I had a Plan for this field season. I made it last winter in front of my computer screen in Colorado, and I quite liked it. I used all the information I had available about the global distribution of barn swallows- range maps, museum specimens, word-of-mouth descriptions- and I came up with a way to collect samples from three subspecies and two hybrid zones across the biggest country in the world in a single summer. We would start in Moscow, collect samples from the first subspecies there, then take the train to Yekaterinburg, sample there, train to Novosibirsk, sample there, drive to Krasnoyarsk, sample there, find the first hybrid zone close to Krasnoyarsk, catch lots of birds in it, drive to Lake Baikal, sample the second subspecies there, drive east, find the second hybrid zone near Chita, catch lots of birds there, then get on a train, go to Vladivostok, and sample the third subspecies. I lined up collaborators in all of these places. I made a schedule- we would start May 15 and be done August 30. I was pretty proud of myself.
Everything went great at the beginning. We hit our target sample sizes, we stayed on schedule, and the birds looked just the way we expected. My plan took a bit of a hit when we got to Krasnoyarsk and Georgy translated a Russian paper published in 1981 for us- completely inaccessible in the US, it claimed the second hybrid zone was not near Chita, but rather 2000km to the east, near the city of Khabarovsk. Georgy was only supposed to take us as far as Chita, but he agreed to drive us the whole way to Vladivostok. The plan was back on schedule- we’d just sample the second hybrid zone after a much longer drive than anticipated. Awesome. We set out from Krasnoyarsk and found the first hybrid zone exactly where we thought it would be, and it was structured pretty much like we expected- a clear, 100km band where birds abruptly transitioned from large, white-feathered Hirundo rustica rustica to small, orange-feathered Hirundo rustica tytleri over the span of a few villages. We figured that finding the second hybrid zone, between the orange H.r. tytleri and far-eastern, white-feathered H.r. gutturalis, would be just as easy- all we had to do was find where the orange birds transitioned back to white birds. Well, now we’re in Chita, and all plans have gone to hell as we’ve found a lawless zone of barn swallow sympatry and hybridization extending at least 400km, and probably closer to 2000km.
Matt is also super excited to be at Lake Baikal Our troubles began 3 days and 250km ago, as we drove from Lake Baikal towards Chita. We were feeling pretty good after a few days of mini-vacation, during which we celebrated the 4th of July with a freezing-cold boat trip on Lake Baikal, complete with a walk along the trans-Baikal railroad, sightings of freshwater seals, and a lunch of smoked and salted lake Baikal fish, followed by dinner and billiards at the worlds least-friendly restaurant- which is saying something in Russia. After a literal and metaphorical charging of batteries (and backing up of data, and answering of email), we were ready to tackle the second leg of our road trip. We caught a bunch of tytleri at a huge barn in the beautiful Selenga delta, then charged east towards Chita to Georgy’s preferred soundtrack of Finnish death metal. Out the window, the endless flat birch forests of western Russia gave way to vistas of Baikal, then the Eastern Sayan mountains, and finally open, rolling steppe coated with purple and yellow flowers. Our plan was to stop 100km before Chita and catch a few more pure tytleri, then drive another 200km and start looking for the contact area with gutturalis.
But that's gutturalis! This is supposed to be a tytleri zone!
The villages in eastern Siberia are few and far between, and about 250 km before Chita I suggested we start looking for places to catch tytleri, and make extra sure there were no gutturalis around. We drove along, and finally saw some swallows flying high over a barn. We pulled into the village, found the barn owners, got permission to go inside- and promptly found two white gutturalis. We all stared at each other- shit. White birds were not supposed to be here! How far west did they go? Had we missed a bunch of them? “Shit, shit, shit,” I thought. We had already driven for 3 hours that day- did we need to backtrack? Did we have time to backtrack? But if gutturalis were here, how far east did tytleri go? Was the paper saying they were in Khabarovsk, 2200km away, wrong? Or was the zone of contact really that huge? Did we have the time and manpower to sample over 1000 miles of contact zone? How many samples would we have to collect over that kind of distance? I could see my beautiful plan crumbling away.
While we’ve been in Russia, we’ve spent a lot of time exchanging and explaining idioms and sayings with our local collaborators - it turns out that Russians love a good saying. I’ve thus discovered that the Russian analogue of the phrase “a bird in the hand is worth two in the bush” is “a tit in the hand is worth a crane in the sky.” Well, in science (and especially in field biology), we have a saying that comes up pretty frequently: if it were easy, someone would already have done it.
I thought about that while we stared at the white birds that were ruining my plan and my schedule. If we already knew where the different barn swallow contact zones were, Matt and I would be at our desks in Colorado instead of in an abandoned barn in Siberia. But we are here precisely because no one knows where the subspecies range limits are or what the contact zones look like, and that is because they are hard to find and hard to study. We’d found gutturalis somewhere unexpected- fine. All that meant was that it was time for a new plan. So we made one.
Net set-up at our best site ever I thought about that while we stared at the white birds that were ruining my plan and my schedule. If we already knew where the different barn swallow contact zones were, Matt and I would be at our desks in Colorado instead of in an abandoned barn in Siberia. But we are here precisely because no one knows where the subspecies range limits are or what the contact zones look like, and that is because they are hard to find and hard to study. We’d found gutturalis somewhere unexpected- fine. All that meant was that it was time for a new plan. So we made one.
First, we caught ten birds in a garage in that village, which turned out to be 3 gutturalis and 7 tytleri. Good- that meant we were still mostly in a tytleri zone. Then, over the next two days, we drove east for 400km and stopped in almost every village to look for birds and check the ratio of orange (tytleri) to white (gutturalis). It stayed around 50:50 the whole way. Ok- that meant that this hybrid zone was different from the rustica-tytleri one we’d already found, and it probably extends east-west all the way to Khabarovsk, consistent with the 1981 Russian paper Georgy read us in Krasnoyarsk. Cool. If we have 2000km of contact zone, we can probably catch lots of hybrid birds, which is great for our genomics analyses (all emails to our genomics collaborators asking about ideal sample sizes have basically been answered with “more is better.”) Then we found an excellent barn, filled with orange and white birds, and pulled off our most productive day ever- 42(!) birds between 8am and 3pm. Our team is a well-oiled machine at this point. Gangbusters.
The (drunk) peanut gallery while banding in the hybrid zone So now, 3 days after our plans began to collapse, we’ve recovered: we have some idea of how long the contact zone is (from around Chita to probably around Khabarovsk), and we’ve caught over 60 birds in this zone. Now we just need to get an idea of how wide the zone is-that is, how far it extends north-south. So tonight we’re driving south from Chita, towards the Chinese border. If we find pure white gutturalis quickly, it will mean this contact zone has a long east-west border but a narrow north-south one: basically, Russian tytleri share a long border with Chinese gutturalis, and some selective force likely keeps these two subspecies from collapsing into one indistinct swarm. If we don’t find pure gutturalis, and instead keep finding mixed groups of tytleri and gutturalis and, especially, intermediate-looking birds (which seem to be a peach color between white and orange), it means that the reproductive barriers between these two subspecies are not very strong, and they may be slowly collapsing into one big, peachy swarm. Either way, it’s pretty cool. After we spend a few days sampling to the south, we’ll get back on the eastern road and continue our drive to the Pacific, stopping along the way to catch birds and see if and when tytleri completely give way to gutturalis.
So there we have it- a new Plan. It might change when we get back from our excursion to the south, or if we find an end to tytleri in the east before we reach Khabarovsk. But it’s the best plan we can make with the currently available data, and it can easily be adapted if the available data change- you can’t really ask for more when doing research. Sure I lost some sleep getting here (in fact, a lot of this post was written by hand, in my tent, during a 2am insomniac attack). But that’s the thing about research- if we knew how everything worked already, we wouldn’t need to do it. And it would be a little boring if everything always worked exactly the way you thought it did. The interest and excitement and challenge of science is in finding a problem that no one knows the answer to, and then figuring out that answer. And there always is an answer- it may be really hard to find, and it may all look like chaos to begin with, but if you keep digging, and if you keep adapting your plans to the best available data, eventually that little bit of the world that you’re studying starts to make sense. So for three more weeks, we’ll be driving around the Siberian steppe, looking for order and reason in a currently chaotic jumble of orange and white birds. We’ll let you know how it goes.
-Liz
-Liz