Regent Honeyeaters are forgetting their songs | The Guardian

[Posted by Chuck Almdale — Suggested by Lucien Plauzoles]

[Editor’s Note: In 1988 when we birded Australia extensively for five months, the Regent Honeyeater was the rarest, most endangered of the 65 species of Australian honeyeaters then recognized.]

How an endangered Australian songbird is forgetting its love songs

New study suggests young regent honeyeaters are not getting the chance to learn mating calls
The Guardian | Graham Readfearn | 16 March 2021 | 4 min read

This Guardian article contains a 2:04 video featuring the variety of wrong songs.

What happens to a species if the music starts to die, or when their songs become corrupted or their singers have never heard the original tunes?

A new study has found that a loss of melody and song could be a bad sign for one of Australia’s rarest songbirds – the Regent Honeyeater.

Once seen in flocks of hundreds across south-eastern Australia, there are now thought to be only a few hundred of the songbirds left in the wild.

The birds are known to imitate the songs of other species, such as friarbirds, currawongs and cuckooshrikes, but there was no clear theory for why they did it. More….

Link to original article in Proceedings of the Royal Society B

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

Ross Crates , Naomi Langmore , Louis Ranjard , Dejan Stojanovic , Laura Rayner , Dean Ingwersen and Robert Heinsohn. Published: 17 March 2021 https://doi.org/10.1098/rspb.2021.0225

Complete paper is available to read or download.

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.

Figure 1. Spatial and acoustic summary of regent honeyeater song types. (a) Locations of contemporary wild male regent honeyeaters (2015–2019) and their song types. The species whose songs each interspecific singing regent honeyeater most closely resembled are shown: (1) eastern rosella; (2) little wattlebird; (3) little friarbird; (4) spiny-cheeked honeyeater; (5) black-faced cuckooshrike; (6) noisy friarbird; (7) pied currawong (electronic supplementary material, text S5). Dotted lines denote the southern and northern limits of distinct breeding areas in the Northern Tablelands (red) and the Blue Mountains (blue), respectively. Centre left inset: data from Capertee Valley, the core breeding area within the Blue Mountains. Bottom right inset: Location of study area on a national scale, with the regent honeyeater’s contemporary range shaded dark. Due to map scale and spatial clustering of sightings, not all individuals are visible. (b) Discriminant function analysis of regent honeyeater song types, including captive-bred and pre-2012 birds from the Blue Mountains. Discriminant function analysis labels each multivariate mean with a circle corresponding to a 95% confidence limit for the mean. Groups that are significantly different have nonintersecting circles. (c) The number of contemporary wild, co-occurring male regent honeyeaters detected within the same breeding season within (i) 1 km and (ii) 50 km for male regent honeyeaters with interspecific songs (yellow) versus males with a species-specific song type (green). (Online version in colour.)