Western Screech-Owl Conservation and Management in the Flathead River

Western Screech-Owl Conservation and Management in the Flathead River

2012 Survey - Final Report

Prepared For: Great Northern Landscapes Conservation Cooperative

Prepared By: Jared Hobbs M.Sc./RPBio - MFLNRO

Prepared: April 4, 2013

Flathead River Western Screech-Owl Conservation and Management

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Acknowledgements

The Western Screech-owl Conservation and Management project was initiated in 2011, through funding provided by the Great Northern Landscape Conservation Cooperative (GLNCC). The project was implemented by the BC Ministry of Forests, Lands and Natural Resource Operations (MFLNRO) and, in its early days, supported and carried into fruition by Al Soobotin’s generous assistance. We wish to thank the Great Northern Landscape Conservation Cooperative for providing funds to support this project and for being pro-active in their engagement of collaboration in management with the BC provincial government. First and foremost, I would like to thank Amanda Lacika for her commitment and professionalism during all aspects of the project. After the initial training provided in the first session Amanda returned to the project to lead the completion of the September and October surveys. She stepped up, admirably, to the task as a field leader. After the surveys were complete Amanda also led the data entry to ensure all data had been entered accurately and completely. Her conscientious and considerate efforts were greatly appreciated for the duration of this project. In addition to Amanda’s contribution, both Chris Chutter and Laura Werden each contributed to the project’s success and demonstrated a high degree of commitment and skill. Other key project participants included MFLNRO staff members Ted Antifeau and Byron Woods. Ted provided the initiative for the project and provided insight, and assistance with some of the field surveys, during project implementation. Byron provided GIS support. Joanne Nielson from BC Conservation Foundation (BCCF) was an invaluable asset as project coordinator on yet another successful collaborative field project. Finally, and most importantly, thanks to the owls for sharing your secrets!


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Executive Summary The interior subspecies of Western Screech-Owl (Megascops kennicottii macfarlanei) is listed as endangered by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC 2002) and is listed on Schedule One of the Canadian federal Species at Risk Act (SARA). In BC, the M.k.macfarlanei subspecies is red-listed by the British Columbia (BC) Conservation Data Center and is recognized as a “Priority 1” status by the BC Conservation Framework. A comprehensive survey was conducted in 2012, with funds provided by the Great Northern Landscapes Conservation Cooperative (GNLCC) and by the Land Based Investment Strategy (LBIS) under allocation from the British Columbia (BC) Ministry of Forests, Lands and Natural Resource Operations. Sixty–five areas were surveyed, including 4 areas in the Elk River Valley and 61 areas in the Flathead River Valley. All areas surveyed were located in the Kootenay Ministry of Environment (MOE) Region (Rgn 4). Surveys were completed over 52 nights, between July 7th and October 6th, 2012. A total of 596 call-playback stations were conducted. During surveys, a total of 158 owl observations were recorded (all owl species). Western Screech-Owls were detected 69 times for a total of 84 screech-owls detected during surveys (note: some detections include multiple owls (i.e. adults and juveniles)). These detections were plotted, in GIS, and territory boundaries were approximated based on detection information, understanding of the species’ ecology and consideration of suitable habitats. In total, 33 territories are recognized; 28 were new territories detected for the first time in 2012 and 5 were already known from previous surveys conducted in 2011 (Hobbs 2012). Breeding was confirmed at four of the territories identified in 2012. These efforts have greatly expanded our understanding of the current distribution and abundance of this blue-listed species within BC. The 2012 surveys within the Flathead (n=32 territories) and Elk River (n=1 territory) drainages confirm the occurrence of a viable population at the very eastern limit of the species range in BC. This raises the current total number of known screech-owl sites to 33 confirmed sites in the Flathead screech-owl population and 91 confirmed sites in the Kootenays MOE region (Rgn 4). Thirty-one new Wildlife Habitat Areas (WHAs) are proposed, mapped and described at all 31 eligible sites (i.e. occupied during the breeding season and located on provincial crown land) to ensure conservation of screech-owl habitat attributes within the project area.


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Table of Contents

Acknowledgements............................................................................................................................2

Executive Summary ............................................................................................................................3

Introduction ......................................................................................................................................5

Species Information .......................................................................................................................5 Subspecies Distribution by Region ..................................................................................................6 Subspecies Distribution by Population ............................................................................................6 Goals and Objectives ......................................................................................................................9

Study Area .........................................................................................................................................9

Methods .......................................................................................................................................... 11

Call-playback Surveys ................................................................................................................... 11 Daytime Site Assessment ............................................................................................................. 12 Conducting Nest Searches ............................................................................................................ 13

Results ............................................................................................................................................. 14

Summary of Active Owl Sites ........................................................................................................ 17 Conservation of Western Screech-Owl Habitat .............................................................................. 27

Discussion ........................................................................................................................................ 28

Management Recommendations ...................................................................................................... 31

Literature Cited ................................................................................................................................ 32

Appendices ...................................................................................................................................... 34

Appendix 1: BC Provincial Western Screech Owl Database ............................................................ 34 Appendix 2: Survey Data .............................................................................................................. 34


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Introduction

Species Information

The Western Screech-Owl (Megascops kennicottii) is a small greyish-brown owl with prominent ear-tufts and yellow eyes. Individuals weigh between 100-305 grams, with a body length of 19-25cm and a wingspan of 55-62cm. Within British Columbia, there are two recognized subspecies, the interior M. k. macfarlanei and the coastal M. k. kennicottii. M.k. macfarlanei (hereafter may be referred to as the “interior screech-owl” or simply as “screech-owl”) is restricted to south-central BC, where it is known to breed throughout the Thompson-Nicola, Okanagan, Cariboo and Kootenay Ministry of Environment regions (Hobbs 2011) (Figure 1). The interior screech-owl is listed as endangered by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC 2002) and is listed on Schedule One of the Canadian federal Species at Risk Act (SARA). In British Columbia (BC), the interior screech-owl is red-listed by the (BC) Conservation Data Center and is recognized as a “Priority 1” under Goal 3 of the BC Conservation Framework (to maintain the diversity of native species and ecosystems). The Western Screech-Owl is also identified by the BC Ministry of Environment (MOE) on the Category of Species at Risk and as a priority species for conservation and management under the Government Actions Regulation (GAR) component of the Forest and Range Practices Act (IWMS-BC MWLAP 2004b). As such, sites detected on Crown land during these surveys are entitled to protection through the designation of Wildlife Habitat Areas (WHAs) to conserve and maintain habitat values (see Results and Discussion). In BC, the interior screech-owl has been recorded at elevations between 169 - 1,501m ASL (based on 2012 data as presented by Hobbs 2013a). The species is generally associated with valley bottom deciduous riparian habitats. Western Screech-Owls are secondary cavity nesters, typically using abandoned cavities excavated by Northern Flickers (Colaptes auratus) and Pileated Woodpeckers (Dryocopus pileatus). Nest cavities typically occur in areas dominated by black cottonwood (Populus trichocarpa), trembling aspen (Populus tremuloides), and water birch (Betula occidentalis) (BC MWLAP 2004b). Annual home range sizes in BC (based on telemetric monitoring) have been estimated between 65 ha (Davis and Weir 2009) and 76.9 ha (Dulisse and Hausleitner 2011) and juvenile straight-line dispersal distances of 14-38km were reported, with a maximum total (cumulative) dispersal distance of 207 km (Dulisse and Hausleitner 2010). Breeding typically begins with territorial defense (vocalization), pair bonding and courtship (commencing in March in most areas); followed by copulation, egg-laying and nesting. Pairs incubate for ~30 days and, after hatching, the nestling phase of the life cycle generally lasts another 20-30 days. Typically nesting occurs between April 1st through to June 30th; however, nesting dates appear to be geographically asynchronous across the province. Juveniles typically fledge from the nest sometime in late May or early to mid-June; however, interior screech-owl surveys in the Flathead in 2012 confirmed fledging dates as late as July 10-14 (n=4). Clutch sizes between 1-5 young have been recorded in BC. During the post-fledging period the juveniles occupy the nest territory, generally remaining within 500m of the nest tree, while they are tended to by the adults. The juveniles begin to vocalize in early July and, as flight capabilities improve, juveniles move increasingly further from the nest as the post fledgling season advances (pers.obs). Juvenile dispersal occurs in early August through September. During this phase both adult and juvenile territorial responsiveness peaks again.


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Subspecies Distribution by Region

In BC, data on interior screech-owl detections and territory locations are collected and maintained (by the author) from multiple sources (including volunteer based surveys and formal (funded) inventory, external consultants, government staff and local area naturalists). This database includes information on breeding (status and chronology), population monitoring (sites and detections are recorded), habitat threats, tenure, elevation and conservation status. In total, at the time of writing of this report, there are 821 recorded detections at 349 discrete sites (or territories) of the interior subspecies (NB: the coastal subspecies is tracked separately by the author). Wildlife management regional boundaries have undergone some changes in recent years; however, in order to maintain consistency with the data through the years, this report continues to use the regional names and boundaries used by MWLAP and MOE prior to the creation of MFLNRO. Sites with confirmed use (including breeding) are summarised by previous MOE regional boundaries below:

Cariboo (Region 5): Eight sites (2%); the first site was confirmed at Big Bar Creek in July, 2011 (J.Hobbs and F.Iredale pers obs). In 2012, seven new sites were detected for a total of eight sites confirmed in the Cariboo region. Breeding was confirmed at three of these new sites.

Thompson-Nicola (Region 3): 54 sites (16%); interior screech-owls are rare throughout most of this region; the highest recorded density of occupancy occurs associated with riparian habitats surrounding Lillooet. This population was thought to have been extirpated (R.Cannings pers.com) until it was rediscovered (J.Hobbs pers obs) in 2001.

Okanagan (Region 8): 195 sites (57%); the Okanagan and Similkameen valleys are the ‘stronghold’ for the interior screech-owl in BC with the highest recorded number of active sites and breeding records (Hobbs 2013).

Kootenay (Region 4): 91 sites (26%); the occurrence of interior screech-owls in the Kootenay Region is a relatively recent discovery. More extensive inventories in 2012 resulted in the detection of 28 new sites in the Flathead River drainage (as summarized in this report).

The inventories conducted in 2012 represent the first confirmed breeding detections of this species in the Cariboo Region (MOE Rgn 5) (three sites) and in the Flathead River Valley (four sites) in the Kootenay Region (MOE Rgn 4). As such, the sites detected in these regions during the 2012 surveys represent a significant range expansion in BC. Furthermore, the detections in the north fork of the Flathead River in Canada represent the highest recorded elevation (1,501m) and the first recorded detections in the MSdk4 BEC zone. This recent work has revealed a consistent and strong population distribution pattern in BC. Interior screech-owls are now known to occur in association with all major river drainages (east of the Cascades) that intersect the international border, connecting the interior subspecies to its core range further south in the United States (US).

Subspecies Distribution by Population

From a biological perspective it is more meaningful to describe geographically distinct populations (versus MOE Regions). In BC, the interior screech-owl occurs in eight distinct populations (Figure 1) east of the Cascades from the international US-Canada border continuing north to Kamloops and up the Fraser River canyon to Big Bar. East of the Rockies and outside of BC (i.e. in Alberta and Montana), records are uncommon however there are two isolated incidental records of the interior screech-owl in Waterton National Park (NP). The northernmost known extent of the interior screech-owl in North America occurs within the Thompson-Fraser population (Figure 1). The Thompson-Fraser population likely constitutes a metapopulation as it is geographically disjunct from the other seven BC populations; however, the


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degree of potential for connectivity between this metapopulation and the rest of the BC populations is unknown1. All of the other (seven) BC populations occur along the international border and are connected with the species contiguous range in the US. The eight discrete extant populations of the interior screech-owl in BC are described below (and as shown in Figure 1):

1. The Thompson-Fraser metapopulation occurs east from Chase along the South Thompson River and north to Westsyde along the North Thompson River. The metapopulation continues along Kamloops Lake and the Thompson River to the Thompson/Fraser River confluence at Lytton. The metapopulation also extends for 20 km up Bonaparte Creek and along the Nicola River Valley to Merritt (J. Hobbs, pers. obs). Along the Fraser River, recent records confirm that the metapopulation extends north of Lytton ~180 km to the Big Bar Ferry (J.Hobbs & F.Iredale as described in Hobbs 2011).

2. The Okanagan – Similkameen population extends from the international border at Osoyoos and continues north along the Okanagan Valley to Vernon and along the Similkameen River valley to Princeton. It then continues north along Princeton Creek to Aspen Grove. Connectivity between the extant population near Princeton and the known extant population further north near Merritt is feasible. The species has been extirpated from much of its former habitat within urban areas in the Okanagan Valley. North of Vernon screech-owls have been documented to Falkland. Further inventory may better define the potential for connectivity between Falkland and Chase.

3. The Midway population occurs from Rock Creek westward along the West Kettle River valley to Midway. From Midway, this population extends north for ~80km. It also continues south of Midway (south of the International Border) along the Kettle River. The Kettle River re-enters BC at Grand Forks, connecting the Midway population to the Grand Forks population.

4. The Grand Forks population occurs from Grand Forks northwards up the Granby River to Lynch Creek. This population likely extends east along the East Kettle River where it likely continues north along the Christina Lake valley; further inventory is required to confirm the actual extent of this population. To the south, this population is connected with the core population in the United States (south of the International Border) below Christina Creek along the Kettle River Valley to where it joins the Columbia River.

5. The Trail/Nelson population continues north, from the US-Canada border to Slocan Lake and along Lower Arrow Lake to Edgemont.

6. The Creston population extends from Creston north along Kootenay Lake to Crawford Bay. Connectivity to the Trail/Nelson population may occur along the west arm of Kootenay Lake (west of Crawford Bay), but further inventory is required to confirm this.

7. The Koocanusa population follows the Koocanusa Valley, with occurrences documented in several drainages along both sides of the valley continuing from the international border northwards to Cranbrook. Suitable habitat also continues east along the Elk River to Sparwood however only one site has been confirmed near Elko (2012).

1: There is currently no available data on juvenile dispersal between populations in BC, however, based on juvenile dispersal studies elsewhere in BC (Hausleitner and Dulisse. 2011) there is potential for connectivity between these areas.


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8. The Flathead population follows the Flathead and Kishinena Rivers north, from their confluence immediately south of the international border, up to a confirmed maximum elevation of 1,501m ASL. This is the highest recorded site in BC. In addition, all sites within the Flathead River population occur in the MSdk4 BEC zone; this is the only area in BC where inventories have been conducted at these elevations or within this BEC zone. The potential for significant range expansions in all other populations (i.e. up to 1500m ASL) is self-evident; however, future inventory is required to confirm this supposition.

The total number of known territories, or sites, within each population is summarized in Table 1.

Table 1: Number of confirmed interior Western Screech Owl territories (sites) in BC Population Name Confirmed Territories Elevation Range (m) BEC Zones

Thompson-Fraser 62 169-1,011 BG/PP/IDF

Okanagan-Similkameen 186 285-1,150 BG/PP/IDF

Midway 6 629-775 IDF

Grand Forks 3 538-610 IDF

Trail/Nelson 34 414-959 ICH

Creston 17 533-987 ICH

Koocanusa 8 788-1,194 IDF/PP/MS

Flathead 33 1,214-1,501 MS

TOTAL 349 169-1,501 5 BEC zones Ttl

Figure 1: Sites with recorded/confirmed interior screech-owl occupancy, in BC, as of March 2013 (n=349). The range of each population is depicted, as labelled. Known sites are depicted as yellow stars.


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Goals and Objectives

The objectives of this project are consistent with recommendations as outlined by the provincial Western Screech-Owl macfarlanei Recovery Team (Western Screech-Owl, macfarlanei subspecies Recovery Team 2008). These include:

Survey of suitable habitats to determine current occupancy status and monitor previously detected occupied territories;

Establish Wildlife Habitat Areas on core occupied interior screech-owl territories on Crown land; Identify areas of suitable and capable habitats; and, Identify core areas for habitat restoration efforts.

The information gathered during the surveys will help address knowledge gaps in distribution, population size and demographics of the species in areas previously thought to be unoccupied (and hence, unsurveyed) by the species. The results of this work will be used to guide habitat protection and restoration measures that will assist the province of British Columbia to meet recovery objectives for the Western Screech-Owl macfarlanei (Western Screech-Owl, macfarlanei subspecies Recovery Team 2008).

Study Area The project area is located within the Lower Elk River drainage, in the area between Fernie and Elko, and in the middle and lower reaches of the Flathead River, including associated tributaries.

The Elk River habitat, near Fernie, is consistent with conventional habitat descriptions in BC and consists of extensive floodplains along the meandering course of the Elk River, from Fernie continuing downstream to Elko. This region contains large ‘patches’ of linearly connected Black Cottonwood Riparian Habitats. Some of the oldest intact Cottonwood riparian habitats known in BC occur along this section of the Elk River. This portion of the study area occurs within the Interior Cedar Hemlock moist cool (ICHmk4) bio-geoclimatic (BEC) zones.

The Flathead portion of the study area is unconventional, relative to screech-owl habitat in other areas of BC (including Elk River). The screech-owl habitat in the Flathead occurs at the upper known elevation limit of screech owls in BC. The deciduous forests in the floodplains of the lower reaches of the Flathead River in BC are dominated by conifers - primarily Black Spruce (Picea mariana) and Lodgepole Pine(Pinus contorta). The Flathead portion of the study area occurs within the Montane Spruce dry cool (MSdk4).

The 2012 survey efforts focused on riparian habitats, along valley bottoms, between 980-1,550m ASL. The MS BEC zone, within valley bottoms of the eastern Purcell and Rocky Mountains, is characterized by 380-660mm of average annual rainfall. Temperatures are below 0C for 5 months of the year and above 10C for 2-4 months. The MSdk4 BEC zone has never been formally surveyed for this species prior to this project. GIS ortho-imaging was used to predict suitable sites for assessment. In total 65 areas were identified for survey prior to the commencement of formal field surveys (Figure 2) (see Methods section). These areas occurred within the Kootenay Ministry of Environment (MOE) region and extended, in geographic scope, along the Flathead River to Lower Squaw Creek and along the Elk River between Fernie and Elko.


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Figure 2: Map of the entire project area, showing call playback stations (red dots) and survey areas (n=65) (orange triangles) in the Elk (n=4) and Flathead River (n=61) drainages. On-site field assessments (within each of the 65 areas) were used to inform efficient, effective and thorough placement of call-playback (CPB) stations to ensure complete acoustic ‘coverage’ of all suitable habitats within each area. These “on site” (field) inspections ensured identification and inclusion of all potential screech-owl habitats within the entire project area.


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Methods

Call-playback Surveys

Survey areas were determined using ortho-image based area assessments conducted prior to the survey period. Criteria, including: habitat "patch" size, presence of mature cottonwood, and edge type (‘hard’ versus ‘soft’ edge2) were used to assign qualitative ratings to each area prior to survey (Appendix 2). This ‘expert-based’ approach was used to inform, guide and refine survey priorities and ensured efficient survey of all potential/suitable habitats. Once in the field, each survey area was accessed by road or on foot. Areas selected for survey were prioritized according to habitat quality and ease of access to optimize survey efficiency and to enable the most effective survey coverage for interior screech-owls within the project area. In order to ensure thorough survey of all suitable habitats, an iPad (Version iii, 64gb) was pre-loaded with ortho-photos of the entire project area prior to fieldwork. The iPad was used as a GIS tablet, using the GIS Roam and GPS Kit applications, to efficiently locate survey areas and to efficiently place call-playback stations throughout all suitable habitat in the area during fieldwork. Station placement considered acoustic conditions to ensure thorough and efficient ‘acoustic coverage’ of all identified suitable habitats. Call-playback surveys followed provincial Resource Inventory Standards Committee (RISC) call-playback standards for nocturnal owls (Hausleitner 2006). Surveys were conducted during the owl’s breeding season and employed a combination of 15-minute CPB stations placed along a linear transect and/or spot checks to inventory riparian habitats. Linear transects consisted of stations placed approximately 400m apart within suitable habitats. This method was used in areas where suitable habitat was contiguous. Surveyors drove, or walked, following linear transects from one station to the next. Spot checks were also used in areas where a continuous transect would be impractical or inefficient; these consisted of a single station and were used to inventory smaller, isolated, patches of suitable riparian habitat. During walking surveys, field staff listened while walking between stations to augment total time spent listening. Surveys were not conducted in adverse weather conditions such as steady or heavy rain or wind speeds > 20km/hr (Beaufort 4) (as per RISC protocol). If an owl was detected (at or between stations) surveyors noted species identification, response times, duration, call type, call rate, direction and distance. This information was used to inform daytime assessments for all interior screech-owls detected. During daytime assessments, surveyors would attempt to ascertain pair status, breeding status and (where applicable) nest location or productivity. Call-playback was ceased if an interior screech-owl or a Barred Owl (Strix varia) was detected. Cessation of call-playback following detection of a Barred Owl ameliorates the risk of predation on any interior screech-owls also attracted to the call. When broadcast was stopped in response to predators, surveyors continued to listen for the remainder of the station time. In addition, recorded survey data included the start and end time of the survey, time of sunset and the weather conditions at the start and end of each survey. Weather conditions recorded included precipitation, temperature (°C) and wind speed using the Beaufort scale (Appendix 1). Each station location and owl location was recorded using a handheld Garmin Map60Csx GPS unit (units recorded were in UTM format, NAD83 datum). 2: Hard edge is defined as nesting habitats that abut unsuitable foraging habitat (such as clearings, farm fields etc). Soft edge is defined as nesting habitats that abut suitable foraging habitats (such as coniferous forests).


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Daytime Site Assessment

Daytime site assessments were conducted for each area where interior screech-owls were detected. Daytime follow-up surveys (i.e. the day immediately post-detection) were conducted to collect additional information regarding the site status of each occupied territory. Surveyors would attempt to add to known information at each occupied owl territory in the following hierarchical sequence:

1) Sex of owl present: determine sex (based on call pitch). This lowest site status was typically achieved upon first detection, but if call duration is brief and surveyors are less experienced, the follow up survey may be necessary to accurately/confidently determine owl sex.

2) Pair status: determine if the territory is currently occupied by a resident pair. Western Screech-Owls are acoustically sexually dimorphic; females have relatively higher pitched songs compared to males. Unfortunately, female screech-owls are generally secretive and reluctant to vocalize so they may often go undetected using standard CPB techniques, even when they are present. Often females are only detected during daytime follow-up site assessments, or in many cases remain undetected until their occupancy is given away by the detection of juvenile screech-owls at the site in the post-fledging period. It is a likely assumption that most sites detected via call-playback during the breeding period (April 1-September 30) are paired; however, this assumption may be violated in a declining population (e.g. Spotted Owls). Generally speaking, however, for stable resident owl populations with life-time pair bonding, most territories are typically occupied by pairs.

3) Breeding status: Western Screech-Owls are suspected to be annual breeders in BC (based on extensive personal observations). Nest searches and/or productivity checks were conducted to confirm breeding based on the visual detection of a female owl in a nest cavity or based on presence of juveniles in the territory post-fledging (see section: “Conducting Nest Searches”).

4) Productivity: Daytime and nighttime searches were conducted at active sites to collect data regarding productivity. Young (fledged) owls begin to vocalize readily in response to call-playback surveys by late June, and continue to vocalize until September when they disperse from their natal area. The responsiveness and curiosity exhibited by juveniles (post-fledging) enables easy/efficient detection of young. Productivity checks often yielded successful results even where pair status and/or breeding status (i.e. nest detection) assessments were unsuccessful.

In addition, daytime site assessments facilitate the collection of habitat information. When feasible, follow-up assessments were conducted during daytime or dusk at locations where owls were found to be nesting or roosting. If a daytime (roost) location was not determined at a site then habitat assessments were conducted proximal to nighttime detection locations. Site assessments were conducted to collect a general habitat description of the immediate area. Each assessment included an estimate of the extent of riparian habitat at the site (in meters and total hectares), the dominant conifer and deciduous species present, and the age class of the stand. Surveyors also recorded the presence of cavities and suitable nest tree species (Black Cottonwood), and the presence of any owl sign observed (pellets or white wash). Occupied interior screech-owl sites were also assessed from a landscape context and habitat threats were noted. Based on these assessments, site-specific recommendations to mitigate threats or improve/conserve habitat for interior screech-owls are also provided.


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Conducting Nest Searches

Interior screech-owl nests were found using the following experience-based methods:

Daytime surveys are most effective at dawn or dusk immediately following the nighttime detection (i.e. daytime response rates decline dramatically if the site is not ‘primed’ the night before). Where feasible, daytime searches were conducted at these optimal times.

Response data from preceding nocturnal surveys was interpreted, in the field, to refine and limit the area(s) that needed to be searched during the day. Search priority was assigned first to areas where pairs responded or to areas where agitated (bark) calls were heard. Other calls that were interpreted to indicate a potential nest stand included courtship and mating calls (cooing, copulation or extended trill). If no agitated, courtship or mating calls were heard at a site, then priority (for nest searches) was assigned to areas that had early evening detections (i.e. detection time was close to dusk) or short response times.

During daytime follow-up assessments, specific vocalizations (“Tee-tee do” call) were broadcast (using a FoxPro4 Megaphone). Calls were broadcast at controlled (quiet) volumes to elicit a response from the male (NB: Females will occasionally peer out of next cavities in response to a call, but, unlike most other owl species, Western Screech-Owls rarely show themselves in response to ‘tapping’ the bole of the nest tree structure, so the latter method is discouraged).

Once the owl (either sex) begins to counter-sing, observers approached (quietly) to determine, via visual search, the roost site of the calling owl. Surveyors would move silently (no talking) and discretely when searching for owls in the day; when the owls do respond the vocalization is typically very quiet (audible at a max of 50m). In the daytime, Western Screech-Owls are nervous when calls of conspecifics are heard and are quickly silenced if any other noise is made.

Once a visual detection was acquired, potential nest cavities were inferred from the male owl’s perch position. Typically the male is found roosting nearby, upslope and facing the nest tree. Care was taken to avoid over-stimulating (via call- playback) the male as he will, if overstimulated, move towards the call source and many important ‘clues’ are lost if the owl has moved from his roost position. For similar reasons, great care was taken to avoid flushing the roosting male as the roost site was approached during searches; again, if flushed then these important clues are lost. When searching for roosting owls, surveyors would pay close attention to owl white-wash and passerine response (mobbing) as these also provide important clues.

Once a roosting male was found all suitable (3” diameter or larger) cavities that were visible from the male’s position in the roost site were searched. Each suitable cavity (including tree-chimney structures) was visually inspected (using binoculars) for presence of cobwebs and flies. Note: active nests will not have cobwebs (over the entrance) and will have flies present (especially as temperatures increase as the nesting phase progresses); flies are often visible flying in/out of the nest entrance. The amount of white-wash (WW) below the males roost site will indicate the extent and duration of use; typically sparse unless the roost is used frequently.

Once a specific cavity was identified, juvenile begging calls were played, whilst visually watching the cavity, to lure the female from the cavity. If there were several potential cavities, each cavity would be monitored simultaneously as the female’s appearance at the cavity entrance is often tentative and brief. If this failed to produce a response (i.e. no visual confirmation), then the suspected nest cavity was observed as night fell as at this point the female will always exit the cavity to defecate and receive food from the male. On cool nights (temp <10°C) she will return within 20 minutes when young are undeveloped. On warm nights she may stay away for >1hr.

These techniques were used effectively and efficiently to determine active interior screech-owl nest locations.


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Results In total, 65 areas were identified for survey prior to survey commencement in 2012. Each area was selected using ortho-imagery to assess variables that affect suitability including “patch size” (cottonwood is visually discernible in ortho-imagery) and presence of mature cottonwood3. Sixty-one areas were located within the Flathead River drainage, four were located within the Elk River drainage (refer to Figure 2 in Methods Section). Once in the field, survey stations were established, around each area identified for survey, to ensure inclusion of all potential screech-owl habitats within each of the 65 areas that had been identified. On-site assessment resulted in the deletion of two areas (unsuitable) and the addition of two survey areas (upstream of F17) that were not included in the pre-field survey areas. (NB: Western Screech-Owls were detected at both additional areas). In total, 65 areas were surveyed; appendix 2 contains survey area information including UTM, quality rating, comments and a measure of effort (i.e. number of repetitions completed at each area). The 65 areas surveyed (Elk=4; Flathead=61) had varying degrees of effort applied, as appropriate depending on the survey result and on-site habitat quality assessments. Funding was insufficient to allow four survey repetitions for all areas so greater effort was allocated to areas with higher quality habitats. Table 2 describes the application of effort for all 65 areas that were surveyed in 2012. Table 2: Summary of survey areas showing the number of repetitions applied and the number of Western Screech-Owl detections found during each successive repetition.

Site Visit Number of Areas # of sites with WSOW Detected

One Visit 65 19

Two Visits 33 14

Three Visits 18 4

Four Visits 11 4

Surveys were conducted on 52 nights, between July 7 and October 6, 2012. A total of 596 Call-Playback (CPB) stations were conducted with temporal effort described as follows: July = 16 nights, August= 10 nights, September= 19 nights, October = 7 nights. On average, 15 minutes of survey was applied at each CPB station representing a total of ~145 hours spent listening for owls. Approximately forty additional crew-days of effort were expended conducting daytime follow-up assessments at all active sites. Daytime assessments were completed, as feasible; to more accurately determine site status, reproductive activity and reproductive success (see Methods-“Daytime Site Assessment” & “Conducting Nest Searches”). In total, screech-owls were detected at 33 (51%) of the 65 areas that were surveyed in 2012. These 33 territories (or owl sites) included five territories that were detected in 2011 and an additional 28 new territories found in 2012. In total, 31 WHAs have been mapped to accommodate all 31 territories detected on crown land. Two territories were detected on private land and are thus not eligible for WHA management consideration (see Table 3 & Management Recommendations). 3: Typically, for the interior screech-owl, nesting occurs within stands dominated by cottonwood however the owls will forage more widely into coniferous forested areas when available. Elsewhere within the owl’s range in BC edge type was also assessed: areas with adjacent forest connecting to the cottonwood riparian areas were labelled as ‘soft edge’, areas of isolated cottonwood were labelled as ‘hard edge’. In this portion of the species range all sites had ‘soft edge’ so this was not an influential variable in the pre-field ortho-based survey area assessment (generally ‘soft edge’ is more desirable as it facilitates foraging movements, by owls, into adjacent coniferous forested areas).


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It should also be noted that the size of the WHAs mapped to accommodate the owls within the Flathead population are intentionally larger, in area, relative to WHAs mapped for conspecifics elsewhere in BC. The rationale for the expanded size was to accommodate the supposition that screech-owls living in the MSdk4 BEC zone would have relatively larger home range sizes. Several studies have documented that species living in highly seasonal (or extreme) environments consistently demonstrate larger home ranges and lower densities in order to compensate for challenges associated with living in relatively more extreme seasonal environments (i.e. deeper snow accumulation and greater snow persistence) (Ferguson and Lariviere 2008). Elsewhere in BC, WHA size is generally between 80-120ha, based on data on HR collected by Davis and Wier (2008) but these HR sizes wsere calculated in the warmer and less extreme climate where their study was completed. In this context, large WHA sizes are recommended for screech-owl WHAs in the MSdk4 BEC zone. Figure 3: Map of the entire project area, showing Western Screech Owl detections (yellow stars) and survey sites (n=65) (orange triangles) in the Elk (n=4) and Flathead River (n=61) drainages. Survey stations are shown as red dots.


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The first Western Screech-Owl was detected on July 9, 2012 with the last detection occurring on October 11, 2012. The average response time (RT) for Western Screech-Owls at survey stations was eight minutes (range 1-17 min; n = 47). RT was not available for every screech-owl detected (n=69) as this variable is not applicable for owls detected calling spontaneously upon arrival or for adult and juvenile owls found roosting without using call-playback to solicit a response. The overall survey success rate was 0.1 Western Screech-Owls/survey station. These values are consistent with response rates for surveys conducted in other areas of the province (J.Hobbs. 2012). All owl species detected during surveys were recorded. In total, 158 owls were detected at 142 stations in 2012. Of these 158 owl observations, Western Screech-Owls were the most commonly detected species (n=84, 54%). Barred Owls (Strix varia) were the next most commonly detected species (n=34, 22%) followed by Great Horned Owl (Bubu virginianus) (n=17, 11%). Northern Saw-whet Owls (Aegolius acadicus) were the least commonly detected species (n = 16, 10%) encountered during surveys. The number of detections, by species, is described in Table 3.

Table 3: Detection frequency, by species, for call-playback surveys in 2012.

Species # of detections % detected

Western Screech-Owl 69 (84 owls) 54%

Barred Owl 34 22%

Great Horned Owl 16 (17 owls) 11%

Northern Saw-whet Owl 16 10%

Unknown 7 4%

142 (158 owls)*

*Multiple individual owls were detected at 8 (of 142) stations where owls were detected. As such, the total number of owls observed (n=157) is greater than the number of stations at which owls were detected.

A nest was located at one site (named “Thunder”). The nest was located in a cavity near the top of a large cottonwood tree. The entrance was obscured by leaves but a prey delivery, to the nest (by the male), was observed on July 14, 2012. This is the latest nest detection date recorded anywhere in BC. It is suspected that this nest fledged shortly after detection. Juveniles were detected, after fledging, at the following three additional sites: Kenow (n=3), Kishinena Bridge (n=2) and Flat Bend (n=3) on July 10, 11 and 23rd respectively, for a total of four confirmed breeding records in 2012. Based on plumage characteristics (of the juvenile owls) it is suspected that fledging had only just occurred at the three other sites that were found during the post-fledging period. All occupied sites detected in 2012 were entered into a provincial interior screech-owl database and overlaid, in a GIS environment, with all previously known sites. Detections greater than 1.5 km from any previous screech-owl detection were classified as independent occupied (breeding) territories (or sites). Prior to 2012 there were only five sites at which screech-owls had been documented within the Flathead River Drainage and no sites had been recorded in the Elk River drainage despite repeated previous survey (by the author in 2011 & 2005 and by Dave Fraser in the 1980’s (D.Fraser.pers.com)). The 2012 surveys resulted in confirmation of continued activity, in 2012, at these five sites and in the detection of an additional 28 new sites in the Kishinena, Sage/Nettie, Flathead, Couldrey, Howell, Middlepass and Bean Creek Drainages.


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There are now a total of 33 confirmed screech-owl territories, within Flathead/Elk project area (including the single site in the Koocanusa population at Bean Creek (near the Elk River). In addition, continued activity was confirmed at five territories and breeding was confirmed at four territories. Table 4 (next section) presents additional site-specific details for each territory in the project area.

Summary of Active Owl Sites

Figure 3, 4, 5 & 6 show the geo-spatial distribution of all sites and depict proposed WHA polygon boundaries for each of 31 active Western Screech-Owl territories found on crown land (of 33 total territories confirmed in 2012). Observations at each site are summarized in Table 4 and cross referenced to the WHA ID number depicted on the maps below. Figure 3: Elk River (Bean Creek) proposed WHA for a single new site (yellow star). The proposed WHA is depicted as a purple polygon and labels can be cross-referenced to site descriptions in Table 4. Private land is depicted in red shading.


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Figure 4: Flathead River proposed WHAs (including Middlepass Creek and Sage Creek). These include new sites (n=20) (yellow stars) and previously known sites (n=5) (red dots). Each WHA is depicted as a purple polygon and labels can be cross-referenced to site descriptions in Table 4. Note: one yellow star is not included within a WHA (Sage-McDougall) as it occurs on private land.


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Figure 5: Upper Flathead proposed WHAs for two of three new sites (yellow stars). Each WHA is depicted as a purple polygon and labels can be cross-referenced to site descriptions in Table 4. The northernmost (unlabelled) star represents the Pincher Creek screech-owl territory however a WHA has not been draw as this site occurs on private land (TFL).


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Figure 6: Kishinena River proposed WHAs for all three new sites (yellow stars). Each WHA is depicted as a purple polygon and labels can be cross-referenced to site descriptions in Table 4.


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Table 4: Summary of screech-owl site observations (n=33) detected during the 2012 surveys. 2011 Detections are also noted where appropriate. WHA ID numbers are provided (in red font) for all active screech-owl sites detected on crown-land.

Territory (Site) Name

Confirmed Sex

Site Classification Observations and Site Comments

Bean Cr WHA 4-238 (119.9ha)

Single Male

Breeding An adult male was detected on September 26 with an eight minute Response Time (RT). Male ceased calling when the recorded female call was played. He resumed calling when the male recorded call was broadcast and continued to call for 10 minutes. This site is located along the Lodgepole FSR, mixed cottonwood (Ctwd) and aspen deciduous component in a coniferous dominated stand.

Burnham Cr WHA 4-258 (84.2ha)

Single Male

Breeding An adult male was detected on September 4 with a 16 minute RT. He may have been calling earlier but creek noise may have muted his response. The male continued to call for 19 minutes after he was detected suggesting a high degree of territoriality. There are no large deciduous trees beside the road but habitat improves closer to the creek. The long RT suggests that the male was lured to the CPB on the road from ~800m.

Couldrey Cr WHA 4-259 (92.8ha)

Single Male

Breeding An adult male was detected on September 23 with a 4 minute RT. He continued to call for at least 20 minutes after CPB was ceased, suggesting a high degree of territoriality. There are several patches of large Ctwd trees along the riparian areas of Couldrey Creek that likely provide nesting habitat.

Couldrey-Flat Con WHA 4-256 (165.0ha)

Single Male

Breeding An adult male was detected, calling spontaneously (without solicitation using CPB) on August 1 by Ted Antifeau. The male Bouncing Ball (BB) and Double-trill (DT) was heard upon arrival at survey station on August 1. The owl could still be heard from the next survey station and, after >20 minutes of continued singing, the male owl crossed the Flathead River and resumed calling on the east side of the Flathead where he called for another two minutes. This behavior suggests a high degree of territoriality at this site. The area contains numerous large DBH Ctwd trees along this meandering section of the Flathead River.

Flat-Bar WHA 4-249 (155.5ha)

Single Male

Breeding An adult male was detected calling spontaneously on July 18 at this site. He called for 18 minutes, indicating strong agitation and territory defense. He was detected again on July 23 (J.Hobbs site investigation). This patch of excellent habitat is likely being used by a nesting pair (based on response strength, call type, duration and habitat quality).


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Confirmed Sex


Flat Beaver WHA 4-253 (173.1ha)

Single Male

Breeding An adult male was detected calling spontaneously on July 24 at this site. He called for 14 minutes, indicating strong agitation and territory defense. This patch of excellent habitat is likely being used by a nesting pair (based on response strength, call type, duration and habitat quality).

Flat Bend (Butts Cabin) WHA 4-248 (148.7ha)

Family Breeding The screech-owl at this site was first detected by Ted Antifeau on October 13, 2011; the sex was not confirmed as the owl only used agitated ‘bark’ calls. The area was resurveyed in 2012 and four more detections were recorded for this territory (on both sides of the Flathead River). In 2012, an adult male screech-owl was detected on July 18. A dusk visit was conducted on July 23 to determine breeding success; during this visit a male, female, and juvenile were detected. A dawn follow-up visit resulted in visual confirmation of an adult male, an adult female and three juveniles at this site.

Flathead Cabin WHA 4-257 (159.2ha)

Single Male

Breeding This site was first detected on July 29, 2011 by Jared Hobbs, Susan Dulc and Ted Antifeau (whilst working in the area on butterflies). A pair of adult screech-owls were heard, and seen, calling above the cabin. This was the first record of screech-owls confirmed in the Flathead River valley and in the MSdk1 BEC zone. The adult male was again detected on September 13 during CPB surveys in 2011. In 2012, an adult male was again confirmed at this site, during CPB surveys, on September 21 and then detected again on October 7 by AL and LW (record/UTM missing in dbase).

Flat-Cell WHA 4-239 (135.1ha)

Single Male

Breeding A single adult male screech-owl was first detected, with a four minute RT, at this site on September 25. The male owl continued to call for six minutes before it began to rain heavily and calling ceased. This site represents the most northerly WHA currently proposed on the Flathead River and, at 1,481m ASL, this is one of the highest elevation sites ever recorded in BC.

Flat-Gumbo WHA 4-241 (184.3ha)

Pair Breeding A pair of adult screech-owls was detected at this site on September 22. The female was the first to respond. Shortly after, an adult male began to call and then they both continued to duet for >15 minutes indicating a high degree of territoriality at this site. There are many large DBH Ctwd trees located within the meandering oxbows along the Flathead River at this site.


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Confirmed Sex


Flat-Howell Con WHA 4-250 (154.5ha)

Single Male

Breeding An adult male screech-owl was detected on August 25 after a 10 minute RT. He called for ~6 minutes as he approached the CPB station but remained on the opposite side of the Flathead River.

Flat Knee WHA 4-252 (193.7ha)

Single Male

Breeding An adult male screech-owl was initially detected at this site on July 24. During this initial detection the male owl responded to CPB with bouncing ball calls, the double trill call and barks. An adult male, believed to be the same owl, was detected a second time approximately 875m north of the initial detection on August 22. This territory occurs along a stretch of high-suitability habitat. The owl appears to be using the Ctwd riparian habitat along both sides of the Flathead River.

Flathead Marsh WHA 4-247 (147.9ha)

Single Male

Breeding This site was initially detected by T.Antifeau on October 14, 2011. As the initial detection was recorded outside the breeding period the site was resurveyed in 2012 to confirm residency (via detection of a territorial male responding to acoustic lure during the breeding period). An adult male screech-owl was detected on August 27, 2012 ~1.2km further downstream along the Flathead River. A large WHA was drawn to accommodate both detection sites however future survey may confirm residence by two territorial owls within this large area. The entire WHA is comprised of high quality habitat.

Flat-Middle Con WHA 4-244 (182.5ha)

Pair Breeding A pair of adult screech-owls was detected calling spontaneously on September 20. The pair was heard duetting for at least 20 minutes before the surveyors moved on. The habitat at this site is comprised of floodplain Ctwd habitat with a health understory and abundant veteran Ctwd trees.

Flat-Parker WHA 4-242 (212.2ha)

Single Male

Breeding An adult male screech-owl was detected calling at this site on three separate occasions in 2012: July 20, July 21 (during dusk follow-up/nest search) and again on July 24 (during day-time search). The July 24 search resulted in the detection of a daytime roost site. Daytime roost locations, at this phenological stage, are typically within 100m of the nest site. It is likely that the female, and young, were nearby but remained undetected as females are typically highly secretive during the daytime in the period immediately following fledging.


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Confirmed Sex


Flat-Trachyte WHA 4-243 (159.1ha)

Single Male

Breeding An adult male was detected on the west side of the Flathead River on September 9 at the CPB station. A second visit to the site on September 26 resulted in the detection of a pair of owls. The male was again detected, calling from the west side of the Flathead, near the CPB station and a second owl (female) was detected counter-singing from the east side of the Flathead River during this visit. An assessment of habitat suitability and RT suggests that the territory epicenter, and nest grove, is likely located on the east side of the river, near the detection site of the female owl. This supposition is further supported by two independent subsequent detections of the male singing from the east side of the Flathead River on October 4 and again on October 7, 2012.

Flat-wok WHA 4-245 (135.9ha)

Single Female

Breeding An adult female screech-owl was detected at this site on September 20, however, surveyors had to move on before the total call time was complete as there was an agitated moose in the area.

Haig Brook WHA 4-246 (101.8ha)

Single Male

Breeding An adult male screech-owl was detected on October 5 at the confluence of Haig Brook and Middlepass Creek at 1:49AM. The male was detected again the following morning at 6:31AM. Curiously, the male was first detected calling from within an open barn/structure however there was no evidence of extensive use (whitewash or pellets) so this was likely simply a fortuitous coincidence.

Howell Cr WHA 4-251 (125.6ha)

Single Male

Breeding An adult male screech-owl was detected on September 23. The male stopped calling when a recorded female call was played and he could not be enticed to call again. The territory contains several grassy openings and marshes; Ctwd trees are in low abundance but Aspen occurs along the edges of the forest openings and may provide alternate potential nest structures.


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Confirmed Sex


Kenow WHA 4-265 (147.6ha)

Family Breeding A pair of screech-owls, and at least one juvenile screech-owl, was first detected at this site on July 10. A subsequent visit to this site on July 11 (by J.Hobbs and S.Dulc) resulted in the detection of the same pair of adult owls roosting in close proximity to three juvenile screech-owls in the same area as the previous night’s detection. There was a suitable nest cavity found in a large DBH Ctwd tree (3”diameter cavity entrance) ~5m from the roosting juveniles; it is suspected that this cavity was used for nesting based on the presence of flies at the cavity entrance. This is a common/reliable observation at recently active screech-owl nest sites.

Kishinena WHA 4-266 (147.8ha)

Pair Breeding A pair (male and female) of western screech-owls was detected at this site, calling spontaneously, on August 29. The male was initially heard calling from the east side of the Kishinena River before moving to call from the west side. The female was detected, doing bark calls, on the west side of the river.

Kishinena Bridge WHA 4-267 (136.5ha)

Family Breeding A male, female, and a single juvenile screech-owl were detected at this site on July 10. The male had a 5 minute RT, the female had a 10 minute RT and juvenile had a 20 minute RT. During a dusk follow-up the next day (by J.Hobbs and S.Dulc) two juveniles, and both adults, were visually confirmed and a suspected nest cavity/tree was found. A third juvenile was suspected (heard but not visually confirmed simultaneously). This site overlaps an proposed WHA for Gillette’s Checkerspot and represents high quality habitat for both species.

Lightning WHA 4-254 (64.4ha)

Single Male

Breeding A single detection of an adult male was made on July 13. The owl was detected at the edge of the road (visual) but flew back east towards a large stand of mature Ctwd. The site was surveyed the next day but no owls were detected; conditions were unsuitable for survey with persistent heavy rain all day. The owl is likely using the Ctwd riparian habitat along Sage Creek, near the center of the WHA. (Note: Three great blue herons flew over the marsh at this site on the July 14 follow up visit.)


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Confirmed Sex


Nettie Sage WHA 4-263 (125.0ha)

Pair Breeding An occupied detection of a single territorial resident male was first detected at this site on September 12, 2011. The male was detected again on September 29, 2011 and then a pair was detected (calling simultaneously) on October 13, 2011. In 2012 this site was resurveyed and although the female was not detected there were three detections of a male resident screech-owl; the first was on July 9 (daytime, male spotted in roost near crown of 30cm DBH spruce tree). The last detection was on July 13, however, this site was not surveyed again after July as residency had been well established at this point.

Nettie Bridge WHA 4-262 (144.4ha)

Single Male

Breeding This site was first detected on September 29, 2011. The site was re-confirmed, and still occupied, on August 15th and September 8th, 2012. The owl appears (based on detections) to be using the riparian habitat associated with Nettie Creek.

Pincher Cr No WHA-private

Single unknown

Breeding An adult screech-owl was detected at this site on September 18. The RT was nine minutes, indicating that the owl moved approximately 400m towards to the CPB station however call duration was less than one minute so the owl’s sex could not be determined. This site represents the highest elevation screech-owl territory in BC, at 1,501 m ASL. A WHA is not proposed for this site as it is believed to be located on private land (TFL).

Pollock Cr WHA 4-240 (139.0ha)

Single Male

Breeding An adult male was detected calling from the east side of Pollock Creek on September 7, 2012. The Ctwd riparian habitat along Pollock Creek, upstream of the confluence of the Flathead River, likely provides suitable breeding habitat. A WHA has been mapped to capture the riparian habitat along Pollock Creek and the Ctwd riparian habitat along the Flathead River downstream of Pollock Creek.

Sage Airport WHA 4-268 (171.2ha)

Single Male

Breeding An adult male was detected on July 12, 2012 at this site. A follow-up daytime assessment the following day resulted in a dusk detection of a territorial male, roosting near the crown of a mature spruce tree, on the south side of Sage Creek. The male called for 64 minutes at this site at dusk. Observers waited in the roost stand for 15 minutes after calling had ended but no female was heard. These observations suggest this site may have been unpaired in 2012.


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Confirmed Sex


Sage-Bar WHA 4-260 (130.9ha)

Single Male

Breeding Male detected calling spontaneously on September 18, 2012 however it was suspected that he was likely responding to the previous CPB station. His response was noted as “vigorous” with both BB and DT call types recorded. The male screech-owl at this site was detected a second time on September 26 (two sets of DT with 30 second RT). A third detection was also recorded at this site on October 10.

Sage Border WHA 4-264 (138.9ha)

Single Male

Breeding This site was noted to contain an abundance of mature, large decadent Ctwd. The site was surveyed on August 26; a single adult male was detected after a 14 minute RT. He continued to vocalized for >15minutes.

Sage Bridge WHA 4-261 (136.8ha)

Single Male

Breeding A pair of adult screech-owls was detected at this site in 2011 (Sept 29 &Oct 6). There were three detections recorded at this site in 2012 (Aug 26, Sept 10, and Oct 11). During the last visit there were likely two owls calling from the same location as two call types (barks and DT) were heard. The habitat at this site is highly suitable for use by screech-owls. (Nb: a Boreal Owl was repeatedly detected whilst camping at the recreation site immediately downstream of the bridge at this site.)

Sage McDougall No WHA-private

Pair Breeding A pair of adult screech-owls was detected at this site on July 14, 2012. The habitat is located on private conservation land, nesting is suspected.

Thunder WHA 4-255 (114.3ha)

Single Male

Breeding First detected by July 13, 2013. On July 14, during daytime follow-up survey, the nest was detected near the top of a large DBH Ctwd. The male was observed delivering prey to the female at the nest. The nest grove is located on the ‘island’ of an old oxbow within an old-growth stand of spruce and Ctwd.

Conservation of Western Screech-Owl Habitat

Habitat conservation will be achieved, in a regulatory framework, through the establishment of WHAs at all occupied interior screech-owl sites found on Crown land: this is currently the only legal mechanism available for conservation of Western Screech-Owl habitat and is therefore a key component towards Goal Two of the Western Screech-Owl Recovery Plan (WSOW-RT2008). Western Screech-Owl habitat (on crown land) will be managed under the Forest and Range Practices Act as Wildlife Habitat Areas (WHAs). A total of 31 new WHAs are proposed to accommodate all active interior screech-owl territories that occur on crown land in the Flathead River valley (see Table 4-red font). In total, these areas include approximately 4,428 ha of riparian and upland habitat in the Flathead River drainage. In addition, survey information was submitted to the BC Conservation Data Center (CDC) to promote improved understanding of the species distribution and ecology in BC.


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Discussion Nocturnal call-playback (CPB) surveys can be used to assess presence of some owl species, however, results should be interpreted cautiously as survey efficacy (i.e. ability to detect all owls present in the survey area) is limited by individual owl and species-specific response rates, observer skill/bias, acoustic conditions (e.g. weather/wind/running water/traffic), time of year and time of day, suppression due to presence of conspecific predators and surveyor proximity to owl. Increased repetition results in an increased confidence of detection however detection certainty is never absolute; owls that are present can often still go undetected even after multiple repetitions. Despite the limitation of this methodology it still provides a very cost-efficient method for survey of these otherwise cryptic species; the use of this method for this project yielded valuable results. The call-playback surveys described in this report; including both formal (funded) and opportunistic surveys, represent the first full season of survey for the blue-listed Macfarlane’s (interior) Western Screech-Owl in the BC portion of the Flathead River Valley in BC. Screech-owl surveys were initiated in the area in the fall of 2011 and expanded (in geographic scope and effort) in 2012. It is of interest to note the following excerpt from the 2011 survey summary report (Hobbs 2011):

“Based on a visual assessment of habitat suitability of the riparian habitat along the Flathead River, it is predicted (in 2011) that there are potentially as many as 32 additional active and occupied western Screech owl sites within the Canadian/Flathead portion of the study area.”

The surveys conducted in 2012 confirmed occupancy at 33 sites and breeding at four sites almost exactly matching the predictions forecasted (a year prior) in the 2011 report. These pre-survey predictions were developed by careful consideration of ortho-imagery (Google Earth) for the project area. Points were marked for each area that was predicted to be capable of sustaining a breeding pair of screech owls (n=32) (Hobbs 2011, Figure 9). A more detailed examination of the ‘gaps’ (areas where screech-owls were predicted but not detected) revealed an interesting pattern. There were four areas that contained suitable habitat but were not (based on absence of detection) thought to be occupied by screech-owls; all four areas were instead occupied by resident barred owls (see Figure 7-next page). Barred owls are known to depredate screech-owls (pers obs); their presence in these suitable habitats, where screech-owls were curiously not detected, may provide an explanation for the failure to detect screech-owls at these sites. As further support, twenty-five of 34 areas where barred owls were detected (74%) contained suitable screech-owl habitat but no screech-owls were detected. From an alternative perspective, only nine of the 33 (27%) confirmed (active) screech-owl sites had overlapping resident barred owls. It would be interesting to monitor these nine sites to determine if the resident screech-owls continue to persist at these sites in future years. Despite the presence of Barred Owls, and the potential associated detrimental effects, Western Screech-owls appear to be relatively common within the project area, occurring in almost all predicted suitable sites within the Flathead River system. The population density is also higher, within the Flathead population, when compared to densities of screech-owls within all other surveyed populations in BC (n=8). The habitat at sites occupied by Western Screech Owls in the project area follows the typical obligate riparian habitat association confirmed elsewhere within the species range in BC (MWLAP 2004b, WSOW Recovery Team 2008). All active sites contained stands of mature cottonwood and/or aspen, with a moderate to dense understory of shrubs. There are, however, two noticeable differences:

1. The elevation tolerances are higher than found elsewhere in BC to date (>1,500m ASL). 2. The population of Western Screech Owls found in the Flathead in 2011 were located within the

MSdk4 BEC zone


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These differences have not been documented previously anywhere else in the province. Both of these findings have significant implications on the potential for this species to occur in many areas that have not received any previous survey4. Figure 7: Screech-owl sites are depicted as yellow stars and screech-owl territories (shown as WHAs) are depicted by green polygons). Barred owl sites are depicted as red ‘triangles’. Note the ‘gaps’, particularly along the lower Flathead and along lower Sage Creek, where suitable habitat exists but no screech-owls were detected.

A third interesting characteristic of the screech-owl population in this area was also noted. In all seven other screech-owl populations in the rest of the sub-species range in BC fledging (date when the young leave the nest) occurs in early June (~June 1-10). In the Flathead four breeding records were detected; one was still nesting on July 14 and the remaining three nests appeared to have fledged just a few days prior to detection. In short, nesting appears to be delayed by at least a month here. These are the only known screech-owl sites in the MSdk BEC zone in BC. It is suspected that this delay in nesting phenology may be related to the cooler climate, and higher snow pack and persistence, relative to BEC zones in which the subspecies has been documented elsewhere in BC (Bunchgrass (BG), Interior Cedar-Hemlock (ICH), Interior Douglas-fir (IDF) and Ponderosa Pine (PP)). 4: throughout the rest of the BC populations I have always limited surveys to 1,200mASL.


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The results of the 2012 surveys suggest that the population of owls that occur along the relatively un-impacted portion of the study area along the Flathead likely represent near-historic densities for this species in the area. Assuming an average reproductive output of 3-4 juveniles/year/pair (average recorded clutch size in BC; pers obs) the annual recruitment rate from these 33 known territories is between ~99-132 young screech-owls fledged each year. This reproductive output likely represents a stable population density in the Flathead. Connectivity, through Harvey Pass, between this population and a geographically separate population along Koocanusa Lake (confirmed site at Gold Creek ~55km west as summarized in Hobbs 2007) is suspected. This supposition is based on the single territory found at Bean Creek, immediately west of Harvey Pass. Connectivity to additional territories further south along the Flathead River (immediately south of the international border) is also very likely. Both ‘corridors’ would allow connectivity, by dispersing juveniles, within the known dispersal capabilities of the sub-species in BC (as reported by Hausleitner and Dulisse 2011). Formal surveys in the US portion of the Flathead River are recommended to assess connectivity with an extant known population ~62km south, near Logging Lake (Glacier National Park) (confirmed by Dick Cannings in 2008 (as presented in Hobbs 2011)). These efforts have greatly expanded our understanding of the current distribution and abundance of this blue-listed species within BC. The 2012 surveys within the Flathead (n=32 territories) and Elk River (n=1 territory) drainages confirm the occurrence of a viable population at the very eastern limit of the species range in BC and raises the current total number of known screech-owl sites to 91 confirmed sites in the Kootenays MOE region (Rgn 4). These sites are the result of several years of collaborative surveys (Hobbs 2007, 2011, 2012) within all four populations in the Kootenay region (including Creston, Flathead, Koocanusa, Trail/Nelson). Based on these efforts, the Kootenay MOE region now supports 26% of the total (n=349) known Macfarlane Western Screech-Owl sites in BC. Future study is required to further our collective understanding of this species distribution, population size and dispersal patterns. More detailed monitoring is also required to refine our understanding of population vital rates including: rate of population change, adult/juvenile survivorship, productivity/fecundity and long-term viability of this population. This approach is recommended as the Western Screech-Owls found within this area represent the eastern-most extant population of the species in BC.


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Management Recommendations The Western Screech-Owl macfarlanei recovery plan recommends the conservation of interior screech-owl nest sites, through stewardship and habitat procurement, as an urgent action item towards reaching the recovery goal of maintaining a viable, well-distributed population of interior screech-owls within the known range of the subspecies in British Columbia (WSOW-RT 2008). At the landscape level, efforts to maintain and conserve occupied habitat and to promote enhancement and conservation of suitable habitats should be made. WHAs should be established at all 31 occupied territories detected on provincial crown land in the project area. The following future recommended actions are proposed:

Continued population monitoring is a vital component of assessing population health, productivity and trend. This important work should be continued for this population in future years.

Insufficient funds prevented access to some areas (e.g. we were not able to hire a helicopter to assist with access of several key areas further upstream along Howell Creek; it is suspected that there are more active screech-owl territories in these areas). Suitable habitat also extends upstream along Couldrey Creek beyond the extent of the area surveyed in 2012. Sites that were not able to be accessed in 2012 should be surveyed in the future.

Habitat on private conservation lands should be managed through directed management as per stewardship agreements.

WHAs should be established for all 31 confirmed (this project) interior screech-owl territories that occur, in part or in full, on provincial crown land (see Results for comment on WHA size ans summaries of observations, or supporting rationale, for each WHA.).

©Ian Routley


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Literature Cited BC Conservation Framework. 2009. http://www.env.gov.bc.ca/conservationframework /index.html (accessed Dec

18, 2012). BC Ministry of Water, Land and Air Protection. 2004a. Appendix 5 in Accounts and Measures for

Managing Identified Wildlife – Accounts V. 2004. B.C. Ministry of Water, Land and Air Protection, Victoria, B.C. Available: http://www.env.gov.bc.ca/wld/frpa/iwms/ procedures.html (accessed April 15, 2010).

BC Ministry of Water, Land and Air Protection. 2004b. “Interior” Western Screech-Owl (Otus kennicottii

macfarlanei) in Accounts and Measures for Managing Identified Wildlife – Accounts V. 2004. B.C. Ministry of Water, Land and Air Protection, Victoria, B.C. Available: http://www.env.gov.bc.ca/wld/frpa/iwms/accounts.html (accessed April 15, 2010).

Cannings, R. J., and T. Angell. 2001. Western Screech-Owl (Otus kennicottii). In The Birds of North

America, No. 597 (A. Poole and F. Gill, eds.). The Birds of North America, Inc. Philadelphia, Pennsylvania, USA

COSEWIC 2002. COSEWIC assessment and update status report on the Western

Screech-owl otus kennicottii in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. 31 pp.

Davis, H., and R. Wier. 2008. Western Screech-Owl Conservation along the Shuswap River. Submitted to

the Bridge Coastal Restoration Program. Project #05W.Sh.01 97pp Ferguson, S.H. and S. Lariviere. 2008. How Social Behaviour Links Environment and Body Size in

Mammalian Carnivores. The Open Ecology Journal, 2008,, 1, p.1-7.

Hausleitner, D and J. Dulisse. 2011. Movement and Habitat Use of Western Screech-Owls in the West Kootenay Region. 2010-11 Field Season Report. Prepared for the Fish and Wildlife Compensation Program and the Columbia Basin Trust. 26pp.

Hausleitner, D. 2006. Inventory Methods for Owl Surveys. Standards for Components of British Columbia’s Biodiversity No.42. Prepared for Ecosystems Branch of the Ministry of Environment for the Resources Information Standards Committee. Victoria, B.C. 52pp

Owls. Submitted to the Bridge Coastal Restoration Program. Project # 05.W.Br.04 Hobbs 2007. (survey data only, no report). March 1, 2007. Hobbs, J. 2012. Western Screech-Owl Conservation and Management in the Flathead River Basin (2011

Surveys-Final Report). March 1, 2012. p. 1-23. Hobbs, J. 2013a Western Screech-Owl Conservation and Management for the Bridge-Seton Area -2012

Survey - Final Report, March 6, 2013.

http://www.env.gov.bc.ca/conservationframework%20/index.html

http://www.env.gov.bc.ca/wld/frpa/iwms/


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Hobbs, J. 2013b. Western Screech-Owl Conservation and Management in the Thompson & Okanagan Regions (2012 Surveys-Final Report). March 11, 2013.

Integrated Land and Resource Registry 2010. Government of British Columbia Crown Registry and

Geographic Base Branch. http://archive.ilmb.gov.bc.ca/ilrr/ (accessed June 17, 2010). MacKenzie, W.H. and J.R. Moran. 2004. Wetlands of British Columbia: a guide to identification. Res. Br.,

B.C. Min. For., Victoria, B.C. Land Manage. Handbook No.52. Tripp, T.M. 2004. The use of bioacoustics for population monitoring of the Western Screech-Owl

(Megascops kennicottii), Thesis, University of Northern British Columbia, Prince George, British Columbia, Canada.

WSOW-RT. 2008. Western Screech-Owl, macfarlanei subspecies Recovery Team. 2008. Recovery

strategy for the Western Screech-Owl, macfarlanei subspecies (Megascops kennicottii macfarlanei) in British Columbia. Prepared for the B.C. Ministry of Environment, Victoria, BC. 14 pp. http://www.env.gov.bc.ca/wld/documents/recovery/rcvrystrat/w_screech_owl_rcvry_strat130208.pdf

Young, V.D., J. Mylmymok, J.Hobbs and F.Iredale. 2011. Western Screech-Owl Conservation and Management for the Bridge River Restoration Area. Prepared for: BC Hydro Fish and Wildlife Compensation Program-Bridge Coastal. 55pp http://a100.gov.bc.ca/pub/siwe/details.do;jsessionid=fda21758ce2b896b9cf2e18956eeaacb2b916f1e881075e0bfad32c5e2186d35.e3uMah8KbhmLe34MaxyNaxmTaxz0n6jAmljGr5XDqQLvpAe?id=4618

http://archive.ilmb.gov.bc.ca/ilrr/

http://www.env.gov.bc.ca/wld/documents/recovery/rcvrystrat/w_screech_owl_rcvry_strat130208.pdf

http://www.env.gov.bc.ca/wld/documents/recovery/rcvrystrat/w_screech_owl_rcvry_strat130208.pdf

http://a100.gov.bc.ca/pub/siwe/details.do;jsessionid=fda21758ce2b896b9cf2e18956eeaacb2b916f1e881075e0bfad32c5e2186d35.e3uMah8KbhmLe34MaxyNaxmTaxz0n6jAmljGr5XDqQLvpAe?id=4618




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Appendices

Appendix 1: BC Provincial Western Screech Owl Database

Available separately (MS Excel)

Appendix 2: Survey Data

Available separately (MS Excel)

Documents

Western Screech-Owl Conservation and Management in the Flathead River