|The Barn Swallow Project||
We reached Harbin, the last stop on our Chinese odyssey, about 10 days after arriving in Qinghuangdao. Our northern transect was substantially easier than our trip through the western desert, although still not without its challenges. In Shenyang we scoured the city for hours and hours but only turned up 15 nests. That would ordinarily be enough- we try to catch 20-30 birds per site, and 15 nests would give us 30 birds since both males and females sleep on or near the nest. Unfortunately, when we returned at night we were banned from two of the houses that had previously granted us permission, robbing us of 3 nests. The other nests we had identified were on the outside of buildings around a market, but it was so windy that netting was difficult and several birds escaped our nets. Two nights of work left us with 14 banded birds and no ideas for where to find more nests, plus rain in the forecast for the next day, so we cut our losses and headed north to Changchun.
If Gansu is China’s wild west- barren, dry, sparsely populated- then Qinghuangdao, the first stop on our northeastern sampling trip, is the foggy, crowded, cosmopolitan east. After 2 weeks of eating nothing but noodles and dumplings, dodging goats and chickens in demolished, garbage-filled lots, and finding barn swallows by going door-to-door in ramshackle old neighborhoods, the humid sea breezes, skyscrapers, and seafood of coastal Qinghuangdao were a welcome change. It certainly helped that within an hour of arriving we found a huge outdoor market with a surrounding neighborhood just teeming with barn swallows.
Once we found evidence of hybridization between rustica and gutturalis in Jiuquan, we needed to map the width of the hybrid zone. We set out on our zigzagging plan: after 3 nights of catching birds in Jiuquan, we hopped the high-speed train to Zhangye. Again, we found excellent stretches of old courtyard-style houses, and again, we found birds that looked like both rustica and gutturalis nesting close to each other. The birds in Zhangye were early in their breeding cycle- only a few had begun laying eggs, and most were still building their nests. Luckily they were sleeping on their nests, and we managed a big sample size over 3 nights of work.
Searching for a hybrid zone over a 600-mile stretch of desert could be like finding a needle in haystack. Luckily for us, there aren’t many towns along the Hexi corridor. It’s a barren strip of land, with only a handful of places big enough to have stops on the high-speed train line (yes, there are high speed trains even in the Chinese outback). Since there wouldn’t be any barn swallows in places with no people, we were able to narrow our search down to five towns: Yumen, Jiuquan, Gaotai, Zhangye, and Wuwei. These fell at roughly 100mile intervals on the train line between Dunhuang in the west (our pure rustica population) and Lanzhou (gutturalis) in the east. Once we identified our sampling options, the tricky bit was to figure out how to allocate our time: we wanted to maximize time catching potential hybrids and minimize time catching pure parentals, but we didn’t know how wide or where the hybrid zone was. I decided we’d have to do some zigzagging- we’d start in Jiuquan, about a third of the way from Dunhuang to Lanzhou. If we found both subspecies there, we’d sample for three days and move on to Zhangye. If we found only gutturalis, we’d sample a little bit and then backtrack to Yumen, and if only rustica, we’d sample a little and then keep moving eastward. We’d do the same thing in Zhangye, moving east to Wuwei or back west to Gaotai depending on which birds we found.
Gansu is the gateway to China’s wild west: a narrow province that skirts the northern edge of the Tibetan Plateau, connecting the cosmopolitan eastern cities of Lanzhou and Xi’an to the true outback of Xinjiang via the Yellow River valley. The thin strip of land along the river, sandwiched between the mountains of Tibet to the south and the Gobi Desert to the north, is called the Hexi Corridor (“the throat”). As one of the only consistent sources of water in an inhospitable region, the corridor was a critical stretch of the Northern Silk Road, functioning as a caravan route connecting eastern China to central Asia, Africa, and the Middle East for over 1500 years. We came to Gansu in a last-ditch effort to find a hybrid zone between the rustica and gutturalis subspecies. Finding evidence for hybridization between this pair of subspecies would help us understand the mechanisms of species divergence in barn swallows. But we had no idea whether such a hybrid zone actually existed
Well, I’m back in China. It feels like I just left China, but I guess it’s been almost a year since our epic trip last summer. In the intervening months we were busy analyzing data, and were particularly focused on variation in color and body size measurements from our 14 different Chinese barn swallow populations. Our intuitions from the field were soon confirmed with quantitative data (always a good feeling for a biologist): there are three distinct “phenotypic clusters” of swallows in China.
Our goal in Egypt was to catch 30 barn swallows. We finished with 36 birds, caught over 10 wild days in the villages around Damietta. Each and every bird had a story attached to its capture- the bucket incident, the bat incident, and, now, the prisoner incident.
After the night we accidentally caught the bats (plus 13 barn swallows), we only had 2 birds to go. However, we suspected some of our birds were juveniles, so we were hoping for 6 or so additional birds. Juveniles may not be fully-grown and have paler plumage than adults, so we didn’t want those birds skewing our data. I was feeling particularly awful- two days after extracting bats from the nets I had gotten sick, and spent 30 hours a little afraid I had rabies (I didn’t, just a bad cold). I may not have been dying, but I was still exhausted and felt miserable.
After the “bucket of barn swallows” day, we were feeling optimistic again about our swallow catching prospects in Egypt. The next afternoon we visited the village of Rekabia, the hometown of Badran, the nice man from the fish farm. Our daytime visit to scout nests in the village provoked stares; when we returned at night, the crowds of children were waiting for us. We caught a pair of birds in a chicken coop, and then moved on to a large garage/storage shed that was full of roosting swallows. In addition to Amanda, Basma, Mamdouh, Badran, and I, there were 4 or 5 other men in the shed, all trying to help by shining bright lights on the sleeping birds and crashing around pointing out other nests. Cell phones were ringing, and were answered with much shouting. No amount of asking them to shut off their flashlights and be quiet made any difference- there were two foreign girls climbing over heaps of equipment trying to catch birds, and people had to be notified.