A manuscript about the association between avian host condition and feather mite load was previously accepted for publication in Journal of Avian Biology. Although correlative, its scientific impact is guaranteed by being based on a large dataset involving 83 host species, >20,000 birds measured over 22 years and across 151 localities by a joint work of 20 researchers all over Europe. The take-home message of the work is that the nature of interaction between birds and feather mites is commensalistic which relies on the consistent minor and overall positive realtionship between mites on host condition (expressed as size-corrected weight). It is for future studies to unravel causation, i.e. whether mites exert weak positive effect on host condition or host condition determines how many mites can inhabit a host “island” (carrying capacity).