Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Chickadees’ alarm calls carry information about size, threat of predators

24.06.2005


Black-capped chickadee


There’s more than meets the human ear when the black-capped chickadee lets its flock mates know a predator is lurking about by giving out its familiar "chick-a-dee-dee-dee" call.

The small songbirds, which are common throughout much of North America, use that signature call in a wide variety of social interactions including warning of predators. And it turns out that those alarms are far more subtle and information-packed than scientists previously imagined.

Writing in the current issue of the journal Science, researchers report that chickadees use one of the most sophisticated signaling systems discovered among animals. The calls warn other chickadees not only if a predator is moving rapidly, but also transmit information on the degree of threat posed by stationary predators of different sizes.



Chris Templeton, a biology doctoral student at the University of Washington and lead author of the study, said chickadees produce two very different alarm signals in response to predators. When they see flying raptors – birds of prey such as hawks, owls and falcons – they produce a soft, high-pitched "seet" call. But when they see a stationary or perched predator, the birds use a loud, wide spectrum chick-a-dee-dee-dee alarm to recruit other chickadees, as well as other bird species, to harass or mob the predator. Spectrographic analysis of more than 5,000 recorded chickadee mobbing alarm calls made under semi-natural conditions showed that the acoustic features of the calls varied with the size of the predator. And when the recordings were played back to the birds through speakers, their mobbing behavior was related to the size and threat presented by the potential predator.

Templeton said chickadees can alter their mobbing calls in a number of ways, most of which humans can not hear. Most typically they change the dee dee dee not at the end of the call, sometimes adding five, 10 or 15 dees.

"You would certainly might notice a change in the number of dee notes in their call if a neighbor’s cats was around harassing them. With something really dangerous, such as a pygmy-owl perched near some chickadees in our aviary, we heard as many as 23 added dees," he said.

The research was triggered when Templeton noticed the chickadees responding differently to a variety of predators inside an aviary. So the researchers set up an outdoor experiment in a semi-natural aviary with 15 different live perched or leashed predators.

Thirteen of these were raptors. Two were mammals, a domestic cat and a ferret, which resembles weasels that prey on small birds.

The birds of prey ranged in size from large owls, such as the great gray owl and great horned owl that usually feed on small mammals, to the small pygmy-owl and the American kestrel that hunt small mammals and birds. The smaller raptors represent a greater threat to the agile chickadees than the larger ones because they are more maneuverable in flight and can readily catch small birds.

"That’s why a pygmy-owl is more dangerous to a chickadee than a great horned owl that has a large hooked beak and big talons. A great horned owl going after a chickadee would be like a Hummer trying to outmaneuver and catch a Porsche, "Templeton said.

The chickadees also were exposed to a perched bobwhite quail, a non-predatory species, as a control animal, and did not react to it.

He noted that the chickadees are assessing risk on the basis of body size, but since they don’t react to the bobwhite quail, they also seem to be assessing individual species.

In the future, Templeton would like to examine the chickadee’s "seet" calls to see if they change in response to different raptors flying above them. If they do, this would be even more impressive since the birds would have such a brief glimpse as a predator flew by.

Joel Schwarz | EurekAlert!
Further information:
http://www.washington.edu

More articles from Life Sciences:

nachricht New photocatalyst speeds up the conversion of carbon dioxide into chemical resources
29.05.2017 | DGIST (Daegu Gyeongbuk Institute of Science and Technology)

nachricht Copper hydroxide nanoparticles provide protection against toxic oxygen radicals in cigarette smoke
29.05.2017 | Johannes Gutenberg-Universität Mainz

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Strathclyde-led research develops world's highest gain high-power laser amplifier

The world's highest gain high power laser amplifier - by many orders of magnitude - has been developed in research led at the University of Strathclyde.

The researchers demonstrated the feasibility of using plasma to amplify short laser pulses of picojoule-level energy up to 100 millijoules, which is a 'gain'...

Im Focus: Can the immune system be boosted against Staphylococcus aureus by delivery of messenger RNA?

Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.

Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....

Im Focus: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

New insights into the ancestors of all complex life

29.05.2017 | Earth Sciences

New photocatalyst speeds up the conversion of carbon dioxide into chemical resources

29.05.2017 | Life Sciences

NASA's SDO sees partial eclipse in space

29.05.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>