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Jack W. Bradbury, Kathryn A. Cortopassi, Janine R. Clemmons
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We examined patterns of geographic variation in contact calls of Orange-fronted Parakeets (Aratinga canicularis) during the nonbreeding season. Calls were recorded throughout the range of that species in Costa Rica. Recordings of wild-caught birds held for one to two weeks indicated that each individual favors one dominant call type and different birds use different favored calls. We used that fact to cull replicate calls from the same individual in field recordings of flocks observed at various locations throughout the sample area. Remaining recordings from a given year were submitted to spectrographic cross-correlation and principal coordinates analysis as described by Cortopassi and Bradbury (2000). Principal coordinates were then correlated with site location using MANOVA. Call durations were also examined for geographical patterns. Like sympatric Yellow-naped Parrots (Amazona auropalliata) studied over the same region by Wright (1996), Orange-fronted Parakeets exhibited significant geographic variation but, unlike the larger species, showed no discrete dialect patterns. Call duration varied clinally but with different patterns for the Nicoya Peninsula and the Guanacaste mainland. Two principal coordinates also showed clinal variation even after removing any correlated duration effects. Scale over which local calls were statistically homogeneous was 7–10 km. We compared that figure to home ranges of 18 birds radio-tracked concurrently with call sampling. Both range areas and range lengths were asymptotic after a week of tracking. Asymptotic range lengths were 2–9 km. Scale of movements of birds, at least during that period, was thus similar to distance within which calls tended to be statistically homogeneous. This study and that by Wright show that several well-known patterns of geographical variation seen with passerine song are replicated quite closely in contact calls of parrots, despite the fact that the functions of vocal signals are quite different in the two taxa.

Jack W. Bradbury, Kathryn A. Cortopassi, and Janine R. Clemmons "GEOGRAPHICAL VARIATION IN THE CONTACT CALLS OF ORANGE-FRONTED PARAKEETS," The Auk 118(4), 958-972, (1 October 2001).[0958:GVITCC]2.0.CO;2
Received: 30 August 2000; Accepted: 24 April 2001; Published: 1 October 2001
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