[Incidence of Upupicola upupae in the crest of the hoopoe].

Hopoes belonging to waves of migrants through the Balearic Islands in August and September showed high rates of infestation by Upupicola upupae (77--85 p. c.). The parasite species was almost exclusively confined to the long and mobile feathers of the bird's crown. And at this time of the year the Mallophaga had put their egg cases on the crest feathers, too. A mean of 7 feather-lice was found at this localisation in 8 positive cases sampled. As some of the birds were moulting just these parts of their plumage, a relative high loss of the lice egg masses had to be expected. Evidently, in these cases, the lice didn't adaptively synchronise laying with the period during which moulting occurs. The wings of hopoes are conspiciously barred glossy-black and white. Here the relative dark coloured lice were sitting predominantly in a dark feather area. In these places they were much less visble than on a neighbouring white area. Thus the parasites hide themselves according to their colour.