Cuckoos in nests help carrion crows

This video says about itself:

Great Spotted Cuckoo (Clamator glandarius)

There were 5 birds together at Anarita Park, Cyprus, on 18th March 2015. Filmed with a Canon PowerShot SX50 HS hand held.

For information about the status and distribution of this species, see the following link.

From Wildlife Extra:

Carrion Crows in Spain thrive when they have a cuckoo in the nest

Carrion Crow chicks derive benefits from having to share their nest, researchers have found

A study in Spain has uncovered an interesting relationship between Carrion Crows and Great Spotted Cuckoos, reports Springer’s journal Behavioral Ecology and Sociobiology.

When the cuckoos lay up to three eggs in the nests of the larger crows, the chicks of both species are often raised together successfully, with the young crows ultimately growing bigger than the cuckoos.

So it’s not so bad for crow chicks as it can be for other species of birds who find their nests taken over by a cuckoo youngster.

When our Common Cuckoos utilise the nests of Reed Warblers, the growing cuckoo chick will push other eggs and chicks out of the nest.

When Great Spotted Cuckoos parasitise and take over Magpie nests, they do not evict the host’s young from the nest. They do, however, succeed in out-competing the magpie chicks for food, which often leads to the latter’s death.

Carrion Crow chicks, by contrast, sit back and wait for food to arrive while the cuckoo chick does all the begging, discovered Diana Bolopo of the University of Valladolid in Spain, who led a study into the pros and cons associated with this particular parasitic relationship.

Bolopo’s team filmed seven parasitised crow nests and six uninvaded ones in Northern Spain from the 2004 to the 2007 breeding seasons.

They observed how intensely the various chicks begged for food, and how adult Carrion Crows responded to these hunger cries when deciding which chick to feed first.

The sampled parasitised nests contained between one to five crow chicks, as well as one cuckoo chick.

The observations revealed that the cuckoo chicks raised alongside the crow chicks were not able to monopolise the food being brought to the nest.

It appears that crow caregivers prefer to feed crow nestlings rather than cuckoo nestlings.

The fact that cuckoo chicks begged more intensely than crow chicks balanced matters out so that the young ones of each species ultimately received an equal amount of food.

“Despite a higher begging intensity, Great Spotted Cuckoos do not out-compete bigger Carrion Crow nestlings,” says Bolopo.

She speculates that the cuckoo’s begging strategies are part of how it has evolved and adapted to a parasitic life in which it has to compete with either similar or larger-sized nest mates.

“It might actually be advantageous to crow chicks to share the nest with a cuckoo, because the crow chicks do not have to waste so much energy on begging intensely for food on their own.”