Cuckoos' shameless egg-laying tactics revealed

A young great spotted cuckoo Cuckoos v magpies: The study reveals new insight into the "arms race" between brood parasite and host birds

Related Stories

Great spotted cuckoos lay their eggs while magpie mothers are still sitting on their nests, a study has shown.

Cuckoos are known for deceiving other birds into raising their young by depositing their eggs into host nests.

It had been thought female cuckoos waited until host birds left the nest before secretively laying their eggs.

But researchers were surprised when they recorded female cuckoos forcing magpies out of the way as they sat incubating their eggs.

The scientists, from Spain and Belgium wrote: "Great spotted cuckoo females entered the nest more frequently when the magpie female was incubating than when the nest was empty.

Nest wars

Common cuckoo

Watch cuckoos and pipits battle it out

See a cuckoo grow big in a warbler's nest

Listen to the distinctive call of spring

"This implies that great spotted cuckoo female behaviour is not secretive at all."

Details of their findings are published in the journal Ethology.

The scientists, who work at the Universidad de Granada, Spain, planted miniature cameras in 29 magpie (Pica pica) nests in the Hoya de Guadix plain.

They had expected to observe great spotted cuckoos (Clamator glandarius) using secretive behaviour around the nests, such as working in pairs to distract the magpies into leaving their clutches unattended.

Instead, they discovered female cuckoos endured attacks from incubating magpies and forced them out of their nests so they could speedily lay their own eggs in the clutch.

This egg-laying tactic appeared to work every time. And after the cuckoo had left, the magpie incubated the imposter egg along with its own.

Cheeky thieves


The birds that cannot resist a bit of bling

"In spite of the violent attacks by magpies, they never succeeded in preventing the cuckoo female from laying her egg," the researchers observed.

The video recordings could offer new insight into the "arms race" between "brood parasite" birds and "host" birds - where species adapt and counter-adapt to try to succeed over each other.

The researchers suggest the magpies may have evolved the defensive behaviour of remaining sitting on their nests in response to cuckoos' attempts to distract them.

"Cuckoos then are forced to adopt the only possible solution: to lay their eggs facing the risk of being attacked by the incubating magpie," they wrote in the study.

The distinctively-patterned great spotted cuckoo is found in southern and eastern Europe and northern, southern and eastern parts of Africa. Magpies, crows and starlings are the main "hosts" targeted by the birds.

Female great spotted cuckoos may lay up to 13 eggs in a single host's nest.

Join BBC Nature on Facebook and Twitter @BBCNature.

More on This Story

Related Stories

The BBC is not responsible for the content of external Internet sites

More from nature

  • Cardinal fish and ostracodFish filmed spitting 'fireworks'

    Film crew captures ostracods' spectacular defensive lightshow that makes predatory fish spit them out.

  • Arapaima'Locally extinct'

    A giant fish which used to dominate the Amazon river is now absent in many areas

  • DragonflyRapid reactions

    Dragonfly's super quick reactions recorded in slow motion by BBC film-makers

  • Wingless adult male of the midge Belgica antarcticaExtreme survivor

    Antarctic midge's small genome may be an adaptation to its extreme environment

  • Myotis midastactus specimen (previously identified as Myotis simus)Golden discovery

    A bat from Bolivia is described as a new species by scientists

  • Dinosaurs 'shrank' to become birds

    Huge meat-eating, land-living dinosaurs evolved into birds by constantly shrinking for over 50 million years, new research shows.

  • Would we starve without bees?

    Honey bees are under threat, and as pollination significantly contributes to the food we eat, what would we do without them?

  • Eggshells may act like 'sunblock'

    Birds' eggs show adaptations in pigment concentration and thickness to allow the right amount of sun for embryos, scientists say.

  • Female shrimps are more aggressive

    Female snapping shrimps are more aggressive than males when defending their territories despite their smaller claw size, a study shows.

BBC iWonder

  • Honey bee close-upInsect intelligence

    Are honey bees as smart as your sat nav?

  • Tyrannosaurus rex skull (c) Mark Williamson / Science Photo LibraryDinosaur dynasty

    One group of dinosaurs survived and their descendants can be seen all around us today

  • Brown rat cluse upRise of the rodent

    Reports of giant, 'super rats' are filling the headlines. But why are we being overrun by rats?

  • Cuckoo portraitHoliday hotspot

    What makes the UK such an attractive destination for visiting wildlife?

There have been 75 solar eclipses and 167 major volcanic eruptions in my lifetime

Nicole Malliotakis on Twitter comments on the events that have happened since she was born by using our personalised Your Life on Earth interactive infographic.

Get Inspired


More Nature Activities >

Copyright © 2015 BBC. The BBC is not responsible for the content of external sites. Read more.

This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.