Northern Pygmy-Owl (Glaucidium gnoma swarthi) Inventory on Vancouver Island - 2007

Photo by Jared Hobbs

BC Conservation Corps Vancouver Island Species at Risk 2008

Prepared for: Sean Pendergast, BC Ministry of Environment

Prepared by: Vicky Young, Matt Dil, Jeannine Randall and Nigel Jackett

Funding Provided by: BC Conservation Corps

October 2008

Project Completion Report for the BCCC 2008 Northern Pygmy-Owl (Glaucidium gnoma swarthi) Inventory

Abstract

This report summarizes the Vancouver Island Northern Pygmy-owl (Glaucidium gnoma swarthi) inventory conducted by the BC Conservation Corps Vancouver Island Species at Risk crew for the BC Ministry of Environment during 2008. The majority of survey effort was focused on northern and central Vancouver Island. From the period of May 15 to July 16, 2008, 428 call playback stations were conducted for G. g. swarthi. A total of 51 owls were detected; 48 of which were G. g. swarthi. The 2008 inventory primarily targeted previous detection sites to verify the repeat presence of G. g. swarthi. Areas of suitable habitat were also surveyed to further determine the distribution of G. g. swarthi on Vancouver Island. This new data will help direct future inventory efforts for G. g. swarthi as well as indicate potential Wildlife Habitat Areas (WHAs) under the Identified Wildlife Management Strategy (IWMS) Forest and Range Practices Act.

Acknowledgments

I would like to thank the BC Conservation Corps Vancouver Island Species at Risk Crew – Nigel Jackett, Jeannine Randall and Matt Dil. We worked as a team to conduct these surveys which would not have been as successful without their dedication and hard work. Thank you to Ministry of Environment biologists Sean Pendergast and Jared Hobbs for providing historical data, maps and guidance; the BC Conservation Corps for providing funding; and the BC Conservation Foundation for providing administrative support. Additional funding for the project was provided by: TimberWest Forest Corp, Ministry of Transport, BCTS and the Ministry of Environment - Conservation Framework.

ii Project Completion Report for the BCCC 2008 Northern Pygmy-Owl (Glaucidium gnoma swarthi) Inventory

Table of Contents

Abstract...... ii Acknowledgments...... ii Table of Contents...... iii List of Figures...... iii List of Tables ...... iii Introduction...... 1 Species ...... 1 Study Area ...... 1 Surveys...... 3 Methods...... 3 Results...... 6 Conclusion and Recommendations...... 7 References...... 10 Appendix 1: Owl Survey Form – Owl Site Description...... 12 Appendix 2: Owl Survey Form – Owl Survey Form...... 13 Appendix 3: Owl Survey Form – Owl Detection Form...... 14

List of Figures

Figure 1. Map of Vancouver Island Northern Pygmy Owl (Glaucidium gnoma swarthi) call-playback stations throughout central and northern Vancouver Island...... 2

Figure 2. Map of Vancouver Island Northern Pygmy Owl (Glaucidium gnoma swarthi) call-playback stations in the Nahmint Valley on Vancouver Island...... 3

Figure 3. Glaucidium gnoma swarthi detections (in red) from call-playback surveys conducted on central and northern Vancouver Island in 2008...... 6

Figure 4. Glaucidium gnoma swarthi detections (in red) from call-playback surveys conducted in the Nahmint Valley on Vancouver Island in 2008...... 7

List of Tables

Table 1 Number of transects, stations, owl detections and total listening time for the 2008 G. g. swarthi call-playback surveys...... 6

Table 2 Number of owl species detected and their relative percentages for the 2008 G. g. swarthi call-playback surveys...... 7

iii Project Completion Report for the BCCC 2008 Northern Pygmy-Owl (Glaucidium gnoma swarthi) Inventory

Introduction

Species

The Northern Pygmy-Owl (Glaucidium gnoma) is a small woodland diurnal owl most active during dawn and dusk (Lewis 2008). It is a year-round resident of western North American forests ranging from British Columbia to Mexico (Darling 2003). The Vancouver Island subspecies, Glaucidium gnoma swarthi, is believed to be endemic to Vancouver Island and adjacent islands (Cooper and Beauchesne 2004). This subspecies is provincially Blue-listed by the Conservation Data Centre (BC Conservation Data Centre 2008) and managed through the Ministry of Environment’s Identified Wildlife Management Strategy (IWMS) under the Forest and Range Practices Act. In general Northern Pygmy-Owls have been reported breeding in mature and second-growth coniferous forests, mixed riparian forest, and pure deciduous stands (Cooper and Beauchesne 2004). They are usually associated with forest edge habitats rather that continuous forest (Campbell et al. 1990; Holt and Petersen 2000; Darling 2003). These secondary cavity-nesters rely particularly on cavities excavated by Northern Flickers (Colaptes auratus) and Hairy Woodpeckers (Picoides villosus) (Cooper and Beauchesne 2004). There is little known however about the habitat requirements of the Vancouver Island Northern Pygmy-Owl (hereafter referred to as G. g. swarthi).

Study Area

Surveys were conducted throughout Vancouver Island (Figures 1 and 2) and targeted historical detections from previous inventories. These included owl surveys conducted in the Campbell River Watershed through BC Hydro’s Bridge Coastal Fish & Wildlife Restoration Program and in the Nimpkish Valley – TFL # 37 for CanFor (now Western Forest Products). Additional surveys were conducted in the following areas: Memekay River, White River, Stewart Lake, McCreight Lake, Nahmint River. These areas did not have previously mapped detection sites but contained a mosaic of mature forest, clear cuts and riparian areas. These are habitat attributes commonly selected for by Northern Pygmy-Owls in other regions of the province.

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Figure 1. Map of Vancouver Island Northern Pygmy Owl (Glaucidium gnoma swarthi) call-playback stations throughout central and northern Vancouver Island.

2 Project Completion Report for the BCCC 2008 Northern Pygmy-Owl (Glaucidium gnoma swarthi) Inventory

Figure 2. Map of Vancouver Island Northern Pygmy Owl (Glaucidium gnoma swarthi) call-playback stations in the Nahmint Valley on Vancouver Island

Surveys

The BC Conservation Corps (BCCC) Vancouver Island Species at Risk crew was tasked with conducting Northern Pygmy-owl surveys during the 2008 field season. Call- playback surveys were used to determine presence/not detected of G. g. swarthi. This listed species is managed under the Forest and Range Practices Act - Identified Wildlife Management Strategy (IWMS). Survey results could help guide management decisions concerning the species and further clarify its distribution and habitat requirements on Vancouver Island.

Methods

Surveys were designed and implemented based on provincial owl and raptor survey standards where possible (Hausleitner 2006, RISC 2001). The methodology regarding

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distance between stations and the timing of the surveys was based on previous Northern Pygmy-Owl inventories conducted on Vancouver Island (Menzies and Tripp 2007). Surveys were not conducted during inclement weather of high winds or steady rain. Surveys were continued if inclement weather stopped or improved. Due to timing restrictions these surveys included only one repetition and were not conducted during the breeding period for G. g. swarthi on Vancouver Island. Spot check stations were used to target historical Northern Pygmy-Owl detections. In areas with no prior detections transects were strategically placed to target habitats consisting of a mosaic of clear-cut and mature forest patches. Transects typically consisted of 12 stations, with stations placed approximately 500 to 800 meters apart with inter-station distance depended on habitat and ambient noise levels. Transect and station placement was determined prior to surveying and set along existing forest road networks. Station locations were marked using Global Positioning System (GPS) units (Garmin; GPSmap 60Cx or Vista HCx). Spot check stations were placed at or near the previous detection and may have included stations on either side. Transects often incorporated a mix of Northern Pygmy-Owl stations followed by Western Screech-Owl (Megascops kennicottii kennicottii) ones. The Western Screech-Owl was another BCCC targeted species and this allowed us to optimize our time in one area (results for the Western Screech-Owl surveys are included in a separate report). Due to the Northern Pygmy-Owl’s crepuscular behavior surveys were conducted at dawn and dusk. Dawn surveys occurred 30 minutes before sunrise and continued until 4 hours after sunrise. Dusk surveys started four hours before sunset and ended 30 minutes after sunset. Call-playback stations consisted of broadcasting a recording of the male territorial call. Stations lasted 15 minutes and consisted of one minute call bouts with four minute listening periods in between, with the first call bout being played at the start of the station time. Broadcasting was done using a portable CD player connected to a TOA® transistor megaphone. Broadcasting was stopped immediately if a Pygmy-Owl was detected. Surveyors then continued to listen for the remainder of the 15 minutes for additional owls. If Pygmy-Owls were calling spontaneously at a station, surveyors listened for 15 minutes without broadcasting. Additional time was added to stations to compensate for any loud ambient noise or if an owl was suspected in the area. Stations

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were omitted if an owl was detected close enough to the next/previous station to result in a repeat detection. Data was recorded on data sheets designed by a MOE biologist (Appendix 1). The following information was recorded for each transect: surveyor names, date, time of sunset/sunrise, transect description (road names, directions, habitat notes), start and end UTMs. At the start and end of each transect, wind speed (Beaufort scale), air temperature (Celsius), precipitation (none, light rain, moderate rain and heavy rain) and cloud cover (clear, <50%, >50% and 100%) were recorded. At each station the surveyors recorded the start and end time, UTM location and comments about any factors which influenced acoustic detection ability (e.g. river noise). If an owl was detected the time was noted and surveyors estimated the direction (using a compass) and distance of the owl from the station. A UTM location of the owl was determined based on these estimates using GPS units. Information recorded for detections included: species, call time (time when the call was first heard), response time (time elapsed between the first broadcasted call and the call time), call duration, call type (territorial, juvenile begging, etc.), type of detection (visual or acoustic), call direction (compass bearing), distance to the owl, age class (adult or juvenile), and gender. When possible, owls were approached during surveys once detected and visually located. Once located, UTM locations were recorded (Appendix 2). All data amassed during the 2008 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. Locations were plotted using iMap web based software.

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Results

From May 18 to June 12 2008, 54 transects were surveyed on Vancouver Island. This resulted in a total of 428 call playback stations with an overall listening time 111.48 hours (Table 1). A total of 51 owls were detected, of which 94% were G. g. swarthi (Figure 3 and Figure 4). Additional non-targeted species detected were Western Screech- Owl (Megascops kennicottii kennicottii), Barred owl (Strix varia), and one unknown (Table 2). The average response time from initial broadcast of G. g. swarthi was 5 min 42 sec. With the exception of one call, which was classified as “other”, all responses were territorial calls.

Table 1. Number of transects, stations, owl detections and total listening time for the 2008 G. g. swarthi call-playback surveys. Target Owl Species Species Code Number of Stations Total Listening Total Owl Transects Time (hours) Detections Glaucidium gnoma NPOW 54 428 111.48 51 swarthi

Figure 3. Glaucidium gnoma swarthi detections (in red) from call-playback surveys conducted on central and northern Vancouver Island in 2008.

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Figure 4. Glaucidium gnoma swarthi detections (in red) from call-playback surveys conducted in the Nahmint Valley on Vancouver Island in 2008.

Table 2 Number of owl species detected and their relative percentages for the 2008 G. g. swarthi call- playback surveys.

Owl Species Species Code Number of Detections Relative Percentage (%) (n = 51) G. c. swarthi NPOW 48 94 M. k kennicottii WSOW 1 1.9 S. varia BDOW 1 1.9 Unknown UNOW 1 1.9

Conclusion and Recommendations

The benefits of this BCCC project were twofold. Firstly it enabled MOE to collect inventory data on this listed species. Secondly, it addressed the BC Conservation Corps objective in providing crew members a chance to gain valuable, first-hand experience in a wide variety of scientific and technical roles (The BC Conservation Corps 2008).

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The 2008 BCCC surveys provided important information on the distribution of the Vancouver Island Northern Pygmy-Owl. This initiative helped address inventory management recommendations for the species under the Ministry of Environment Conservation Framework (Conservation Framework 2007) and the Forest and Range Practices Act - Identified Wildlife Management Strategy. It is important to note that call playback surveys of this nature can only result in presence/not detected. The total number of owls detected along transects can be inflated due to the event of counting an owl more than once. All measures were taken during surveys to limit this occurrence yet it is impossible to prevent entirely. Birds may travel long distances to respond to call playback broadcasts (RISC 2001). Therefore multiple repetitions of surveys are highly recommended to determine occupancy. Surveys should also be conducted during the territory and courtship period (February – April) when owls are more responsive. G. g. swarthi is managed under IWMS through WHAs. WHAs are based on known nests or occupied residences, with residency indicated by detection during breeding season (Cooper and Beauchesne 2004). This definition of residency is often used for the establishment of WHAs under IWMS for inconspicuous raptors such as owls. Occupancy surveys for most small owls of British Columbia should take place between February and early September (Hausleitner 2006). The Northern Pygmy-Owl is not a bird of continuous old-growth coniferous forest and is most frequently encountered along forest edges (Cooper and Beauchesne 2004). Forestry practices that include conservation of riparian forest, smaller cut blocks and wildlife tree retention areas would likely benefit the species (Cooper and Beauchesne 2004). G. g. swarthi populations are possibly limited by availability of cavities for nesting (Darling 2003). All of the Northern Pygmy-Owl nests reported in British Columbia by Campbell et al. (1990) were in old woodpecker cavities in coniferous trees (Cooper and Beauchesne 2004). Because of this association management practices that benefit woodpeckers could also enhance habitat for G. g. swarthi (Cooper and Beauchesne 2004). There is no apparent long-term threat to G. g. swarthi although inappropriate forest management practices could negatively impact the population (Campbell et al. 1990; Fraser et al. 1999; Cooper and Beauchesne 2004). The current safety practices that

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require cutting of snag “danger trees” removes potential high quality nest trees. Reassessing these practices for areas with known Pygmy-Owl occupancy would limit their impact and lessen potential threats to the species. These surveys were strategic in that they targeted previous G. g. swarthi detections or areas that were judged to have suitable habitat. This strategy did prove useful for conducting basic inventories and assessing re-occupancy. However, future surveys using a more systematic survey design could provide additional information on habitat selection for this species.

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References

BC Conservation Data Centre. 2008. BC Species and Ecosystems Explorer. BC Ministry of Environment Victoria, BC. Available: http://srmapps.gov.bc.ca/apps/eswp/ (accessed July 29, 2008).

Campbell, R.W., Dawe, N.K., McTaggart-Cowen, I., Cooper, J.M., Kaiser, G.W., and McNall, C.E. 1990. The Birds of British Columbia. Volume II. Nonpasserines. Diurnal Birds of Prey through Woodpeckers. Royal British Columbia Museum, Victoria, BC.

Conservation Framework. 2007. Ministry of Environment. Available at: http://www.env.gov.bc.ca/conservationframework/index.html (accessed October 29, 2008).

Cooper, J and Beauchesne S.M. 2004. Accounts and measures for managing identified wildlife. Ministry of Water, Land and Air Protection, B.C. Accounts V.

Darling, L.M. 2003. Status of the Vancouver Island Northern Pygmy-Owl (Glaucidium gnoma swarthi) in British Columbia. B.C. Minist. Sustainable Resour. Manage., Conservation Data Centre, and B.C. Minist. Water, Land and Air Protection, Biodiversity Branch, Victoria BC. Wildl. Bull. No. B-113. 14pp.

Fraser, D.F., W.L. Harper, S.G. Cannings, and J.M. Cooper. 1999. Rare birds of British Columbia. B.C. Min. Environ., Lands and Parks, Wildl. Br. And Resour. Inventory Br., Victoria, B.C. 244 p.

Hausleitner, D. 2006. Inventory methods for owl surveys: Nocturnal owls that respond to call playback of recorded calls. 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.

Holt, D.W. and J.L. Petersen. 2000. Northern Pygmy-Owl (Glaucidium gnoma). In The birds of North America, No. 494. A. Poole and F. Gill (editors). The Birds of North America, Inc., Philadelphia, Penn.

Lewis, D.P. 2008. Owl Pages. Available at: http://www.owlpages.com/owls.php? genus=Glaucidium&species=californicum. (Accessed September 30, 2008).

Menzies, L. and Tripp, T. 2007. Campbell River owl monitoring and habitat restoration – summary report Campbell river watershed, project #: 06.W.CBR.02 BC Hydro Bridge Coastal Fish and Wildlife Restoration Program.

RISC (Resource Inventory Committee). 2001. Standards for Components of British Columbia’s Biodiversity No.11. V 2.0 Inventory methods for raptors. Prepared by

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Ministry of Resource Management, Environment Inventory Branch for the Terrestrial Ecosystems Task Force Resource Inventory Committee.

The BC Conservation Corps. 2008. http://www.bcconservationcorps.ca/

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Appendix 1: Owl Survey Form – Owl Site Description

Owl Site Description

Survey (route) Name: ______Station Labels: ______

Observer(s)______Day ___ Month ___ Year______

Transect Description (include start and end UTM’s and road marker points for start and end (where applicable), call station intervals (if greater than 500), description of length of suitable habitat surveyed, number of stations, direction of stations, etc).

______

______

______

______

Transect Diagram/Sketch:

(NB: at the end of each survey the route should be drawn on a photocopied map of the area and labeled and affixed to the Survey Form, the Transect description form and the Owl Detection Form)

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Appendix 2: Owl Survey Form – Owl Survey Form

Owl Survey Form (______) Survey (route) Name ______Observer(s)______Day ___ Month ___ Year______Weather Conditions at Start of Survey: Start Time_____ Time Of Sunset______TOTAL SURVEY MINUTES ______Temp.____oC Wind (circle one) 0 1 2 3 4 5 Cloud Cover (circle one) 1. Clear 2. <50% 3. >50% 4. 100% Precipitation: 0. None 1. Light Rain 2. Mod. Rain 3. Heavy Rain 4. Station # Z Easting Northing Start End Time Sps Code Form # Station Comments Time

Weather Conditions at END of Survey: End Time_____ Temp.____oC Wind (circle one) 0 1 2 3 4 5 Cloud Cover (circle one) 1. Clear 2. <50% 3. >50% 4. 100% Precipitation: 0. None 1. Light Rain 2. Mod. Rain 3. Heavy Rain 4.

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Appendix 3: Owl Survey Form – Owl Detection Form

Owl Detection Form (______) FORM #: _____

Survey (Route) Name ______Observer(s)______

Day ___ Month ___ Year______Start Time: ______Sunset At: ______Station Species Call Response Call Call Visual/ Direction Distance Projected AC/ Comments / Owl # Code Time Time Duration Type Acoustic of Call to Owl UTM Sex Movement

Data Definitions: Call Time: time of first detected response (military time). Response Time: time (minutes) elapsed between station start time (first call) and first detected response from owl. Call Duration: Duration (minutes) of owl vocalization. Call Type: Identify the vocalizations of the responding owl (Rack Call, Co-weep, Cooing, 4-note, Series call, Barking Call, Copulation Call) Visual/Acoustic: Identify if the owl was actually seen or just heard. Direction of Call: Provide the bearing (in degrees) of the direction of the responding owl, relative to the survey station. Distance to Owl: Provide the estimated distance (in metres) from the station to the calling owl. Projected UTM: Provide the NAD 83 UTM (Z/E/N) for the projected coordinate of the owls estimated location (based on distance and bearing) Age Class / Sex: Identify the owl (based on call type) as adult or juvenile and identify sex (when certain) as male or female. Owl Movements: record comments on the owls movements, relative to the station, for the duration of the owls response activity.

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