Bad news for birdies

10 Day Old nestling barn swallows wait for mom and pop to bring food

Throughout the field season, the birds in our study have worked diligently to pair up, build nests one beak full of mud at a time, lay and incubate eggs, feed nestlings, and in their down time, feed themselves by hunting down hundreds of fast-moving aerial insects. You have to be impressed with the little guys. But often times, despite all this effort, eggs disappear in the night, nestlings are pushed out onto the ground, or the entire nest falls or gets knocked down by a careless site owner. In recent days we have lost around four entire broods of nestlings. A nest check one day--four hungry baby barn swallows; then, on Day 10 after hatching, when we are scheduled to go measure nestlings and take a small blood sample for paternity analysis--an empty nest. Or a destroyed nest. Or four crumpled, pitiful grey bodies on the ground. Nine out of ten times this is the work of "serçe", the global invasive species known elsewhere as the house sparrow (Passer domesticus). Everywhere I have recorded barn swallows (in Colorado, Israel, Romania, and here in Turkey), the songs have often been overlapped by the strident, monotonous calls of house sparrows. Like pigeons, house sparrows have colonized the globe, thriving in the urban habitats created by man. Unlike pigeons, though, house sparrows are very aggressive, and will often raid a swallow nest, nuzzle the nestlings out, and then "redecorate" the place with a mess of straw and lay a clutch of eggs.

At one of our sites in Karadyi, for example, a pair had built a nest in a tractor shed where several house sparrows were living under the roof tiles. As I sat in the garage one day, waiting for the male to revisit the nest and fly into our mist net, I watched a male house sparrow come in, fluff up his feathers and strut about, calling noisily. About that time, my target male came back, swooped at the sparrow, who ducked and flew away. Unfortunately, this particularly wily male also saw my net and flew out. We still haven't caught him, but during the following nest checks we saw the nest go from four chicks, to three, to one. Each time, a new nestling was found on the floor. What can you do? What should you do? As a biologist you shouldn't interfere--it's my job to observe and try to have as little affect on what I'm studying as possible. But then, we're already interfering--it is human constructions that barn swallows use for their nests. But humans are also responsible for creating a seemingly ideal and unlimited habitat for house sparrows all over the world...In any case, it just kills me when this stuff happens because the nestlings aren't eaten, they're just killed. And what's worse, the nest is often not even used by the offending sparrow. 

A mother and baby common pipistrelle (Pipistrellus pipistrellus)

But on a more positive note, when we were last trying to catch the male at the tractor shed site, we rolled down the garage door a little so our nets could cover the whole entrance and two mouse-looking things and a lot of droppings fell out onto the ground. On closer examination, there were actually six bats--two females, each with two suckling babies attached. They weren't hurt from the fall, fortunately, and were not aggressive when we picked them up to put them back. I don't really know bats, but my best guess is they are common pipistrelles (Pipistrellus pipistrellus). Anyway, it was a pretty cool encounter. I was really impressed that once put back on the wall, the females carried two pretty large babies (each attached to a teat) up the concrete face, back to whatever small entrance they used to access the garage door roll. It's sometimes scary to think about how much we've reshaped the earth's landscape in a very short time. But when you see three species like these somehow living together (not peacefully, but coexisting nevertheless) in a small, totally artificial space, it's kind of reassuring in a way.

A black-winged stilt (Himantopus himantopus) hunting in the shallows of the Koprulu River

Well, as for the rest of the project--we've caught all but one of the birds with active nests at our sites and we're wrapping things up to prepare for my departure in 12 days. Some of the birds will continue to raise a second or third brood after I'm gone, no doubt. Hakan, Ozgun, and Leyla will be in charge of collecting these final data and Hakan will bring any remaining samples with him when he comes to Boulder in October to help out with the analysis portion of the study. I'm happy to say things are finally quietening down around here and I've even had time to check out some other birds, like the stilt above. I have also started getting my 50GB of audio data in order to start analyzing songs. I'll be presenting a poster on geographic variation in barn swallow song at the end of this month at the Animal Behavior Conference in Virginia. More on that later. For now, I'm looking forward to watching the Ghana-Uruguay World Cup match in a couple hours! Both teams have been playing really well and it promises to be an exciting game. (And since Ghana eliminated the US, I'd like to see them go far, as it would make us look better.)

Well, görüşürüz.

Matt