Loss of vocal culture and fitness costs in a critically endangered songbird

Abstract

Cultures in humans and other species are maintained through interactions among conspecifics. Declines in population density could be exacerbated by culture loss, thereby linking culture to conservation. We combined historical recordings, citizen science and breeding data to assess the impact of severe population decline on song culture, song complexity and individual fitness in critically endangered regent honeyeaters ( Anthochaera phrygia ). Song production in the remaining wild males varied dramatically, with 27% singing songs that differed from the regional cultural norm. Twelve per cent of males, occurring in areas of particularly low population density, completely failed to sing any species-specific songs and instead sang other species' songs. Atypical song production was associated with reduced individual fitness, as males singing atypical songs were less likely to pair or nest than males that sang the regional cultural norm. Songs of captive-bred birds differed from those of all wild birds. The complexity of regent honeyeater songs has also declined over recent decades. We therefore provide rare evidence that a severe decline in population density is associated with the loss of vocal culture in a wild animal, with concomitant fitness costs for remaining individuals. The loss of culture may be a precursor to extinction in declining populations that learn selected behaviours from conspecifics, and therefore provides a useful conservation indicator.

A deepening understanding of animal culture suggests lessons for conservation

“…[72,74]). Finally, severe population declines can result in loss of song culture, as shown in critically endangered regent honeyeaters (Anthochaera phrygia) [75]; cultural decline may be a precursor to extinction thus providing an important conservation indicator [75].…”

Like Father Like Son: Cultural and Genetic Contributions to Song Inheritance in an Estrildid Finch

“…Genetic and behavioral change is frequently reported in captive breeding programs and can accumulate over relatively short time periods, spanning few generations (Håkansson and Jensen, 2005;Frankham, 2008;Suzuki et al, 2013), and these differences may extend to vocal behavior (Tanimoto et al, 2017). The potential for song evolution and cultural divergence in the Java sparrow is, therefore, likely to be of interest to conservation practitioners, as vocal changes may influence the success of conservation programs and in particular reintroduction programs (Lewis et al, 2020;Crates et al, 2021).…”

Born to Be Wild: Evaluating the Zoo-Based Regent Honeyeater Breed for Release Program to Optimise Individual Success and Conservation Outcomes in the Wild

“…We found a negative association between song tutoring and male reproduction; however, this association did not hold when individuals that were not resighted during the breeding season were removed from the analysis. Regent Honeyeaters that can sing the full repertoire of wild individuals may be better able to attract mates and establish pair-bonds, negotiate conspecific interactions, and maintain social cohesion of flocks (Crates et al, 2021). We suggest tracking birds in the field over longer periods time to understand if there is behavioural modification of song structure over time and associated breeding/survival success.…”