Cuckoos & Hoatzin: The Wonders Of The Cuculiformes

Cuckoos & Hoatzin: The Wonders Of The Cuculiformes

The Cuculiformes is a medium-sized order, comprising 143 species in 6 families and 30 genera.

Many of which are brood parasites and thus fit the classical image of a cuckoo.

Besides cuckoos, members of this family are known as Anis, Couas, Coucals, Malkohas and Roadrunners.

Family Name Genera species Distribution
Cuculidae Old World Cuckoos 17 79 Africa, Eurasia
Centropodidae Coucals 1 30 Africa, Australasia
Coccyzidae American Cuckoos 4 18 New World
Opisthocomidae Hoatzin 1 1 Central + South America
Crotophagidae Anis and Guira Cuckoo 2 4 Tropical New World
Neomorphidae Roadrunners, Ground-cuckoos 5 11 North America, Asia

Cuckoos are medium sized birds ranging in length from 16cm to 70cm (6.25 to 27.5 ins).

They are a diverse family, found in many habitats from open moorland through savannah and desert to tropical rainforest.

Three Guira Cuckoos Sitting on a Branch Cuckoos & Hoatzin
Three Guira Cuckoos Sitting on a Branch
Cuckoos & Hoatzin

Most Cuckoos are carnivores, with many feeding on hairy and distasteful (to other birds) caterpillars – though others feed on a variety of insects, lizards, small snakes and mammals. The exceptions to this rule is the Channel-billed Cuckoo (Scythrops novaehollandiae) and the Koel (Eudynamis scolopacea) which feeds mostly on fruits.

Many cuckoos are relatively dull coloured birds with various forms of mottling, i.e. stripes and spots. Some however, such as those in the genera Chrysococcyx and Cerococcyx, have bright colourful glossy plumage. The best example is the Emerald Cuckoo Chrysococcyx cupreus from Africa which is green and gold.

Many parasitic cuckoos are mimics of either the species they parasitise, or of hawks.

Thus C. canorus is a mimic of the Sparrow Hawk, Accipter nissus except for a rare brown form which is a mimic of the Kestrel Falco tinnunculus. While the Indian Hawk-cuckoos Cuculus varius and Cuculus sparveroides are mimics of the Shikra Sparrow Hawk (Accipter badius) and the Besra Sparrow Hawk (Accipter virgatus) respectively.

The Koel which is a parasite on the House Crow (Corvus splendens) and the Drongo Cuckoo (Surniculus lugubris) which parasitises the Black Drongo (Dicrurus macrocercus) are mimics of their hosts.

Those species which are hawk mimics usually parasitise smaller birds – and use their mimicry to scare host females away from their nests. Those species which mimic their hosts have hosts of a similar size to themselves and use their mimicry to allow them to get closer to their hosts without being mobbed.

Most Cuckoos have moderately sized, slightly down curved bills, medium to long wings and zygodactylous feet -meaning they have two toes (digits 1 and 4) pointing backwards and two toes (digits 2 and 2) pointing forwards.

Tree dwelling (i.e. arboreal) species tend to have rather short legs, while ground living (i.e cursorial) species such as the well know cartoon hero Geococcyx californianus, the Greater Road Runner have long legs.

Many Cuckoos, particularly the parasitic ones, are shy retiring birds not often seen.

There is great diversity of nesting habits within the Cuculiformes – perhaps greater than in any other order.

The cuculidae are the traditional Cuckoos, exemplified by in the European Cuckoo (Culculus canorus). C. canorus spends the cold European winter in Africa and migrates to Europe in the spring to breed – quite why I have no idea. Males set up vague territories which will overlap with one or more female territories.

C. canorus is an obligate brood parasite, meaning the females build no nest of their own and they can only reproduce by laying their eggs in the nest of other birds.

This is the meaning of ‘Cuckoo’.

The list of hosts for C. canorus includes Dunnocks, Robins, Reed Warblers, Various Pipits, Redstarts and Pied Wagtails.

The European Cuckoo has a wide distribution throughout Europe and east to India. Within this area over 125 different species of birds have been recorded as being used by it as hosts. Although nearly 100 species have been recorded as hosts for C. canorus in Europe, only 11 of these are regularly used.

C. canorus comes in a number of different races, each of which is distinguished by the species of bird it predominately uses as its host. Each race has evolved egg mimicry, so that the eggs it lays look like the eggs of its host.

This would only be possible if there was host fidelity within a breeding lineage – and Cuckoos normally parasitise nests of the same species as they were raised by.

It is possible to estimate the amount of time a particular host-cuckoo relationship has been evolving, by the degree of egg mimicry exhibited – obviously the more successful the mimicry the longer the relationship has been in operation!

In C. canorus – and other species which specialise in smaller species of birds – the egg is smaller than would be expected. Thus it is nearer the size of the host’s egg and therefore unlikely to be noticed by the host as different.

The eggs start developing while still inside the female bird, which gives them a head start and allows them to hatch before any of the host female’s natural eggs. The young cuckoo is then in a position to evict these young from the nest as they hatch, ensuring that it is the only one fed by the hard working parents.

Non-parasitic Cuckoos

The Malkohas are the subfamily Phaenicophinae.

There are about 28 of them and they are mostly New world species, living in tropical Central and South America – but some are found in South-east Asia and Africa.

Cuckoos & Hoatzin Perched on Tree Branch
Cuckoos & Hoatzin Perched on Tree Branch

Yellow-billed Cuckoo (Coccyzus americanus)

Two species, The Yellow-billed Cuckoo (Coccyzus americanus) and the Black-billed Cuckoo (C. erythropthalmus) are migratory.

Though many of them look similar to the traditional Cuckoo, their breeding habits are quite different. The nest is a flimsy platform of twigs and leaves. The 3 or 4 pale blue or green eggs are incubated by – and the young fed by – both partners.

The young leave the nest when only a week or so old, though they cannot fly for another two weeks. Interestingly, occasionally – especially in years of plentiful food – species of Coccyzus will lay eggs in the nests of other birds, as well as in their own.

This occurrence is not common, and the list of species used is small – about 12.

However it offers a fascinating insight into a possible course for the evolution of nest parasitism.

The Couas are a single genus of birds confined to Madagascar. They are all non-migratory. Three species are primarily arborea, while the other 6 or 7 are predominantly cursorial. They are mainly solitary only forming pairs in the breeding season.

Their nests are simple. Little is known about their lifestyles.


Ground Cuckoos are family Neomorphidae, include the celebrated non-parasitic Roadrunners of North and Central America. The family also includes three parasitic species, the Striped Cuckoo Tapera naeviaDromococcyx phasionellus and D. pavoninus.

The Greater Road Runner Geococcyx californianus, is the best known and most famous of the group.

They feed on insects, scorpions, lizards, snakes, and other birds. They build their nests in low trees, or clumps of cactus, and the male bird usually incubates the 2-7 whitish eggs. They lay twice in a year, once in April and again in late July.


The 30 species of Coucals are all contained within a single genus (Centropus).

Anatomically they are recognised because they have a straight hind claw, resulting in their sometimes being referred to as Lark-heeled Cuckoos.

They feed mainly on the ground on large insects and small vertebrates. Their nest is a large globular structure built near the ground, 2-4 white eggs are laid and both partners take part in the incubation of the eggs and the feeding of the young.

Coucals have a monotonous hooting call, which the natives of Africa interpreted as a prayer for rain – or as a prayer for sunshine, depending on which part of Africa you are in.

The Anis are from South America and represent a completely oppressive breeding system to the traditional cuckoo.

The birds live in a colony which has its own territory. Within this territory, a single large nest is built – within which the eggs are laid by several females. Either altogether – as a single large clutch as in the Smooth-billed Ani (Crotophaga ani), a promiscuous species – or in separate chambers such as the Greater Ani (Crotophaga major), a monogamous species.

All members of the colony help looking after both the eggs and the young.

In some species, such as the Groove-billed Ani Crotophaga sulcirostris there is a tendency for the dominant female to evict the eggs of other females to ensure that most of the clutch is hers.


Hoatzin is single unique species which lives in tropical rain forests of South America.

Looking somewhat like a pheasant, their affinities are unsure. They were considered to be part of the galliformes for some time, before more modern analyses moved them to the cuculiformes.

Among other unique characteristics, the young have surveyed two claws on the mid joint of their wings.

Common Cuckoo on Tree Branch
Common Cuckoo on Tree Branch

This makes them look superficially similar to the fossil archeopteryx. Thus this lead early researchers to hypothesise that the Hoatzin was a missing link – but later studies suggested these characteristics are recently evolved and not a relic from the past.

Hoatzin are largish birds, 64 cm (25 in) long, predominantly brown in colour with blue bare skin around the eyes and a prominent crest. They have strong and beaks and feet but are weak fliers – limited to distances of less than 30 m.

They are non-migratory and live in flocks, in the flooded forests of South America. They are herbivores possessed of a large crop, which allows them to store a large amount of vegetable material for later digestion.

Outside of the breeding season, Hoatzin can be found in medium sized flocks of about 40 individuals. During the breeding season – which corresponds with the onset of the rainy season – these flocks break up into smaller groups of 2-6 birds.

There is some doubt as to the nature of the mating system, though obviously groups of 2 are monogamous… at least for that season.

The nest is a loose collection of sticks into which the 2-5 buff coloured eggs are laid. Both sexes incubate the eggs and raise the young. Incubation starts with the laying of the 1st egg, meaning the nest his later occupied by young of different ages. Incubation takes 28 days.

Hoatzin young are quite agile from the day they hatch, and have the unusual defence of throwing themselves into the water below their nest and swimming away underwater.

When they surface they clamber back out into the vegetation using the 2 claws they have on the mid joint of their wings as well as their feet.

Once out of the water, they make their way back through the vegetation to the nest. It takes about 2 weeks of young Hoatzin to start feeding themselves.

Flesh of Hoatzins is not considered edible known locally as a ‘Stinking Hannah’ – however the eggs are eaten by local people.

Final Thoughts

Well, I hope you have learned a little about the world of the cuckoo and the hoatzin!

Gordon Ramel

Gordon is an ecologist with two degrees from Exeter University. He's also a teacher, a poet and the owner of 1,152 books. Oh - and he wrote this website.

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