About Cuculus canorus Linnaeus, 1758
Description: The common cuckoo (Cuculus canorus Linnaeus, 1758) measures 32–34 centimetres (12.6–13.4 inches, rounded to 13–13 in in the source) in total length from bill to tail. Its tail is 13–15 centimetres (5.1–5.9 in) long, and its wingspan ranges from 55–60 centimetres (22–24 in). It has short legs, a slender greyish body, and a long tail. In flight, it resembles a sparrowhawk and has steady regular wingbeats. During the breeding season, common cuckoos often perch on open perches with drooped wings and a raised tail. A rufous colour morph occurs occasionally in adult females, and more often in juveniles. This morph has been hypothesized to have evolved to deter male harassment or mobbing by host species. All adult males are slate-grey, with the grey throat extending far down the breast and ending at a sharp border with the bird's barred underparts. The iris, orbital ring, base of the bill, and feet are yellow. Grey adult females have a pinkish-buff or buff background on their barred neck sides. They sometimes have small rufous spots on the median and greater wing coverts, and on the outer webs of the secondary feathers. Adult females of the rufous morph have reddish-brown upperparts marked with dark grey or black bars. On these birds, the black upperpart bars are narrower than the rufous bars; this differs from rufous juvenile common cuckoos, which have broader black bars. Common cuckoos in their first autumn have variable plumage: some have strongly-barred chestnut-brown upperparts, while others are plain grey. Rufous-brown birds have heavily barred upperparts, with some feathers edged with creamy-white. All first-autumn birds have whitish edges to the upper wing-coverts and primaries. Their secondaries and greater coverts have chestnut bars or spots. In spring, birds hatched the previous year may still retain some barred secondaries and wing-coverts. The clearest identifying features of juvenile common cuckoos are a white nape patch and white feather fringes. Common cuckoos moult twice per year: a partial moult in summer and a complete moult in winter. Males weigh around 130 grams (4.6 oz), while females weigh around 110 grams (3.9 oz). The common cuckoo is very similar in appearance to the Oriental cuckoo, which on average has slightly shorter wings. This similarity applies even to the rufous morphs, which are also found in Oriental cuckoos. The presence of rufous morphs is likely an ancestral trait shared by both species. Distribution and habitat: The common cuckoo is primarily a bird of open country. It is a widespread summer migrant that breeds in Europe and Asia, and winters in Africa. Birds arrive in Europe in April and depart in September. The common cuckoo has been recorded as a vagrant in Barbados, the United States, Greenland, the Faroe Islands, Iceland, Indonesia, Palau, Seychelles, Taiwan, and China. Within the United Kingdom, the common cuckoo's distribution shifted northward between 1995 and 2015, with populations declining by 69% in England and increasing by 33% in Scotland. Food and feeding: The common cuckoo's diet is made up of insects, with hairy caterpillars (which are distasteful to many other bird species) being a preferred food. It will also occasionally eat eggs and chicks of other birds.
