If you think tui sing better at dawn than they do at dusk, you’re right - and scientists say there’s an intriguing reason behind the difference.
In a new study, Massey University researchers suggest the more complex choruses we get in the morning have less to do with the glory of a new day, but turf wars with other males - a finding with potentially big implications for other songbirds.
It’s the latest fascinating insight into the famously charismatic native bird that Sam Hill and his colleagues have uncovered.
Their earlier research revealed how the tui’s song is more impressive when heard in the bush - and how cheating males make better singers.
The team recorded the songs of 17 male tui they marked with unique colour bands at Tawharanui Regional Park, north of Auckland, over three hours at dawn, noon and dusk.
They then analysed the songs on sound spectrograms and examined the captured data.
“In a nutshell, we found that male tui sang more complex songs during dawn than they did around noon and dusk,” Mr Hill said.
“These same male tui also suffered a greater number of attempted ‘territory invasions’ by rival males during dawn than any other time of day.
“However, we also found that those individuals that produce more complex songs in terms of higher entropy, or spectral complexity, and syllable rate, or ones that squeeze more notes and syllables into their songs, suffered less territory invasions.”
The results were largely as the team had predicted - but were significant nonetheless.
“The findings are important because first of all this is the first study that has found that tui song complexity is higher at dawn,” Mr Hill said.
“Secondly, it gives further insights into why complex song may have evolved - this study suggests complex songs may have evolved partly to help reduce territory invasions from other males particularly during times like dawn when invasions are generally at their highest.”
Thirdly, he said, it provided a greater understanding of the intensified singing of songbirds at dawn.
While it was common knowledge that songbirds sing more intensely at dawn, the reason for this has remained poorly understood.
“Our results suggests that not only do tui sing more during the dawn period but they also sing more complex songs at this time - something we did not know before.
“Dawn has always been thought of as a very important time of day for songbirds, but we are only really just beginning to find out why this might be.
“Our findings in this study support the theory that dawn is important for songbird vocal communication in terms of males asserting territory.”
However, Mr Hill said, it likely wasn’t the only factor behind the fancy morning symphonies. One further explanation was that dawn offered birds better climactic conditions.
“Local air turbulence, for example, can cause attenuation of sound and create background noise, reducing the effective transmission of sound and is generally at its lowest at dawn.
“The production of more complex songs would therefore be most ideally suited to dawn as this will maximise the effective transmission of their songs so other tui can hear them.
“Although these are all only theories at the moment, and warrant further work in tui.”
The study, just published in the journal Emu - Austral Ornithology, was co-authored by Dr Michael Anderson, Dr Matthew Pawley and Dr Weihong Ji, all of Massey’s Institute of Natural and Mathematical Sciences.
What's your favourite bird?
Meanwhile, Kiwis are being urged to back their favourite New Zealand bird in an awareness-raising annual contest.
Forest and Bird’s Bird of the Year campaign began on Sunday, with people being encouraged to vote for their pick between next Monday and Sunday, October 30.
“Our birds are in real trouble,” campaign co-ordinator Kimberley Collins said.
“Their habitats are being destroyed and introduced mammalian predators such as stoats, possums, and rats kill their eggs, young, birds, and even adults.
“There’s also the threat of climate change, which has the potential to limit their habitat range, increase pest numbers and, in some cases, reduce their ability to forage for food.”
This year, the conservation status of each bird has been added to the competition’s website, showing Kiwis just how many native birds are threatened.
“I think a lot of people will be surprised to see how many of our native birds are at risk,” Ms Collins said. “Tragically, a third are in danger of becoming extinct.”
Groups campaigning for different birds have come out in force - rangers at Wellington’s Zealandia have today thrown their weight behind the tieke, or saddleback.
“The competition can be fierce, and people find all sorts of ways to promote their bird,” Collins said.
“We’ve had people making videos, running serious online campaigns, designing posters, reading poetry in the street - even getting tattoos of their bird.
“Already, we’ve had campaign managers come out swinging.
“Team Kaki have produced a music video, Team Kereru have released some bird-themed memes, and Team Kea have been filming a promo video.”
The previous years’ winners, respectively, have been the kokako, bar tailed godwit, fairy tern, yellowhead, karearea, pukeko, kakariki, kiwi, kakapo, grey warbler, fantail - and tui.
