On Tuesday 27 September 2022, the Asian Infrastructure Investment Bank (AIIB) hosted a special seminar to publicise the results of the pilot Beijing Nocturnal Bird Migration Project.
Hosted by AIIB’s Vice President for Policy and Strategy, Sir Danny Alexander, and moderated by Tian Hua, the seminar included speakers from Peking University, the Beijing Municipal Government, Cornell Lab of Ornithology and embassies along the flyway, including Australia, New Zealand and Indonesia. It was a wonderful opportunity to raise awareness of the miracle of bird migration that happens over Beijing as its residents sleep at night.
Every spring and autumn millions of birds fly over China’s capital city between breeding grounds in Siberia, Mongolia and north China and non-breeding grounds in south China, S & SE Asia, Australasia and even, in the case of Beijing’s Swifts and Common Cuckoos, to Africa. Some of these birds migrate during the day – for example, the larger soaring birds, such as birds of prey, cranes, storks etc that rely on thermals to assist their flight. However, the majority of birds (around 80%) – especially the smaller species – migrate at night. This is because there are fewer predators active during the dark hours, the weather tends to be cooler and more stable and some birds navigate using the night sky.
Many of these birds vocalise as they migrate – to keep in touch with each other as they fly and, towards the end of the night, attempting to initiate responses from their own kind on the ground, which could indicate a safe place to stop for the day. Using a simple sound recorder, it’s possible to gain an insight into the volume and diversity of birds flying over at night.
In autumn 2021, Birding Beijing, in collaboration with AIIB and Peking University, began a pilot project to record bird sounds at night from the roof of the Asian Infrastructure Investment Bank. AIIB’s building is ideal – it’s 15 storeys high, not close to any major roads, free from aircraft noise and close to one of Beijing’s largest urban green spaces, the Olympic Forest Park. During the period 25 August to 2 November 2021 we programmed the recorder to record every night from sunset to sunrise, resulting in over 700 hours of recordings.
- 34,713 bird calls recorded
- Around 95% of calls identified to species or, in the case of buntings, flycatchers and thrushes, to family, with more than 60 species identified so far
- Most common calls were Olive-backed Pipit (12,411), Black-crowned Night Heron (5,358) and Eurasian Skylark (2,611).
- Five nights recorded over 2,000 calls (in order of volume`)
- 27/28 September (2,703 calls)
- 28/29 September (2,405 calls)
- 14/15 October (2,270 calls)
- 9/10 September (2,233 calls)
- 22/23 September (2,025 calls)
- The busiest hour-long file was 0502-0602 on 29 September with 1,012 calls
Rarities included possibly only Beijing’s 8th Grey-tailed Tattler Tringa brevipes 灰尾漂鹬 Huī wěi (piào) yù and at least two Little Curlew Numenius minutus 小杓鹬 Xiǎo biāo yù (not annually recorded in Beijing).
The graph below shows the volume of bird calls recorded by date.
More detail about the results, including the species recorded, volume per species and date ranges, as well as example calls, can be found here.
Liu Shuangqi from Peking University briefed how the project is now expanding to six recording locations across the city in spring 2022 covering areas with varying light pollution to gain a insight into whether artificial light affects the calling rate of migratory birds.
Assistant Professor Hua Fangyuan provided some important context about the loss of 3 billion birds in North America since 1970, something scientists can estimate with some confidence given the strong datasets in the continent (13 datasets were used for the North American study, some of which stretch back more than 50 years). Those data are lacking in East Asia – in particular for migratory land birds – but what we do know, for example about shorebirds, is that bird populations here are likely to be on a similar trend. Long-term, standardised, monitoring is key.
So, what do the results of Beijing’s pilot project tell us?
First, that there is a high volume and diversity of birds migrating over Beijing, confirming that it is on a major ‘flyway’ or expressway for birds.
Second, that most of these migratory birds are species that pass through several countries, reinforcing that migratory birds do not belong to any single country – they are shared natural heritage and, with that, comes a shared responsibility to protect them and the places they need.
And third, if Beijing is to fulfil its responsibility to the flyway – to facilitate safe passage, the city must manage urban spaces in a way that helps birds to cross the hostile urban environment. Given the diversity of species migrating over Beijing (the top three by volume are a woodland bird, a wetland bird and a grassland bird), that means providing a diversity of habitats including natural forest, wetland and grassland.
After interventions from Peking University’s Professor Lu Zhi, embassies from flyway countries, a video message from Dr. Andrew Farnsworth of the Cornell Lab of Ornithology, and a lively Q&A with AIIB staff and invited guests, the event was wrapped up by AIIB’s General Counsel, Alberto Ninio, and culminated in the signing of a ‘letter of intent’ between AIIB and the Beijing Municipal Government.
AIIB and the Beijing Municipal Government agreed to cooperate on the nocturnal migration project and biodiversity conservation more broadly, including a commitment to use the data about the diversity and volume of migratory birds flying over China’s capital to inform land management policies in Beijing. This would ensure they help the city fulfil its role in the flyway – to facilitate safe passage of these migratory birds that are shared by so many countries.
After having trawled through 700 hours of recordings, to see the energy and commitment of the participants at this special seminar made it all worthwhile!
I was struck by the openness and willingness of the Beijing Municipal Government to take into account the data from this project in their land management policies. This is a big deal when one considers that the Beijing Forest and Parks Bureau manages around 75% of the capital’s landmass.
Huge thanks to AIIB, in particular Sir Danny Alexander, Alberto Ninio, Erik Berglof, Tian Hua, Li Zeyu and Yan Bo for allowing use of their roof and for their incredible support since the beginning of the project. It has been a delight to work with friends and colleagues from Peking University, especially Assistant Professor Hua Fangyuan, Professor Lu Zhi, Liu Shuangqi, Zhang Shen, Ren Xiaotong and Yang Xiaotong. The team at the Beijing Forest and Parks Bureau are a joy to work with and wonderful advocates for biodiversity in Beijing. Dr. Andrew Farnsworth and Benjamin Van Doren from Cornell Lab of Ornithology have been a great source of inspiration and encouragement. Finally, a thank you to the many birders who have helped with identifications of some of the calls, including Jonas Buddemeier, Geoff Carey, David Darrell-Lambert, James Eaton, Paul Holt, James Lidster, Magnus Robb, Seán Ronayne and Joost Van Bruggen, to whom we owe a debt of gratitude.
More detail on the Beijing Nocturnal Migration Project, including results of the spring 2022 and the ongoing autumn 2022 projects, can be found here.
All photos here provided by AIIB.