Planet, Asia Pacific, Natural Capital & The Environment

Where did the birds go?: Q&A with river tern researcher Bosco Chan

Shreya Dasgupta | Jul 26, 2019


This article was originally published by Mongabay and is republished with permission.

  • The river tern, a bird species that nests on sandbars, seems to have gone missing in China. Once thought to be common in Yingjiang county, Yunnan province, its population there dropped to just five birds in 2018.
  • Researchers at the Kadoorie Farm and Botanic Garden (KFBG), a Hong Kong-based NGO, are trying to protect this tiny population of a handful of birds.
  • Mongabay spoke with Bosco Chan, head of KFBG’s Kadoorie Conservation China, about his team’s plans to save the incredibly rare species in China.

The case of the river tern is a curious one. The medium-sized gray bird with a forked tail, a black cap and a white belly is quite common along rivers in India, although populations there appear to be decreasing. But move east toward China and Southeast Asia, and the tern’s fate takes a darker turn. In Cambodia, for example, there are estimated to be fewer than 50 adult river terns (Sterna aurantia), while in Laos, the bird could well be extinct, researchers say. In Myanmar, Thailand and Vietnam, the bird is thought to be extremely rare.

River terns seem to have gone missing in China too. In 2014, bird-watchers reported seeing only 14 terns in Yingjiang county, Yunnan province, one of the last refuges of the bird in China. This number was down to only five birds in 2018.

Researchers at the Kadoorie Farm and Botanic Garden (KFBG), a Hong Kong-based NGO working on biodiversity conservation in Hong Kong and south China, are trying to protect this tiny population of a handful of birds. In March this year, they conducted China’s first ever focused survey on river terns, spotting seven birds and three nests in Yingjiang.

River terns have been known to nest along the Daying River in China’s Yunnan province. Image courtesy of KFBG.



Why are river terns disappearing from Southeast Asia? Researchers are unsure, but they speculate that disruptions at the bird’s nesting sites on sandbars could be to blame. Multiple hydropower dams along the Mekong and Irrawaddy rivers could be threatening these nesting sites through changes in water flow and flooding, for example. Human activity along riverbanks, including sand mining, could also be disturbing the birds and their nests, while illegal fishing may be threatening the species’ food source. Predation by dogs, crows and rats is also thought to have put the bird at peril.

China’s river terns are a mystery, Bosco Chan, head of KFBG’s Kadoorie Conservation China, told Mongabay. But his team wants to find out more about the birds, and then use the information to protect the species. Meanwhile, the researchers, along with local authorities, have negotiated with a hydropower company to keep the bird’s nesting sites from flooding. They have also enlisted the help of local community members to monitor the nests and protect them from human disturbance.

The species is currently listed as near threatened on the IUCN Red List, mostly thanks to India’s relatively large river tern population. But whether the river tern will make a comeback in China remains to be seen.

Mongabay spoke with Chan about his group’s plans to save the incredibly rare species in China.

Mongabay: Could you start by telling me a bit about your background?

Bosco Chan: I studied freshwater fish for my Ph.D. So I’ve always had this fascination for freshwater ecosystem. After I finished my Ph.D. in 2001, I joined Kadoorie Farm and Botanic Garden at the Kadoorie Conservation China where I’ve been working on biodiversity conservation projects in tropical China for some 19 years now.

Could you tell us about river terns in China? Where can one see them?

Bosco Chan in Cambodia. Image courtesy of KFBG.

The river tern is only found in two provinces. One is Yunnan, bordering Laos and Myanmar. The other is southern Tibet, I think close to Arunachal Pradesh in India.

In Yunnan, it used to be found in the Mekong — when it’s in China, we call it the Lancang — and also in the Daying River (also called Dayingjiang), a tributary of the Irrawaddy from China. There were breeding records in both rivers and the species was considered to be common there, according to the authoritative monograph The Avifauna of Yunnan China (1995).

But then the species just went unnoticed. Nobody ever looked at it closely, that is, until bird watching and bird photography became a very popular hobby in China. Then some photographers started to take note of the very small breeding population in Yingjiang county, along the Daying River. When they discovered the river terns in Yingjiang in 2014, the population was already down to 13 adult birds.

There’s been no record from the China section of Mekong for many years. In fact, even in Laos, where the river exits China, it is almost extinct. There has been no record of the bird for many years.

What conservation status does the river tern have in China?

The river tern is a Class II species under the state key protection list.

What does being a Class II species mean for the river tern in China in theory and in practice?

In theory, you need permission from the authority to hunt it, but China hasn’t issued any hunting permit for at least a decade. In practice, the listing means that conservationists or the relevant government authorities can show people how important the river tern’s habitat is because the species is considered to be rare in the country. For example, when we need to do some negotiations with government departments, one of the very first things we say is that this is a Class II nationally protected species.

River terns nest on sandbars along rivers. Image courtesy of KFBG.

What prompted the river tern project now?

When we started reading about the species, I realized it’s in serious decline globally. Along the whole Mekong drainage, there are estimated to be less than 100 birds and it’s the same case for the Irrawaddy. So it was a shock to me. I thought the bird was in trouble only in China because of pollution or overfishing or other disturbances. I couldn’t believe it was so rare, even in the mighty Mekong and Irrawaddy. Only in the Indian subcontinent, this species seems to be doing OK. But as soon as you step into the Irrawaddy and Mekong regions, the situation is very bad.

I contacted some ornithologists and conservationists and started asking them if they think it’s even worth doing some serious conservation efforts for such a small population of river terns in China. And, you know, all my friends came back very strongly and said that every birds counts, especially in this part of the world, and they all encouraged me to do something about it.

So, in last August, I got in touch with the local authority responsible for conservation in the Yingjiang region. I briefed him about the global, regional and local situation of the birds. And then I suggested we do a survey because there has never been any kind of focused survey for the species. We think there are a dozen or so birds because all the birders go to one particular spot and that’s what they regularly see. But that doesn’t mean there are no other birds elsewhere that birders don’t go to. So I suggested we do a widespread survey along the whole Yingjiang drainage.

The Oriental Bird Club (OBC), which is concerned with the conservation of oriental birds or Asian birds, has a small conservation funding opportunity. Luckily, we got a small grant from the OBC conservation fund, which partially funded our surveys during this breeding season in China, which is in March. We started our first survey on March 11, then we conducted a second survey in late March, just to make sure we had covered all the potential sites in those areas. Within the Yingjiang drainage, there are two major tributaries that eventually join the Irrawaddy. One is a birding hotspot, so we knew already there are birds there. But nobody really goes and does any kind of systematic survey along the other, so we did that.

What did you find?

During our interview survey, everybody told us that the bird used to be very common and that it just suddenly disappeared in the last 10 or so years. But we saw seven birds, and we were also lucky to find three nests amongst the seven birds — the birds nest on sandbars, which are basically very flat sand islands along the river. We then worked with the local authority, the local forestry department, to do daily monitoring of the birds. We also organized a small task force and fenced off one of the nests. The other two nests were on the sandbar of a small island in the middle of the river, so we felt that disturbance threats were not so high for the other two nests.

One nest was enclosed off to reduce disturbance. Image courtesy of KFBG.

What kind of threats did you did you see during your survey?

Electric fishing. Even though it is supposed to be a no-fishing season, people are illegally fishing along that section of the river. Then buffaloes. People graze the buffalo along the river. The buffaloes can wade or even swim across to the islands for fresh grass [and trample on the nests]. Also, dogs. Because the nests are quite close to villages, the nests are under threat from dogs.

Overall, there are villages dotted along the whole river. And both sides of the rivers are mostly farmlands and some small fish ponds. So the birds nest with this human landscape.

There’s actually a wetland park downstream of where the river terns nest, which has very low human disturbance and apparently quite a nice habitat, but the birds don’t use that. Instead, they nest amongst village landscape.

I read that you’ve been negotiating with a hydropower company to protect the nests. Could you talk about that?

Yes, that is very exciting. Upstream, there are quite a few hydropower companies. One of them put a notice to downstream villages, telling them that they are going to do dam maintenance, and they’re going to discharge all the water in a few days. But that would’ve definitely destroyed the three nests, and the entire breeding population of China’s river terns. Thankfully, the government there is pro-conservation because they see nature-based tourism, especially bird-watching, as a major source of revenue. So together with the local partners and the Dehong forestry department, we went and negotiated with the dam company. And surprisingly, they were quite cooperative. We agreed upon a safe discharge of volume to make sure the water doesn’t flood the nests on the islands.

They complied, and happily, we will say that we got six chicks out of the three nests. The chicks grew into immatures, and then they flew off with their parents. Basically, two chicks per nest survived and fledged. After just one year of very focused efforts of conservation work, we almost doubled the China population from seven to now 13 birds.

Where did the birds go?

We don’t know. When I asked some of the experts, they don’t think the river terns of our regions along the Mekong and the Irrawaddy are migratory, but funnily enough, the river terns of Yingjiang disappear every year. The earliest bird comes in around December, and then disappears around June to July. Now, there are no river terns in the region.

Juvenile river terns eventually flew off with the parents. Image courtesy of KFBG.

Are there other conservation measures you put in place?

From upstream to downstream, there were three nests, which I would say were maybe 10 kilometers [6 miles] apart. We found one villager from the closest village of that particular nest and we sponsored them to become nest protectors. One villager, one nest. They monitored the nest and the chicks for the whole breeding season, until they flew off.

Because we knew nothing about the breeding ecology of river terns in China, we designed some simple forms and asked them to collect some basic ecological information for the species.

People also mine the sand along the river for construction sometimes. Some of the sandbars are pretty big, like the size of a stadium, and they build a makeshift bridge to connect the mainland to the islands. We asked the village heads to help us cut off this access to reduce disturbance to the nests.

What has been the biggest challenge so far?

In terms of preserving the birds, I think it’s been excellent this year. But we really need to find out where they go and what is limiting their population. How come their numbers dropped so dramatically? There appear to be several questions, especially along the Mekong and Irrawaddy.

When you look at the size of these two rivers, people will say the decline is because of overfishing, but when we observed the birds, whenever they hunt, they get a fish. So I don’t think food source is the limiting factor to this population. So what is killing all the birds? That’s something we need to find out. Are they migrating to an area where they are under immense threats and they never come back? We don’t know.

So if possible, we plan to do some kind of GPS radio tracking next year. As soon as the birds disappeared this year, the three nest protectors informed us, ‘Oh, today, we don’t see the birds anymore.’ We were hoping the birds go down the river into Myanmar and we asked some people to check downstream, but they didn’t see any bird. So basically nobody knows where they fly off to.

So you plan to radio track some birds next year?

We need to explore that possibility. But since it’s a protected species, we have to get all the necessary permissions.

Do you have any other future plans to protect the bird?

Well, I think the first thing is to find out where they go over the winter and then try to expand our conservation network to make sure they are not hunted, or that they get as little disturbances as they can as they migrate back to breeding sites. That’s our plan next year.

Also, at the moment, they are breeding at a section of the river, which is just upstream of a wetland park, which is quite extensive and over 20 kilometers [12 miles] long along the river. Maybe we can discuss with the local government to see if they want to expand the wetland park and include the known breeding sites into the wetland park, because a wetland park is better protected.

Chan’s team has sponsored three “nest protectors” from the local villages. Image courtesy of KFBG.


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