SURVIVAL, MOVEMENTS AND HABITAT USE OF APLOMADO FALCONS RELEASED IN SOUTHERN TEXAS

Aplomado falcons (Falco femoralis) formerly bred in Texas, New Mexico, and Arizona. Nesting in the U.S. was last documented in 1952. In 1986 , aplomado falcons were listed as endangered and efforts to reestablis h them in their former range were begun by releasing captive-reared in dividuals in southern Texas. From 1993-94, 38 hatch-year falcons were released on Laguna Atascosa National Wildlife Refuge. Two to 3 wk afte r release, 28 falcons were recaptured for attachment of tail-mounted r adio-transmitters. We report on survival, movements, and habitat use o f these birds. In 1993 and 1994, four and five mortalities occurred wi thin 2 and 4 wk of release, respectively. From 2-6 mo post-release, 11 male and three female radio-tagged aplomado falcons used a home range of about 739 km(2) (range = 36-281 km(2)). Most movements did not ext end beyond 10 km from the refuge boundary, but a monitored male disper sed 136 km north when 70 d old. Average linear distance of daily movem ents was 34 +/- 5 (SD) km. After falcons had been released 75 d, they consistently used specific areas to forage and roost. Woody plant dens ity averaged 2.6 plants/ha on forage areas and 3.6 plants/ha at roost sites. Ground surface area was 60% vegetated in foraging areas and 46% vegetated at roost sites.