Summarised from a paper by Willy Raitière and Patricia Audureau
On July 05, 2008, while we were surveying the town of Bouin in search of urban breeding birds, as part of the Atlas of Breeding Birds in Brittany, we found two active colonies of House Martins Delichon urbica. One of them had about 10 nests located under the roof of a house in the main street. When counting nests of this colony, we noticed that one of them had very dark primaries visible over the edge of the nest. On closer inspection, we concluded that it was a Common Swift brooding in a House Martin's nest, which was very cramped.
|The back of the Swift protrudes from the martin's nest (Boin - Vendee, July 2008). W. Raitière|
|White faces of 2 chicks are just visible|
Similar occurrences were recorded at Anton during the nineties (Deliry, pers comm); near Loches in the 1950s, and at and Brétigny-sur-Orge in the early 2000s (Voisin, pers comm); and in the 8th arrondissement of Paris in 2007 (Detalle, pers comm). Beyond our borders, similar cases have also been noted in Moira, County Antrim, Northern Ireland in 2007, Markgröningen, northwest of Stuttgart in Germany in 1987 (Wendt, 1988) and more recently in Mengeringhausen in Hesse in the center of Germany in 2007 and 2008 (Bergmann, 2008). Moreover, in the Handbuch der Vögel Mitteleuropas (1980), the authors note that in river valleys that do not have trees, Swifts have used the nests of both House Martins and, more rarely, Sand Martins Riparia riparia.
Raitière, W., & Audureau, P. 2010. Un couple de martinets noirs Apus apus nichant dans un nid d'hirondelle de fenêtre Delichon urbica. Ar Vran, 21(2): 19-20