|The Barn Swallow Project||
Well, it was inevitable. It just hasn’t been possible to stay current on blog posts this field season, what with crazy work and travel schedules and lack of internet access. I’ll try to write belated posts for each of the sites we’ve visited, as each was interesting enough to merit it’s own treatment. In the meantime, though, here’s an update on where we are in the field season- and, most importantly, what’s going on with the barn swallows.
After Beijing, Caroline, Liu Yu, and I headed to Heilonjiang, China’s northernmost province and the final stop on our south-to-north barn swallow sampling transect. We visited Liu Yu’s hometown of Shuangyashan, in eastern Heilonjiang, and Qiqihar, closer to the Mongolian border in the west. The main goal of the north-south transect was to characterize variation within the Hirundo rustica gutturalis subspecies. Remember, there are three widespread subspecies of barn swallows in Eurasia: H. r. rustica in Europe and western Russia, H. r. tytleri in the Lake Baikal region of Russia and Mongolia, and H. r. gutturalis, in eastern Russia, China, Korea and Japan. Last year, we drove west-to-east through the breeding ranges of these three subspecies, with the primary goal of describing and sampling the contact areas (and possible hybrid zones) between the subspecies.
This year, our goals in China were twofold. First, we wanted to characterize variation within H. r. gutturalis in the rest of its breeding range. This subspecies is highly variable in both size and coloration, and historically has been divided into as many as four different subspecies. However, comprehensive sampling has never been undertaken, particularly in China. The main part of Liu Yu’s thesis project will thus be analyzing phenotypic variation in the samples we collected this summer. Already some interesting patterns have emerged: birds in the south are very pale in coloration, whereas those we collected north of Beijing are much darker, similar to the birds we caught around Vladivostok last summer. Liu Yu definitely has some interesting work ahead of him.
The second goal for our fieldwork in China was to determine where (if anywhere) H. r. gutturalis comes into contact with rustica or tytleri. For this goal, we needed to sample east-west rather than north-south. We visited sites in central China earlier in the trip (check out our posts from Xi’an and Yinchuan), but the birds there looked pretty similar to the ones in southern China. We needed to get further west if we wanted to find rustica or tytleri. We therefore flew from Heilonjiang to the oasis town of Dunhuang, located in the westernmost part of Gansu province and wedged between the Gobi Desert to the north and the Tibetan Plateau to the south. Here we hoped to find a mix of rustica and tytleri or rustica and gutturalis. However, we arrived to find only rustica, the European subspecies, with no evidence for hybrids. That the birds could survive in Dunhuang at all was amazing- the town was surrounded on all sides by miles of enormous sand dunes and rocky desert, but still dozens of swallows were foraging over the sand and nesting in temples and camel shelters and, most conveniently, the courtyard of our hostel.
After Dunhuang we had planned to head further west to Urumqi, but a terrorist attack 4 days before we were due to arrive forced us to change plans. Instead, we went straight south to the town of Golmud, perched nearly 10,000 feet up on the Tibetan Plateau and the farthest west towards Tibet that foreigners can go without special permits. I didn’t expect to find any swallows there, but we went anyway. Why? Well, sometimes the absence of birds can be just as informative as the presence of birds. As speciation biologists, we’re interested in the factors that facilitate or prevent gene flow among different populations. In many (if not most) cases, those factors are geographical: mountains, deserts, rivers and oceans can all effectively block migration between populations and allow groups to evolve in isolation, sheltered from the homogenizing effects of interbreeding. The Tibetan Plateau- the highest, and one of the most inhospitable, places on the planet- has the potential to be a pretty big barrier to gene flow, cutting off swallows in Europe from those in China. But swallows are resilient, and after seeing them surviving the sand dunes in Dunhuang, I wanted to know just how big a barrier Tibet might be for them.
So, we took a 7-hour bus across miles and miles of desolate wasteland and arrived in Golmud in the middle of a sandstorm. We scoured the town and found no signs of swallows, so we asked a taxi to take us to some nearby villages. He thought we were a little crazy- there’s not much around Golmud- but he drove us to the outskirts of town. There we found what looked like excellent swallow habitat: irrigated fields, sheep and cows, old buildings. But no swallows. I was relieved. The world made sense. Then we decided to check just one more street, and lo behold, there was a male barn swallow perched on a wire. We asked around, and people confirmed that although they were very rare, swallows did sometimes breed in the villages. We ultimately found 6 birds and managed to catch three of them- all rustica- that night. They were three of the dirtiest, grimiest, poorest-condition barn swallows I have ever seen, and two didn’t even have a nest, but one of the home owners confirmed that barn swallows had been breeding in her shed for 10 years. Even in Golmud, in what felt like the ends of the earth, barn swallows somehow managed to hang on.
After Golmud, we took an 11-hour train back east across the Tibetan Plateau to Xining. Xining was a big city at a lower elevation, so I was sure that if there were birds in Golmud, they would be in Xining. Additionally, Xining was in between Dunhuang and Xi’an, meaning that it was a good candidate location for a contact zone between the rustica from the west and either gutturalis or tytleri from the east. The morning after our long train ride, we set out to search for birds and found…nothing. No sign of any swallows in the Xining markets, the old neighborhoods, the new neighborhoods. Nothing. We moved the next day to Huangzhong, a village an hour outside of Xining that had green fields and livestock and old mud-walled houses, and still nothing. The next day we moved south again, to the town of Tongren, an even smaller, older village. Tongren was the most beautiful and idyllic place we’d seen in China- a lovely Tibetan town with monasteries and temples and picturesque old houses and emerald green fields and sparkling rivers and fluffy sheep. It looked like barn swallow paradise. It was certainly biologist paradise. We spent two days searching the region around Tongren and interrogating locals. No one could remember ever having seen a barn swallow there.
Frustrated, we gave up and headed to Lanzhou, a big city closer to Xi’an, and our last stop before heading back to Beijing and leaving China. After a morning of searching markets and old neighborhoods, we stumbled on a literal demolition zone: giant heaps of rubble and garbage, with a few old houses marooned like islands among the trash, surrounded by new high rises. This situation was clearly temporary, as the few remaining houses would soon be bulldozed for even more high rises. And there, in the old houses, amidst the garbage and filth, were 20 barn swallow nests. Typical.
After catching a bunch of birds in the dump in Lanzhou, we headed back to Beijing, where we had a day to pick up our bags and sort equipment before parting ways. Liu Yu was staying in China- he’ll be doing some work in Beijing before coming to Colorado in the September to work on data analysis. Caroline and I were headed to Japan for 10 more days of barn swallow catching before separating, with me going on to Mongolia and Caroline flying to South Africa to start her PhD research on African buffalo. We had one last celebratory dinner in Beijing, which Liu Yu insisted on paying for in accordance with Chinese tradition. That celebratory dinner was well earned- our field season in China was spectacularly successful. We caught nearly 300 birds, visited 17 different sites, and covered the majority of suitable swallow habitat in world’s 4th largest country. And as with any good research project, we were left with as many questions as we were answers: why are the birds so variable throughout China? Is there gene flow between the western rustica and the eastern gutturalis? How do birds survive on the Tibetan Plateau? Why aren’t there any birds in Xining? Some of these questions will be answered by our lab analyses in the coming months, and some will require more data collection. Regardless, despite nearly 8 weeks of intense fieldwork, our work on Chinese barn swallows is just beginning.
When Caroline and I got back to our crummy airport hotel after saying goodbye to Liu Yu, we looked up at the neon sign above the door. There was a swallow nest wedged in the characters, and just below the image of an airplane taking off along a rainbow, a male swallow was fast asleep. We took this to be a fitting farewell from China. It was time to move on to Japan.