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

Abstract

Summary1. Translocation of individuals from healthy source populations to newly colonize or recolonize suitable habitat is a vital tool for the conservation of a species. Demographic, genetic and landscape factors, but also acoustic signals and cultural factors, will all affect translocation success. 2. We investigated variation in song, and response to song, of the endangered North Island k okako Callaeas wilsoni (Bonaparte 1850) in New Zealand in two translocated populations and their source population. 3. We found significant vocal variation between the source population and both translocated populations, the latter of which had reduced repertoire sizes and increased repertoire sharing, as well as structurally different song elements of higher frequency and shorter duration. 4. Despite the song divergence and clear variability in the nature and level of response among populations, we did not find any evidence for discrimination against nonlocal song in our reciprocal playback experiments. 5. Synthesis and applications. Vocal divergence and reduced variability in translocated populations suggest founder effects or reduced social interaction rates. The variation could be viewed as cultural erosion and may undermine translocation success. Persistence of response to playback, despite vocal divergence, suggested that social restrictions on gene flow require at least a few decades of separation after translocation. The decision to translocate individuals of threatened species is becoming a more common tool for species conservation world-wide. We argue that it is important to take vocal variation into account during such management decisions as it may affect success of establishment and persistence of translocated populations.

The uses and implications of avian vocalizations for conservation planning

“…2013), although this result is not consistent among sites (Valderrama et al. 2013). Further examination of responses to dialects across populations is necessary to determine the nuances of differential discrimination.…”

“…Serial translocations, where populations from successful translocations are used as source populations for future translocations, may increase the rate of song differentiation among populations, resulting in population divergence, isolation, and reduced retention of animals near release sites. In the North Island Kokako, in translocated populations, songs are shorter and of higher frequency and phrase repertoires are lower than in source populations (Valderrama et al 2012(Valderrama et al , 2013. Vocal activity is also markedly reduced, potentially reducing immigration and retention of birds in already small populations (Valderrama et al 2012).…”

“…In the North Island Kokako, in translocated populations, songs are shorter and of higher frequency and phrase repertoires are lower than in source populations (Valderrama et al. 2012, 2013). Vocal activity is also markedly reduced, potentially reducing immigration and retention of birds in already small populations (Valderrama et al.…”

Post‐translocation assortative pairing and social implications for the conservation of an endangered songbird

“…Knowledge of mate choice decisions may be facilitated by information concerning responses to simulated territory intrusion experiments. In previous studies of Kōkako, our research group has documented low responsiveness to playback of non‐local dialects by resident pairs (Bradley et al ., ; Valderrama et al ., ). Although these studies do not address sexual selection per se , they do show that both males and females respond much more strongly to familiar songs.…”

The effect of isolation, fragmentation, and population bottlenecks on song structure of a Hawaiian honeycreeper

“…In oscine Passerines (e.g., songbirds), song is a culturally transmitted trait that is acquired through social learning and imitation (Lynch, ). Thus, geographic variation in song can rapidly arise through the interplay of geographic isolation (Laiolo, ; Parker, Anderson, Jenkins, & Brunton, ; Robin, Katti, Purushotham, Sancheti, & Sinha, ; Valderrama, Molles, Waas, & Slabbekoorn, ) and localized generation of novel song elements or “memes” during song learning (Lynch, Plunkett, Baker, & Jenkins, ; Slabbekoorn & Smith, ). Natural (e.g., geographic distance, uninhabitable areas) or anthropogenic barriers (e.g., deforested landscapes, urban development) can resist or prevent meme flow between populations, much in the same way that barriers restrict gene flow (Lynch, ), and over time lead to the formation of unique dialects among populations across a landscape (MacDougall‐Shackleton & MacDougall‐Shackleton, ; Parker et al., ).…”