Western Burrowing Owl (Athene cunicularia hypugaea): Species Conservation Assessment

The primary goal in the development of at-risk species conservation assessments is to compile biological and ecological information that may assist conservation practitioners in making decisions regarding the conservation of species of interest. The Nebraska Natural Legacy Project recognizes the western subspecies of Burrowing Owl (Athene cunicularia hypugaea) as a Tier I at-risk species. Provided are some general management recommendations regarding Western Burrowing Owls (hereafter Burrowing Owls). Conservation practitioners will need to use professional judgment for specific management decisions based on objectives, location, and site-specific conditions. Based on a considerable body of literature, this particular species conservation assessment provides an overview of our current knowledge of Burrowing Owls and may aid in decision-making for their conservation or in identifying research needs for the benefit of the species. Species conservation assessments will need to be updated as new scientific information becomes available. Though the Nebraska Natural Legacy Project focuses efforts in the state’s Biologically Unique Landscapes (BULs), it is recommended that whenever possible, practitioners make considerations for a species throughout its range in order to increase the success of conservation efforts. Criteria for selection as Tier I Ranked as imperiled or vulnerable in nearly all states in its range Trends since 2005 in NE Increasing Range in NE Western two-thirds of state Habitat Prairie dog towns, short-grass prairie, mixed-grass prairie, heavily grazed grasslands Threats Prairie dog control; habitat conversion (center pivots); loss of short, open grasslands; plague in prairie dogs; industrial, utility, and wind energy development; insecticide impacts; vehicle collisions and other impacts associated with disturbance by humans Climate Change Vulnerability Index: not vulnerable, presumed stable (NatureServe 2013) Research/Inventory Expand surveys to assess distribution and abundance; determine productivity, cause of population variability (predators), status and trends of prairie dogs, effects of wind energy development Landscapes Central Loess Hills, Cherry County Wetlands, Dismal River Headwaters, Elkhorn River Headwaters, Keya Paha, Kimball Grasslands, Loess Canyons, Middle Niobrara, North Platte River, Oglala Grasslands, Panhandle Prairies, Rainwater Basin, Sandhills Alkaline Lakes, Sandsage Prairie, Upper Loup Rivers and Tributaries, Upper Niobrara River, Verdigris-Bazile, Wildcat Hills, Willow Creek Prairies Burrowing Owls (Athene cunicularia) are listed as a Species of National Conservation Concern in several Bird Conservation Regions (BCRs), including BCR 18 (Shortgrass Prairie) that extends along the western border of Nebraska (U. S. Fish and Wildlife Service 2008). According to the last global status review in 2011, the state of Nebraska Heritage status rank of Burrowing Owls is S5, U.S. national status is N4B,N4N, and global conservation rank is G4 (NatureServe 2009). Natural Heritage conservation ranks range 1 to 5 with 1 being the most critically imperiled (for definitions of ranks, see Appendix 4 of Nebraska Natural Legacy Project; Schneider et al. 2011). Overall, populations of Burrowing Owls in the Great Plains have experienced declines (Klute et al. 2003). From 1966–2011, Burrowing Owls in Nebraska have increased slightly with a trend of 3.2, 95% CI = -0.1–6.5; however, data during the same time frame show a decline for the central mixedgrass prairie region as a whole (-4.2, 95% CI = -6.2 – -2.1) (Sauer et al. 2012). The Nebraska Natural Legacy Science Team set a goal of maintaining at least four populations in the state, assuming there is little movement between populations during the breeding season and fates of populations are not correlated (Schneider et al. 2011). Moderate viability (40% chance of survival) of each population gives >99% probability of at least one population surviving 100 years (Morris et al. 1999). However, there is recent verified documentation of a female Burrowing Owl that flew during the breeding season between two migration corridors that were largely believed to be separated, indicating that there may be more crossover between populations than previously believed and possibly greater genetic exchange (Holroyd et al. 2011). Global population size is thought to be >1,000,000 individuals (NatureServe 2011) and may be 2,000,000 with ~31% in the United States and Canada (Rich et al. 2004). Partners in Flight (2007) estimate the population of Burrowing Owls in the United States to be 700,000 with 15,000 in Nebraska.

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