Wintering ecology of prairie falcons in the Snake River Birds of Prey National Conservation Area

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We determined differences in winter home ranges and observed hunting attempts of nine male and six female prairie falcons (Falco mexicanus) trapped in the Snake River Birds of Prey National Conservation Area (SRBOPNCA) in Idaho, between November and March, 1993. Winter home ranges of females were not larger than males. Successful capture attempts suggest prairie falcons prey mainly on horned larks (Eremophila alpestris) (seven of nine successful attempts). There appears to be two groups of falcons wintering in the SRBOPNCAI those that bred there the previous summer and those that migrated into the SRBOPNCA. The sex ratio of the nine breeders that remained was significantly biased toward males (nine males: one female; X² = 4.01, P < 0.05). However, the sex ratio of the 17 birds trapped during the winter (that likely migrated into the SRBOPNCA) was not significantly different from a 1:1 ratio (10 males: seven females; X² = 1.41, P < 0.25). We will discuss different migration strategies, methodology, climatology, and status of resource base as alternative explanations for the difference in sex ratios between the two groups of wintering prairie falcons.

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Reference Code: A95PRO01IDUS

Full Citation: Prokop, R. S., and J. M. Marzluff. 1995. Wintering ecology of prairie falcons in the Snake River Birds of Prey National Conservation Area. Journal of Raptor Research 29(1): 64-65. Abstract.

Location: ANIMAL EF: BIRDS