Which bird sings the most pleasant song? Science reveals answer

By Stephen Beech

Blackbirds have the most beautiful songs, suggests a new scientific study.

But barn owls' sounds are considered the least pleasant, according to the findings.

Researchers set out to discover the key ingredients that make birdsong pretty.

Their findings show that calls which are varied, higher-pitched and not too loud are considered most pleasant — with blackbird songs topping the charts.

Participants rated the perceived pleasantness of 123 different bird songs on a scale from one (not very pleasant) to five (very pleasant).

The blackbird topped the pleasantness table with an average score of 4.52, just beating the willow warbler (4.45) with the blackcap completing the top three.

The barn owl finished rock bottom with an average pleasantness score of just 1.32.

The German research team explained that identifying what makes birdsong beautiful could improve understand how soundscapes make the natural world relaxing for humans.

They say their findings, published in the journal Frontiers in Bird Science, could help to improve parks, upgrading the design of stressful places such as hospital waiting rooms, and promote conservation through birds with especially lovely songs.

By asking people to listen to birdsongs and rate them for pleasantness, then cross-referencing the results with information about the calls' acoustic characteristics, the scientists identified key aspects that make some birdsongs seem more pleasant than others.

But although people who valued birds more rated songs more highly, knowing more about birds didn't influence perceived pleasantness.

Study lead author Nadine Kalb, from the University of Tübingen, said: "You don't have to be a 'bird person' to find bird sounds beautiful.

"Being able to recognize birds by their appearance or song did not affect how people rated calls.

"This suggests that enjoyment of birdsong is connected to something more fundamental than just knowing what you are listening to."

She explained that pleasantness is a subjective, perceived measure which is affected by personal taste.

The research team suspected that some acoustic characteristics, such as a high amplitude — perceived as a loud noise — would be associated with a lower pleasantness rating.

But they also suspected some personal characteristics, such as individuals' knowledge about birds, would influence pleasantness ratings.

Study senior author Christoph Randler, also from the University of Tübingen, said: "I have been a birder since I was 10, although at that age I didn't know about ecosystem services or acoustic analyses.

"I'm very interested in human-bird relationships.

"Bird sounds are often considered one of the most enjoyable aspects of spending time in nature, and previous research has shown that they can contribute to psychological restoration and well-being.

"However, not all bird sounds are perceived equally positively."

The scientists recruited 84 people and played them short clips of 123 songs from wild birds commonly found throughout Germany.

Participants were then asked to rate each clip on a scale from one to five — the higher, the more pleasant.

Participants were also asked questions which measured their birding skills and their perception of birds.

The researchers then analyzed the clips, measuring aspects of each song's amplitude, frequency, complexity — the number and variety of elements in the song — and bandwidth, which captured the range of frequencies a song used.

A song with a big difference between its highest and lowest frequencies would have a wide bandwidth.

The data was then cross-referenced with participants' pleasantness scores for songs and their pre-existing interest in birds.

The scientists identified 21 species among their samples which had also been included in a study about perceptions of birdsong as restorative — helping people to recover from mental fatigue or stress.

They compared the ratings these birds received in that study with their pleasantness scores.

A blackbird's song was considered most pleasant while a barn owl's was considered least pleasant.

Blackbirds' songs were also considered highly restorative.

A narrower bandwidth and greater complexity were perceived as more pleasant, as were birdsongs at a higher frequency or with a relatively low amplitude.

The songs that scored highest also avoided a key frequency range where human hearing is highly sensitive.

People who liked birds more tended to rate them more highly, but their level of bird knowledge had no effect on ratings.

Kalb said: "We might be wired to prefer more variable sounds with moderate amplitudes and frequencies because they signal a safe, healthy, and restorative environment where we can relax."

The scientists pointed out that factors they couldn't test, such as call rate — some birds call more frequently than others — might affect perceptions of pleasantness.

To follow up the research, they want to carry out larger studies with broader samples including more men, different cultures and more experienced birdwatchers.

Randler said: "I would love to investigate how bird sounds influence people in real-world environments."

He added: "I would also like to integrate ecological data, acoustic analyses, and psychological responses to understand how changes in biodiversity - like species loss - translate into changes in human experiences of nature.

"That would help us better understand the role that healthy ecosystems play in supporting both biodiversity and human well-being."

Top 20 most pleasant bird songs

1. Common blackbird (4.52 average pleasantness score)
2. Willow warbler (4.45)
3. Blackcap (4.43)
4. Mistle thrush (4.33)
5. Garden warbler (4.30)
6. Dunnock (4.30)
7. Chaffinch (4.29)
8. Common nightingale (4.26)
9. Common linnet (4.26)
10. European goldfinch (4.26)
11. European pied flycatcher (4.25)
12. Eurasian wren (4.24)
13. Skylark (4.23)
14. Eurasian golden oriole (4.17)
15. Common cuckoo (4.13)
16. Tree pipit (4.08)
17. Common redstart (4.08)
18. European greenfinch (4.08)
19. Eurasian treecreeper (4.05)
20. European robin (4.04)

Source: University of Tübingen