The University of Washington doctoral student has found the first example of an animal making sophisticated decisions about the danger posed by a predator from the information contained in the alarm calls of another species.
In a paper published this week in the on-line edition of the Proceedings of the National Academy of Sciences, Templeton reports that red-breasted nuthatches (Sitta Canadensis) eavesdrop on the alarm calls of the black-capped chickadee to glean information about predators in their environment. Two years ago, Templeton showed that the chickadees’ (Poecile atricapillus) familiar chick-a-dee-dee-dee alarm calls contained a surprising amount of information. Now, it turns out, the nuthatches can understand the warnings given by the chickadee.
"No one has ever seen this behavior before. There are a fair number of animals that respond to other animal’s alarm calls. But this is the first example of subtle information from a call being interpreted by another species," said Templeton. "Nuthatches can tell if a raptor poses a high or low danger from the chickadee’s alarm call."
His earlier work showed that the chickadees had two types of alarm calls to warn about predators. When they see flying raptors – birds of prey such as hawks, owls and falcons – they issue a soft, high-pitched "seet" call. However, when they see a stationary or perched predator, chickadees use a loud, wide-spectrum chick-a-dee-dee-dee alarm to recruit other birds to harass, or mob, the predator and chase it away.
Analysis of recorded chickadee mobbing calls indicated that the acoustic features of the calls varied with the size of the predator observed. Most typically chickadees change the dee-dee-dee note at the end of the calls, sometimes adding five, 10 or 15 dees. When the recordings were played back to other chickadees their response was related to the size and threat presented by the potential predator. Small, agile raptors such as the pygmy owl which can prey on small songbirds present a greater danger to the chickadees than does the great horned owl, a larger, less maneuverable raptor.
Chickadees and nuthatches are similar in size, occupy many of the same habitats, exist in mix-species flocks during the winter and are attacked by the same predators. To see if and how nuthatches responded to the chickadee alarm calls, Templeton placed a speaker at the base of trees in a forest where pairs of the nuthatches were present. He observed their behavior when he played chickadee calls warning about pygmy and great horned owls. All trials were conducted when no live chickadee were present so their behavior wouldn’t influence the nuthatches.
The nuthatches exhibited strong mobbing behavior – more of them responded, flew closer to the speaker and appeared to be more agitated by flicking their wings when they heard the small predator alarm than when they heard the large owl alarm.
"It turns out that these animals are pretty smart," said Templeton. "Knowing what kinds of predators are around could be a matter of life or death for them, so it pays for them to listen to the alarm calls of other species. That one animal has cracked the code and extracted the information from another species is pretty amazing."
He said this appears to be learned behavior because the mobbing calls of the two songbird species are very different.
"Mobbing seems to be a way of teaching birds which predators are dangerous. But we have no idea how nuthatches learn to interpret the chickadee calls."
Source: University of Washington
Related stories:
'Enlightened' Atoms Stage Nano-Riot Against Uniformity
(PhysOrg.com) -- When atoms in a crystal are struck by laser light, their electrons, excited by the light, typically begin moving back and forth together in a regular pattern, resembling nanoscale soldiers marching in a lockstep formation. But according to a new theory developed by Johns Hopkins researchers, under the right conditions these atoms will rebel against uniformity. Their electrons will begin moving apart and then joining together again repeatedly like lively swing partners on a dance floor.
Deaths uncounted in China's tainted milk scandal
(AP) -- Li Xiaokai died of kidney failure on the old wooden bed in the family farmhouse, just before dawn on a drizzly Sept. 10.
A single gene leads yeast cells to cooperate against threats
An ingenious social behavior that mobilizes yeast cells to cooperate in protecting each other from stress, antibiotics, and other dangers is driven by the activity of a single gene, scientists report this week in the journal
Cell. The cooperating cells use the same gene, dubbed FLO1, as a marker for detecting "cheaters," cells that try to profit from the group's protection without investing in the group's welfare.
Chumby puts a host of widgets at your fingertips
Never let it be said that I don't listen to readers. In April, after I favorably reviewed a wireless product that elegantly displayed baseball scores, Don wrote: "How could you recommend that, especially at the price of $200 for a unitasker? This isn't worth $20 for what it does. What a joke. Please check out Chumby for a slightly cheaper and much more functional alternative."
Migrating songbirds learn survival tips on the fly
Migrating songbirds take their survival cues from local winged residents when flying through unfamiliar territory, a new Queen's University-led study shows. It's a case of "When in Rome, do as the Romans do," says biologist Joseph Nocera, who conducted the research while working as an NSERC Postdoctoral Fellow at Queen's under the supervision of Biology professor Laurene Ratcliffe.
Meaningful monkey calls
Researchers have made what they say is the first experimental demonstration that a primate other than humans conveys meaning by combining distinct alarm calls in particular ways. The study appears in the March 11th issue of
Current Biology, a publication of Cell Press.
Lessons from evolution applied to national security and other threats
Could lessons learned from Mother Nature help airport security screening checkpoints better protect us from terror threats? The authors of a new book, Natural Security: A Darwinian Approach to a Dangerous World, believe they can -- if governments are willing to think outside the box and pay heed to some of nature’s most successful evolutionary strategies for species adaptation and survival.
Island monkeys do not recognize big cat calls
Monkeys living on an island without big cat predators do not show any particular alarm when recorded tiger growls are played to them, according to research by a UC Davis graduate student. The pig-tailed langurs do, however, flee in a hurry from the sound of human voices.
