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 from all banded barn owls. Dr. Karl Kleiner from York College and a student began analyzing these feathers to determine sex ratios. Further analysis of feathers will attempt to determine the genetic diversity of barn owls in Pennsylvania.

RESULTS AND DISCUSSION

Assess Abundance and Distribution of Barn Owls in Pennsylvania In 2008, RWDBs conducted over 200 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 (Table 1). RWDBs confirmed 49 active barn owl nests in 2008, bringing the total number of known current and past nest sites to 102 since nest searches began in 2005 (Figure 1). Confirmed nests continue to be concentrated in the southeastern and southcentral areas of the Commonwealth. There were no confirmed second clutches in 2008, though RWDBs were not actively looking for them. Data was submitted to Pennsylvania Natural Diversity Index (PNDI) and the second BBA.

The second BBA, which began in 2004, was completed in 2009 (Note: some minor data entry may continue through July 2009). Results can be compared to the first BBA, which took place from 1984-1989 (Figure 2). In the first BBA, barn owls were observed in 251 (5.1%) blocks and confirmed in 107 (2.2%) of those blocks. In the second BBA, barn owls were observed in 114 (2.3%) blocks and confirmed in 78 (1.6%) of those blocks. In the second BBA, RWDBs accounted for the only barn owl records in 51 (45%) of the 114 blocks in which barn owls were observed, and for 47 (61%) of the 78 in which breeding was confirmed (Figure 3). Despite the greater observation effort during the second BBA, breeding was confirmed in only 73% of the blocks in which breeding was confirmed during the 1st BBA. Therefore, it can be 79801 5 argued that barn owls continue to decline in both abundance and distribution and may be in steeper decline than previously thought.

Evaluate Barn Owl Habitat Use and Prey Use in Pennsylvania GIS analysis was initiated in 2007 by former RWDB Justin Vreeland, now PGC Regional Wildlife Management Supervisor, southcentral Region. Locations of 73 known barn owl nests in the southeast and southcentral regions were plotted and circular buffer zones corresponding to 250-ha home-ranges (estimates derived from published literature) were created around each site. Landscape-level habitat characteristics (cover types, land use) were extracted for home ranges. No further GIS analysis was performed in 2008. In the future, GIS analysis may assess larger home range habitat, compare habitat characteristics from those nest home ranges to random sites, and better define habitat parameters and/or use additional habitat data.

RWDBs continued to collect pellets from active barn owl nest sites to determine the selected prey of Pennsylvania’s barn owls. Pellets will be analyzed by outside resources (including Jim Hart from the Pennsylvania Natural Heritage Program and some universities). Results are pending.

Assess Survival and Dispersal of Barn Owls RWDBs banded 150 nestlings in 35 nests in 2008 (Table 1). The earliest nest was banded on 16 May and the latest nest was banded on 30 August; most nests were banded in June (Figure 4). Clutch size ranged from one to eight (average = 4.3); majority of the nests banded had a clutch size of 4 to 6 (Figure 5). Because most nestlings were banded at 5 to 7 weeks of age, and females incubate eggs for 32 days, and the owlets fledge approximately 60 days from the hatching date, it can be assumed that 1) eggs were laid between 3 March and 16 June, 2) hatching took place between 4 April and 18 July, and 3) the owls fledged between 3 June and 16 September (Figure 6).

To date, 13 banded barn owls have been recovered (Figure 7); 10 were banded in Pennsylvania and 3 were banded in other states by other bird banders. All were banded as nestlings and all but 1 were recovered dead. Four of the 9 recoveries were birds found dead previous to fledging or immediately post-fledging, therefore providing little information on dispersal of these individuals.

Two of the 9 recoveries (bands 1807-71075, 2206-89105) were nestlings banded in June 2006, recovered dead approximately 10 miles from their natal site in February 2007. This provides information on where some barn owls reside during the winter months. Four other dead barn owls (not banded) were recovered following a severe ice storm in the southcentral and southeastern parts of the state in February 2007. A necropsy was performed on 1 owl at the Penn State Animal Diagnostic Laboratory; results confirmed starvation/malnutrition as the cause of death.

Two barn owls (bands 1687-31890, 2206-54968) dispersed <35 miles from their natal site to breed while 5 barn owls (bands 1687-31870, 1807-50368, 1807-97178, 2206-48560, 2206-54952) dispersed >100 miles to breed (other researchers have reported dispersal distances 79801 6 • 50 miles). These birds all dispersed in different directions (other researchers have also reported dispersal in all directions).

One owl (band 1687-31870) was a female found nesting in a nest box in a barn, reported by a researcher in New Jersey. This is the first recovery of a live barn owl during this project and the first owl where the natal and breeding sites are confirmed.

One owl (band 2206-48560) was recovered 6 years after it was banded as a nestling, providing good information on longevity (reported average life span of barn owls is 2-4 years).

Improve Nesting and Foraging Habitat and Protect Existing Barn Owl Nest Sites to Encourage Expansion of the Barn Owl Population in Pennsylvania RWDBs have distributed and installed barn owl nest boxes in appropriate locations to provide secure nesting structures. Landowners with active or potential barn owl nest sites are given information on barn owls (e.g., status, identification, reproduction, habitat, threats/reasons for decline, management recommendations, nest box placement, etc). When appropriate, RWDBs have provided recommendations on grassland management, specifically to landowners with barn owl nests, but also to other landowners through the Private Landowner Assistance Program (PLAP).

Education and box installation efforts will continue throughout the life of this project. This education and outreach with landowners aids in protecting nest sites, including providing continued access to the nest site, avoiding disturbance, and preventing destruction of sites. For example, there were a few instances where RWDBs moved young barn owls out of the way of a farmer’s activities (e.g., birds nesting on the top of silage that needs to be removed) and transferred them to a more secure nest site (e.g., a nest box mounted on a silo, but out of the way of a farmer’s activities). Otherwise, these nests may have been destroyed. In addition, RWDBs gave 19 presentations on barn owls to an estimated 723 people, including Lancaster Mennonite cchool, Lebanon County conservation camp, boy scout troop in Lycoming County, PGC WCO cadet class, West Chester bird club, Wyncote Audubon, Conococheague Audubon, Cumberland County Woodland Owners Association, Blair County Fish and Game Association, Shade Mountain landowner banquet, PGC teacher's workshop, PPL grasslands workshop, grassland workshop for landowners, PPL wwl workshop, PGC Middle Creek lecture series, PGC Southeast Region annual meeting, PGC Bureau of Wildlife Management meeting, Northampton Biofuels conference, and PA Chapter of the Wildlife Society annual conference.

While most barn owls are found nesting in barns and silos, often in a nest box (Figure 8), they have also been found nesting in a variety of other structures over the last few years, including a tree cavity, bat condo, brick chimney, house attic, feed mill, and in the roof trusses above a wall.

Examine Genetic Diversity of Barn Owls in Pennsylvania RWDBs collected feathers for the second year from all banded barn owls. Dr. Karl Kleiner and students from York College have begun analyzing feathers to determine sex ratios. To date, sex ratios of 29 young from 7 nests have been determined; 20 were female and 9 were 79801 7 male, ranging from 33-100% female per clutch. Further analysis of feathers will attempt to determine the genetic diversity of barn owls in Pennsylvania.

RECOMMENDATIONS

It is recommended that RWDBs continue to conduct site visits to verify barn owl nest sites or sightings, monitor barn owl nests, conduct public outreach, determine suitability for barn owl box placement, distribute barn owl boxes, install barn owl boxes, collect pellets, band nestlings, and collect feathers to expand our knowledge on this declining species.

Recommendations for expanding the project, based on recommendations stated in the barn owl species account in the WAP, are to evaluate habitat use and prey availability within the species’ core range by 1) using radio telemetry to evaluate foraging habitat use by adult barn owls throughout the breeding season and 2) live-trapping studies of small mammals within the farmland landscape to provide information on prey densities in the barn owl’s key foraging habitats (Wilson 2005). These studies could be used to devise models of landscape use by this species, which could shed light on the local causes of the decline in numbers witnessed in recent decades. Volunteers and professors and students should continue to be utilized when available.

LITERATURE CITED

Colvin, B. A. 1985. Common barn owl population decline in Ohio and the relationship to agricultural trends. Journal of Field Ornithology. 56(3):224-235.

Marti, C. D. 1992. Barn owl (Tyto alba) Account in A. Poole, P. Stettenheim, and F. Gill. eds. The Birds of North America, 1:1-16. Academy of Natural Sciences, Philadelphia, Pennsylvania, and American Ornithologists’ Union, Washington, DC., USA.

McWilliams, G. M., and D. W. Brauning. 2000. The Birds of Pennsylvania. Cornell University Press, Ithaca, New York, USA.

Pennsylvania Breeding Bird Atlas [BBA]. 2009. BBA home page. . Accessed 8 Oct 2008.

Rosenburg, C., G. Hammerson, M. Koenen, and D.W. Hehlman. 1992. Barn Owl. Species Management Abstract. The Nature Conservancy, Arlington, Virginia, USA.

Sauer, J. R., J. E. Hines, and J. Fallon. 2007. The North American Breeding Bird Survey, Results and Analysis 1966-2006. Version 10.13.2007. USGS Patuxent Wildlife Research Center,

Taylor, I. 1994. Barn owls: Predator-prey relationships and conservation. Cambridge University Press, Cambridge, United Kingdom.

Wilson, A. 2005. Barn Owl (Tyto alba) species account. In 79801 8 Wildlife Action Plan. Pennsylvania Game Commission and Pennsylvania Fish and Boat Commission.

Table 1. Summary of statewide BOCI activities conducted by PGC RWDBs, January - December, 2008. Region Site Visits Active Nests Nests Banded Owls Banded NW 0 0 0 0 SW 1 0 0 0 NC 31 6 5 24 SC 74 16a 12 50 NE 12 5 5 20 SE 94 22b 15c 59c Statewide 212 49 37 153

a 3 nests had eggs that did not hatch b 1 nest had eggs that did not hatch, 1 nest had nestlings that did not fledge c 2 sites were roost sites banded on 11/18/08; because they were not confirmed as nest sites, data (e.g., clutch size, banding date, nesting structure) for these 2 nests are not included in this table

Figure 1. Barn owl nest sites, 2005-2008. Open circles indicate a nest that was last active in 2005, 2006, or 2007 (n = 53). Solid circles indicate a nest that was active in 2008 (n = 49). Nests newly discovered in 2008 are identified with a red ring around the solid circle (n = 16).

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1st BBA: 1984-1989 2nd BBA: 2004-2008

Figure 2. Barn owl results from the 1st and 2nd BBA. Source: http://bird.atlasing.org/PA.

Figure 3. Barn owl observations in the 1st (1984-1989) and 2nd (2004-2008) BBA. The 2nd BBA results are presented with all data (“w/ RWDB effort”) and without data collected by RWDBs (“w/o RWDB effort”).

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Figure 4. Number of barn owl nests banded per month (2007: n = 29, 2008: n = 35).

Figure 5. Clutch size of banded barn owl nests (2007: n = 29, 2008: n = 35).

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20 approx. egg laying 2007 approx. egg laying 2008 approx. hatching 2007 15 approx. hatching 2008 approx. fledging 2007 approx. fledging 2008 10 # of nests # of

5

0 Mar c h April May June July August September

Month Figure 6. Approximate egg laying, hatching, and fledgling times of barn owls, determined by assuming owlets were 6 weeks old when banded (usually banded between 5 and 7 weeks of age) (2007: n = 29, 2008: n = 35).

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Figure 7. Summary of all barn owl recoveries. with band number, shortest dispersal distance, direction of dispersal, original banding date and location, and band recovery date and location.

Figure 8. Nest sites for active barn owl nests (n = 49), January - December, 2008. “Other” nesting structure was a feed mill.