Microgeographic Song Dialects in the Orange-Tufted Sunbird (Nectarinia Osea)

Abstract

SummaryIn a study of male song in the orange-tufted sunbird (Nectarinia osea) in an urban neighborhood in Ramat-Aviv, Israel, we discovered the occurrence of song variation on a microgeographic scale in the form of two distinct dialects with a sharp boundary between them. The main distinction between the two song dialects is the frequency of the trill, which comprises the terminal part of the song. A large difference of 2-3 kHz in the peak frequency of the trill was discovered between the two dialects, which could be easily distinguished by ear. Thirtyseven males were recorded singing the 'low' dialect and 21 birds sang the 'high' dialect. Four other birds sang both dialects or 'hybrid' songs. Along the boundary that separated the two dialect populations, neighboring birds sang different dialect songs, although they were only 20-30 meters apart. All four 'bilingual' birds occupied territories near the dialect boundary. The historical processes leading to the formation of this dialect system may result from the pattern of human settlement at the time of the establishment of this neighborhood in the early 1950's. The spatial distribution of the two sunbird dialect populations, and the apparent low dispersal rates of birds from their natal dialect area, suggest the existence of a mechanism, which currently maintains these dialects at the current boundaries.2) Corresponding author; e-mail address: leader@ccsg.tau.ac.il 4) We thank A. Elkayam for assistance in the eld and R. Zilberman for valuable information and help. We are grateful to L.F. Baptista, C.K. Catchpole and P.K. McGregor for providing helpful comments on earlier drafts of this manuscript.

Dialect Discrimination by Male Orange‐Tufted Sunbirds (Nectarinia osea): Reactions to Own vs. Neighbor Dialects

“…The two distance variables, although highly correlated (Pearson correlation r=0.8, p < 0.001, n=23), show discrepancies and therefore differ, in our opinion, in their usefulness as informative measures of the distance of territorial birds. This is due to the presence of a recreational park, lacking sunbird territories, which forms most of the boundary between both dialect populations (Leader et al. 2000).…”

“…(1999) have found high territorial fidelity and a high degree of relatedness between neighboring individuals, as evidenced from high proportions of band sharing discovered in genetic analysis of this population. In addition, we have found very low dispersal rates of birds from their natal dialect area to the adjacent one (Leader et al. 2000).…”

“…data). Recently, two distinct local dialects with a sharp boundary between them were discovered in a study of a stable population of 63 territorial sunbird pairs in a small (1.5 km 2 ) urban neighborhood in Ramat‐Aviv, Israel (Leader et al. 2000).…”

“…The historical processes leading to the formation of this dialect system probably result from the pattern of human settlement at the time of the establishment of this neighborhood in the early 1950s (Leader et al. 2000).…”

Urban Wildlife Behavior

“…Some animals do not extend their range to traverse roads or buildings, suggesting that roads and buildings can serve to define home ranges and create linear range borders (Leader et al 2000;Etter et al 2002;McCleery and Parker 2011). The avoidance of vehicular traffic differs from road surface avoidance in that some animals may cross roads but appear to cross only when traffic is decreased, such as nighttime (Jaeger et al 2005).…”