Post-fledging survival and dispersal of Peregrine Falcons during a restoration project

  • Powell A
  • Calvert D
  • Barry M
 et al. 
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We monitored 38 juvenile Peregrine Falcons (Falco peregrinus) up to 3 mo
immediately after their release from a hack box during 1999-2000. The
restoration site was a cliff near Eagle Point Park in Dubuque, Iowa.
Falcons were released in a staggered manner from mid-June until late
July each summer. Older falcons remained at the site longer than at
previous urban releases and interacted with the younger falcons. The
four mortalities (11%) confirmed during the observation periods were
discovered and reported by citizens near the release site. We used
radiotelemetry, observations of color-marked birds at the hack site, and
recovered mortalities to estimate weekly survival rates and dispcrsal
patterns. We estimated weekly survival rate to be 0.988 (SE = 0.01), and
our weekly resighting rate was high: 0.885 (SE = 0.03). juveniles were
observed for an average of 4.3 wk in 1999 (SD = 2.5), but only 3.4 wk in
2000 (SD = 2.3). Accordingly, weekly fidelity rates were year-specific:
0.903 (SE = 0.03) in 1999 and 0.795 (SE = 0.05) in 2000. No mortalities
were attributed to Great-horned Owl (Bubo virginianus) predation, but
substantial numbers of owls were seen in summer 2000. The presence of
owls in 2000 may have contributed to the difference in fidelity rates
and dispersal patterns between years.

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  • a Powell

  • D J a N J Calvert

  • M Barry

  • L a Powell

  • I M Barry

  • L Washburn

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