title: MIGRATION PATTERNS, USE OF STOPOVER AREAS, AND AUSTRAL SUMMER MOVEMENTS OF SWAINSON'S HAWKS.
abstract: From 1995-1998, we tracked movements of adult Swainson's Hawks (Buteo swainsoni) using satellite telemetry to characterize migration, important stopover areas, and austral summer movements. We tagged 46 hawks from July - September on their nesting grounds in seven U.S. states and two Canadian provinces. Swainson's Hawks basically followed three routes south on a broad front, converged along the east coast of central Mexico, and followed a concentrated corridor to a communal austral summer area in central Argentina. North of 20° N, southward and northward tracks differed little for individuals from east of the Continental Divide but differed greatly (up to 1700 km) for individuals from west of the Continental Divide. Hawks left the breeding grounds mid-August to mid-October; departure dates did not differ by location, year, or sex. South migration lasted 42 to 98 days, and north migration took 51 to 82 days. On south migration, 36% of the Swainson's Hawks departed the nesting grounds nearly 3 weeks earlier than the other radio marked hawks and made stopovers 9.0 - 26.0 days long in seven separate areas, mainly in the southern Great Plains, southern Arizona and New Mexico, and north-central Mexico. The austral period lasted 76 to 128 days. All Swainson's Hawks used a core area in central Argentina within 23% of the 738800 km2austral summer range where they frequently moved long distances (up to 1600 km). Conservation of Swainson's Hawks must be an international effort that considers habitats used during nesting and non-nesting seasons including migration stopovers.
authors.affiliation: U.S. Geological Survey, Forest and Rangeland Ecosystem Science Center, Snake River Field Station, Boise, Idaho 83706, USA.
authors.forename: Michael N
authors.initials: MN
authors.lastname: Kochert
authors.affiliation: U.S. Geological Survey, Forest and Rangeland Ecosystem Science Center, Snake River Field Station, Boise, Idaho 83706, USA.
authors.forename: Mark R
authors.initials: MR
authors.lastname: Fuller
authors.affiliation: U.S. Geological Survey, Forest and Rangeland Ecosystem Science Center, Snake River Field Station, Boise, Idaho 83706, USA.
authors.forename: Linda S
authors.initials: LS
authors.lastname: Schueck
authors.affiliation: Boise State University, Department of Biology, Boise, Idaho 83725, USA.
authors.forename: Laura
authors.initials: L
authors.lastname: Bond
authors.affiliation: Boise State University, Raptor Research Center, Boise, Idaho 83725, USA.
authors.forename: Marc J
authors.initials: MJ
authors.lastname: Bechard
authors.affiliation: Boise State University, Raptor Research Center, Boise, Idaho 83725, USA.
authors.forename: Brian
authors.initials: B
authors.lastname: Woodbridge
authors.affiliation: Environment Canada, Edmonton, Alberta, T6B2X3, Canada.
authors.forename: Geoff
authors.initials: G
authors.lastname: Holroyd
authors.affiliation: University of Minnesota, Raptor Center, St. Paul, Minnesota 55125, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Martell
authors.affiliation: Environment Canada, Edmonton, Alberta, T6B2X3, Canada.
authors.forename: Ursula
authors.initials: U
authors.lastname: Banasch
keywords: Argentina; Buteo swainsoni; Swainson’s Hawk; austral summer; connectivity; migration; migratory behavior; movements; stopovers