American crows: the ultimate angry birds?

crows remember the faces of people who have been threatened or injured, and the last memories for the entire life of the bird (probably). Crows scold dangerous people and bring family members and even strangers in the crowd. Ravens exposed naive crowds to learn to identify dangerous person, and to associate that person's face with danger and react accordingly.

recently published research shows that crows remember the faces of people who have been threatened or injured and probably the memories of the bird. Not only do crows scold dangerous people, but are members of the family - even strangers - in your mafia. The hostile behavior of ravens in flocks enables naive birds to learn indirectly from a dangerous person, and also learn to associate that person's face with danger and react accordingly.

During graduate school, I lived in a suburb of Seattle, where he announced the presence of a particular person and movement provided by a multitude of crows. Ravens upset, crying. In a perverse sort of way, almost seemed to enjoy the attention, making frequent references to the horror film by Alfred Hitchcock

Birds

, crows caw cried while swirling on or near power lines.

Although claimed completely confused as to why hordes of crows chosen as the target of their hostility, the reaction of the birds probably should not be a surprise to every human sense. This man, in a fit of fuel testosterone, was shot and killed a young cock a few years earlier.

However, the laboratory director is working on his graduate student days was well known by the campus of crows. She took a handful of dry cat food every morning and it dropped a little slowly along the path of the parking area to the laboratory. As expected, the flocks of crows followed too, but this time his behavior was totally different: they were more relaxed and enjoyable, even. They expected a sandwich.

John Marzluff is a wildlife biologist who is fascinated by crows. Dr. Marzluff is a professor at the School of Forest Resources in the mi

alma mater

, University of Washington (UW) in Seattle, where he studied crows with an eye toward understanding how they are intelligent and adaptable.

previously published research has shown that despite "all crows are equal" to us, crows recognize each individual, even after being separated for many months. A study by Dr. Marzluff suggests that crows recognize individual human faces, too [doi: 10.1016/j.anbehav.2009.12.022]. In this study, published recently, Dr. Marzluff continuing its investigation into the discovery of a crow that had a bad experience with a particular human being, remember - and crows have memories like elephants.

"Our study shows that the memory lasts at least five years and counting," said Dr. Marzluff. Although ravens high mortality rate among young people who reach adulthood can live very long.
• "individual crows are adults 15 to 40 years can live in freedom and is likely to remember important partnerships that have shaped much of their lives," Dr. Marzluff said.

Since adults are highly territorial crows his knowledge of man and other dangerous enemies should last as long as these birds have direct knowledge and stay in there a little - less than ravens at the About learning potential enemies by observing their neighbors. As a "social learning" is supposed to be restricted to humans and other social animals, although there is no good reason not to give the birds credit for those skills, too.

When some wild birds are captured, measured and band before the release, or direct observation of these activities with other crows has been identified as dangerous human orientation and reacts accordingly. Of course, this could be a problem if you happen to be a scientist who studies wild crows.

"I felt like we recognized," Dr. Marzluff said.

over the years, he realized that much more crows seem to know their human enemies that only the rare birds that direct experience, individual (being captured and the bands, or watching Besides being captured and bands). Dr. Marzluff also noted that the area occupied by ravens that knowledge increased over time, extending well beyond the immediate catchment areas and the birds were not seen with my own eyes the events of the capture of origin.

How

sings without any direct experience of human beings come to recognize their friends and enemies? He made particular individuals, who have experience with these people, to share this knowledge with other birds? These crows were really

communicate information

each other on human beings in particular? If so, how?

"Crows recruit and tolerate others of their species and different in a crowd formed around dangerous people," said Dr. Marzluff. "This social tolerance could allow naïve crows to learn about dangerous situations, places and people."

Dr. Marzluff and two colleagues, Heather Cornell, a graduate student in his laboratory, and Shannon Pecoraro, undergraduate student, designed and built an experiment to answer these questions. The purpose of this study was to provide a limited number of crows with a single negative experience which then associate with a particular face, and to document the subsequent conduct of the people close to the crows time and space.

over a period of five years, the researchers used Cat Chow and Cheetos to attract crows near a network of pitcher, and ravens took 7.15 in five different locations. Captured birds were marked with a unique combination of colored rings before their release. Captured birds were held for 10-30 minutes by investigators masked, while the crows around reacted to the threat situation by forming crowds screaming of birds flying over or perched nearby. Because of their experiences and observations of birds in the harvest areas subsequently identified the capture of the mask as "dangerous" and reacted with hostility to any holder (Figure 1):

know that the above figure is a bit complicated, but it is instructive once you understand the story it tells. First, the researchers classified each location along the route, or to be exposed (100 meters) to a crowd (big sign "more" with little black crows about it in the figure) or not.

To test the birds, the male and female volunteers of different ages, shapes and sizes and used randomly capture the dangerous mask, neutral mask (not used for capture) or no mask at all, then a -2 hour walk along a route that included 2 to 3.8 km from the capture site. For each of the 11 trials, researchers and observers - who were "blind" to experimental objectives - observe and document the responses of solitary crow that had not been captured (non-banded crows). These responses were classified as follows:

crows scolded (photo black crow in the figure)

crows do scold (photo White Crow in the figure)

crows were exposed to the crowds ("plus" sign in the image of cock in the figure)

crows are not exposed to the crowd (unsigned "plus" to the image of a rooster in the figure)

But how many crows scolded or beaten the person wearing the mask of catching dangerous, and how did you change the number over time? To answer these questions, the team conducted a series of tests rather than long-term study, the campus of the University of Washington (Figure 2):

The researchers found that in the first two weeks after capture, an average of 26 percent of crows found scolded the person wearing the mask of dangerous traps. However, during a period of five years after capture, the capture of a dangerous mask received a response to increasingly hostile birds in the region, suggesting that birds captured had warned the other (Figure 2
). Moreover, the number of crows react to the capture of a dangerous mask has increased steadily over time to include naive birds (Figure 2