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Barn Owl Conservation Initiative PENNSYLVANIA GAME COMMISSION WILDLIFE DIVERSITY DIVISION PROJECT ANNUAL REPORT PROJECT CODE: 06798 TITLE: Barn Owl Conservation Initiative JOB CODE: 79801 PERIOD COVERED: January 2008 to December 2008 COOPERATING AGENCIES: York College, Pennsylvania Natural Heritage Program (PNHP), Pennsylvania Natural Diversity Index (PNDI). FIELD PERSONNEL: PGC Regional Wildlife Diversity Biologists – Jamie Flickinger, SC; Dan Mummert, SE; Mario Giazzon, NC; Richard Fritsky, NE; Tammy Colt, SW; Timothy Hoppe, NW; and NE Wildlife Management Supervisor Kevin Wenner. WORK LOCATION: Statewide PREPARED BY: Jamie Flickinger, Dan Mummert, Mario Giazzon, Richard Fritsky, Tammy Colt, Timothy Hoppe, Kevin Wenner. DATE: April 15, 2009 ABSTRACT: The Regional Wildlife Diversity Biologists (RWDBs) began a Barn Owl Conservation Initiative (BOCI) in spring 2005 to study the biology and ecology of barn owls in an effort to better understand and conserve this species. The project started in the southeast and southcentral regions and has since expanded to the current statewide effort. RWDBs conducted site visits to verify barn owl nest sites or sightings, monitor barn owl nests, conduct public outreach to farmers and other landowners, determine suitability for barn owl box placement, distribute barn owl boxes, and/or install barn owl boxes. Pellets were collected from some active barn owl nest sites and feathers were collected from nestlings for future analysis. Barn owls were banded to provide information on longevity, causes of mortality, and dispersal. In 2008, RWDBs conducted over 200 site visits and confirmed 49 active barn owl nests, bringing the total number of known current and past nest sites to 102 since nest searches began in 2005. Comparisons of the 1st and 2nd Breeding Bird Atlases (BBA) suggest that barn owls continue to decline in both abundance and distribution and may be in steeper decline than previously thought. RWDBs banded 150 nestlings in 35 nests in 2008; the earliest nest was banded on 16 May and the latest was banded on 30 August. Clutch size ranged from one to eight (average = 4.3). To date, 13 banded barn owls have been recovered. OBJECTIVES 79801 2 1. Assess the abundance and distribution of barn owls in Pennsylvania. 2. Evaluate barn owl habitat use and prey use in Pennsylvania. 3. Assess survival and dispersal of barn owls. 4. Improve nesting and foraging habitat and protect existing barn owl nest sites to encourage expansion of the barn owl population in Pennsylvania. 5. Examine genetic diversity of barn owls in Pennsylvania. INTRODUCTION With 36 subspecies and populations found on every continent except Antarctica, the barn owls (Tyto alba) is one of the world’s most widely distributed birds (Taylor 1994). Though this species is globally secure, significant population declines have occurred in North America over the past 30-50 years (Colvin 1985, Marti 1992). Breeding Bird Survey (BBS) data has found that the North American barn owl population declined by 1.8% annually between 1966 and 2005 (Sauer et al. 2007). Although insufficient barn owl data prevent BBS data from being used for determining regional or statewide trends, Colvin (1985) found that barn owls declined drastically in the upper midwestern states and limited data suggest a general decline throughout the Northeast (Rosenburg et al. 1992). In Pennsylvania, the conservation status of barn owls is unclear. This species is rare, nocturnal, secretive, and has not been thoroughly studied in this state. Though uncertain, trends suggest a decline in Pennsylvania’s barn owl populations. According to McWilliams and Brauning (2000), “barn owl breeding populations are not monitored, but numbers apparently have dwindled since the late 1970s on Christmas Bird Counts.” McWilliams and Brauning (2000) also mention that “they are absent from Greene and Washington Counties, where they were formerly regular,” suggesting a reduction of distribution within Pennsylvania. Data from the second BBA also provide evidence that barn owls may be declining in both population size and distribution throughout the state. The barn owl is designated a “candidate at-risk” in Pennsylvania (Ornithological Technical Committee, Pennsylvania Biological Survey) and is identified as a species of concern in the Wildlife Action Plan (WAP). The Pennsylvania Game Commission’s (PGC) mission is to manage and conserve all wild birds and mammals, as well as their associated habitats. The Barn Owl Conservation Initiative addresses Goals 1, 2, and 4 of the PGC’s Strategic Plan. By studying current barn owl distribution and abundance, causes of mortality and habitat requirements, and working to educate landowners on barn owl biology and habitat management techniques, this project will help maintain and possibly improve populations of barn owls and other grassland-associated wildlife for nonconsumptive recreational use and their many public values (Goal 1). By working closely with landowners who have barn owls using their barns and silos, this project provides outreach and education to landowners about the value and importance of barn owls and their associated 79801 3 grassland habitat (Goal 2). Through education about proper grassland management and by installing barn owl nest boxes, this project protects, maintains, and enhances habitat on public and private lands for barn owls and other grassland-associated species (Goal 4). The project also addresses various priorities in the WAP. By conducting site visits and determining barn owl breeding activity, we are assessing the current status of the barn owl in Pennsylvania (Research and Survey Priority, Level 2). By building an inventory of known nest sites, developing links with landowners, and providing education and outreach to the public, we are protecting nest sites (Conservation Management, Implementation Priority 2). By providing nest boxes in areas that have suitable foraging habitat, defining the most suitable areas for concerted efforts to provide nest sites, and monitoring nest boxes, we are increasing nest site availability (Conservation Management, Implementation Priority 3). A future radio telemetry project that evaluates priority foraging habitats and acreages required per pair would address Conservation Management, Implementation Priority 4, which is to maintain or expand the availability of high quality foraging habitat. Barn owls are sexually mature at one year, frequently have large clutches, and occasionally have two clutches per year (Taylor 1994). Barn owls are closely associated with humans in that they frequently use barns, silos, and other artificial structures. Efforts to offset population declines by providing nest boxes in appropriate locations have been successful in several areas (Marti 1992). These factors indicate that barn owls have high recovery and management potential and can be positively influenced by conservation efforts (Rosenburg 1992). Likely because of their nocturnal and secretive habits, barn owls are a poorly studied species in Pennsylvania. To properly manage for this species, information is especially needed in the areas of fledgling dispersal, habitat requirements, distribution, and population trends. METHODS Study Area The BOCI is a statewide project, though confirmed active nest sites have only been confirmed in the southcentral, southeast, northcentral, and northeast regions. Assess Abundance and Distribution of Barn Owls in Pennsylvania RWDBs conducted site visits to locations where barn owls were expected to occur. During site visits, RWDBs determined presence or absence by searching for barn owls and fresh sign (e.g., pellets and “whitewash”). Locations of breeding activity were determined by the confirmation of eggs, nestlings, or recently fledged young. GPS devices were used to record location of active sites. Data related to site location, reproductive status, nest site characteristics, and adjacent land use were recorded. Data will be submitted to PNDI and BBA. Evaluate Barn Owl Habitat Use and Prey Use in Pennsylvania If appropriate, GIS analysis will continue from efforts initiated by Justin Vreeland in 2007. Pellets were collected from active barn owl nest sites and will be analyzed by outside resources to determine prey usage. 79801 4 Assess Survival and Dispersal of Barn Owls To provide information on longevity, causes of mortality, and dispersal, barn owls were banded following standard protocol of the Patuxent Wildlife Research Center Breeding Bird Lab. Improve Nesting and Foraging Habitat and Protect Existing Barn Owl Nest Sites to Encourage Expansion of the Barn Owl Population in Pennsylvania RWDBs provided recommendations on grassland management to landowners with nesting barn owls, to those who receive nest boxes, and to landowners wishing to provide habitat for barn owls and other grassland-associated species. To provide additional nesting sites safe from many predators and hazardous ledges, RWDBs installed barn owl nest boxes at appropriate locations with the permission and cooperation of landowners. RWDBs, volunteers, or the landowner monitored nest boxes to determine use and nesting success. Landowners with active or potential barn owl nest sites were given information on barn owls related to such topics as conservation status, habitat requirements threats and reason for decline, habitat management recommendations, and proper nest box placement. RWDBs gave presentations on barn owl conservation to many different groups. Examine Genetic Diversity of Barn Owls in Pennsylvania RWDBs collected feathers
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