Geographical variation in the contact calls of orange-fronted Parakeets

We examined patterns of geographic variation in contact calls of Orange-fro nted Parakeets (Aratinga canicularis) during the nonbreeding season. Calls were recorded throughout the range of that species in Costa Rica. Recording s of wild-caught birds held for one to two week indicated that each individ ual 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 spect rographic cross-correlation and principal coordinates analysis as described by Cortopassi and Bradbury (2000). Principal coordinates were then correla ted with site location using MANOVA. Call durations were also examined for geographical patterns. Like sympatric Yellow-naped Parrots (Amazona auropal liata) studied over the same region by Wright (1996), Orange-fronted Parake ets exhibited significant geographic variation but, unlike the larger speci es, showed no discrete dialect patterns. Call duration varied clinally but with different patterns for the Nicoya Peninsula and the Guanacaste mainlan d. Two principal coordinates also showed clinal variation even after removi ng any correlated duration effects. Scale over which local calls were stati stically homogeneous was 7-10 km. We compared that figure to home ranges of 18 birds radio-tracked concurrently with call sampling. Both range areas a nd 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 per iod, was thus similar to distance within which calls tended to be statistic ally homogeneous. This study and that by Wright show that several well-know n patterns of geographical variation soon with passerine, song are replicat ed quite closely in contact calls of parrots, despite the fact that the fun ctions of vocal signals are quite different in the two taxa.