Repertoire Sharing and Song Similarity between Great Tit Males Decline with Distance between Forest Fragments

Abstract

Birdsong can play a critical role in establishing a territory and finding a mate among individuals from local and foreign populations. Variation in birdsong among populations can be influenced by habitat fragmentation and might affect successful dispersal among habitat fragments. We studied variation in great tit song in a long‐term study population distributed over nine forest fragments. All individual males recorded had a known dispersal history within the fragmented forest habitat. We found spatial structure of declining song‐type sharing with distance, with a marked drop from an individual’s own forest fragment to another across a habitat gap. We also found decreasing song similarity among increasingly distant fragments in terms of temporal and spectral characteristics of shared song types. The change in acoustic structure was more gradual and seemed less affected by habitat discontinuity but also showed a tight correlation with dispersal index among forest fragments. Immigrant birds shared fewer song types with neighbouring birds that were born within the same forest fragment, but not less compared to birds born in another forest fragment within the study area. Our data provide detailed insight into the relationship between song differentiation and male dispersal and contribute to our understanding of the potential role of song in reproductive exchange and avian speciation. The fact that birds in small forest fragments shared more songs than birds in larger forest fragments confirms that song analysis has potential as a tool for conservation in rare species.

Effects of Population Size on Singing Behavior of a Rare Duetting Songbird

“…Physical connectivity of habitat within populations, for instance, can affect dispersal and cultural transmission of song elements (e.g., Thielcke 1973;Laiolo & Tella 2007;Rivera-Gutierrez et al 2010). In Great Tits (Parus major) and Dupont's Larks, more song types are shared among males in small fragments than in large fragments, and sharing is negatively affected by habitat fragmentation (Laiolo & Tella 2005;Rivera-Gutierrez et al 2010). Physical connectivity is low in Mapara, in contrast to the other 5 areas, which have more continuous forest.…”

Conservation implications of song divergence between source and translocated populations of the North Island Kōkako

“…The reduced repertoire size in birds from both translocated populations relative to birds in the source population may therefore be related to increased levels of territorial interactions or just a reduced number of long‐term neighbours (as found in other species: Koetz, Westcott & Congdon ; Rivera‐Gutierrez et al . ).…”

“…We believe that the k okako may be comparable to the larks in that a lack of vocal interactions and connectivity may explain divergence among population fragments in vocal repertoire composition, while limited resources may play a particularly strong role in one of the translocated populations (T1). The reduced repertoire size in birds from both translocated populations relative to birds in the source population may therefore be related to increased levels of territorial interac-tions or just a reduced number of long-term neighbours (as found in other species: Koetz, Westcott & Congdon 2007;Rivera-Gutierrez et al 2010).…”

Repertoire structure, song sharing, reproductive success, and territory tenure in a population of Canada Warblers (Cardellina canadensis) in central New Hampshire

“…Song sharing between neighbours is prevalent in many songbird species, such that repertoire similarity decreases as distance between territories increases (e.g., Hill et al 1999;Foote et al 2007;Koetz et al 2007;Rivera-Gutierrez et al 2010). Song sharing may increase reproductive success (Payne et al 1988) and length of territory tenure (Beecher et al 2000b), by allowing males to engage in aggressive intrasexual encounters using shared songs (Krebs et al 1981;Beecher et al 2000a;Vehrencamp 2001).…”