© Marcel Burkhardt
Arlettaz, R., J. Fournier & N. Zbinden (2000)
Nos Oiseaux 47: 19–27
A small population of Hoopoes inhabiting the plain of the Rhône (Valais, SW Switzerland), which has been monitored since the late seventies, was again checked in 1998. The number of breeding pairs recorded in 1998 (n = 12) equated a previous peak in 1982. However, Hoopoes did no longer occur on the foothill slope, where most pairs still used to breed in natural cavities about ten years ago. The recent installation of numerous nestboxes in the plain, where natural breeding holes are absent, has obviously attracted U. epops closer to its main food source, molecrickets Gryllotalpa gryllotalpa, a prey that inhabits solely the soft alluvial soils of the plain. In 1998, the reproductive success was greater than the overall success during the period 1979–1992 (5,7 versus 4,8 fledglings, respectively, per successful brood), presumably as a consequence of a larger clutch size (7,3 versus 6,4 eggs per brood). A better breeding success could be due to lower provisioning costs faced by parents that benefit from breeding closer to molecrickets: compared to the past situation, adults are indeed no longer constrained to transport molecrickets over long distances, from the plain up the slope, to the breeding sites on the foothills. Yet, favorable climatic conditions in 1998 could also have played some role. In the short-term, offering an unlimiting number of nestboxes in the plain seems to be the best strategy for the conservation of this local population.