February 25, 2009
Posted: 10:53 AM ET
Common ravens, contrary to what was thought, sometimes forage in gangs.
You may think of ravens as solitary creatures rapping at chamber doors, but new research shows that some of young ones form gangs when they look for meals, which consist of animal carcasses.
Gangs, in this context, mean groups of juvenile ravens that forage together and overwhelm the territorial adults defending the animal carcass, said researcher Sasha Dall of the University of Exeter in the United Kingdom, in an e-mail. In other words, the kids get together try to chase off the adults defending the food, which may influence their social standing among their peers.
This is the first time that flock foraging has been observed in common ravens, Dall said. In a typical raven roost, a bird attains dominance by finding a carcass alone.
"Since most birds will therefore have to suffer being bullied a lot, there is a strong advantage to doing things to avoid giving any one bird such finder advantages," Dall said. "Turns out foraging in gangs is one such tactic."
In fact, the birds' behavior can be explained by game theory, a branch of mathematics that looks at strategic interactions, Dall's research found. The ravens forage in gangs when searching for food alone is no more efficient than foraging with others, the model shows. It's unlikely that the birds are consciously making such calculations, however, and these responses are likely hard-wired, Dall said.
Any analogies to human behavior are limited, but the research does illustrate how food availability, environment, and other external factors can influence social advancement and the stability of groups, Dall said. Scientists believe human ancestors also faced problems of food scarcity, and one solution to surviving in particular environments is to pool the food-finding efforts. If the group solution works in particular circumstances, it's "nevermore" to individual foraging.
The research is published Wednesday in the journal PLoS One.
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