IDENTITY, PREVALENCE AND INTENSITY OF INFESTATION WITH WING FEATHER MITES ON BIRDS (PASSERIFORMES) FROM THE SETUBAL PENINSULA OF PORTUGAL

The results of a 4 year project investigating species of mites infesti ng wing primary feathers on 21 species of Passeriformes are reported. The majority of species were identified as belonging to the genus Proc tophyllodes Robin, 1877 with one new host record. In addition Pteronys soides obscurus Berlese 1884 was found on European swallows, also a ne w host record. A novel method to enable quantification of mite intensi ties without causing harm to the birds was devised and evaluated. This relied on visual inspection of wing primary feathers and assignment o f subjective infestation scores to individual feathers, the sum of the individual scores comprising the primary feather total mite infestati on score (PTMIS). Comparisons between species revealed that birds coul d be grouped into four categories depending on their infestation inten sity with mites. Swallows, sand martins and greenfinches showed the hi ghest prevalence and most intense infestations (mean PTMIS greater tha n or equal to 6.8). Blackbirds, blackcaps, serins, goldfinches, Cetti' s warblers,eat tits and house sparrows showed moderate levels of infes tation with prevalence in the range 60-90.9% but a mean PTMIS lower th an in the former group (1.6-5.8). The third group comprised Sardinian warblers, nightingales and short-toed tree creepers and was characteri zed by a prevalence of mites greater than or equal to 40% and a mean P TMIS of 0.6-1.4. The final group, representing wrens, chiffchaffs, fan -tailed warblers and waxbills were without detectable mites, the only exception being wrens on which mites were identified in only three bir ds of the 32 sampled. These results are interpreted in the light of pu blished information and possible explanations for the observations are discussed.