Common cuckoo of two years. More than 100 host species have been recorded: meadow pipit, dunnock and Eurasian reed warbler are the most common hosts in northern Europe; garden warbler, meadow pipit, pied wagtail and European robin in central Europe; brambling and common redstart in Finland; and great reed warbler in Hungary. Female common cuckoos are divided into gentes – groups of females favouring a particular host species' nest and laying eggs that match those of that species in color and pattern. Evidence from mitochondrial DNA analyses suggest that each gene may have multiple independent origins due to parasitism of specific hosts
European Bird Census Council forces behind population changes and use common bird indicators as a proxy for environmental health, and thus inform policy. Monitoring data is published as the European Breeding Birds Atlas, the second of which (EBBA2) is currently in preparation. The data collected as part of the PECBMS and EBBA2 programmes is also distributed on the EBCC-run portal, EuroBirdPortal, as well as through the Global Biodiversity Information Facility (GBIF). The EBCC run a conference every three years, devoted to ornithological monitoring, conservation and research in Europe and abroad. The organisation also publishes the Journal of the European Bird Census Council, entitled "Bird