Birds use social learning to enhance nest defense

June 4, 2009

Reed warblers live with the threat that a cuckoo bird will infiltrate their nest, remove one of their eggs, and replace it with the cuckoo's own. This 'parasitism' enables the cuckoo to have its young raised by unsuspecting reed warblers.

However, scientists at the University of Cambridge have discovered that reed warblers will attack or 'mob' cuckoos on their territory and so prevent the parasites from laying eggs in their nests. However, this behaviour can backfire because it may cause injury and expose warblers to .

New experiments show that inexperienced warblers can learn to defend themselves against cuckoos by observing the mobbing behaviour of other members of their species. This social learning was specific to cuckoos but not to harmless control birds, such as parrots, suggesting that the warblers are primed to learn defensive behaviour but only in response to true threats. These findings were reported today (05 June) in the journal Science.

Dr Justin Welbergen explained the significance of their research: "Our previous work showed that reed warblers distinguish cuckoos from other nest enemies and adjust their defences according to local parasitism risk. Our current work demonstrates that reed warblers can use social information to fine-tune their defences to the nature of the local threat."

It had previously been established that cuckoos (the parasites) and reed warblers (the hosts) are engaged in a co-evolutionary arms race - once one had evolved an advantage (such as the reed warblers' ability to eject the cuckoos' eggs), the other would evolve a counter tactic (as when the cuckoo evolved eggs similar to the warblers' eggs). However, although genetic adaptations were to be expected, it was a surprise to the scientists that social learning provided another mechanism by which the warbler rapidly increased their nest defence.

Dr Welbergen continued: "Studies of co-evolutionary arms races between brood parasites and hosts have emphasised genetic adaptations and counter adaptations; however, our field experiments show that transmission through social learning provides a mechanism by which hosts can adjust their nest defence and so respond rapidly to changes in parasitism."

More information: The paper, "Social Transmission of a Host Defense Against Cuckoo Parasitism", by Nicholas B. Davies* and Justin A. Welbergen* (*authors contributed equally to the work), will be published in the 05 June edition of the journal Science.

Source: University of Cambridge (news : web)

Explore further: Migrating birds detect latitude and longitude, but how remains a mystery

Related Stories

How birds spot the cuckoo in the nest

July 15, 2008

It's not always easy spotting the cuckoo in the nest. But if you don't, you pay a high price raising someone else's chick. How hosts distinguish impostor eggs from their own has long puzzled scientists.

Birds' strategic mobbing fends off parasitic invaders

January 29, 2009

Reed warblers use mobbing as a front line of nest defense against parasitic cuckoos, according to a new report published online on January 29th in Current Biology, a Cell Press publication. Cuckoos act as parasites by laying ...

Recommended for you

Genomes uncover life's early history

August 24, 2015

A University of Manchester scientist is part of a team which has carried out one of the biggest ever analyses of genomes on life of all forms.

Rare nautilus sighted for the first time in three decades

August 25, 2015

In early August, biologist Peter Ward returned from the South Pacific with news that he encountered an old friend, one he hadn't seen in over three decades. The University of Washington professor had seen what he considers ...

Why a mutant rice called Big Grain1 yields such big grains

August 24, 2015

(Phys.org)—Rice is one of the most important staple crops grown by humans—very possibly the most important in history. With 4.3 billion inhabitants, Asia is home to 60 percent of the world's population, so it's unsurprising ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.