Our luck turned again today – for the better! After spending much of the morning looking for banded birds and their nests, we located two more and by the end of the day, the tags were in our hands! So, we are now up to 3 tags from this region. While this might not seem like a lot, retrieving these tags is somewhat of a miracle. First, the tags have to actually stay on the bird….for 11 months. Then, the bird has to actually survive migration from this location and back to it. Next, we actually need to recapture this bird in our hands to carefully remove the tag to retrieve the data. This depends on both the bird itself as well as the owners of the house where the individual has built its nest. And finally, finally, the tags actually have to operate well over the time period in which they traveled with their host. So, it is really a lot to ask and you can imagine how happy we are to have these tags back in our hands!
You might wonder: is all of this effort worth it? Barn swallows are one of the most widely distributed vertebrate across planet earth. Their breeding distribution spans most of the northern hemisphere and they migrate to destinations south during the winter. There are at least six sub-species of barn swallow and their migratory behaviors are quite different among them. The populations we have studied in the Middle East (Israel and Egypt) do not migrate and instead winter locally and start breeding as early as June. Farther north in continental Eurasia and North America, populations fly huge distances to and from breeding grounds each year. Several subspecies of barn swallow meet up with one another in Asia and in some cases, the birds freely interbreed and in others, they remain quite separate. Other pieces of data we’ve collected hint at an important role of variation in migratory behavior of these populations. Thus, one hypothesis that we are testing with these tags is that the migratory routes of these birds differ where subspecies meet up. The tags we have attached are 1 gram in weight and can record the birds location on planet earth for up to 12 months. These are quite simple tags – they have on board a small battery, a light sensor which records the bird’s position relative to the sun (how we can infer where they are traveling), and a place to attach a small harness so the tag is securely placed over the bird’s center of gravity.
The live of a barn swallow closely follows the life of a human. These birds nearly exclusively build their nests on human structures throughout their huge breeding distribution: bridges, barns, under doorways, and so on. Our work thus affords us the opportunity to meet with people all over the world, many of whom hold the swallow in high regard. Indeed, swallows feature prominently in human art dating back to the pyramids and have been found in cave paintings, floor mosaics and weavings throughout the world and dating back to early human populations in Eurasia, North American and the Middle East.
Here in China, we have met some incredible people in the village of Sitancun where we are currently working. By going door to door, many people remember Sheela and are happy to show us their birds again (for some this is not the case). Some people have even toured us around all of the other barn swallow nests they know of in their village. For the past two days, we concentrated on the small village that is across the river from our lodge. There, several people have appointed themselves as our ambassadors and have walked us through several houses in the village to show us where the birds are. They really do keep track of these lovely animals as they are a sign of good luck! Nearly every courtyard or gate to every house has a pair of swallows. Many people invite us in to see their swallows and to have a drink. They are as curious about us as we are of them. I so admire their efficient lives – their homes are extremely clever and smart in many ways for both outside and indoor living. There are many energy efficient adaptations to be found here, particularly for heating water. This is a highly civilized and clever culture where three generations can often be found living together under one roof. We commonly encounter grandparents with their grandchildren walking through the streets or working together around the house. Here, family is first! Good food must also be quite high in terms of daily living: small trucks filled with the freshest produce you can imagine can be found driving through the streets announcing their wares. People typically buy only what they will cook for that one day: an amazing variety of fresh vegetables cooked with a small amount of meat. The food here is deliciously spicy and colorful. The variety of vegetables (mushrooms, greens, peppers) is astounding!