for Flammulated owl), call time (time when the call was first heard), response time (time elapsed between the first broadcasted call and the time of the first detected owl call), call duration, call type (territorial, juvenile begging, etc.), type of detection (visual or acoustic), call direction using a compass, approximate distance to the owl, age class (adult or juvenile), and gender was recorded. In some species the difference in calls between male and female can be quite obvious and in others it is more difficult to confirm. Thus, sex of the owl was recorded only when the surveyors were certain, otherwise it was marked as unknown. Locations for owls that could be approached safely at night were taken directly at the owl. All owl species were recorded and their location projected using a handheld GPS unit using the estimated distance and direction. The GPS co-ordinates (owl

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detections and survey stations) were uploaded onto field laptops using Garmin MapSource and were later entered into MOE’s Geographical Information System (GIS). Surveyors also incidentally noted any Common Nighthawks (Chordeiles minor) heard or seen during the surveys since these have recently been listed as “Threatened” by COSEWIC. However, these species were not noted throughout the entirety of the owl survey; they were noted from May 28th onward. Additionally, Common Poorwills (Phalaenoptilus nuttallii) were also noted. These birds are not listed but the surveyors thought it worth collecting this information as they are from the same family as the Common Nighthawk and are also insectivores. All data amassed during the 2007 inventory was then entered into a MOE Species Inventory (WSI/SPI) Data System spreadsheet that will be added to the Species Inventory Web Explorer (SIWE) dataset. Maps were developed using Arcmap9 by creating shapefiles based on UTM locations.

Results From May 18 to June 12 thirty-six acoustic-lure (call playback) transects were completed in the Okanagan, Kettle, Thompson, Shuswap and Similkameen drainages. The survey effort consisted of a total of 523 survey stations with a total survey time of 9007 minutes or 150 hours (Table 1). Owls were detected at 27% of the stations we visited (140 out of 523) and of the 523 stations, Flammulated Owls were found at 117 of them, resulting in a success rate of 22%. Table 1. The number of transects, stations, owl detections and total listening time for the 2007 Flammulated Owl inventory. Target Owl

Species (Common

Name)

Target Owl Species

(Scientific Name)

Species Code

Number of

Transects

Number of

Stations

Total Listening

Time (hours)

Total Owl Detections (Including

Non-Target Species)

Flammulated Owl

Otus flammeolus

FLOW 36 523 150 205

A total of 205 owl detections, including 6 owl species, were made over the survey period (Figures 5, 6 and 7) with the highest amount of detections being Flammulated Owls at 157 (76%). The 48 other incidental owls that were detected are represented by species and relative percentage in Table 2 and by number in Figure 4. 37% of Flammulated Owls detected (57 of 156) were spontaneously calling at the stations, as well as the following: 29% of Great Horned Owls (Bubo virginianus) (9 of 31), 13% of Barred Owls (Strix varia) (1 of 8), 50% of Northern Saw-whet Owls (Aegolius acadicus) (3 of 6), 50% of Northern Pygmy Owls (Glaucidium gnoma) (1 of 2) and 0% of Western Screech-Owl (Megascops kennicottii macfarlanei). This includes all owls that were already calling when surveyors arrived at the station or started calling within the first 2 minutes, prior to broadcasting.

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Table 2. Number and relative percentage of each owl species detected during the 2007 inventory. Owl Species

(Common Name) Owl Species (Scientific Name)

Species Code

Number of Detections

Relative Percentage (%)

Flammulated Owl Otus flammeolus FLOW 157 76 Great Horned Owl Bubo virginianus GHOW 31 15 Barred Owl Strix varia BDOW 8 4 Northern Saw-whet Owl Aegolius acadicus NSOW 6 3 Northern Pygmy Owl Glaucidium gnoma NPOW 2 1 Western Screech-owl Megascops kennicotti

macfarlanei WSOW 1 1

63% of the Flammulated Owls detected (99 of 156) were not spontaneously calling at the stations but responded after the calls were broadcast on the megaphone. 35% (71 of 205) of all the owls detected were spontaneously calling while 65% (134 of 205) only responded after a territorial call was broadcast. The average response time of Flammulated Owls to the broadcasted calls was approximately 5 minutes. Response times varied from zero to seventeen minutes. As mentioned in the Methods section, the sex of an owl was only noted when surveyors were certain of it. Thus, of the 157 Flammulated Owls detected, 5 were male, 3 were female and 149 were unknown. These numbers include two pairs that were heard calling together at two separate stations. Of the 31 Great Horned Owl detections 3 were female, 4 were male and 24 were unknown. For the Barred Owls, 2 were male, 2 were female and 4 were unknown. All of the Northern Saw-whet (6), Northern Pygmy Owl (2), and Western Screech-owl (1) detections were of unknown sexes. During the Flammulated Owl surveys, 9 Common Nighthawks and 36 Common Poorwills were detected. Of the Common Poorwills, 15 were detected on the west side of Okanagan Lake, 9 were detected on Highway 3A, 6 were detected east of Rock Creek, and 2 were detected at each of the Garnet Valley, Midway and Winfield. Of the Common Nighthawks, 6 were detected on Highway 3A, and 1 was detected at each of the Christian Valley, Rock Creek and Midway.

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Figure 4. Number of each owl species (by species code) detected during the 2007 inventory.

Figure 5. Flammulated Owl (O. flammeolus) detections (red) in the Okanagan, Thompson, and Shuswap drainages for the 2007 inventory.

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Figure 6. Flammulated Owl (O. flammeolus) detections (red) in the Kettle drainage for the 2007 inventory.

Figure 7. Flammulated Owl (O. flammeolus) detections (red) in the Okanagan and Similkameen drainages for the 2007 inventory.

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Discussion

It is important to note that the percentage of Flammulated Owls that were heard calling spontaneously (37%) may be overrepresented. In areas having good acoustics it is possible that spontaneously calling owls were responding to the broadcast calls from the previous stations but could not be heard until surveyors moved on to the next station. For a better estimate of the distribution and area of occupancy of the Flammulated Owl within BC’s southern interior, transects should have been surveyed more than once during the breeding season. A second year of surveys should also be completed to comply with provincial protocols. As owls are able to fly into the survey area from surrounding areas, future studies could also include nest searching, which would help to augment our knowledge of the habitat actually used by the Flammulated Owl. This knowledge could be used to refine habitat suitability models for the species.

Conclusion and Recommendations The results from the 2007 survey provide information on the occupation and distribution of Flammulated Owls in BC’s southern interior. These results could potentially be used to refine the provincial habitat suitability model, which could then in turn be utilized as a management tool to help designate future Wildlife Habitat Areas for the species.

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References BC Conservation Data Centre. 2007. BC Species and Ecosystems Explorer. BC Ministry of Environment Victoria, BC. Available: http://srmapps.gov.bc.ca/apps/eswp/ (accessed September 6, 2007). Cannings. R.A. and A.M. van Wouderenberg. 2004. Flammulated Owl Otus flammeolus. Accounts and measures for managing identified wildlife. Ministry of Water, Land and Air Protection. BC Accounts V. Hausleitner, D. 2006. Inventory methods for owl surveys: Nocturnal owls that respond to call playback of recorded calls (Barred, Strix varia, Boreal, Aegolius funereus, Flammulated, Otus flammeolus, Great Horned, Bubo virginianus, Northern Sawwhet, Aegolius acadicus, Northern Spotted, Strix occidentalis caurina, and Western Screech, Megascops kennicottii). Standards for Components of British Columbia’s Biodiversity No.42. V. 1.0. Prepared for the Ecosystems Branch of the Ministry of Environment for the Resources Information Standard Committee.

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Appendix 1. Owl Survey Data Forms

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