Note 46 — Chapter VI · THE ALPS IN SEPTEMBER.

They will often build their nests in holes in the timber of the houses. Anderegg tells me that this was the case in his own house two years ago. Nor is this the only instance of the habits of birds being affected by the nature of the house-architecture in these parts; for the House-martins, being unable (I suppose) to make their nests adhere securely against timber, or disliking the large projecting eaves, build in the Haslithal under ledges of rock, and are known there as the Rock-martin, as distinct from the Rock-swallow (Felsenschwalbe), which is the name there given to the Crag-martin. It is well-known that there are places even in England where this bird prefers rocks to houses.