Movements, Fate, and Survival of Translocated Western Burrowing Owls
The western burrowing owl (Athene cunicularia hypugaea) is a species of special conservation concern throughout most of its range in western North America due to local to regional population declines (Desmond et al. 2000, Murphy et al. 2001, Wellicome and Holroyd 2001, Klute et al. 2003, Conway and Pardieck 2006). The species is strongly migratory in northern parts of its range; resident, migrant, and overwintering individuals occur in southern parts of its range. In some locales of the owl���s southwestern U.S. range, habitat is being converted to other land uses such as urban areas and energy development sites. Because the species relies on burrows throughout its entire annual life cycle (Haug et al. 2011), losses of burrows due to development in southwestern states could diminish breeding success plus year-round survival of both resident, migrant, and overwintering non-resident birds. When a burrowing owl habitat is to be converted to another land use, the area must first be ���cleared��� by checking burrows for presence of burrowing owls and removing owls. This work must be done under permit from the U.S. Fish and Wildlife Service, as take of the owls, their eggs, or nestlings is a violation of MBTA. Except in emergency situations, clearing is to be done outside the normal breeding season, to avoid take of eggs and young. Burrows are checked via fiberscopes. The owls typically are captured at burrow entrances by using 1-way door traps or noose carpets. Then, burrows are entirely excavated and collapsed; care is taken during excavation to detect and capture any owls that remain. Captured owls are moved to a holding facility for 30 days to attempt to interrupt fidelity to the cleared site, then are moved to a pen for hack-release at a new site where, typically, artificial burrows are created. After another 30 days, the hack pen is opened such that owls may move in and out, with opportunity to explore new burrows. If there appears to be suitable habitat near the area to be cleared, i.e., with burrows present and possibly other burrowing owls, captured owls may be released at such a site, or the owls may be expected to move to the site after being captured and released at the area being cleared. This approach is known as passive relocation. Occasionally, eggs, nestlings, or fledglings are found in burrows during clearing outside of the normal breeding season. These are transferred to a rehabilitation facility where they are hatched and reared to post-fledging age, then are released typically at sites with artificial burrows. Regardless of origin ��� either removed from burrows as eggs or dependent young, or captured by trapping ��� the fate and survival rate of translocated burrowing owls in the Southwest is unknown. This information is critical in supporting the Service���s decisions to issue permits for translocations, and, if permit is issued, how to develop conditions for such permits in ways that enhance success, from specific modifications for release protocols to post-release monitoring requirements. Objectives of this research include: (1) documenting fates of translocated burrowing owls (2) estimating survival rate of translocated owls [& comparing to what���s known in lit.? basing this on a ���control��� group may be too much, unless capture-recapture can be used based on banded birds] (3) documenting post-release movement of translocated burrowing owls methods: VHF telemetry; color/alpha-numeric banding
Office: U.S. FISH AND WILDLIFE SERVICE
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