French word of the day: hirondelle = swallow
The Common house martin (Delichon urbicum) is one of the two most common swallow species in Europe, with the Barn swallow (Hirundo rustica). Originally, it nested in cliffs and caves, but it now largely occupies human structures, including house eaves in city centers. I visited a colony in Domène, near Grenoble. Occasionally, nesting platforms can be built so that swallows settle in some place, but this colony was 100% natural 🙂
The typical size for such a colony is around 10 nests, but this one was larger, maybe 60 nests. The cup-shaped nest is made of mud taken from lakes and rivers, and built at the junction of the wall and the roof, so that it’s attached to both planes. House martins only nest outside buildings, unlike the Barn swallow.
I have read that House sparrows (Passer domesticus) try to steal nests while they are still under construction. I saw some sparrows roaming near the colony in Domène, but the nests were already occupied so I don’t know if they really expected something. Once the construction is complete, the entrance to the nest is too small for the sparrows to enter.
I observed adults flying high overhead, catching flying insects likes flies and aphids. They came to the nests, hanging to it while feedings the chicks appearing through the entrance. Sometimes they go inside, and we can see their head from the outside.
There was also this youngling that had already left the nest, but was still fed by the adult, except it was hanging on the outside of the cup, in full sight. Sometimes I noticed feeders with white at the back of the head; I suspect it was younglings from the first-brood helping to feed the second-brood, as House martins usually breed two broods a year.
The colony was vibrant with life: younglings and adult were squeaking, feeders were bumping into each other when going to the nests, while swifts were hunting insects nearby, gliding between houses at high speed.
More pictures in my Wildlife gallery. Many pieces of information come from Wikipedia.