The Cuckoo Family Cuculidae
The cuckoo family Cuculidae is the only family of the order Cuculiformes. The family is represented on all continents except Antarctica. Most species reside in tropical or subtropical environments. Those in temperate locations migrate to avoid cool or cold winters. In addition to cuckoos, the family Cuculidae also includes the roadrunners, koels, malkohas, couas, coucals and anis. The coucals and anis are sometimes separated as distinct families. The cuckoos are generally medium sized slender birds. The majority are of the cuculidae family are arboreal, with a sizeable minority that is terrestrial.
Cuckoos are medium sized birds that range in size from 15-63 cm. There is generally little sexual dimorphism in size, but where it exists, it can be either the male or the female that is larger, depending on the genera. There are two basic body forms, arboreal species which are slender and terrestrial species which are more heavy set and have stronger legs. Almost all species have long tails which are used for steering in terrestrial species and as a rudder during flight in the arboreal species.
Many species are brood parasites, laying their eggs in the nests of other species, but the majority of species raise their own young. The brood parasitic birds usually only parasitize a single host species or a small group of closely related host species. They tend to remove a host egg when they lay one of their own in a nest. This both prevents the host species from realizing their nest has been parasitized and reduces food competition for the parasitic nestling once it hatches. Some brood parasites will eliminate all their nest-mates shortly after hatching. If the host removes a parasitic egg or chick, the adult parasitic birds may retaliate by destroying the nest.
There has been an evolutionary arms race between the cuckoos that leave their eggs in other nests, and the hosts that get these unwanted presents. The cuckoos have evolved to be able to lay their eggs faster than most other species and the eggs need less incubation time before hatching. These eggs often resemble the host eggs to prevent detection of an invader egg. The drongo-cuckoos resemble their host. Some hosts have evolve to be social, so the colony can be on the lookout for an invader trying to deposit an egg. Others have more than one brood of chicks per year, so there will be replacements for any losses due to cuckoos.
Cuckoos feed on insects, small animals, seeds, and fruit. For many cuckoo species, caterpillars are their favorite food; even hairy caterpillars that are avoided by most other birds. Cuckoos can consume hairy caterpillars because of their ability to shed their abdominal lining and get rid of the hairs via a pellet. Another favorite food of many cuckoos are grasshoppers. We may find it repugnant that some cuckoos are brood parasitic and they or their offspring even kill the host’s chicks, but on the plus side cuckoos help prevent plagues of caterpillars and grasshoppers!
Almost all cuckoos are shy which can make them a challenge to observe and photograph. Consistent with this behavior, they are not colonial breeders. These traits may be have their roots in their brood parasitic behavior. Stealth is a good characteristic if you want to sneak an egg into a host’s nest. Cuckoo family members are zygodactyl: they have the 2 inner toes facing forward and 2 two outer toes facing to the rear.